isdyl
Feb 29 2020, 06:15 AM
Hi all - so I've refitted d-jet on my 1.7 which had a single weber when I bought it. It's almost running but I've run out of ideas as to what to adjust or check. I've recorded a video of it starting. You'll hear that it starts quite lumpily and wants to stall. I manage to get the revs up by feathering the throttle and they go up to 2.5 or 3000 revs on their own for a second, and then it all dies again. I can keep it running by feathering the throttle again.
https://www.youtube.com/watch?v=Y06kdQC2IZgFuel pressure when running is 2 BAR. Theres no cold start valve connected. All injectors are 'squirting' as I took them out and checked in a jam jar. I've tried adjusting timing, mixture screw, air screw. I haven't checked the valve clearances yet but have had the distributor in 100 different settings with no improvement. I just wondered if anyone has any ideas please?
Thanks, Dylan
BeatNavy
Feb 29 2020, 06:29 AM
You haven't run out of ideas - you haven't adjusted the valves yet
1. Adjust valves
2. Set dwell (45 to 50 degrees) and THEN set timing right where it should be 27 BTDC
Must do dwell before timing, as dwell adjustments will throw dwell off. With those variables out of the way, you can see if there's any improvement or if you need to get into testing / adjusting specific D-Jet components and vacuum setup.
isdyl
Feb 29 2020, 06:41 AM
Ok thanks - I was hoping to avoid climbing under the car but I can see I'm going to have to. At the moment it won't idle or hold steady revs to set the timing. Would the valve clearances make that much difference please?
Dylan
QUOTE(BeatNavy @ Feb 29 2020, 06:29 AM)
You haven't run out of ideas - you haven't adjusted the valves yet
1. Adjust valves
2. Set dwell (45 to 50 degrees) and THEN set timing right where it should be 27 BTDC
Must do dwell before timing, as dwell adjustments will throw dwell off. With those variables out of the way, you can see if there's any improvement or if you need to get into testing / adjusting specific D-Jet components and vacuum setup.
BeatNavy
Feb 29 2020, 06:45 AM
I will add that if you've had the distributor in 100 different settings you are probably struggling to even know which direction to go at this point. I've been there, and it's usually caused by timing mark confusion or even a distributor gear being aligned differently than stock. I'd put the engine at TDC. Verify where the timing mark is on the fan (and verify that you know which mark is 27 BTDC). See if the rotor is generally pointing toward plug 1. Understand which way the fan rotates with engine running and which way you need to turn the distributor to advance (CCW to advance, CW to retard).
You need to get it within the right "ballpark" so you can make fine adjustments.
BeatNavy
Feb 29 2020, 06:52 AM
QUOTE(isdyl @ Feb 29 2020, 07:41 AM)
Ok thanks - I was hoping to avoid climbing under the car but I can see I'm going to have to. At the moment it won't idle or hold steady revs to set the timing. Would the valve clearances make that much difference please?
If the valves are significantly out of adjustment yes. You're going to need to verify / adjust them at some point anyway (unless you know they were set correctly before).
Goal at this point is to get everything close enough that it will run / idle enough for you to make fine adjustments. It may help to have another person available. It takes practice to do the timing by yourself, but it's certainly possible. One hand on throttle body one hand on light, leaning over timing hole, one eye on mark, one eye on tach...etc.
isdyl
Feb 29 2020, 06:54 AM
Yes I'm not sure where it is set now! I initially set it statically to TDC (the white mark I think) and it started in a similar fashion to the video. I then moved it in about 1 degree increments about 30 times in both directions, each time starting it to see if it would improve the running. This is why I assumed it wasn't a timing issue as I'd tried it in every position possible! I'll check the valve clearances. It's something I'll need to do as some point anyway.
Dylan
QUOTE(BeatNavy @ Feb 29 2020, 06:45 AM)
I will add that if you've had the distributor in 100 different settings you are probably struggling to even know which direction to go at this point. I've been there, and it's usually caused by timing mark confusion or even a distributor gear being aligned differently than stock. I'd put the engine at TDC. Verify where the timing mark is on the fan (and verify that you know which mark is 27 BTDC). See if the rotor is generally pointing toward plug 1. Understand which way the fan rotates with engine running and which way you need to turn the distributor to advance (CCW to advance, CW to retard).
