Winter D jet tinkering, Are parts still available? Options

[robkammer]

The TTS is a temperature dependent sensor, it only provides ground to the AAR, completing its circuit to the AAR based on the ambient air temp just above the engine case. Super simple, just the we like it.

Brad Anders D-Jet pages have a new link, actually its now hosted directly on his personal server: https://pbanders.synology.me/914/

The previous site may remain accessible on rennlist for awhile, they don't keep them updated. Use the new link which has the most up to date information.

Thanks Jeff! This is confusing, the one lead to the AAR is it's 12 v power, isn't it? It seems to me that both, or all of the sensors, the AAR , cold start, etc all connect to/from the ECU. I'm thinking that with a meter I should be able to confirm continuity and voltage, if I can find a good diagram. I'll head back to Brads collection again. I have your diagram from the harnesses, and a Haynes, but neither detail these connections or routes. I've gotta believe theres a more comprehensive diagram out there after all these years.
Rob

[Superhawk996]

Haynes and factory service manual wiring diagrams have the info you need.

Anders site has all the theory of operation, parts table, and how to bench test various sensors.

[Superhawk996]

It seems to me that both, or all of the sensors, the AAR , cold start, etc all connect to/from the ECU.

You are mistaken - the AAR and the cold start valve are not input/output from the ECU.

Bench test them & then let us know how it goes.

[Superhawk996]

If you keep all information in one thread it will be easier to help you troubleshoot.

Here’s how to test the thermoswitch from the other thread:

The thermoswitch controls the cold start injector. Has nothing to do with the AAR.

The thermoswitch and cold start injector don’t even come into play unless vehicle and ambient temperatures are around 32F and below.

Review the Anders overview of d-jet operation and components.
https://pbanders.synology.me/914/djetfund.htm

Thermoswitch can be tested by placing in the freezer and then monitoring continuity with a DMM as it warms back to room temperature. It should be closed when it first comes out and then should go open as it warms towards ambient.

The AAR can be bench tested by simply powering it with 12v and observing the port (and or blowing air through it) to make sure the port closes after the AAR warms up.

The easiest way to test the cold start injector is to block its fuel supply line.

Given it is winter in Ohio, you’ve made no mention of whether you’re working in a heated shop or doing this work out doors in sub 32F weather where the cold start injector would be needed & used.

Given your description of how you’ve had to plug the decel valve ports, it would seem you probably have multiple issues with the system and previous band-aids going on that will need to be methodically worked through to get to what the actual issue is.

[robkammer]

Thanks Jeff, Wonki and Superhawk. I spent quite some time on the PBanders site, when he got to the Oscilloscope screen shots, I'm gone! He's at a way different level that this old wrencher. Part of my dilemma is that the car runs great, starts right up, once I get the temp gauge to move a little, it's all good!
My goal is to find the test specs for as many components as I can. Temps and resistance values, etc.. The decel valve is shot, It's been ok duct taped off for 3 years, but I know it's not right.
Our BB is a beauty, it's not my fave in our garage, but it's cool. I'm vacillating on taking it from a #2, to a #1 in anticipation of values coming back. To do that I need to pull the motor, fix some leaks, freshen up some things, detail the engine compartment, yada, yada.
At that point it becomes much easier to fiddle with all of the sensors and other EFI stuff. And some engine tin that was butchered when AC went in in 74.
I'm just getting back on my feet from a new knee. Tomorrow I'll be at my shop getting ready to refresh the suspension on our 986. Once that's done the lift will be open!
I really appreciate your input, and understanding
Rob

[rjames]

Cold start no problems, let it sit and idle for 5 minutes, ls no problem.
Once underway, as soon as I let off the pedal, it would want to stall. I was able to get through it by using the hand brake, but that's a pain.

Does this happen even after driving for 15+ minutes when the engine is fully warmed up?
Has the timing been checked and a valve adstment been done recently?

What is the idle RPMs when cold? If you let it idle for more than 5 minutes without driving it (engine fully warmed up and the AAR is closed), will it stall, or does it only stall after you start driving it?

[robkammer]

Once underway, as soon as I let off the pedal, it would want to stall. I was able to get through it by using the hand brake, but that's a pain.
I know I have a bad vacuum valve that is supposed to shut the throttle body down on decel, but I've just plugged it and left it place. If it's not plugged, the open vacuum takes the idle way too high. It's been like that for two years, but not for long if I can find a new one.

