Hi Guys

Have a 2.5 STi hatch with a forged rebuild, built 2500 miles ago.

Recently I began to notice that on a flat out pull through the gears - the power delivery was not smooth all the way - its as if there was a very very slight hesitation twice from 5-6k revs. Previously it pulled hard all the way up to 7k revs no problem.

This REALLY bugged me for couple of weeks then disappeared as quick as it came ?????

Next few weeks pulling strong + smoothly from 3-7k revs = great again. Weird ?

This week car now has a much more noticeable flat spot between 5-6k revs - sorta eases off a little then blam back on it ?

Any ideas what could cause this ? Ruled out fuel as it always gets Shell super duper and the first issue disappeared in the middle of a tanks worth, second issue appeared in middle of tanks worth ?

Ruled out weather, as when it sorted itself first time round it went on to be normal / great again during the hot weather (remember that?).

Cant be mapping as its good then off - off then good - good then weird... etc

Could the maf be playing up ?

What do ya think ?

Any clues... ?


A

 

This happened to a friend of mines car, 2 weeks laterit was in for a new engine. Is the car on the standard map or has it been remapped with Ecutek.

Friends was on the OE map which is part of the problem with the hatches popping pistons.

 

got to be honest it is a sign of rings lands starting to fail with flat spots,having said that also could be maf.

 

Hey guys.... this has been rebuilt already... velly expensive....

I had the ringlands go back in February, now all nice and forged.

A

 

Was it done under warranty if not who did the build?
If it's the linglands then thats two in two days theres another thread down below with someone having the same issue his car used all his oil in a week.

Immy

 

Has it been mapped since new engine?
Compression will be altered by forged pistons.
Could also be the ecu backing timing off due to forged piston noise.

Regardless of cost of rebuild or pistons used if the oe map is still used it may do the ringlands again
Has it had the reflash?

Simon

 

Guys its a very professional rebuild by one of the most respected engine shops in the country. All the right bits and ecutek'ed.

Trouble is they are 'miles away' and thus a right pain to pop in for a look.

I have emailed my tuner for advice, and thought I'd stick it on here to see who answers first.

I presumed it would be an easy answer as everything internal is good and new. probably old maf being used...


A

 

You will get much better info from them or someone else looking at the car rather than posting on here without all the info

Maf will not do this

Either it is something like the ecu pulling timing due to forged piston noise or the original issue still there.

It needs ecu learnt data to be checked to find out and the engine checked

Simon

 

Thanks Simon....

A

 

Cripes ... 500 mile round trip it is then.....