You need to get it within the right "ballpark" so you can make fine adjustments.
BeatNavy
Feb 29 2020, 06:57 AM
Don't forget that dwell though (assuming you have a conventional dizzy with points)! If that's not in spec that'll cause a host of issues too.
Good luck, Dylan!
QUOTE(isdyl @ Feb 29 2020, 07:54 AM)
Yes I'm not sure where it is set now! I initially set it statically to TDC (the white mark I think) and it started in a similar fashion to the video. I then moved it in about 1 degree increments about 30 times in both directions, each time starting it to see if it would improve the running. This is why I assumed it wasn't a timing issue as I'd tried it in every position possible! I'll check the valve clearances. It's something I'll need to do as some point anyway.
Dylan
QUOTE(BeatNavy @ Feb 29 2020, 06:45 AM)
I will add that if you've had the distributor in 100 different settings you are probably struggling to even know which direction to go at this point. I've been there, and it's usually caused by timing mark confusion or even a distributor gear being aligned differently than stock. I'd put the engine at TDC. Verify where the timing mark is on the fan (and verify that you know which mark is 27 BTDC). See if the rotor is generally pointing toward plug 1. Understand which way the fan rotates with engine running and which way you need to turn the distributor to advance (CCW to advance, CW to retard).
You need to get it within the right "ballpark" so you can make fine adjustments.
TheCabinetmaker
Feb 29 2020, 06:02 PM
Have you checked vacuum on the mps? How about the throttle position switch? Condenser on the distributor? Have you actually checked or set dwell? Have you ohmed the head temp sensor?
Bleyseng
Feb 29 2020, 07:48 PM
QUOTE(TheCabinetmaker @ Feb 29 2020, 04:02 PM)
Have you checked vacuum on the mps? How about the throttle position switch? Condenser on the distributor? Have you actually checked or set dwell? Have you ohmed the head temp sensor?
What he said....
Also is the advance working on the distributor? 45 grease on the weights inside can freeze em and so no advance.
Spoke
Mar 1 2020, 12:08 AM
It would help to have an AFR sensor to tune your FI. Good running FI is all about proper fuel mixture and without AFR info it is very difficult to tune FI. You may want to consider installing an oxygen sensor and gauge or logger to get it tuned well.
isdyl
Mar 1 2020, 02:07 AM
Hi - Thanks for your replies. I have checked the head temp sensor and the air sensor. The MPS holds vacuum, I haven't actually checked the vacuum advance on the distributer so will look at that. I don't have a dwell meter so have the points set to 0.4mm gap. How do I check the condenser please? I haven't done anything with the throttle position switch either - is that something that should be adjusted somehow please?
Many thanks, Dylan
euro911
Mar 1 2020, 02:45 AM
on the valve adjustment taking priority. My '71 (with a 1.7L at the time) would hunt for an idle when I bought it. I checked all the FI components, replaced all the vacuum and fuel lines, checked/adjusted the dwell & timing, all to no avail. After performing a valve adjustment, the idle hunting went away. One cylinder had the valves adjusted too tight.
The TPS board's traces can get worn down and cause dropouts. You
may get by trying to clean the traces and repositioning the 'fingers' to a better looking portion on the trace(s).
If the traces are real bad, 914 Rubber sells new reproduction TPS boards.
isdyl
Mar 1 2020, 03:09 AM
Thanks - I'd better get under that car....
QUOTE(euro911 @ Mar 1 2020, 02:45 AM)
on the valve adjustment taking priority. My '71 (with a 1.7L at the time) would hunt for an idle when I bought it. I checked all the FI components, replaced all the vacuum and fuel lines, checked/adjusted the dwell & timing, all to no avail. After performing a valve adjustment, the idle hunting went away. One cylinder had the valves adjusted too tight.
The TPS board's traces can get worn down and cause dropouts. You
may get by trying to clean the traces and repositioning the 'fingers' to a better looking portion on the trace(s).