If anyone has suggestions on what might be the problem here, I'm open to all suggestions.
Cheers!
Rob

do you reckon that all you might have to do is adjust the decel valve?

i don't know hanee-tink about d jet, have an L jet.
but i too have a substitute decel valve which effectively means i do not have one.
and occasionally when a little cold and not fully warmed up it will stall when i come off the pedal and then immediately bring itself back to life. due of course to the particular nature of L jet and the AFM flapper going past its idle position and then coming back again. which the decel stops from happening. but if the decel is not adjusted just right it can have an unusually high idle in an L jet.

i mean i dunno. like i say i don't have a D jet.

I found a nice one on Ebay, even has the oem bracket. Let's see what shows up!

[pbanders]

Thanks Jeff, Wonki and Superhawk. I spent quite some time on the PBanders site, when he got to the Oscilloscope screen shots, I'm gone! He's at a way different level that this old wrencher. Part of my dilemma is that the car runs great, starts right up, once I get the temp gauge to move a little, it's all good!

Rather than go into it in detail here, I'm going to start another thread about starting behaviors of 914 D-Jet cars. Basically, what you describe sounds pretty optimal to me. We've all gotten spoiled by modern cars with modern engine management, where they start and run flawlessly under nearly all conditions. 914's don't, and there are some workarounds that can help.

My goal is to find the test specs for as many components as I can. Temps and resistance values, etc.. The decel valve is shot, It's been ok duct taped off for 3 years, but I know it's not right.

There's some good info on that in this thread, and my parts section covers some of it, too. Make sure you're using my updated site at Brad's 914.

I've been thinking about writing up a component test guide, or updating what I have already. I've also been thinking about adding a step-by-step tune section, to provide a starting point for dealing with problems. Too many times, people post here about issues they're having, but there are underlying tune or engine condition problems that obscure the real issue.

[pbanders]

Cold start no problems, let it sit and idle for 5 minutes, ls no problem.
Once underway, as soon as I let off the pedal, it would want to stall. I was able to get through it by using the hand brake, but that's a pain.

Does this happen even after driving for 15+ minutes when the engine is fully warmed up?
Has the timing been checked and a valve adstment been done recently?

What is the idle RPMs when cold? If you let it idle for more than 5 minutes without driving it (engine fully warmed up and the AAR is closed), will it stall, or does it only stall after you start driving it?

It may be even simpler. It may be that the idle was set while the AAR was open. Once closed, it's too low. You set the idle using the bleed screw once the car is fully warmed up (15+ minutes) and all electrical loads are on (lights {high beams, fogs, too}, heater blower, fresh air blower, etc.). FWIW, I have had best results by setting the idle higher than the spec 950 rpm, to 1000 rpm. Note this means your non-loaded idle will be higher than 1000 rpm, so you've gotta make sure your 1st gear synchro is in good shape, however, when you put it in gear at the higher idle. I always clutch and say "one thousand one" before engaging 1st. (IMG:style_emoticons/default/driving.gif)

But, as you say, that's only after you're sure of a ton of other stuff, e.g. valves adjusted, no vacuum leaks, timing and dwell, compression, etc. I'm going to write a basic tune guide, or a "before you start turning all the knobs guide" and add it to my site.

[robkammer]

Hey all, from the frigid North: My plan is to start piece by piece with the FI bits, get it started and see if I can replicate the problem from last Fall. I found a new decel valve that'll be here tomorrow, and I've ordered a TPS board only because the tps adjustment plates are WAY out of whack, and the throttle body is filthy. Once started again I'll check to be sure I have voltage to the AAR, I'll also check the Thermotime switch when it's cold and after.
Any other suggestions will be welcome.
Rob

[robkammer]

Hey Teeners! Hope your weekend is warmer than ours. As I poke through the EFI, I find that the TPS is fine, a nice surprise that it is a new Bosch unit installed in 04, only 7k miles ago. Somewhere I found the test spec for the Thermotime to be at 300 ohms at 65degrees F.
My reading are 8 ohms with the sensor connected or not, and with the key on or off. should I start looking for a replacement? What other options are there if that particular part number is not available.
Rob

