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Turbo misfire

1K views 35 replies 13 participants last post by  MARK BEESON 
#1 ·
My let is misfiring.Ive got new plugs gapped to 0.7mm new leads, new cap, new rotor arm,new coil and a new coil amplifier.Its a bit intermitant which is a pain. To describe it the engine doesnt seem to misfire but pops and bangs out of the exhaust.Could it be a fuelling probem?Codes stored 12 12 12 12 12 12 12 nothing wrong ther then!Lavinder :p sensor on the way out?fuel pump? or the FPR .Its had a new fuel filter 6 mnoths ago.I think im going to take it to velos and put it on there rollers if non of you can help
 
#3 ·
BTW?????????????????? They are the standard let cams but i surpose that i should check that.
Cheers
 
#5 ·
I meant "wot does that mean?"
 
#7 ·
If the Cam timing was off or the belt had jumped it would show a hall sensor fault, either 93 low voltage or 94 high voltage. This would be becuase the crank sensor is not in line with the cam sensor and so fueling goes to pot and it don't run.

I would check fueling. Make sure you have the right fuel pressure from the pump and check that all injectors are working. Have you had the injectors cleaned recently?? How many miles have they done?? Is your idle air controller stuck open and pumping to much fuel through?? Does the car just pop and bang but still drive fine or is the car not as responsive??
 
#10 ·
do you have an adjustable fuel pressure regulator on your car? running more than std boost etc?

when i first got the old cav gsi turbo bus, it was running std boost and was fitted with an adjustable fuel pressure regulator. every time the revs were backing off it popped and farted out the back like mad. the adjustable fpr was fitted inline after the std regulator. removed it and problem solved, smoother running and also didnt pop out the back.

probably not of any help but thats what caused mine to sound like a miss fire
 
#11 ·
Sorry ive been at work .Cheers for the replys.
It pops and bangs when nailing it when the turbo kicks in .If i drive it normal its ok.After inital start up in a morning and after about 2 miles if im on the overrun going down bank it pops and bangs but this is ok i think and this is normal.The misfire is different than this though.The injectore have never been cleaned although the engine has been rebuilt.

Ste velos is the closest to me and its doing my nut in.Ive just spent £100 on all the parts above and it didnt solve it!
 
#13 ·
I think £40 or 30
 
#14 ·
Is 0.7mm the right gap for 12 -15 psi?
 
#16 ·
Vega, - Your car will feel under powered. If the timing is only just off you won't notice to much of a change, but it's enough to flag a fault. check your timing is set correctly and have you replaced your crank sensor. The cam sensor is intagrated into the dizzy and if your cam sensor and crank sensor don't match then it flags a hall sensor problem. Have you checked the cables to the hall sensor, they do go brittle after a time and tend to break near the plug. Your ECU will be fine. If there was a problem with your ECU if would flag more than a hall sensor fault. Which code are you getting 93 or 94.

Mark - When it bangs and pops under load does the car cut out and then come back in again with full power. If so, it sounds like it's running to lean and hasen't got enough fuel to run on. What mods have you done to the car?? I had this problem with mine. I wound the boost up to 14PSI and it kept cuttting out at 12 and then coming in with full power. I fitted a FSE and the problem went away. But, Gavin Wallace sells uprated fuel pressure regulators and getting a 3.5bar one to replace your standard 3bar one will sort the problem. This also leaves the engine looking standard as it's a direct replacement for the standard one.
 
#17 ·
this is the problem im havin...shows code 93.....i asked for a crank sensor and i was told i dont need 1...also pretty much everything is new...leads...plugs...and all distributer components have been checked and r ok:confused:

the car really goes well but i couldnt tell if it didnt anyways:rolleyes:...just driven it twice in two months....forgot how its supposed to be...

cheers for help:beer:
 
#20 ·
MARK BEESON said:
Sorry ive been at work .Cheers for the replys.
It pops and bangs when nailing it when the turbo kicks in .If i drive it normal its ok.



only on boost you say.....my car done this for a while after i washed the engine bay so i just wiped everything down to dry it all off nad sprayed some wd 40 in there as this is a moisture repellant. i guess it must have just been excess moisture in the cap or wherever on the igntion parts but after i done this it was ok

HTH

rodgerq
 
#21 ·
The buggering thing is running ok now well sort of the misfire has stopped but the light comes on in 3rd -5th .As soon as it starts boosts hard and long the light comes on but no codes are stored.I had a code of 116 - boost contreol once
 
#22 ·
i think the fault has to last somethin like 12 seconds before the ecu stores it mate. if your gettin a boost fault stored like you say 116 then the misfire could be that the engine is overboostig and the ecu is cutting it back
there are 2 types of overboost cut

1 - just a gentle control of boost by ecu - a feeling of lack of power

or

2 - a harsh control and the car feels like its misfiring or backfiring really badly(and loudly).

what boost are you running? what fuel do you use?

rodgerq
 
#23 ·
I always use optimax.

It runs about 10-12 psi.

It still revs but missfires.I know what you mean about the sudden cut back and it isnt that as ive had that before
 
#25 ·
what do you mean torqued up right? as in not itght or just not to the correct torque?

i doubt the knock sensor would cause the engine to misfire like that. as far as i know it just retards the igntion so this would judt result in a loss of power.

rodgerq
 
#26 ·
blue Its seems to be running ok now.But sometimes the power just isnt there pleaty of boost but no power sometimes
 
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