If the traces are real bad, 914 Rubber sells new reproduction TPS boards.
isdyl
Mar 1 2020, 06:56 AM
Follow up - TPS is all working correctly.
QUOTE(isdyl @ Mar 1 2020, 02:07 AM)
Hi - Thanks for your replies. I have checked the head temp sensor and the air sensor. The MPS holds vacuum, I haven't actually checked the vacuum advance on the distributer so will look at that. I don't have a dwell meter so have the points set to 0.4mm gap. How do I check the condenser please? I haven't done anything with the throttle position switch either - is that something that should be adjusted somehow please?
Many thanks, Dylan
BeatNavy
Mar 1 2020, 06:59 AM
These are legit suggestions, but IMO you do have to prioritize the fundamentals such as valves and dwell/timing (which can be difficult if it won't stay running of course). If it won't stay running after that then it is definitely time to test / troubleshoot the D-Jet components that have the biggest impact on mixture (e.g., MPS and CHT). After you get it to the point that it will stay running, then you can focus things that impact drivability and reliability more (e.g., TPS, AAR, CSV, decal valve, etc.). As Spoke says the AFR is good for troubleshooting that at some point if you don't already have one.
isdyl
Mar 1 2020, 10:33 AM
Great - thanks. I'll get on to it. D
QUOTE(BeatNavy @ Mar 1 2020, 06:59 AM)
These are legit suggestions, but IMO you do have to prioritize the fundamentals such as valves and dwell/timing (which can be difficult if it won't stay running of course). If it won't stay running after that then it is definitely time to test / troubleshoot the D-Jet components that have the biggest impact on mixture (e.g., MPS and CHT). After you get it to the point that it will stay running, then you can focus things that impact drivability and reliability more (e.g., TPS, AAR, CSV, decal valve, etc.). As Spoke says the AFR is good for troubleshooting that at some point if you don't already have one.
Tdskip
Mar 1 2020, 04:40 PM
Just a thought - you have flow when testing the injectors off the car by are you sure you are getting flow when on the car?
Question for the brain trust here - does his set up have a cold start injector or any other way to getting fuel to the car outside the four main injectors?
isdyl
Mar 2 2020, 12:47 AM
Hi - there is a cold start injector but it’s not yet plumbed into the fuel hose that runs past it between cylinders 2 and 4. I did wonder a bit about fuel pressure and flow as I only get 2 bar when the pump is running. As soon as it stops running (like when the engine is off) the gauge drops to about 1.2 bar. I assumed it’s leaking back past the pump. D
QUOTE(Tdskip @ Mar 1 2020, 04:40 PM)
Just a thought - you have flow when testing the injectors off the car by are you sure you are getting flow when on the car?
Question for the brain trust here - does his set up have a cold start injector or any other way to getting fuel to the car outside the four main injectors?
ndfrigi
Mar 2 2020, 01:03 AM
QUOTE(isdyl @ Mar 1 2020, 10:47 PM)
Hi - there is a cold start injector but it’s not yet plumbed into the fuel hose that runs past it between cylinders 2 and 4. I did wonder a bit about fuel pressure and flow as I only get 2 bar when the pump is running. As soon as it stops running (like when the engine is off) the gauge drops to about 1.2 bar. I assumed it’s leaking back past the pump. D
QUOTE(Tdskip @ Mar 1 2020, 04:40 PM)
Just a thought - you have flow when testing the injectors off the car by are you sure you are getting flow when on the car?
Question for the brain trust here - does his set up have a cold start injector or any other way to getting fuel to the car outside the four main injectors?
fuel pressure should be between 28 and 31 psi. probably your fuel pump need replacement or getting low voltage.
isdyl
Mar 2 2020, 01:13 AM
Yes that’s about 2 bar - should it hold at that when the engine is off please? D
QUOTE(ndfrigi @ Mar 2 2020, 01:03 AM)
QUOTE(isdyl @ Mar 1 2020, 10:47 PM)
Hi - there is a cold start injector but it’s not yet plumbed into the fuel hose that runs past it between cylinders 2 and 4. I did wonder a bit about fuel pressure and flow as I only get 2 bar when the pump is running. As soon as it stops running (like when the engine is off) the gauge drops to about 1.2 bar. I assumed it’s leaking back past the pump. D
QUOTE(Tdskip @ Mar 1 2020, 04:40 PM)
Just a thought - you have flow when testing the injectors off the car by are you sure you are getting flow when on the car?