[robkammer]

Update on the BB. Granted, my ramblings may seem disjointed, but today I think it's called ADD. Here's where I am at this point:

Just received a nice decel valve from Ebay, tests good
Thought I found a good Thermo sender on Ebay but it tested NG, as does mine.
The plenum temp sensor tests fine.
The Head sensor is puzzling to me. It tests at 5 ohms at room temp, disconnected. 68 degrees F.
The lead wire shows 12 volts with the key on. What I can't wrap my head around is how this sending unit send info through the hot wire that is the only connection other than ground. It seems to me that when connected there would be a direct short, but the car ran fine with it connected.
I'm going to search for a working Thermotime before putting it back together. Any suggestions on a source would be appreciated.
I reached out the the good DR. but have not heard back
Cheers!

[pbanders]

Just received a nice decel valve from Ebay, tests good

Remember, when you connect it, that the 5 mm port connects to the intake manifold (vacuum), the opposite/end port also connects to the intake manifold, and the side port connects to the air box (atmospheric pressure). Some of the hose diagrams are wrong, this is the correct way to connect it, otherwise, it won't work. It should limit the manifold vacuum to about 18 in. Hg.

Thought I found a good Thermo sender on Ebay but it tested NG, as does mine.

What are the part numbers on the thermo sensors you have? This sensor is open for all temperatures above 32 F and closed for all temperatures below. The CSV is provided +12V during cranking on one terminal, the thermo sensor provides ground to the other terminal of the CSV when it's closed.

The plenum temp sensor tests fine.
The Head sensor is puzzling to me. It tests at 5 ohms at room temp, disconnected. 68 degrees F.

The lead wire shows 12 volts with the key on. What I can't wrap my head around is how this sending unit send info through the hot wire that is the only connection other than ground. It seems to me that when connected there would be a direct short, but the car ran fine with it connected.

If the head temperature sensor tests at 5 ohms 68 F, it's no good. Should test at 2.5K ohm at that temperature. I suggest you test it again, possibly with a different multimeter to be sure.

See ECU Schematic Page 2 and Cylinder Temperature Compensation to understand how the head temperature sensor works in the system with the ECU to adjust the mixture.

[pbanders]

Hey Teeners! Hope your weekend is warmer than ours. As I poke through the EFI, I find that the TPS is fine, a nice surprise that it is a new Bosch unit installed in 04, only 7k miles ago. Somewhere I found the test spec for the Thermotime to be at 300 ohms at 65degrees F.

This is not correct. The thermo sensor should test as a short for temperatures below 32 F, and an open for temperatures above. You can only test the sensor with the connection to the CSV unplugged. Also, is your sensor a thermo sensor (p/n's 311 906 161 A and 311 906 161 C) or is it a thermo-time sensor (p/n 022 906 163 A)? The thermo-time switch has a timer that enables it only for between 5 and 20 seconds of cranking.

My reading are 8 ohms with the sensor connected or not, and with the key on or off. should I start looking for a replacement? What other options are there if that particular part number is not available.
Rob

OK, I've edited this part about 10 times so far, finding I was wrong every time I tried explaining what's going on with a thermo-time switch. Not having access to one doesn't help. I'm going to come back here later when I'm 100% certain of how it works and describe it. Wish me luck.

[robkammer]

Hey Teeners! Hope your weekend is warmer than ours. As I poke through the EFI, I find that the TPS is fine, a nice surprise that it is a new Bosch unit installed in 04, only 7k miles ago. Somewhere I found the test spec for the Thermotime to be at 300 ohms at 65degrees F.

This is not correct. The thermo sensor should test as a short for temperatures below 32 F, and an open for temperatures above. You can only test the sensor with the connection to the CSV unplugged. Also, is your sensor a thermo sensor (p/n's 311 906 161 A and 311 906 161 C) or is it a thermo-time sensor (p/n 022 906 163 A)? The thermo-time switch has a timer that enables it only for between 5 and 20 seconds of cranking.

My reading are 8 ohms with the sensor connected or not, and with the key on or off. should I start looking for a replacement? What other options are there if that particular part number is not available.
Rob

EDITED: I deleted my previous reply, it doesn't make sense. Give me a few minutes to think this through and I'll re-post. It's possible you have a thermo-time sensor as you said above, not a thermo sensor.

