Ok , so I have the engine running but it needs tuning. A little background, rebuilt stock 2.0 with D Jet, running a 123 dizzy. It fires right up and idles a little rough at first then smooths out. It revs fairly well and sounds good. The problem starts under load, it starts to stutter a bit.
I have not messed with the adjustment screw on the ECU or tried adjusting the throttle position sensor, or been able to check my fuel pressure.
I’m hoping to rally any troops in the north Florida area to help me get these final details ironed out.

Thanks in advance,
John

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SET RUNNING FUEL PRESSURE BEFORE ANYTHING ELSE.

The ECU knob only impacts mixture at idle (assuming your TPS is good) The way I normally set that is to get the car fully warmed up, let it idle, start with it on the rich side and then lean it out (turn knob counter clockwise) until the engine starts to hunt and then turn it back clockwise 2-3 clicks. You may want to rev it a couple times in between adjustments of the knob to see where it settles.

Rough idle when cold? is your AAR kicking up the idle speed when cold as it should? guessing it either isnt or your idle mixture isnt ideal.

Stuttering under load? That one is a little tougher to guess at without more information or seeing what the car is doing. Could be a lot of things but if your fuel pressure is adjusted properly and you dont have any restrictions in fuel flow then you may be looking at a bad/futzed with MPS, or possibly bad TPS. Other than fuel pressure there is no adjustment that is supposed to be occurring on d-jet that would affect mixture under load.



Good Luck! Looks like you have a really clean setup there.

Looks gorgeous. None of those things besides fuel pressure will help you assuming the tps was installed correctly. Hopefully someone close can pop by. If you want to do the basics yourself, go to a flaps and rent a fuel pressure gauge, make sure it is 29lbs. Make sure the timing is good. Do you know what they set the 123 to? Is it Bluetooth or pot? That alone could be your problem. I see the advance port on the throttle body is plugged.

Thanks, I’ll start with the purchase of a fuel pressure tool

I set the 123 to the #1 setting, it’s the non Bluetooth unit.

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I'm not gonna lie. I stopped reading the thread and just gazed upon the beauty of that restored engine

No kidding. Looks like new. Maybe better.

1 should be fine as long as the port on the distributor isn't going anywhere. Is there a vacuum line on the dizzy? It may not have a port, depends on the model of 123.

There could be a number of things going on, but JamesM is always a great source on FI knowledge and troubleshooting.

Having said that, it won't run right until you get the proper tune selected for your 123 based on your specific FI setup (ECU, throttle body, etc.) AND get the timing dialed in. When I was running my 123 I was using curve "B" and retard only as my FI components were basically correct for a '74. I can't remember when curve "1" is correct, but you need to verify if that's correct for you. 123's are great once you navigate a couple of initial installation challenges.

There are a couple of good threads out there on this, including this one: http://www.914world.com/bbs2/index.php?showtopic=324473

That engine and engine bay are beautiful

and thanks!

Need the proper setting on the 123dizzy and the vac port should be retarding on manifold (not ported) vacuum. "B" is what i run on my 74 as well.

It is an interesting mix, can't wait to hear what year it is. I say early early 74.

Thank you, now if I can just get it dialed in.

There is a port on the dizzy, I have been experimenting with it on and off, seems to run better with it off.
The engine is an early ‘73 2.0, it originally had a 1.7

Ahh! That explains the advance port on the TB. My 73 has the same dizzy and it really likes the advance port attached (to the correct port on the TB) but you do need to make sure the timing is good. I do it by feel, idle, and performance, then double check with a light. Mine is on #1 with advance connected, very happy. Is it a big difference between advance and not? No, but I like it. I am running about 36-37 all in currently. Engine is running cool and AFR looks good. Idles at 900 (well, at least that is what the gauge says). No stumbles anywhere. This is a 9/72 build date GA engine. I tried running the retard setting, and it worked fine, but no real point in doing that.

29 psi on the fuel pressure gauge.

Its probably running better with it off as the 123dizzy should be retarding rather than advancing the timing on vacuum. On a stock setup the vacuum retards the timing at idle and overrun.

Timing should be checked with the vac line disconnected @ 3500 RPM to the 27 deg mark on the fan.

Set the 123 to the A or B curve and make sure the port it is connected to is below the throttle plate, the port that is seeing vacuum at idle. This will most likely cause your idle speed to drop quite a bit which you will need to compensate for by opening the air bypass screw on the throttle body which will then also probably require a minor adjustment to your idle mixture knob as well.

This may help your cold idle as well but...