Question for the brain trust here - does his set up have a cold start injector or any other way to getting fuel to the car outside the four main injectors?
fuel pressure should be between 28 and 31 psi. probably your fuel pump need replacement or getting low voltage.
BeatNavy
Mar 2 2020, 06:02 AM
I've heard conflicting things on whether it should hold pressure after shutting off (and how long), and whether there's a check valve in the old 3 port pump to keep up pressure (or not). I really cared when my old engine ALWAYS required two starts (unless I immediately feathered throttle). I figured it was not getting enough fuel initially, and I did notice that my fuel pressure dropped off pretty steadily after shutting off the engine. Having said that, I don't think that was the root cause of the minor issue.
In terms of whether it's an issue for you: if you have a leaking injector that is letting fuel bleed out (both with engine running and not running) that would be an issue - cause an over rich fuel mixture. If you're maintaining pressure while the engine is running and not otherwise leaking fuel anywhere, I wouldn't think it would be a significant problem.
If you suspect fuel delivery might be an issue even after confirming that the injectors are firing, you need to look for some clues. Be careful about chasing your tail though - focus on getting things right in one area (e.g., ignition and timing, then fuel delivery, etc.) and then move on to the next.
If you have a conventional dizzy with points, get a dwell meter.
More reading:
https://members.rennlist.com/pbanders/DJetParts.htm
isdyl
Mar 2 2020, 07:29 AM
Thanks very much, and yes I'm on the case re the valve clearances - new feeler gauges just arrived! D
QUOTE(BeatNavy @ Mar 2 2020, 06:02 AM)
I've heard conflicting things on whether it should hold pressure after shutting off (and how long), and whether there's a check valve in the old 3 port pump to keep up pressure (or not). I really cared when my old engine ALWAYS required two starts (unless I immediately feathered throttle). I figured it was not getting enough fuel initially, and I did notice that my fuel pressure dropped off pretty steadily after shutting off the engine. Having said that, I don't think that was the root cause of the minor issue.
In terms of whether it's an issue for you: if you have a leaking injector that is letting fuel bleed out (both with engine running and not running) that would be an issue - cause an over rich fuel mixture. If you're maintaining pressure while the engine is running and not otherwise leaking fuel anywhere, I wouldn't think it would be a significant problem.
If you suspect fuel delivery might be an issue even after confirming that the injectors are firing, you need to look for some clues. Be careful about chasing your tail though - focus on getting things right in one area (e.g., ignition and timing, then fuel delivery, etc.) and then move on to the next.
If you have a conventional dizzy with points, get a dwell meter.
More reading:
https://members.rennlist.com/pbanders/DJetParts.htm
isdyl
Mar 14 2020, 10:59 AM
Hi all,
So I've checked the valve gaps and all were fine. I've just been looking at the distributor now and checking it all works ok but am wondering if the vacuum advance is working - should I be able to move the plate by sucking on the pipe please?
Dylan
914_teener
Mar 14 2020, 12:22 PM
QUOTE(isdyl @ Mar 14 2020, 08:59 AM)
Hi all,
So I've checked the valve gaps and all were fine. I've just been looking at the distributor now and checking it all works ok but am wondering if the vacuum advance is working - should I be able to move the plate by sucking on the pipe please?
Dylan
You should check it like an MPS. Vaccum is no more psi (bar) than manifold vaccum...8-10 psi. You can observe the arm move and it should hold vaccum. If you have a distributor with both retard and advance and one test bad....the can is kaput and good luck finding one that work. This issue is exactly what lead me to get the 123 distributor years ago. Clean the plate and dizzy before you do this test. Sucking on it won.t tell you if it is leaking.
