OMP

Hi.
For some months, my 200 10V AUTO. has been doing things wrongly. Head gasket was replaced and everything put together but from that point on, symptoms are as follow:
- Cold start: Car will turn for about 3 to 5 seconds and the car will start with low idle and then pick up at around 1000 rpm and then drop to 800, but somehow, with a sensation of a "fragile" idle once going down to 800rpm. It will hold, but not very "nice" to see. Cold valve works ( as it was tested disconnecting it an checking fuel coming out)
- Hot start: Very long engine turning times. Up to 8 to 10 seconds and with the help of the gas pedal. If not aided by the gas pedal, idle will be very low and then pick up again to about 800, but again, hesitating, not very "solid". Although no stall once stabilized ( after a few 3 to 4 seconds holding it to about 2000 rpms)
.- Running cold. Not an issue. When started, she would run like it should.
- Running hot. Here is the big problem. Once started and transitioning from cold to hot ( at about 75ēC ( a bit before the middle mark)), the car will sputter from standstill up to about 1800 rpm. From that point on, no issues at all, no sputters, no ignition related issues, no nothing beyond 1800 or so.
WUR was bought new about 6 years ago and has no more than 10000 KM in it, but all symptoms point to that, but not willing ( yet) to gamble by buying a new one. Suspicion is that either because it was disconnected for some time ( head gasket and getting back the car took about 2 months ) some dirty deposits are blocking fuel lines and thus, fuel pressure. Or the WUR itself has been upset somehow and it is not anymore set up as per specs, and again, having fuel pressure issues......
I am not a big WUR specialist ( although I do know about this car mechanics), but I just have this idea arounf the WUR, since everuthing has been checked/tested/changed. Both temp sensors ( the small ones) were replaced ( in case they had to do anything with the hard start situation), and all vaccum lines, plugs, ignition set, distributor, all is as it should be.....

SO, are these symptoms related to a wrong WUR? Could these go bad or maybe just dirty? Before the Head gasket job, everything was running beautifully...

Thanks for any advice......

a-talk

Hey OMP,

I would suggest checking every connector in the engine compartment. Several times I have seen wiring get pulled or even cut accidentally during major engine work. The last three drivability issues I chased down with my old Avant were related to damaged/cut wiring or something being left unplugged.

Second, I would test your fuel pressures at both cold and warm running. The system pressure and control pressure should both be tested and verified, as a low system pressure might indicate a fuel pump issue. This will determine whether your WUR is working properly.

Thirdly, I do have a known working WUR that is for sale. But truthfully, I don't think that is your issue.

bradwilcox

O2 sensor?

Ensure ALL fuses are present and good, even including the so-called spares and especially the ones dedicated to the engine computer or however they call it, which is usually under a dedicated red cover.

jaka54

Hi!
This winter my Audi 100 Avant 2,0E -89 (5000 to you in the US) was very hard to start cold.
Thought first that the cold start valve was faulty ,but it wasn't. Second thoughts went to the "termo time sensor" that sits at the back of the engine but nothing wrong with that either.
Finnaly I removed the solenoid on the starter motor and check it. -It did not work! Bought a new one and my engine started instantly!

audi_marv

Check your Idle Stabilizer for your weak idle issues. Clean thoroughly. There also may be an idle control unit in the aux. fusebox below the steering wheel that may be an issue. Also check the sensor right below the power steering bracket for a bad sensor or wire, which affects the idle.

Also sounds like you have a heat soak problem. Either your injectors are leaking fuel when hot, or your fuel pressure regulator has gone bad. These will result in long starts when hot...but fine when the engine is cold (the cold start valve kicks in). Further issue could be your fuel pressure accumulator, located in front of the rear passenger wheel. If when you shut the car off too much fuel goes back into the tank, it takes a long time for the fuel to get back up the lines, causing a hard start.

Hope this helps.