You mentioned your motor is an early 73, looks like your airbox isnt though so it makes me wonder if you may have other part mismatches going on. Early 73 2.0s I find are a little more temperamental when it comes to parts as they were a very unique setup (hack) from the factory and the temperature curve on the sensor is very different than all other years. Need to be sure your MPS, ECU, and Head Temp Sensor all match for the year, either 73 or 74 and that if they are 73 you also need to be sure you have the inline resistor to the head temp sensor.

Yikes, yeah, hopefully it is just the snorkel. I saw that strange plugged port and wondered about that. A quick look at the CHT for a resistor in line might help, so would a look a the ECUs number. I think I would get the number off the block, check the CHT, and check the computer. Does it have a PCV valve or is it passive? All of those things will help determine what you are working with.

James, 73 had retard and advance on the 009, it's choose your own adventure with the 123. You can go for #1 and hook it to the ported vacuum or put it on A and go for the retard port. Unless you are having issues with a high idle, there is no reason to mess with the retard side of things.

Ok, a lot of investigating to be done. I can tell you that the ECU that came with the 2.0 was not working so I swapped the one that was on the original 1.7 and it worked. I’ll get the #s off of everything and report back.
The air cleaner that came with the 2.0 looks to be for a late model with smog. This will have to do until I can locate the correct unit.

You're using the ECU off a 1.7 on a 2.0? It will run, as in fire the injectors, but it's a mismatch and will never be properly tuned. You need to make sure in particular that the ECU and MPS are matched properly for a 2.0 engine: https://members.rennlist.com/pbanders/DJetP...m#Compatibility

You also need to make sure your CHT / ballast resistor setup is matched to the ECU (assuming you get a '73 setup).

Correct matching for early '73 setup is an 037 ECU with an 037 MPS and the proper ballast resistor (IIRC).

My bet is on fuel pressure or fuel delivery.

But listen to what James or Rob adds. They've BTDT.

That is quite the engine bay.


Check fuel pressure first.....and make SURE none of your fuel lines are kinked otherwise you will chase your tail.

You didn't say where the fuel pump is located.....in the front?


Good luck.

@Morph914 - Damn that's a nice engine bay! It reminds me of mine but you've got FI and it's nicer (IMO)! Great job!

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Oh...I just noticed...did you check your vaccum line routing? Go to Jeff Bowlsby website and check.

Maybe its an optical illusion but the vaccum hose routing to the De-cel valve doesn't look right.

What are your D-jet components matched for? A 73 2L or 74?


Edit....Ooppps Rob's already asked that.

Thank you for the chart, this is very helpful. I do have the 0 280 100 037 ECU, but my MPS is a 0 280 100 019, this is clearly mismatched. I will go on the hunt for the 037 MPS.

I had the more flexible German fuel line under the tank but I switched everything over to the high pressure FI hose and this stuff does not bend nearly as well. I did notice a kink in one of the lines but think I solved it. I will double check. Thank you!

Ok, so hereis a more detailed description of what I have now. First of all as reported above my MPS is not correct for the 037 ECU that I’m running. So I’m on the hunt for one of those.

Engine is GA000328

MPS is 0 280 100 019 (wrong)

Head temp sensor is 0 280 130 01, on the side it has a #227

Ballast resistor for head temp sensor is 039 971 762A

Fuel pump is a Bosch 69133 unit mounted on lower portion of the firewall

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123 dizzy is the 4-R-V- IE unit

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I tried to include more pics but unable to pull from the library for some reason.

Thank you ! From the picture on the link, I realize that I had my advance hose connected to the retard side. I’ll plug off the back port and hook it up to the front.

Very Nice!!! I like yours better

The 73 did have both but the advance side does very little and is also somewhat counteracted by the retard side as they are the same vacuum can. At best it was helping to overcome mechanical resistance and pull back the timing retard quicker at throttle tip in. It was never intended to run as advance only and the necessity to overcome mechanical resistance is moot on the 123dizzy as it is fully electronic, the "vacuum" port is just a map sensor so any response is already instantaneous.

Having tuned 914s with Megasquirt for close to 20 years now I can say that the range of both timing and AFRs that they will run under without noticeable drivability issue is pretty staggering, but the "optimal" window is far narrower and may not be known until you throw your car on a dyno or a smog machine, or even over a 10,000 ft mountain pass. I am assuming you dont get your car smog checked? Over advancing the timing may give the impression that the motor is more responsive as it is essentially ramping up the advance faster in the lower RPM range however 36-37 degrees advance is pretty far out from where stock type 4s are known to make their best power when optimized at WOT. Its also worth noting that as changing to timing impacts fueling requirements it is possible that the fact you feel its running best with that much advance may be an indicator that it is masking/compensating for an issue with your injection.