Bleyseng
Mar 14 2020, 12:54 PM
We check a MPS by putting 15 hg of vacuum on them as that's about idle vacuum. Shouldn't leak down in 5 minutes more than a few lbs.
isdyl
Mar 14 2020, 01:56 PM
Thank you. I'll do as you suggest. Dylan
TheCabinetmaker
Mar 14 2020, 02:48 PM
Just because the mps holds vacuum does not mean it's working properly. That just checks the diaphragm for leakage.
porschetub
Mar 14 2020, 02:58 PM
[quote name='isdyl' date='Mar 15 2020, 05:59 AM' post='2794130']
Hi all,
So I've checked the valve gaps and all were fine. I've just been looking at the distributor now and checking it all works ok but am wondering if the vacuum advance is working - should I be able to move the plate by sucking on the pipe please?
Dylan
[/quote
Yes that will confirm that the vacuum canister is working,if no movement don't assume the canister is bad as it may be that the advance plate is gunked up.
You can remove the canister and test it to confirm this is the issue,sometimes you can free up the advance plate with brake clean then lube it but in my experience it is better to dismantle it and clean the two parts properly.
Good luck.
isdyl
Mar 15 2020, 04:11 AM
Thank you for your suggestions. From the video I posted at the beginning it seems to run well at certain revs, which is leading me to think that the advance/retard isn't working properly. If I suck really hard on the advance pipe I can get a tiny bit of movement on the advance 'arm', but not nearly as much movement as I get on another vacuum unit I have from a different car. I'll see if I can free it up, but I imagine the diaphragm is made of some material which has gone hard.
Dylan
BeatNavy
Mar 15 2020, 05:57 AM
Go ahead and take out and clean the dizzy as Porschetub suggested. Take it apart and do a thorough cleaning and lightly lube everything. Check the ground strap between the two advance plates. This is all good maintenance.
I'm not sure the advance arm moves much even when operating properly (IMO it's not a very "gratifying" movement, so to speak, and hard to tell). It could be your problem, and I'll defer to others if they think that, but I generally put this in the category of "drivability" issues (unless it's really bad).
Did you get a dwell meter and set dwell properly? Then, are you confident you know TDC and the timing marks? If it won't stay running without revs, get someone to help you keep it running while you get the light on it.
isdyl
Mar 15 2020, 11:43 AM
Will do, and thanks again for your help.
Dylan
QUOTE(BeatNavy @ Mar 15 2020, 05:57 AM)
Go ahead and take out and clean the dizzy as Porschetub suggested. Take it apart and do a thorough cleaning and lightly lube everything. Check the ground strap between the two advance plates. This is all good maintenance.
I'm not sure the advance arm moves much even when operating properly (IMO it's not a very "gratifying" movement, so to speak, and hard to tell). It could be your problem, and I'll defer to others if they think that, but I generally put this in the category of "drivability" issues (unless it's really bad).
Did you get a dwell meter and set dwell properly? Then, are you confident you know TDC and the timing marks? If it won't stay running without revs, get someone to help you keep it running while you get the light on it.
ClayPerrine
Mar 16 2020, 11:44 AM
Dylan,
That stuff sat in my garage for years before I sent it to you. The distributor could use a good cleaning. I thought there were two distributors in the stuff I sent. You might try the other one.
Make sure you oil the felt inside the top of the distributor shaft. That lubes the advance mechanism.
Clay
isdyl
Mar 16 2020, 12:10 PM
Thanks Clay - I’ll do all those things. There was just the one distributor but two ecu’s, two throttle bodies and two looms. D
QUOTE(ClayPerrine @ Mar 16 2020, 11:44 AM)
Dylan,
That stuff sat in my garage for years before I sent it to you. The distributor could use a good cleaning. I thought there were two distributors in the stuff I sent. You might try the other one.
Make sure you oil the felt inside the top of the distributor shaft. That lubes the advance mechanism.
Clay
PCH
Mar 16 2020, 12:18 PM
We've recently problem solved the following: Good idle but no power above 3500 rpms. Solved with a new set of trigger points. Old trigger point pick ups were too worn to work properly.
