VR6 Lurching when accelerating

[peterdinosaur 10]

Small problem with the Vr6 at the moment and really don't know where to start!

 

When I accelerate off the line the car goes, then bogs down, then it feels like a lurch wobbling the car and off it goes again.

 

Wondering if anyone has any ideas what may be causing this?

 

The car has new plugs, ht leads, coil pack and I have put a second hand ISV on it when another one had a problem.

 

Possible other symptoms could include a strong smell of fuel from the exhaust (possible over-fueling).

 

Any ideas would be great, if you can think why it is causing that smell as well that would be good, give me a task list. Also did run VAGCOM on it and it did not come up with any errors, but that was a few weeks ago before the current symptoms appeared, shall run that again this evening!

[Jim Bowen 1]

What coilpack did you put on it, thats usually a sign of coilpack issues. Or the coolant sensors can lead to overfuelling.

[GlosterOx 0]

Was thinking of the Blue Temp Sensor too Jim!

 

Ian.

[peterdinosaur 10]

It is a Bosch/Saab Coilpack with the suitable wiring loom (was going to check that for shorts as well this evening) and I did change the coolant sensor about a month ago, can they go this quickly?!

[Jim Bowen 1]

Shouldn't really go that quickly, i think you can look at the sensors in vagcom and check the readings the ecu is getting to determine if they are working correctly (i'm not totally sure how to do it though).

 

Am not sure if lambda sensor can cause similar symptoms. tbh i could just name lots of random sensors or parts which is what usually happens on the internet :lol: I seem to end up renewing everything and buying spares i don't really need.

[peterdinosaur 10]

Was the plan I was going to go for, just hopeful someone had had the problem! I have already done some of the sensors and known causes, so Lambda next, could the MAF also be another culprit?

[Kevin Bacon 5]

Maf

[peterdinosaur 10]

Right shall get a new MAF sourced and give that a go, shall report back when done!

[A5 VRX 0]

You want a good one though, Bosch is it? I'm sure people will tell you buy cheap buy twice with those things!

[peterdinosaur 10]

Agreed, I am on the hunt for the best price, good one, does anyone know if the 4 pin maf which mine has is the same as a mk3 golf vr6?!

[peterdinosaur 10]

Quick update, ran VAGCOM on it and it pulled up the MAF and Lambda sensor, so should hopefully get those fixed this week and shall see if that brings the engine back.

[peterdinosaur 10]

So update on progress but not a solution yet:

 

I have fitted:

New MAF

New Camshaft Sensor

 

Also run the car with the lambda disconnected and then reconnected making near enough no difference.

As it still returns a code regarding the Lambda is it good to assume that this may be causing the issue.

 

Another point that has come to light is that it seems that 263 cams have been fitted to the engine, but no mention of a re-map, could this also be part of the equation as it does seem to be running very rich atm.

 

As the engine does sound very rattly I was beginning to contemplate just fitting a 2.8 bottom end and refurbishing the head and see where that lands me.

[Jim 2]

Interestingly I've always had similar behaviour from my VR but only really when it's cold. Very similar to what you describe where you start to accelerate and it just feels as if it's trying to cut out almost, and then splutters back into life a bit again and then it's ok. Only really happens for the first 60 seconds of driving or so. Has done it for the last 4 years or so with no real hint of getting better or worse.

 

I too have the SP263's but an engine rebuild hasn't changed the behaviour so it must be something electrical - a sensor or something.

[Dox 23]

Have you checked the condition of the various plugs on the engine loom?

[peterdinosaur 10]

Mine seems to be all the time, but I also suspect the thermostat is broken, so not letting the engine heat up so is always a little cold........another problem I think.

 

I will have a good look round the loom, as some of the plugs look awful. Got some contact spray as well, can't hurt!

[Dox 23]

Well enough of these cars need uprated headlamp looms due to voltage drop, I suspect the engine and ABS looms suffer exactly the same in this respect.

 

If it was mine I'd clear the codes, disconnect the battery for a few hours before a varied drive stopping and starting the engine several times before rescanning without interfering with anything.

 

You'll create a "ghost code" every time you unplug something whilst the engine is running throwing you off the scent. Check for a spark at all 6 plugs and a compression test would be a good move too

[peterdinosaur 10]

Thanks for that plan Dox, I shall have a go at that over the next day or so, hopefully getting something a bit more concrete!

 

Shall also buy a compression tester which should get here for after the check, has had new plugs and leads very recently so would hope that is not the problem.....