Gti6 Hesitation At High Revs

[James_K 6 1 Cars]

I was driving my 205gti6 yesterday having had the exhaust repaired and was able to stretch its legs for the first time in a while.

 

I found however, that at about 6,000rpm the engine was hesitating and acceleration was quite jerky beyond this point. This happened consistently in 2nd & 3rd gear. It's never done this before.

 

I've done a few searches and suspect the MAP sensor may be at fault. Does this sound familiar to anyone?

Is there any way of testing what the fault is or should I just replace it and hope it was the cause?

 

The lambda sensor is fairly new, so don't think that would be the problem.

 

If I do get a new MAP sensor should I go for a bosch one from peugeot or are the pattern parts worth a punt?

 

thanks

James

[bas1974 0]

You could replace the MAP sensor with another one wich is working well, however a faulty MAP sensor will have a greater effect on the engine.

 

You mentioned you repaired your exhaust, was this before or after the lambda sensor?

 

Air could be sucked in the exhaust resulting in a faulty lambda.

 

Peugeot is quite expensive on electrical.

[James_K 6 1 Cars]

Thanks for the reply, the lambda was fitted new before the exhaust blew in the centre box, so maybe that has caused the problem.

Is there any way of easily testing either the MAP or lambda?

 

What doesn't seem to make sense is that it's only above 6k revs that there's any sign of a problem, I would expect issues across the rev range, but I'm no expert..

[bas1974 0]

Centre box, so air should not be the problem.

 

You can test lambda by unplugging the sensor, the ECU will be given a default lambda=1

 

The MAP sensor should give a fluctuating value between 0 and 5V, if you unplug the sensor with a running engine the engine will shut down.

[Vili 18]

Lambda shouldn't cause hesitation at 6000 rpm, since the ecu is running on open loop at those revs and doesn't use the lambda signal for anything. Did your center box blow because of backfire? Do you have the original style split downpipe? The dividing wall in the downpipe has a tendency to well err.. split and block the exhaust. It causes pretty significant backpressure and loss of power.

Edited September 5, 2012 by Vili

[James_K 6 1 Cars]

Vili, thanks for the input, the centre box blew on track, mainly because it was old and had been previously repaired.

I'm not sure about the downpipe confirguration, but everywhere else in the rev range the engine pulls really well - doesn't feel like there's any back pressure through the exhaust.

I suppose I could take the downpipe off and have a look, other than that, if it's not the lambda sensor I'm running out of ideas..

[James_K 6 1 Cars]

Since the previous suggestions I've tried various things to try and find the source of the problem with my car.

If anyone has any more ideas on what might be wrong, please let me know as I'm getting seriously annoyed by it, since the last suggestions I've tried the following:

 

Unplugged lambda sensor - no change

Unplugged map sensor - no change (other than rough running)

Changed the spark plugs - made no difference

Changed the coil packs - again no difference

 

The 'K-light' warning light now occasionally flashes on when the car gets to 5-6k revs and starts hesitating, there's also a rapid fire pop pop pop sound from the exhaust (this has been there since the start).

 

Is it worth getting diagnostics on it, bearing in mind its a phase 1 gti6 conversion so not sure if this can easily be done?

As I understand it the k light means either ignition or fuelling issues, could it be related to the fuel pump/fpr?

The car runs perfectly well through the rest of the rev range, any ideas would be welcome as I've run out..

 

thanks

[Miles 331 1 Cars]

If it's a phase 1 then the 2 pin plug should still be by the ECU, Mind not many people know have the kit to test these older car's, But if you can get it done then at least you have a idea of what's what

 

I can loan my Diag out but would need a £500.00 deposit for it, Just in case

[James_K 6 1 Cars]

Thanks for the offer Miles, I'll see if I can get some diagnosis done locally, if not I might take you up on that.

 

cheers