90Audi200TQ

Gentleman and Ladies,

Thank you for all your assistance, it has been greatly appreciated.

That being said, for those just reading: This is a continuation of a post "Where to begin, Idle trouble."

Well here is what is new, this morning I got up early before work and replaced the intake hoses that I took off and sealed.

Long story short, the car started right up... though there was still a slight engine misfire and an undertone like the car would stall.

So I played around with the throttle screw a bit taking it out a small distance from its all "In" position and that seemed to help.

Next I began to play with the WOT, and the ISV, here is what happened:

1) With the ISV disconnected and the WOT connected: the car ran but it was a little rough. When I would Revv the engine the car would stumble before catching and returning to 1000 rpm idle.

2) With the WOT disconnected and the ISV connected: Starting the car from "Off" the idle rose to 2500 and stayed there until I either disconnected the ISV or Reconnected the WOT.

While Running: With the WOT disconnected, there were no idle problems, nor stumbling of the engine... even during times when the car was revved heavily.. each time the idle fell to 1000 rpm ... with little to no misfiring.

Now to those reading this, one can assume that It is obvious that the WOT sensor is bad....

My question is... Is my WOT malfunction hypothesis a correct one?

The car will not start with the WOT disconnected, but it wont run correctly with the WOT Connected...

Thoughts and opinions are greatly appreciated.

Arent Audi's Fun

Thanks Guys

Regards
Martin.

comp_jas

Did you pull the codes?

Any chance the coolant sensor is bad?

jurq

Test the MFTS, as this sits between the throttle switch and ecu.

90Audi200TQ

Hey Guys, thanks for the replies.

1) What does the MFTS stand for? Also how do I check that?

2) Where can I get a code reader for Audi? I went to my local European car parts store and asked if they had code readers and I was all but laughed at when I mentioned I was working on a 16 year old car.

Also I believe the coolant temp sensor was replaced by the dealer about a year and a half ago when the PO took the car in for service.

The car runs great with the WOT sensor disconnected. Basically all I need it connected for is to start the car... Once its running... if I unplug the WOT, all hesitation and poor idling goes away... at least so far as I have been able to test in the short term.

I do have a question for you guys who know: What Bosch injection system does the Audi 200 use? Is it the KE Jetronic, L-Jetronic, or Motronic? I have tech books for tuning every bosch injection system, but my glossary of car makes and models does not list the Audi 200. So I am curious which it could be.

Thanks Again Guys... I think this car is getting close to being on the road again.

Regards
Martin.

jurq

1. Multi Function Temp Sensor. Part is cheap enough, so if it hasn't been replaced in a while, if ever, then now is the time to do it. Not sure of a continuity test that you could perform to determine if your is still good?

2. Your ecu will flash codes without a 'code reader'. Start the car, drive it, including a full-boost pull in 3rd, drive it home, leave it running, open the fuse box, and insert a fuse into the relay that has two slots in the top to accept a fuse (you'll know it when you see it). Then pull the fuse back out. Get into the driver's seat and the orange 'check engine light' will flash any stored codes to you. Scott Mockry's web site (sjmauto.com) has info on this as well as the fault codes and what they mean.

HTH,
Jim

comp_jas

1) Multifunction Temperature Sender. I don't think this is the problem.

2) YOu can't use a code scanner. Visit

sjmautotechnik.com

Diagnostics will give you the information.

Will Ng

Just thought I'd mention...if memory serves me, the WOT switch is daisy chained to the idle switch. I believe when the WOT switch is off, it routes GND to the idle switch circuit. Disconnecting it may be confusing the ECU, or the idle switch is bad, and the ECU thinks it's idle all the time when you connect the WOT.
Just a thought.

ISV should be out of the loop whenever not at idle.
With the ISV disconnected, and the throttle screw in, your engine should maintain 650-700rpm idle.

ISV working should bring it up to 800rpm and 950-1000rpm with the AC on high.

But before any tweaking, verify there are NO vacuum leaks. These cars are prone to them. If you can't get to all the lines, then pinch off every line as a possible source of leakage before diagnosing sensors, switches, etc.
With no leaks, the engine should be able to maintain a perfect smooth idle of 650-700 as mentioned.