But then, the minute the engine got warm/ hot, it would just stop running. Removed the computer and the insides smelled of burnt electrical. A fellow 914world enthusiast lent us a computer and the problem was solved. Green pea is now running sweeeet!
Good luck and just go down the check lists, item by item.
isdyl
Mar 16 2020, 02:52 PM
Thanks. Actually there is a spare set of trigger points here too. Maybe I'll try swapping them. I can't do much till next weekend now though, although we may all be told to stay at home for a month soon! Dylan
QUOTE(PCH @ Mar 16 2020, 12:18 PM)
We've recently problem solved the following: Good idle but no power above 3500 rpms. Solved with a new set of trigger points. Old trigger point pick ups were too worn to work properly.
But then, the minute the engine got warm/ hot, it would just stop running. Removed the computer and the insides smelled of burnt electrical. A fellow 914world enthusiast lent us a computer and the problem was solved. Green pea is now running sweeeet!
Good luck and just go down the check lists, item by item.
isdyl
Apr 15 2020, 10:07 AM
Hi,
I've spent a long time trying to improve the running now and think it's running too rich. My CH temp sensor is reading 4000 ohms and I think it should be nearer 2000 ohms. Would this cause it to run rich please, and is it a big job to change it? The wire goes into a hole in the tin but I can't work out if I have to remove the tin to get it out.
Thanks, Dylan
BeatNavy
Apr 15 2020, 10:32 AM
There are some vagaries about which sensor you should be using, but 4000 ohms is probably on the high side with an ambient temperature (car cold) of 60 degrees. If it's colder (e.g., 40 degrees), then that is not necessarily way out of normal range.
What makes you think it's running rich at this point? Did you get the other things checked (dwell, timing, dizzy cleaning, etc.)?
Changing the CHT is a bit of a PITA the first time you do it, and you have to do it very carefully or you can bugger up the threads in the head. Basically you need to get a deepwell 13 mm socket inside that hole in the tin. Your options are either attempt to stuff the wire lead up into the deepwell socket OR grind off the corner of a short socket extension so the lead can go out there. You use the same tool when installing the sensor, but again, need to be VERY careful not to cross thread.
Again, I recommend reading this page, particularly all the parts about CHT (it's covered in several places):
https://members.rennlist.com/pbanders/DJetParts.htm
isdyl
Apr 15 2020, 10:44 AM
Hi - yes I'm sure I have the timing & dwell as best as I can get it. It starts easily and revs zoom up to about 2500 revs and it holds there for a while, and then will drop down and 'sort of' tick over at probably 300 rpm - only just running. If I rev the throttle it will go up to 2500 rpm again and can either hold there (on its own) or die down to 300 again. The air screw makes no difference, and the knob on the ecu make a bit of difference, but very little. I removed the plugs and they are very black and sooty, and the exhaust smells rich. This CHTS reading is the only measurement that is not correct so I guess I'm clutching at straws! That web page you posted just now is something I have printed out and have read it quite a lot now!
Thanks, Dylan
QUOTE(BeatNavy @ Apr 15 2020, 10:32 AM)
There are some vagaries about which sensor you should be using, but 4000 ohms is probably on the high side with an ambient temperature (car cold) of 60 degrees. If it's colder (e.g., 40 degrees), then that is not necessarily way out of normal range.
What makes you think it's running rich at this point? Did you get the other things checked (dwell, timing, dizzy cleaning, etc.)?
Changing the CHT is a bit of a PITA the first time you do it, and you have to do it very carefully or you can bugger up the threads in the head. Basically you need to get a deepwell 13 mm socket inside that hole in the tin. Your options are either attempt to stuff the wire lead up into the deepwell socket OR grind off the corner of a short socket extension so the lead can go out there. You use the same tool when installing the sensor, but again, need to be VERY careful not to cross thread.