OMP

Thanks guys. I have been away for some time but I am back.
OK, so. I had the chance to drive the car after it has spent about 3 months in a known fuel injector shop. This was done after my initial post in this thread.. Here is the thing.
O2 was bad, so CO could not be regulated. All fuel pressures have been revised and WUR has been set at its proper values.
So, WUR is supposed to be good. O2 changed and CO corrected. Both small temp sensor ( the single wire ones) were replaced by new ones as first options because of the temp related behavior.
So I have had the chance to drive the car around after all this and still crappy:
- Cold start: Ramdom "good" start: Just by turning the key, the car will start nicely ( around 1000 rpm, solid, no shakes)....But, after a few secs, idle would come down dramatically, almost to a stall situation ( around 400-500 rpm), then, a few seconds after this, it will pick up at around 700 and it will hold it. It never stalls, but it does fight a lot not to happen.
So I said "random", because other times, I would have to crank for about 3-5 seconds and it idles very low right away ( no "trip" to 1000 rpms), just barely turning, at around 400-500, then will pick up at around 700, but fragile. Still no stall. So that is for the Cold start
- Hot start: I have ALWAYS have to give gas ( have way) to start the car if I don't want to burn the starter. Just for testing, I did start once without the gas pedal, and it will, but not willing to do it on a regular basis.
- Driving the car: Here is also a "random" situation ( don't you love these!!!!???). Car will sputter a bit up to 1500-1800. It is not as dramatic as when I first wrote, but still does it. This sputter manifests itself once the car gets hot ( about the 75ēC-80ēC mark). Before that the car runs very good. So when the car is hot, it sputters between 1500-1800 rpms. It does it way less than when the car was brought to the injection shop. HOWEVER, and is the catch: Randomly, the car will just "switch" to normal, completely normal situation: Stable idle, to sputters at all, and just plain, solid driving.

So, up to this point, the shop tells me that:
- Cold start valve is working fine ( I assume as on those "random" good cold starts, it is because it is working fine)
- Idle Stabilization system ( Unit, basically), has been switched with a known working one...... On this, the guy tells me they have a "good" unit, even if I haven't seen it...Telling you this because the Automatic MC-11 uses a specific Unit, and that of a manual one or from an Audi 100 is not supposed to work, even if they look the same. Mine doesn't have a letter at the end and all of rest I believe they do. So, on this, I am a little bit sceptical.
- Fuel pressures are set at WUR side ( don't have the values right now but I'll ask for them).
- New O2 sensor
- Guy tells me he has checked for Idle switch position sensor and it's working fine.
- Of course, no air leaks
- Everything on the car has been changed in past 7 years or so, including the new WUR ( now set up with good pressures), fuel pressure accumulator at the back, new fuel pump, injector seals ( no leaking at all - tested and proven as this was the very first thing people looked at).

Telling you additional things:
Yesterday I spent a little time driving the car, and I thought about a few things. So I stepped out of the car I went to check the idle screw on the front of the manifold. The screw was almost all the way out, about 2 turns of falling off.....I said "WTF"!!!!!, there is huge amount of unmetered air going into the engine......My extensive experience in this car tells me that the screw is to be all the way in, completely close. I know some of you guys will tell me that it is used to adjust idle speed. I am OK with that, but maybe one half turn or one full turn, but not 8 or 9 like it was.......I didn't like to see that.
One other things that strikes ( and I have had the car for a long long time and have learn a lot), is that the CIS frequency valve ( I a referring to the one sitting below the fuel distributor plate that buzzes). Anyway, I know ( maybe you can second me on this one) that it has to be bussing at cold and then, cycle ON-OFF ( 1 second frequency approx.), BUT, Mine buzzes ALL THE TIME. And this is pissing me off, as I know that in the past the car has been running well and this buzzing was clearly ON-OFF once the car would get warm.
Except for this I haven't seen anything else "suspicious". HOWEVER, here my final thoughts:
- I am still sceptical on the Idle control unit the guys used and switched for mine to check ( Will have to see it with my own eyes)
- I am very sceptical about having the idle screw almost about to fall. I pushed it all the way in when I was about to leave the car parked. Idle went down and a bit crappy, but no stall. Will have to drive it more with this set up
- Very, VERY sceptical about not hearing the CIS Frequency Valve cycling ON-OFF and hearing it ON always. Guy tells me this has to do with the canister and letting gas fumes come out of the fuel tank. Again, not so expert on this but still, very sceptical.

