Uneven power delivery
 

Hi all. Having recently had my engine replaced after an unfortunate encounter with detonation, I am experiencing some uneven power delivery, particularly in 3rd, 4th and 5th in mid to higher revs.

What happens is if I accelerate gently rather than balls out, it feels like the turbo is sort of switching on then off two or three times. Its not really that rough either, feels sort of smooth but is very annoying as the only way to get round is to completely put my foot to the floor, which is not always convenient.

I have had other work done on the car previous to the engine replacement; STI intercooler and panel filter, pro drive exhaust system, walbro fuel pump and a remap to 270bhp/1.2 bar turbo pressure.

Any ideas what could be causing this problem and how to resolve it ?

D

Anyone ?

Boost solenoid not working/inadequate for the boost pressure being run perhaps?

Have you spoke to your mapper?

Ns04

did you find the cause of the engine failure?

hessitation could be many things.. lean for example... could be maf failure.. what year is it?

Simon

^^^^Mapper here, listen to him!^^^^^^^ :thumb:

BTW if you haven't already got a knocklink, I'd give VERY serious thought to getting one!

Ns04

The guy that changed the engine for me couldn't be certain what had caused the detonation no, but I am beginning to suspect that it may be due to lean running at the higher revs - I have certainly been driving very carefully since I got it back on the road.

I plan to get an STI8 bonnet scoop fitted and I am definately going to get a knocklink fitted ASAP. Hopefully those two things should build in a margin of safety to reduce the chances of future nightmares

It is a worry that I don't know exactly what caused the engine to blow, but I am trying very hard to learn more about the technical side of things - I think ignorance probably paid a big part.

Is the boost solonoid something that I could change myself or is it a complicated garage job ?

I haven't been back to the original mapper as I don't feel I can have confidence in their work as although the surge problem is worst since the engine blew, it was evident immediately after the remap.

I also heard that getting the exhaust headers ported would help with power delivery - does that ring true ?

D

Sorry missed the year - its 31/12/01.

sounds like a mapping issue.. the dead engine showed signs of det??

ported headers are better than non-ported but you need to resolve the problem not through more mods at it.

Get it checked out.

Simon

Yes there was a four inch hole in the block - apparently it was cylinder 3 that went, a common thing to happen ?

I am planning on taking a trip to Swindon to see Bob Rawle - I am told he is very good.

Cheers for the advice, I am convinced now to act sooner rather than later, will post the results when I know them :thumb:

Yep, if you're running lean number 3 usually goes first (IIRC cause of its position on the fuel rail).

Simon is spot on, you simply must determine why an engine went bang to prevent it from happening again- that's just good sense.

Bob Rawle is superb! He mapped my MY99 with Ecutek; absolutely flies now and is as civilised as you like.

Ns04

Once again cheers guys for the advice. Will phone Bob tommorow.

Darren ;)