Again, I recommend reading this page, particularly all the parts about CHT (it's covered in several places):
https://members.rennlist.com/pbanders/DJetParts.htm
isdyl
Apr 15 2020, 10:48 AM
Oh I forgot to say that it will only 'tick over' at 300 rpm if I disconnect the air temp sensor. With that connected it pretty much stalls after the surge to 2500. I know this points to it being lean as this sensor would richen the mixture if unplugged normally, but why the black plugs? D
QUOTE(isdyl @ Apr 15 2020, 10:44 AM)
Hi - yes I'm sure I have the timing & dwell as best as I can get it. It starts easily and revs zoom up to about 2500 revs and it holds there for a while, and then will drop down and 'sort of' tick over at probably 300 rpm - only just running. If I rev the throttle it will go up to 2500 rpm again and can either hold there (on its own) or die down to 300 again. The air screw makes no difference, and the knob on the ecu make a bit of difference, but very little. I removed the plugs and they are very black and sooty, and the exhaust smells rich. This CHTS reading is the only measurement that is not correct so I guess I'm clutching at straws! That web page you posted just now is something I have printed out and have read it quite a lot now!
Thanks, Dylan
QUOTE(BeatNavy @ Apr 15 2020, 10:32 AM)
There are some vagaries about which sensor you should be using, but 4000 ohms is probably on the high side with an ambient temperature (car cold) of 60 degrees. If it's colder (e.g., 40 degrees), then that is not necessarily way out of normal range.
What makes you think it's running rich at this point? Did you get the other things checked (dwell, timing, dizzy cleaning, etc.)?
Changing the CHT is a bit of a PITA the first time you do it, and you have to do it very carefully or you can bugger up the threads in the head. Basically you need to get a deepwell 13 mm socket inside that hole in the tin. Your options are either attempt to stuff the wire lead up into the deepwell socket OR grind off the corner of a short socket extension so the lead can go out there. You use the same tool when installing the sensor, but again, need to be VERY careful not to cross thread.
Again, I recommend reading this page, particularly all the parts about CHT (it's covered in several places):
https://members.rennlist.com/pbanders/DJetParts.htm
isdyl
Apr 15 2020, 01:25 PM
I swapped the sensor out for a 2k resistor just to see but it made it harder to start and worse running. I think I'll take the whole lot apart again and pay more attention to avoid any possible vacuum leaks. I'm almost past it with this car.....
BeatNavy
Apr 15 2020, 01:48 PM
So you just put a 2k resistor between wiring harness and ground? How long did it run before running badly? The heads start to heat very quickly, so simply adding resistance won't "help" long while engine warms from ambient temp.
Clean the plugs and try again to see if they foul after a couple of starts. Other than those plugs the symptoms say you may be running way too lean, but it's hard to tell with the info provided.
You'll get there, but you have to be methodical and be sure about things before checking them off as verified.
isdyl
Apr 15 2020, 02:11 PM
Yes, just the resistor between the harness wire and ground. It was just a few seconds of running just to see what would happen.
i think vacuum leaks may be the next thing then. i'll try a bit of brake cleaner spraying.
Thanks for your advice. Dylan
QUOTE(BeatNavy @ Apr 15 2020, 01:48 PM)
So you just put a 2k resistor between wiring harness and ground? How long did it run before running badly? The heads start to heat very quickly, so simply adding resistance won't "help" long while engine warms from ambient temp.
Clean the plugs and try again to see if they foul after a couple of starts. Other than those plugs the symptoms say you may be running way too lean, but it's hard to tell with the info provided.
You'll get there, but you have to be methodical and be sure about things before checking them off as verified.
Bmw635
Apr 15 2020, 02:25 PM
Check your fuel filter as it may be clogged. I flush the tank and clean filter on a car sat for 23 yrs. Put new fuel in and it washed debris down clogging filter causing choking above 3k rpm then die. Restart rub fine until above 3k rpm , samething happened. Checked filter and it was clogged, clean up then ran up to 5k rpm now.
isdyl
Apr 15 2020, 02:30 PM
Thanks - I've had that on a few previous cars actually, but this one is ok. D
QUOTE(Bmw635 @ Apr 15 2020, 02:25 PM)
Check your fuel filter as it may be clogged. I flush the tank and clean filter on a car sat for 23 yrs. Put new fuel in and it washed debris down clogging filter causing choking above 3k rpm then die. Restart rub fine until above 3k rpm , samething happened. Checked filter and it was clogged, clean up then ran up to 5k rpm now.
ctc911ctc
Apr 15 2020, 03:42 PM
Hi,
I went down all of the paths that you did with a barn find that had not been running for 30 years.
