Engine spluttering at high revs

[Damo]

Hello all,

Was wondering if anyone could shed any light on a possible problem I have with the car.

It only seems to happen at high rpm in 5th gear.

Basically I was travelling home late last night, had a nice clear stretch of road in front of me so I thought I'd open the car up as I don't get much of an oppurtunity to do this very often. Got up to a silly speed and then backed off. As I said above, I was in 5th gear and got up to about 5500rpm and then backed off. The engine started spluttering and I noticed the boost gauge was going nuts. I wasn't even touching the accelerator but the needle on the gauge was going up and down between -24 and 0. Also, I could hear/feel the engine spluttering/shuddering. It tends to shake the whole car when this happens. I tried it again in case it was a freak occurrence but it does it consistently every time I go over 5000rpm in 5th and then back off the gas. It's fine if I don't go over 5000rpm and I also tried the same thing in 4th gear, taking the revs up to 6000rpm and then backing off and the car was fine.

It's quite difficult to decribe but I hope you get the jist of it.
Anyone know what's causing this, or what's actually happening?

Ta,
Damo

 

[Saul]

could be a spark problem, maybe a coil on the way out

n75 poss, or MAF, or even a perished hose leaking under the heat at the top end

needs logging to help find the route of the problem, have a good nose under the bonnet also and pull a few hoses aswell as inspecting the joints for cracks

 

[Damo]

Cheers for the quick response Saul.

I'm pretty sure the hoses should be ok as I do tend check them over every now again. I will double check them though just in case. I do have a spare N75 valve but it's an H version as opposed to an F. Do you think it's wise to swap these over purely to test this?

MAF could well be the issue. Not sure I should unplug it to do this type of test though. Could I damage the car in any way by doing this?

I had the car rolling roaded on Sunday at Stealth and managed to get 251bhp and 282lb ft so it seems as though the car is quite healthy in that respect.

I just find it a bit strange that it only happens in 5th gear and over 5K rpm. Surley this should be happening in other gears also?

Is there anyone around the Bracknell (Berkshire) area with VAG.com who'd be prepared to help. A few beer tokens available to anyone who wouldn't mind doing some logging for me.

 

[Damo]

Anyone available to do any logging for me then ^

Beer tokens on offer!

 

[Damo]

Pretty please with cherries on top

 

[Damo]

Sorry to revive this but I'm still trying to figure out what the problem is.

I've been told this could be down to the EGR valve not being set right.

I've done a search on EGR and there's lots of posts (mainly for dervs) but nothing that matches my problem above.

Apparently this valve is adjustable with VAGcom but could this valve really cause the issue on my car?

 

[Deleted member 10725]

Egr or a bad n18 can cause boost to go crazy..

I have hesitation at low rpm and im almost sure its the egr not working right.
Mpg is horrible, and sometimes when i acelerate it seam that someone is pressing the brakes

 

[Damo]

To be honest the car is boosting fine.
MPG is quite normal too.

The problem only comes about when I'm in 5th gear and over 5000rpm on a coast down. It's almost like it wants to stall. However, once it falls below 5000rpm it sorts itself out.

I've checked all hoses and there's no splits or loose pipes etc.
I've also changed the N75 valve over for an H type briefly, just to see if this was causing it but the problem was still there so I've swapped back to the original F type.

Would VAGcom actually show anything for this problem ie fault logged?

 

[Copra]

damo, long time no speak

how are you?

i could help you out RE vag-com, im going on holiday for a week this weekend though, so you;d have to wait till im back (monday 1oth july onwards)

let me know if you want to.

mark

 

[Damo]

Aha so that's your new username, lol.

How ya doin mate? It's been a while. You couldn't resist the lure of another SEAT then, lol.

Would very much appreciate your offer when you return off your hols.

Have a good one. PM/email me when you return and we'll sort something out.

Damo

P.S. Nice Leon you've got there. Love the colour too.

 

[Copra]

yeah sorry damo, forgot i changed usernames

i will do, pm me your mobby number and ill contact you when im home

MArk

 

[Damo]

PM sent

 

[Damo]

Hi all,

Sorry to revive this thread but I still haven't resolved this problem.

The cars gone into an independant garage for servicing etc and I've asked them to investigate this problem. He's just called me and mentioned about fuelling. I've got a 4bar FPR on there as part of the K03S conversion. He says the fuelling's fine at idle and also under full throttle but he says that once the throttle is released the amount of fuel going in goes down to a dribble. He says this amount of fuel maybe fine if pottering around town but higher up the rev range the ECU is asking for fuel which isn't there????

I did have a fault code logged which was "17538 P1130 Long Term Fuel Trim mult.,Bank2 System too Lean"

Could my car be running lean at high rpm on a coast down?
Also, is this something that's configured on the mapping side of things?

Really need your input on this as this problem seems to be taking an age to resolve.

Ta,
Damo

 

[Saul]

i take it you had the car mapped for the 4bar fpr?

could mean a lamda probe is knakcered or on its way out

 

[Damo]

Hi Saul,

Yes the car was mapped with 4 bar FPR.

I've just called the mechanic with regards to the Lambda probe. Apparently the probe after the cat was giving some dodgy readings. He said the readings were fine at lower rpm's but seemed to go blank at higher rpm's (over 3K), almost as if it couldn't keep up with the airflow.

Hmmm, nail, hit, head comes to mind. Think you've cracked it mate

Any ideas how much these things cost?

 

[Forbez]

Saul, take your left hand, and pat yourself on the back!!

Cant SCN, have you as a pop up like the microsoft paperclip??

 

[Damo]

Ok, nearly there now!

I'm going to get hold of a new lambda probe. A guy here at work owns an Audi TT and he also had to replace the lambda probe on his. I believe the part is quite expensive but he has a friend who works at an Audi dealership and can get 40% discount. Will I be able to get this part from an Audi garage or is it SEAT dealerships only?

Also, on the parts list at the top of the MK3 forums, kindly prepared by Forbez,
there is a part number for a Lambda probe. Is this the part number I need as I believe there are 2 probes on the car, 1 before the cat and 1 after? Are both probes exactly the same?

Cheers,
Damo

 

[claudefrog]

not sure on the part numbers, but both probes are different in that one has a longer wire than the other and the plugs are different on the end where it plugs into the loom.

 

[Damo]

Thanks Claudefrog.
That may possibly rule out the part number from Forbez. Can anyone confirm this?
Also, if that's the case, please could someone tell me the part number for the Lambda probe after the cat?

 

[Damo]

Managed to get the part no. for this probe. I'll put it on to the parts list thread along with cost.

I now have another problem which I'll create a new thread for (God it's never ending!!!!!)