petes555

MY95 STi 555, de-cat, Tsl group N, K&N panel filter, Run on Optimax plus O/b
As above accelerate nomal and car is perfect, baring a few pops now and then !
BUT give some hard throttle and I have to peel my eyeballs off the windowsceen !!!!!!!!!!
Basically it backfires and holds back then goes and then backfires and holds back and so on , If you ease throttle slowly its fine !
THE TWIST is now and then the Rev counter drops to zero and its as if the engine is off , Dip the clutch and everything is fine until you need to give it some stick !
I have done a search a week ago and lots of people keep coming up with Coils, but not sure if they would make the rev counter drop ?
New NGK/R plugs and gapped to 7, cleaned valve with three pipes which clicks when plugs under dash are joined, 2 timing censors on engine cleaned plus cleaned air filter and reoiled and even down to cleaning all pipes from airfilter to turbo ( carb Cleaner )
Im really stuck for ideas other than taking to Power Engineering who everybody seems to recomend, I just wondered if anybody had come across this fault before ??????????????

Pete

DeanF

iTrader: (1)

Try shortening the plug Gap to 6.5 & see if it makes a diff, You have nothing to loose , only Knuckle skin . If it improves i would defo think about coil packs

Dean

Another thought, Boost spikes & Fuel Cut !!!!!

[Edited by DeanF - 10/29/2003 11:13:11 PM]

ALi-B

iTrader: (1)

I had that exact fault once...scary, I was thrashing it at the time, so I thought I blew something.

After a few miles the Check Engine light turned on....

Turned out the connector on MAF sensor had come loose, clipped back in..it was fine - happened again later on, I now fixed it with a cable tie

Seeing that you don't mention the CEL it's probably not that, but it's worth checking - just incase.

I've also seem seen similar occurances on another car, using our ignition tester equipment, it showed a fault with the coil pack but on closer inspection, the fault actually was a duff plug lead -which made the coil pack look faulty when it was ok.

Food for thought!

petes555

Great ! Thanks for the replies !
Sorry not fully up on all these valves and censors ,
Where is the MAF censor ?
Also I had a light come up on the dash this morning ( cylinder with wavey lines around it ) not the same light that came on on my other Sti I had before this one . The check engine light came on then and one of the coils had just packed up , easy to find and cure problem, But this is just driving me mad !!!!!!
The gaurd around down pipe had come loose and was making an awfull rattling so I got the spanners to it before I came home, found a censor in the down pipe loose so tightened this up but I still have my misfire !
I have a spare coil so what I may do is keep changing them around and hope I find a faulty one ,
Ill do that after I give the plug gaps a few adjustments and check this MAF censor ( when I know where to find it )

Many thanks

Pete

ALi-B

iTrader: (1)

MAF sensor is the one on the front LH side of the engine bay in the pipework from the air-filter

Sensor on the downpipe is the oxygen sensor.

Haven't a clue what the light is, low fluid on something or your fogs are on??