Looks like you are missing a digit off your Temp sensor part number, 0 280 130 017 is going to be the part you want to run the 037 ECU on a 2.0 motor. As these were very hard to come by for a long time a lot of them were replaced with 0 280 130 012 (or other) which has the wrong resistance curve and will absolutely impact performance, most notably during warm up. ill have to dig into my parts stash and see if that additional 227 number correlates at all with the bosch PN. You can get by with the wrong CHT sensor but it is far from ideal and you will have idle/warm up issues.

Wrong MPS could for sure be contributing to the stutter under load as this is the sensor the system is the most sensitive to, especially when looking at load vs idle.

If I remember correctly, didn't the first 2.0s all use the 1.7 ecu and just add that cht resistor and bigger injectors.

Yeah, I dynoed mine some months ago, it seems to like 35-37 (all in, not at 3k, that is max advance). I should say that's what I get on my cheap timing light. It may not reflect reality. We set the timing at the Dyno by the numbers, after which I checked to see where it was on my timing light.

Chris fowley (tangerine racing) might have some suggestions on the 037 vs 019 mps as well.

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The VW # I have for the head temp sensor is 022 906 041A

I also have a 0 280 100 049 MPS which I believe was on my 1.7

Gents, those engines/wells are amazing. I'm speechless.

Yeah, the 73 2.0 ECU is the same as the 72 1.7 ECU but they changed every other component to compensate, this is why the 73 2.0 setup has a lot of unique components. specifically the ECU, MPS, and CHT all must match for that year. Injectors are specific to the 2.0 but unchanged for 74.

Both the 019 and the 049 MPS are 1.7 sensors, the 019 being an earlier version for 70-71 1.7 914s and 411s. I dont recall the specifics but believe those 2 should be more or less interchangeable with each other, if i recall they were mainly internal physical differences.

I thought I had the correct ballast resistor for the head temp sensor, but after looking through my pictures , I found the # to be 301 540 0265 kz.
With that discovery, I will now have to locate the correct ballast resistor #039 971 762A

Anyone else having difficulty loading pictures from a library of photos? I normally have no issues with this, but for some reason today I’m unable.

Just make your own resistor, that is what I did. Makes me feel closer to my cht.

One thing you might want to keep in mind given how rare the 0 280 130 017 sensor is, you may be better off sourcing a 74 ECU and MPS

Here is a little more info on the head temp sensor differences
http://www.914world.com/bbs2/index.php?sho...351065&st=0

You will notice that at operating temps they are pretty close but during warmup they vary significantly.

The 74 ECU is a better ECU to run on the D-jet 2.0.

If you can find one.

I ran the 037 for years and with a matched MPS NP, ran like a bat out of hell.

It\s fuel delievery but I'd assumed that you had matched D-jet components. That's a D-jet Golden Rule.

I've already commented on the retard setting on the 123 many times in other threads....it's stupid to run it IMHO...the only reason it's there is to try to match the stock dizzys so for component sake....to be pure.

If you aren't going to smog it then it doesn't matter, if you have a switched 123 then I wouldn't recommend using that setting.

If used for advance it does make a difference on part load and far as responsiveness....really like James says the only way really to know is on the dyno.

Good luck.

That is my experience as well, it responded better on the butt and the Dyno with advance and #1 on the 123 but truthfully, I really don't think you would notice if you didn't use it. I wouldn't go mucking with a 74+ tb to get an advance port. Luckily not your problem. Post Dyno and some later mps fine tuning on my stock 73 2.0 we were looking at probably 85ish hp 110ish lbs torque at the rear tires (225/50r16) with an Ansa exhaust. Without the mps fine tuning the Dyno had us at 74 hp and 104trq at the tires. After fine tuning the mps the upper rpms opened up quite a bit so I suspect my butt feel is pretty close to reality. This summer I will Dyno again if I get a chance. I wonder if one of Chris's kits would allow you to use your mps? Probably not, but you never know. A good mps is not an easy find.

Ok, so after locating the proper mps (037), and verifying that the fuel pressure is good (28-30)


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I tried to start it but it would not fire. After adjusting the timing, It started up and then I fiddled with the timing a little more just by sound and feel. It is running much better now Now the idle is up too high, around 1500 or so. I turned the idle screw in at the throttle body, but it seemed like it was in all the way with my fingers, so unable to get the idle down where it should be.

Any thoughts on fixing the high idle?

Check your vacuum hoses. D-Jet will idle high when there is a vacuum leak.

Will do

YES!

