UR Turbo / Intercooler / Sensor query

Started by FRANS, April 07, 2005, 03:34:20 PM

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FRANS

My car has recently been at Continental for servicing and a 'new' (ex 200T) head. It was running 100% perfectly before, but the day I got it back there was a problem. Like two years ago, when accelerating it would hesitate (like rev. limiter) when hitting approx 3800 revs. Since it ran perfectly before, my simple reasoning is that the garage didn't put things back together properly (when fixing various things last Saturday we also did find several spare nuts lying around the engine bay, left over from the stay at Cont. and a loose driver's armrest). It is only intermittant, so not the ECU ?!!
I dropped the car of at Cont. on Wednesday 6th to fix it: it still hesitates at 3800 when accelerating slowly, but when accelerating with foot to the floor: no problem all the way up to top revs !! The latest from Cont. is that the Intercooler is leaking and being repaired, but how does that tally up with the car running OK with foot to the floor ??
Please contact [email protected] or mob.: 0274 961789 / office: 5270025 if you can help.

orggti

i bet theyll charge you heaps to fix the intercooler and all you do is put knead it over the end seams. i checked the switches and they were fine once i put the wires on correctly. there was also a wire broken off from a three wire plug that goes into the metering head, whats this one for ?

John Stone

It sounds like the air temp sensor at the front of the inlet manifold, check those wires under the rubber boot, they can break and cause exactly this fault.
As Rex says any air leak will cause hesitation.
Also worth checking the injector shrouds aren't loose.
I'd be surprised if it's the intercooler.

John
86 WR
04 A3
05 V50T5

orggti

9i think its the air temp sensor too by the sounds of all this. Frans said this broke before and it did this, we checked the wires and none were broken this time but maybe its just broken  anyway.

Mike

You are doing exactly the right thing - it is well worth getting expert advice when getting a car like this fixed at the dealer. Since they can't plug in a diagnostic device, they get caught out when they have to do some old-fashioned head-scratching, which to a large degree depends on knowledge and experience. Many mechanics at dealers these days weren't far out of nappies when the Ur-quattro was in production, and they rely heavily on diagnostic devices.

An example: Koni Sports put in my 1987 (non-turbo) Coupe quattro. When I got it back the ABS did not work (was working perfectly before). It was caused initially by the dealer deforming the sensor teeth on one of the hubs. After I'd taken the car back two or three times they realised this and fixed it - but then they adjusted the sensors so they were too far away from the hub so they did not detect that the wheels were turning. The ABS light did not illuminate, but the ABS would not work at all. Took them another day to work this out. Good job I'm not paying for it.

The problem is finding someone who really knows these cars.

SimonS2

#5
As a long sufferer of cut-out/hesitation issues I'll make a comment, based on various cut-out hunts undertaken with my S2 by myself and Continental.
-Inlet leaks (as Rex notes) will cause the mixture to mess up. I've had a blown bypass valve cause problems, then a dodgy intercooler o-ring cause rough idle. Result always looked like a mixture/sensor problem on the surface. Should be easy to pressure test with the right gear, but I don't think CCS do this.
-Connections to all sensors can be cleaned with isopropol if you think they might be dirty/corroded.
-Then you can test the output of the switches and sensors that Rex notes.
Anyway, this probably doesn't help much, but I once had CCS go through absolutely everything, including testing output of all sensors, finally to find something inside my ECU was playing up. Several days in their workshop was quite pricey: the best solution would have probably been to find another similar vehicle and swap bits over until the faulty component was isolated.

Let us know how you get on: I'd say Continental are pretty good, but it might cost you a lot as they go through all the possible problems (if it can't be confirmed the fault is theirs). Cheap DIY like presure tesing and checking connections might be a better start.

RichardNZ

I had the temperature sender thing happen to me a while ago.  From memory, what happens is when you get a high resistance joint the ECU see's it as a very high temperature and therefore limits the maximum revs to around 4000.  Given that your machine performs OK when you 'floor it' I don't expect it to be the temperature sender. What typically happens is that the connection on top of the inlet manifold gets physically knocked or torn away from the sensor.  From memory it is covered by a small rubber boot.  At the end of the day it is a very easy component to test.

John OB

The problem has been cured. Cause was poor connections on the throttle/intake sensors. These were removed during head overhaul and maybe when they were replaced there must have been some corrosion which preveted a good contact. Running beautifully now!