Djet will only work correctly if the vacuum system is solid.
Repeat after me:
Djet will only work correctly if the vacuum system is solid.
Hate to suggest this but the Plenum is very susceptible to leaks, especially if the car has been in humid geography.
Take the Plenum out and get some plumbing stoppers. Plug it up and pressurize then immerse in water. Mine had a dozen leaks. I welded AND JB Welded (epoxy) the thing. Re-installed in a car that I had already:
Valves Adjusted
Timing
Rebuilt Throttle Body (throttle position switch)
New Fuel Pump
All new hoses
Calibrated Fuel Pressure to 29 psi
rebuilt injectors.
New MPS
New Engine Temps Sensor
When the plenum was complete, the car started, idled, went from 1200 cold to 900 after warmed up.
The next thing I chased was Exhaust leaks. But that is another thread.
isdyl
Apr 16 2020, 03:22 AM
Thanks - ok so I've done a bit of testing this morning and found quite a bad leak around the cold start valve. I put duck tape over the throttle body opening, blocked the AAV, and blew into the MPS hose whilst spraying with leak detection spray. I don't need a cold start valve here as it's quite warm so I removed it and covered the hole with aluminium tape.
It now starts up ok and revs at about 1500rpm. It holds for a couple of seconds but then dies. I'm now wondering if it's getting enough fuel, but when running the fuel pressure stays constant at 29 psi.
Dylan
QUOTE(ctc911ctc @ Apr 15 2020, 03:42 PM)
Hi,
I went down all of the paths that you did with a barn find that had not been running for 30 years.
Djet will only work correctly if the vacuum system is solid.
Repeat after me:
Djet will only work correctly if the vacuum system is solid.
Hate to suggest this but the Plenum is very susceptible to leaks, especially if the car has been in humid geography.
Take the Plenum out and get some plumbing stoppers. Plug it up and pressurize then immerse in water. Mine had a dozen leaks. I welded AND JB Welded (epoxy) the thing. Re-installed in a car that I had already:
Valves Adjusted
Timing
Rebuilt Throttle Body (throttle position switch)
New Fuel Pump
All new hoses
Calibrated Fuel Pressure to 29 psi
rebuilt injectors.
New MPS
New Engine Temps Sensor
When the plenum was complete, the car started, idled, went from 1200 cold to 900 after warmed up.
The next thing I chased was Exhaust leaks. But that is another thread.
isdyl
Apr 20 2020, 03:36 AM
Hi - sorry to keep asking questions - I'm still finding vacuum leaks. There are some around the bakelite spacers between the intake runners and the heads. Should there be gaskets there as well as the spacers please, or would instant (liquid) gasket be ok please? They weren't tightening up properly either as some of the studs had wound out too far and stripped.
Thanks, Dylan
Bleyseng
Apr 20 2020, 07:55 AM
yes, the spacers come with a paper gasket glued to them but I use a liquid gasket sealant when installing them to the heads and intake manifolds.
ctc911ctc
Apr 20 2020, 08:14 AM
Getting all of those leaks will result in a fine running car!
Good Luck! Keep at it!
QUOTE(isdyl @ Apr 20 2020, 03:36 AM)
Hi - sorry to keep asking questions - I'm still finding vacuum leaks. There are some around the bakelite spacers between the intake runners and the heads. Should there be gaskets there as well as the spacers please, or would instant (liquid) gasket be ok please? They weren't tightening up properly either as some of the studs had wound out too far and stripped.
Thanks, Dylan
euro911
Apr 20 2020, 12:22 PM
I didn't read through all the replies so I'll ask: Did you ever spray a 'combustible' liquid or vapor around the motor while it was idling to locate any vacuum leaks? It's the easiest method to find them
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