Engine stalls right after starting

[Lago Blue]

6) OK then as per 20v.org the connectors would be in the driver's foot-well. The ends of them look like this:

Audi diagnostic connectors wiring diagram.png

They are roughly above where your left foot goes, originally likely attached to the bottom of the dash, right where the carpet disappears up behind the dash, mine where just hanging loose back there.


7) IIRC, in that manual there is an illustration of the instrument panel and a list of what the little lights idiot lights in the cluster all mean, correct? Perhaps it lists the CEL, yes? What all lights up during your start sequence currently?

8) If you don't have a functional CEL you will have to either make one light in the cluster work as one or use a hand-held 12v test light (home-made like at 20v.org or store-bought). Some bed-time reading:

http://s2central.com/inst_clust_mil.html#Top

9) What about a jumper cable, do you have one of these?

Audi diagnostic connectors jumper cable.png

10) Further reading, in your case (a 7A engine) ignore the 2 x 3 connectors:

http://s2central.com/blinkhow.html

Want even more reading, photos above came from the SJM website, lots of applicable stuff to read there also:

sjmautotechnik.com

[lukebenish]

I have found my diagnostic connectors. They were shoved up under the dashboard. The illustration in 6 is what my connectors look like. I have a test light. Which points do I connect the test light to?

[newsh]

It was in Lago’s post above

http://s2central.com/blinkhow.html

[lukebenish]

I don’t have the blue connector

[Lago Blue]

That's OK. Why, because as we have read (as per the 20v.org link (in post 6) above), your early build car has only two DTC connectors. Examine the two different shapes, the ends of the two connectors have; and arrange them side by side such that they mirror the arrangement of those in the black & white 2 x 2 connector diagram above. That orientation of the two connectors is also the same as those in the illustration at the 20v.org link. Now read the five numbered steps at that 20v.org link.

Tell me about your test light:
- is it 12v?
- is it incandescent or LED?
- does it function?

[steve briance]

Have you actually done the simple stuff first like check for big air leaks? An air leak might not actually throw up a fault code...

[Lago Blue]

How you making out here sir? Did you have a chance to go through those 5 steps listed under the first paragraph of the Diagnostic Fault Codes page at 20v.org? More experienced folks are piping in with suggestions about what your issue(s) might be and to possibly shorten the process which is fine. When you're just learning about a new car, it is often more difficult to pick a direction for further fault-finding, but you are not wrong to pull the codes first. You need to learn this in any case and to be able to do it as a quick first step in your process.

While tis true that no codes may be found stored, or that codes found are irrelevant, no matter as just like learning to do a detailed survey of the engine bay, one learns by doing it a few times.

Since your connectors were shoved up under the dash-board and IIRC, would originally have been fastened to the package shelf, someone has likely used them before. They may have also installed a bulb to make your 49-state car's CEL circuit function. We shall see. Although not entirely clear in the text of the 20v.org reference above, one probe of your test light (the positive probe if an LED type) goes onto the positive terminal of the "I"-shaped connector (as opposed to the "D"-shaped one). The explanation at the "blinkhow" link in post 16 above is really pretty good, just recognize that to cover all bases, he includes the construction and use of a homemade test light using a diode in his description, so just screen that out as you are reading it.

Questions?

[lukebenish]

I ordered a new test light and I'm waiting on that right now. I have cleaned the ISV even more thoroughly. It still stalls. When I start it, I have to give it a little gas to get it to about 2000 so it doesn't stall. The revs will start dropping without me moving the gas pedal, so I have to give it even more gas to get it back up to 2000. I can then let off very slowly and the revs will settle at about 200 and always feel like it's about to stall. Revs will settle at 1000 if the engine is warm, but I still have to give it gas when I start it or it will stall. But no matter what, if I put in neutral, the revs drop extremely fast and the engine stalls. It also stalls if you keep it out of gear for too long. The engine could be warm, I could reverse about 10 feet, and by the time I would have had it in first gear, the engine would have stalled.

[lukebenish]

I don't believe there are any large air leaks, as I've checked all the hoses (even the one on the bottom of the main airflow hose). The o-ring on the idle screw is very hard but not crumbly or anything.

[lukebenish]

I have cleaned the MAF sensor, but i read on a different post that the female connectors to it can become corroded. When I took off the MAF i did notice a bit of white chalky powder that i scraped off on the housing.

[twoqu]

http://www.20v.org/engprob.htm#isv

You could do worse than work through this.

[Lago Blue]

While waiting for the light...

This is by no means a complete list but gives you some next possible steps:

a) If the powder you found is on the MAF electrical connectors, it needs to come off. Likewise the ISV connector;

b) If the idle screw's O-ring is hard &/or flattened, it may not seal out air from leaking in. When removed, did you make a note of its' position and replace it to that same adjustment spot or where did you set it to? Did you clean out the passage it is installed into?

c) One should not simply think there are no relevant air leaks, one might be best served by proving there are none. Towards that end, find the vacuum diagram/under-hood sticker for your car and do a physical survey tracing its' branches to ensure all is connected and not cracked, crumbling or torn (the little rubber elbow boots and fabric covered hoses are famous for this). Often overlooked (cause they're -not- on the vacuum diagram, but are part of that system) are the dip-stick O-ring, the oil fill-cap gasket and that entire crankcase vent tube (the one which connects to the underside/mid-point of the M/M hose) all the way back down onto the lower engine block on the LH side, they need to be un-split, complete, compliant and current century;

d) Try to do step 2 in particular if possible, of twoqu's suggestion above if you haven't yet done so;

e) Go back through this thread and try to answer any outstanding unanswered questions asked of you where you can;

f) What is the state of your filter-box interior?

g) Did you carry on through the code pull procedure to see if you may have a functional CEL (or not); and consequently have no need for a test light?

[twoqu]

Might be worth checking some basics such as the spark plugs. Perhaps they are loose or something. In fact they might give a clue as to whats goings on if you fancy removing them and replacing them. If I have understood the info correctly even if the ISV fails the engine should still idle. Of course if you have bought the car like this its difficult to know what somebody else has done beforehand. They could have altered the idle screw for some reason for example.
I would follow the advice about trying to pull the codes first. It looks like a Maf issue would cause those issues but without confirmation its pointless replacing things in the hope of getting lucky, not to mention expensive! So basically its a process of testing and eliminating things.

[twoqu]

Is the fuel fresh? Petrol degrades quite quickly and in effect causes a richer mixture and possibily plug fouling. I know we are quick to point the finger at external factors without examing some of the basics. So as above I would whip the plugs out and either clean or replace them and stick some fresh fuel in it. If you know the fuel is stale then you could either try and drain it or use it up before replacing the plugs and fuel. If you have access to a compression tester then it would be a good opportunity to confirm that the engine is healthy.

[lukebenish]

The fuel is fresh. I did check the spark plugs and one of them was wet. Not sure if its gas or oil.