UPDATED: OK, I have an idea of how the thermo-time sensor works, but I'm not fully there. I think the "thermo" and "time" parts are in series. The "time" part is possibly a bimetallic switch that's thermally coupled to a resistive heater. The CSV coil is 4.2 ohms, and the resistive heater is in series with it. The two resistances form a voltage divider to the +12V being applied across it. I don't know what the onset voltage of the CSV is, I'll attempt to measure it, but it's below +12V because voltage will be dropped across the resistive heater. I don't have a thermo-time sensor to experiment with, maybe someone who has one can help figure out what the resistance value of the heater is. This also implies to me that the "on" resistance of the regular (non-"time") thermo sensor must be similar to the resistance of the heater in the thermo-time sensor, to limit current through the CSV (or, maybe not). I'll do some more experimentation and measurements.

Regardless, a thermo sensor or a thermo-time sensor should read open at 68 F. If yours doesn't, it's no good.

Brad: Thanks for the follow up. The sensor part number is 0336 003 008 and has only a single terminal. Most recent testing, with 3 different meters show it with no continuity at all from 25 degrees F to room temp of around 68 degrees. ISO of replacement. I could not replicate my earlier reading of 8 ohms, at any temp or with any meter. All test were done on the bench.
I have not yet tested the CSV, but cold start is not an issue with this car.
Also, I checked and I do have 12 V to the AAR when the fuell pump in energized.
Hope this makes sense.
Robbo

[pbanders]

Brad: Thanks for the follow up. The sensor part number is 0336 003 008 and has only a single terminal. Most recent testing, with 3 different meters show it with no continuity at all from 25 degrees F to room temp of around 68 degrees. ISO of replacement. I could not replicate my earlier reading of 8 ohms, at any temp or with any meter. All test were done on the bench.
I have not yet tested the CSV, but cold start is not an issue with this car.
Also, I checked and I do have 12 V to the AAR when the fuell pump in energized.
Hope this makes sense.
Robbo

OK, you have a thermo sensor. I have the same one you do as a spare, it shows open at temperatures above about 32F and closed below that (maybe some resistance, I'm checking that now). That 8 ohm reading must have been a fluke. Your two sound like they're bad. However, you've gotten me interested in the thermo-time sensor, so I'll post a new topic on that, later. Good luck.

[JeffBowlsby]

Recall that some of the original factory TS may have switching temps below 25F (not TTS), these sensors are not very precise which determine when the CSV activates:

311 906 161 : -12 to -18 deg. C / 10 to 0 deg. F
311 906 161 A : 0 to -10 deg. C / 32 to 14 deg. F
311 906 161 B : -2 to -8 deg. C / 28 to 18 deg. F
311 906 161 C : -6 to -14 deg. C / 21 to 7 deg. F

I found a source online that references PN 0336003008 to 311906161C.

[pbanders]

Recall that some of the original factory TS may have switching temps below 25F (not TTS), these sensors are not very precise which determine when the CSV activates:

311 906 161 : -12 to -18 deg. C / 10 to 0 deg. F
311 906 161 A : 0 to -10 deg. C / 32 to 14 deg. F
311 906 161 B : -2 to -8 deg. C / 28 to 18 deg. F
311 906 161 C : -6 to -14 deg. C / 21 to 7 deg. F

I found a source online that references PN 0336003008 to 311906161C.

I just tested my spare 311 906 161 C sensor. I set my freezer to -5 C, left the sensor in there for about 90 minutes. The freezer had cooled to an indicated -3 C when I removed the sensor and promptly tested it, reading 3 or 4 ohms on the 0.25 V range of my DMM. Within a minute or so of sitting on a warm granite countertop, it was back in an open state, so the trigger temp slightly above -3 C.

[robkammer]

Thanks Brad: I found one on Ebay, won'y know if it's working until it arrives. Am I understanding correctly that this sensor is only effective if I try to start the car when it's freezing or below? If that is the case, I really only need something as a placeholder as I doubt I ever be driving it under that condition.
Rob

[brant]

That’s why earlier in the thread people said to cap it for testing.
It makes no difference unless below zero for starting


Your problem lies elsewhere

Start with the easy test of mps and cht