Did you switch back to the proper timing map/vacuum retard on the dizzy? (and set your timing properly with a timing light)

I wanst talking out of my when i mentioned this earlier.

Manifold vacuum at idle pulls timing which results in lower idle speeds.



Beyond that, check to make sure the Aux air valve fully closes and that the crank case venting valve on the oil tower isnt letting to much air past.

I switched the hose from the retard side of the throttle body to the advance side and reconnected to the dizzy, plugged the retard port and it brought the idle down to about 1000. Now need to test drive again and see if this worked.

How would I check the aux valve to see if it is closing?

pinch off the hoses is an easy test. you can use this method on your decel valve as well. And AAR/AAV that isn't closing or a decel valve that remains partially open can both cause a high idle. Your decel valve works best if you set the diaphragm screw to begin opening at 20 inhg in my experience. lower can potentially cause a high idle as well.

If you can only get idle down to 1000 rpm with the TB bypass screw all the way in, something is wrong. Turning the screw all the way in should stall the engine, or at least bring it very close to it.

It sounds like what you did by moving the vac hose for the 123 is just stop it from ADDING extra advance at idle that the "1" curve supplies when vacuum is applied.
Less advance at idle is a step in the right direction, but you are still running to much advance at idle.

it sounds like you had the hose in the right place before you moved it, you are just running the wrong curve.

You gain nothing from running the wrong curve but the inability to fully control/set your idle properly. If you want to try to pick up low end throttle response by futzing with the advance curve then get the fully programable 123 or go aftermarket injection to do it properly otherwise you compromise your idle by running to much advance.

D-jet is a fixed system, designed to be set one way so that all components interact properly with each other.

So again...

Set the 123 to Curve "B"
Dizzy vacuum line to the port that sees vacuum at idle.

i am running either B or C on my current 2056 motor with d-jet and123,
this is different than my stock motor due to the increased displacement, compression,
etc. and different cam, so i think i found for this motor the C was working better than B, which is what is recommended on the 2.0 75 according to the distributor numbers listed on 123 website and in the manual, and the stock motor was perfect smooth idle at 900rpm, no issues at all once timing was set.
75 throttle body does not have both vac ports only one, the retard.

Some guys run it without that hooked up but i think most do.

Phil

I got stuck at the idle speed screw all the way in. Could an issue with the Throtte Body add to the problem?

Anything is possible, but with d-jet a lot of issues share similar symptoms and more commonly people overlook things that you wouldnt immediately expect, like idle speed problems being related to a distributor, timing, fuel or PCV issue rather than an airflow issue.

I have a ebay 2.0 TB in my parts stash that it appears someone tried to "fix" an issue by drilling a larger hole through the throttle plate and another one that it appears someone tried to "fix" by plugging the stock hole with a screw. So yeah, people seem to jump to the TB being an issue first but if your TB is unmolested its usually isnt a problem.

Here is something else worth pointing out that most dont usually consider, or that flys right over their head...

With a MAP (speed-density) based injection system (which d-jet is) changing your timing is also going to change your fueling under the same operating conditions, so when you are running your part/no load timing (vacuum advance/retard) outside of what was specified by the factory, d-jet is no longer delivering the proper amount of fuel for those operating conditions.

Why?

Because changing the ignition timing impacts the amount of vacuum that the engine produces and the amount of fuel a speed density based injection system delivers is based primarily on the vacuum it is sensing.

Adding advance under part/no load from stock settings is generally going to generate more manifold vacuum. With a simple/analog/linear speed density system like d-jet the MPS sensing more vacuum tells the system to inject LESS fuel and while this can be compensated for when the throttle is in idle position by way of the idle mixture knob, as soon as the TPS comes off idle you are LEAN due to the increased vacuum from the advanced timing.

Richer mixture and less advance are both things that will make throttle response feel more sluggish which is why people think they are improving things by jacking the advance BUT advancing timing and leaning fuel mixture (which happens by default when you advance timing with d-jet) are both good at increasing head temps. Meanwhile none of this makes ANY difference at WOT as at WOT there is zero manifold vacuum so you are timing solely off your RPM based advance curve. So your full throttle dyno runs are going to be exactly the same. So while it may feel different there are in reality ZERO POWER GAINS.

Do you really think Porsche engineers left anything on the table with what they had to work with?

Bottom line, to get the best running d-jet system possible EVERYTHING should be set to factory spec, including the distributor advance curve. Seriously think worn out distributors are responsible for far more injection/drivability issues than people realize. Yes gains can be had on a stock motor with a fully programable injection system, but d-jet isnt fully programmable, its fueling curve is fixed and already optimized for the motor. Taking anything out of spec with d-jet causes cascading issues.