90Audi200TQ

Gentleman and Ladies,

Well let me run this by you and see what every one thinks.

1) Poster "Jurq" Offered advice on how to pull engine codes: I drove the car as suggested, not easily I might add, however when I inserted the fuse into the holder and then removed it, no codes came up, infact the screen didnt even flicker... So I am at a bit of a loss on that one. In fact the only thing that did happen with the fuse in place was it caused the idle to fall hard, which stalled the car making it really hard to re-start.

2)With regard to the WOT, the only thing I can notice with it connected vs Disconnected is that:

=> After Full Acceleration and Decelration:
a) With the WOT connected the car stumbles and almost stalls
b) with the WOT disconnected, the car runs normally after hard acceleration and deceleration.

I checked for vacume leaks, and I sealed every hose I could find, using gasket silicone and new clamps on every end, and pressure testing each hose before re-installation.

Unfortunately I dont think this is going to be an easy fix. One thing I will add, this car was HIT and HIT badly in the right front when it was new. Dealer records say that the engine is the original, and all sensors along that side were tested to be good and were NOT replaced. The WOT sensor is right behind where the car was badly crunched, and as I had posted in other threads, the PO had a seasonal idle problem which needed an adjustment every six months.

So It is possible a Tech, at the Dealer was performing some adjustment to the throttle body or the WOT. All I know is that the car runs at 1000 rpm with the WOT disconnected, and doesnt with it connected.

Basically all I need the WOT connected for is to start the car... other than that it only seems to hinder the process..

Also Any thoughts on why my engine codes are not flashing when the fuse is inserted and then removed???

Thanks Guys

I dont think this job would be as "Easy" with out your input.

Regards
Martin.

90Audi200TQ

Hey Guys,

I was sitting at work, and of course I was thinking of my Audi instead of working .... and a thought came to me...

1) Before I left for work today, I took the car on two test drives.
a) The first drive I had the WOT connected, and it was terrible, bucking, stalling, no power etc...
b) The second I disconnected the WOT just after getting the car to start, and my gosh what a wonderful drive. I had it winding out, the turbo screaming, and there was power to spare.

When I got home after the second drive, I plugged back in the WOT sensor and the car immediately began to falter.

SO I took the WOT off again, and began to play with the ISV and a 9V battery.

Now let me prefface the second test drive success by saying that the idle screw on the throttle body was about 1/3 of the way out when I drove the car... it is only in this position that I was able to at the very least start the car with the WOT connected.

With the WOT disconnected, and a 9V battery hooked to the ISV, I was able to maintain a stable idle with the screw all the way IN.

If I tried this with out the 9V battery, within a half a screw turn of adjustment the car would stall flat.

However with the 9V on the ISV, I could turn the screw all the way in with out any problems, and revving the engine was a breeze... I didnt have to worry about stalling.

SO, any thoughts here??? I am reasonably sure all the vacume leaks are gone as the car behaves normally with poster "tonyj's" vacume leak tests. Besides with the WOT disconnected the car has plenty of power...

So I am inclined to think that either the WOT is bad OR that what ever process operates the WOT and ISV together is out of sync.

An added thought... On a lot of other bosch cars that I have worked on there was an AFM/Air flow meter... I cant seem to locate one on this car... usually on the air box on other cars, I cant seem to be able to take this one apart to check.... Thoughts???

Any who, thanks guys for reading... I appreciate all your help... When she is back on the road it will be a great joy and success for every one.

Thanks Again
Regards
Martin.

Will Ng

With the ISV/9v battery, you're able to idle because the ISV is cycling and adding extra air, the screw can stay closed.
Once without the ISV, it needs the screw opened to get more air.

I'm going to go on the limb to say by running without the WOT switch must be leaving the car in open loop WOT mode. Hence running rich...and this must be compensating for extra unmetered air from a leak somewhere. The car feels good.
Connecting the WOT may be returning the ECU to closed loop mode. And the ECU can't compensate due to out of range perhaps. Is the O2 sensor good? Any trouble codes?