Anyway, sorry for the loooooong story. But I am determine to make the sucker run flawlessly before I die in the attempt of it....

Oh, one thing......When the car pasts this "sputter" situation or ( in the case it doesn't do it - the random thing), the car just drives PERFECT. The fuel pressure set up and maybe the new O2 have make the car fly at normal, highway speed situations. I have the QLCC Stage 1 chip and 1.9 BAR spring and boy does it go........It is really nice to drive.

OMP

OK guys. I'll just keep writting in case you guys want to follow up.
OK, so the day before yesterday, I closed completely the intake air screw all the way in.
Yesterday, went to test and here is what happened:
- Cold Start: Around 20ēC, I guess that is considered as a cold start. Anyhow, no foot on gas pedal: crank, crank, crank, crank.....after a freaking 7-8 seconds, car starts, idle at 600 rpm, battery light on as no yet charging.....I don't do anything and I wait....Then have to give just a bit of gas so that system start charging. It does and comes back to 600, very fragile but no stall, although shaky and with a little oscillation ( +/- 30 rpm . Let it just warm a little bit....no changes. From time to time it does "try" to come up a bit ( maybe around 750 rpm or so, but nothing really picks up solidly).
So I go for a ride: Lights on, car barely holding idle ( but not stalling at any time). Car is about 65ēC ( refrigerant temperature). Car drives quite well! No sputter, no hesitation, no nothing. It pulls strong and drives very well.
Come to a red light, idle at around 700 rpm, still feel it fragile. So I go on the highway ( a short, about 3 mile ride), then it has reached its 90ēC operating temperature, come to a "yield" and then, car sputters from stop. It is less than initially, but still sputters.......not good, although not that tragic....It is still a problem, though.
Come back to the parking spot, let it idle, open the hood and disconnect the TPS connector.....rpm's rise a little bit ( and still some oscillation, again +/- 40 rpms or so. Idle maybe at 700 or so). So I said to myself the TPS is working.
I keep hearing the CIS frequency valve working all the time, to cycling ( Don't like that), so I see the O2 sensor and just for testing sake, I disconnect it. No changes at all, not a minimal change in idle.....At this point, question is: Should the O2 disconnected "cause" anything? Should I notice anything on the idle?
Based on the above......I would be very grateful it you could answer the O2 disconnection issue......
Anyhow, next step would be the ISV system: I know the temp sensor is new, the ai pass valve works as intake screw is all the way in and car holds idle ( erratic and low, but holds it). I did once disconnect the air pass valve and the car stalled....So, I assume it is OK, unless I am not doing the right checks.

Anyway, will go on with my searched.

Thanks for reading anyway

bradwilcox

Just want to ensure you read this, if you haven't: http://www.sjmautotechnik.com/troubl...g/nostart.html

I have a 1990 turbo 10v, stock, and it starts hard 90% of the time, no matter hot or cold. Always runs fine, however. 10% of the time, hot or cold, it just leaps to life in half a second. No common denominator.

The car has been extensively combed through by a well-known Audi repair shop for many issues, this being one of them. They could find nothing addressable. The mechanic who specializes in the turbo 5 says that when the engine has miles on it, every engine he sees exhibits this issue. He told me to just tip in on the gas pedal while starting and live with it, assuming the engine runs fine once stabilized.

briangates

My 87 5000CS has a super similar situation but almost every cold start i have to actually use starting fluid to start the car, and then it wants to die for about 20 seconds and then runs 100% perfect, drives amazing etc. Hot Starts its a 50/50 shot of turn key and go or pop the hood and spray the starting fluid. i have a 10vT MC1 and have not for the life of me been able to figure it out.

briangates

Also note on my 87 5000 i drove it all the way across the country with that condition..... and i have been trying to diagnose it for the last 3 weeks since ive been home.