Idle issue ABY

[tacq]

Im trying to address an issue with the idle on a S2 ABY. Sometimes, when clutching the rpm drops very low and often engine dies.
The issue is most common driving in heaving traffic, where you can drive 10-15meters and then have to stop again (citydriving).
Once rpm has stabalised idle rpm is fine around 900rpm.

Its tested for leaks, idlemotor is replaced, tried with other throttlevalve, tried with other maf etc but we still have the symptom.
Im more into the possibility that the combination of how the head is modified, cams and inlet manifold is causing this. The question is if there is some thing to adjust that we have missed. Does anybody know if theres something that can be adjusted to address an issue like this?
Its as if the responce is too slow at some points for the motronic to do the job properly.

Engine is "slightly" modified.. : aan-based modified inlet manifold for short intake path, hks 40mm race blowoff, hks i/c, rs2 exhaust manifold, modified cams, modified cylinder head, k26/27:8 turbo, verdi rods, balanced internals, all new bearings, pistonrings and gaskets etc.
Besides this with the idle the engine runs really nice and smooth!

[valjo]

my aby does same things.... but i dont care about it. I will clean idle stabilizator in future.

[Pisobiker]

Try the Lambda probe.
Just posted something about that in the "Guides and Top-Tips" section.

Marco

[S2central.net]

The only item to ADJUST is the throttle position switch - if it is misaligned on the throttle body then the idle mode of the ECU won't engage properly.

Other suspect candidates are the PCV hoses - well any hose really in the air system.

What 'load' figures do you see at idle on VAG-COM when logging ?

Cheers,

Paul

[tacq]

Still problems....<sigh>

I tried with simulated narrowband lambda output from my wideband lambdasensor and I still have problems with engine dying on me.
I havent yet soldered the vag-com interface togehter finally so i cant tell what load it is. The "load" value, what does it really tell? is it relating to boost pressure? - on idle its approx 0.4bar absolute.
And as always if anyone got any idea it would be appretiated...

[Mihnea]

your motronic might need readjusting of the idle pre-stabilization areas, that's quite tricky to do and not anyone can do it. otherwise I can't see anything that could do that. one question, does it do it every time, doesn't the ECU "learn" this? normally the idle stabilization feature is adaptive and it should be able to learn that kind of behavior so it doesn't happen anymore after happening once....

oh and one more thing, is the throttle valve damper still there or not? if it isn't there, it could be the reason for the engine stalling...


anyway, congrats for the irry website, the jettasaurus is a model for my project car, though it most likely won't do the same horsepower!


cheers,

Mihnea

[porkkis]

Just a thought but what about the blow off. Try to disconnect it for a while and go for a test drive.

[Mihnea]

oooooh, I didn't notice that he was running an HKS blow-off valve! An RS2 I've recently tuned is also running such a valve and he was also getting idle problems, most often after restarting the ECU with a new chip version inside, but after a little while the ECU was learning that and no problems anymore.... can't you set the BOV so it opens less under light vacuum?

[tacq]

da hks bov

Actually the hks is actually feedback connected so the maf is actually as correct as possible. I have also tighted the adjustment on the hks without any changes to it.
It doesnt seem like the adaptive adjustments is having any major impact on the issue unfortunately but lets give it some more time I guess.

[tacq]

AF measurement

Today I did pay notice to the a/f value a bit more when it stops on me. It appears as if its rather low values - its running rich that is killing it, something in the range of mid/high the 10's. If I remember I will bring with me a laptop and start to log the data. I can log rpm and two additional 0-5V signals with it which really would help me determine the reason for it.
Still, any ideas are appretiated... :confused:

[Mihnea]

@Tacq: just a question regarding your WB unit, are you using the tech-edge unit? if so, how do you log RPM with it on a coil per plug engine? do you use the tach signal from the ECU itself or ????

Regarding your problem, if you send me by email the contents of the chips you're running, I might be able to solve that issue for you, if you want of course. Be assured that the chip(s) will only be for solving this issue, I only resell my own chips and I've never sold someone else's so far, nor do I intend to do so someday!


Cheers,

Mihnea

[tacq]

Wideband lambda

Yea Im using the techedge unit. Assuming I just can find a pulse signal, I plan to take one it at a ignitor, I do expect that the rest is easily solved since I have written my own software to log the data. The logged rpm signal from the unit is actually not rpm but a time measurement between pulses. I can therefore easily put in the correct calibration value and have a very neat loggin system - im workin on having a realtime 3D surfacechart with afr versus map and rpm

Currently the box has stock chip and unfortonately I do not have tools as of now to read/write chips myself.

Mihnea, do you think a proper mapping would be able to address the issue ?

[Mihnea]

Tacq, I defintely think appropriate remapping will address this issue, especially if you're running stock chips. What stock chips do you have, RS2? Anyway, you can email me at mik@info.fundp.ac.be and we can try to solve your problem through the internet if you get access to an eprom programmer/eraser....

Talk to you soon,

Mihnea

[tacq]

Further information

Well last night I was out with a friend in his car; also an S2 ABY '95 and similair mods as the one I have described above. Exhaust manifold is custommade and inlet manifold has a little different design but its also modified for short intake path. He's running on a MTM 370hp chip with RS2 injectors and "interestingly" is that his engine also had a poor idle handling and stopped on him quite often. Last year when that car did have a more stock inlet manifold it was not showing any issues at all with the idle so Im defenetly in to that its the redesigned inlet manifold (for short intake path) that is causing this.
I did monitor and log his afr value for some time and at highway cruisespeed is like 15-16 and egt of 600-650°C, and at load afr was down to as low as 10-10.5 and egt 650-700°C; boost at 0.7bar with the valve disconnected.

[Henkjan]

I have the same problem on my ABY (Abt chip), and also some members of Meckis forum (very active german audi forum) and of have the same problem.

I did not solve the problem (in the sense that I know what caused it) but at least got rid of the worst of the concequences (the engine dying, could loose the turbo) by adjusting the damper (see pic) that sort of brakes the throttle valve on the last few degrees of travel, I put it so that it dampens the throttle valve a bit earlier, now at least the engine keeps running, even with A/C on, rpms drop to ~500 min. did clean the idle stabiliser (soaking it in carburetor cleaner) but did not yet test drive it (bit hard with the wheels off, I am putting on steel wound brake lines) but will report any positive results here.