my95 uk turbo.Full decat and boost set at 16psi.
When i set off from cold, drive steady untill warm then boot it, it goes like a dream but after a few miles and it has warmed up, when i boot it it coughs and splutters and back fires.
I've tried new NGK'R' plugs, 4 new coil packs, new 10/60 oil, cleaned air filter, new knock sensor,cam sensor and crank sensor, but to no avail.
PLEASE, PLEASE help.
Thank's............

 

Have you cleaned out the turbo pressure sensor..!!

Just another thing which i didnt think would work... but did... was the engine earth mod have you done this..???? Mine runs alot smoother from cold now..

All i did was buy some earth cable from halfords, in the stereo section and then some terminals and fitted it as per: here

Dan

 

Hi Dan.
Where is the turbo preasure sensor????????
I'm a bit thick.

 

bttt

 

Its on the left hand side of the engine bay as you look at it... in front of the strut tower and behind the air filter box..!!

Ignore the part circuled..!! its the bit near the arrow..





Dan

 

Cheers for that Dan.
Took off pipe and cleaned with loads of break cleaner but didn't help???????????????
Still baffled.

 

You did clean the bit with three pipes going to it didnt you..????

Dan

 

Have you tried lowering your boost..????

Dan

 

Just been out and watched the boost carefully, when i boot it the boost goes up and down slightly. I've got a dawes set at 16 psi when cold, when its warmer it reads more like 15 psi. The boost now reads 13/14 psi when its spluttering. I've cleaned the dawes device and still does it. Checked for loose pipes and found one (the one from inlet manifold to the air intake nearly above the turbo with an arrow on it) so glued it and now waiting till glue sets to try again.

 

If it's spluttering, it's misfiring.
Almost definitely nothing to do with turbo.
Check the following:

CoilPacks are all firing correctly (and not earthing). As you have already changed these, this seems unlikely. It's possible the wiring is responding badly to heat.

Check for Cracks in exhaust headers. Unlikely to cause this, but possible.

Get your engine compression tested (pref when hot). It COULD be the engine is heating up and a cylinder is not working properly.

Hope it's not that.

 

Now come to think of it this problem has been hear for 20,000 miles on and off but i thought it was cured after doing certain things but it's the same problem. I've spent 1,000's on it an think the best thing to do is to tourch it and buy one off you guy's. It realy is nothing but it's bugging me so. Does any one any one local that could sort it or should i just buy a new STi and be done with it.............

 

Coughs and splutters really do sound like misfiring. I am assuming this happens whether or not you are on boost, and that it isn't just fuel cut.

As you've changed your coil packs, check your HT leads and spark plugs. Then get it compression tested.

 

thanks steve