VW Corrado Loss of Power

[Mignon]

Looks like a MAF so you're probably reverting to a default fuel/air mixture built into the ecu with it unplugged.

[Tony1963]

Yep, maf.

So, you’ve handily carried out some fault finding there!

As mentioned above, your ECU has now reverted to a basic mode. The good new is that a new maf is fairly cheap, and easy to fit.

I think you’ll be surprised at how much better your engine performs as the maf has probably been giving poor signals for a very long time.

[Jim H]

Thanks for all your help and advice chaps..
Got to admit I'm fairly embarrassed it's taken so long to narrow down! I've been running Corrado's for 20 years, this is my second, the reason being they are fairly bullet proof and very reliable.. This has been my first major issue in all that time.. They rarely go wrong!

[Tony1963]

Well, I suppose your fault finding skills would be suffering if you drive a reliable car! Don't be embarrassed

[Jim H]

Salut Mignon!
It looks like you were right on the money a few posts down. It appears that item on the air box is what measures the rise and fall of the air flow plate via some sort of potentiometer which is now worn. There is no seperate MAF.The whole metering plate is NLA .. There is just one on e bay but very pricy! However there is a replacement potentiometer arrangement also on the bay (from China?!)
It looks a bit of a faff but doable.. Has anyone attempted a repair like this?

[Mignon]

Nope.

[Mignon]

The replacement potentiometers are readily available from Bosch. Cheapest on Ebay is about £115.

If you take your potentiometer off and remove the cover to look at the tracks you may see something like this where part of the resistive track has been worn through.

http://www.peachparts.com/shopforum/attachments/te...

[Mignon]

I've not looked into it much but there's a resistive substrate material available called Graphit 33 which you can paint on and maybe restore a worn potentiometer track. About £10 for a small bottle of the stuff. I have no idea if it will work though.

[Jim H]

Hi Mignon, many thanks for that. Have you a link for the Bosch e bay kit? Or PM me.. I've had a quick look on the bay and can't see anything specific.

Regards Jim.

[Mignon]

Google this part number F 026 T03 02 plus 1 digit for your specific application. Can be a 1,2,3,4. I'm not going to do your homework for you.

[Jim H]

Yup! This ye olde chestnut again!
I purchased the part from China an received within 5 days!
Perfect quality and replica to original Bosch part.
When fitting I realised after a bit of thinking - and poor results...
The Spring contacts that make contact with the circuit board were not making contact! Weakened with age. Gently bent them to make contact, and it runs ok - except it won't tick-over.

It will at idle, but as soon as you load up the drive train, it dies, it re - starts ok, but as soon as you go for a run and dip the clutch. It stalls..

I opened up the throttle butterfly's on their 'stop' adjustment. And it fixes when the engine is warm..

When cold - NO..

Any ideas ?

[GreenV8S]

Jim H said:

.
The Spring contacts that make contact with the circuit board were not making contact! Weakened with age. Gently bent them to make contact, and it runs ok - except it won't tick-over.

Is this a spring contact between the moving vane of a mechanical air flow sensor and the resistor track? If so i wonder whether the moving vane is sticking, perhaps aggravated by excess spring force causing friction.

[Jim H]

^ After time to think about it, I was thinking similar. I'll have another fiddle later.

[Mignon]

I gave you a link when I first suggested it was the potentiometer. It's likely to have different resistance values to the original one so the engine is running weak I'm guessing. You need to go through all the calibration steps.

[Jim H]

Many many thanks Mignon.
Without your advice I think I'd be chasing this issue for a long time!

It did need adjustment, I read the link you'd previously provided (I'd forgotten you'd placed it)

It's not running perfectly, but it's a huge improvement - and I'm in the ball park now!..

I owe you a few Beers sometime - cheers fella!

[Mignon]

Glad I could help. It's been a long time since I played with those systems but the potentiometer is usually favourite when they play up. I assume your car is closed loop so it'll learn the fuel trims soon enough and drive better and better.