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Miss / Sputter Under Boost
Posted: Tue Mar 22, 2011 10:03 am
by Fastlane
Hi Guys,
There is a constant miss / Sputter under boost.
What could this be??? Any Settings???
Or perhaps faulty coilpacks???
Miss
Posted: Tue Mar 22, 2011 10:05 am
by Fastlane
Sorry, meant to add, noticed the miss on idle as well after driving about 50km to work.
Posted: Tue Mar 22, 2011 10:08 am
by djtreble
Could be one of many things:
- boost leak
- spark plugs
- coil packs
- AFM
Is your car standard? Or what has been done to it?
Check for any obvious things in the engine bay such as pipe splits/disconnected pipes. Clean the AFM with carb cleaner spray, check the spark plugs and clean/replace if necessary.
Posted: Tue Mar 22, 2011 2:01 pm
by aep886
mine was like that... it was the turbo... and dirty AFM~!
Miss
Posted: Tue Mar 22, 2011 3:06 pm
by Fastlane
Thanks guys,
I have replaced plugs with a set of BCP7ES.
I have cleaned AFM with carb cleaner.
Boost is steady 0.4 bar.
I did fiddle with TPS. Could this be the cause?
Also fiddled with CAS, trying to set timing, but timing marks not visible on Crank pulley (pully damaged on edges).
Also overfuelling : dumping fuel (''mini-explosions'' in exhaust on deceleration).
Idle is at +/- 1000rpm (i picked up idle because car was cutting off intermittently (on idle only) when at stop streets.
Motor was completely rebuilt about 1000km ago.
Added a Walbro 255lph fuel pump 2 weeks ago.
t25g Turbo (off SR20DET) with t25 actuator.
Posted: Tue Mar 22, 2011 3:14 pm
by djtreble
Before you go any further, take the car to get it timed properly and mapped correctly, you dont want to waste the rebuild.
Also the TPS may cause issues if it's out but it all depends on how bad the missfire is.
So get it all checked properly.
Miss
Posted: Tue Mar 22, 2011 3:23 pm
by Fastlane
Okay cool, will do.
Want to take it to Gary, but he's a bit of a distance away from me, so have to arrange to have car dropped off with him.
Posted: Tue Mar 22, 2011 3:50 pm
by NIZAN-R
also check vacume lines .stock turbo is around 0.7bar boost so yours is a bit low.
Re: Miss
Posted: Tue Mar 22, 2011 4:46 pm
by P3g4sus
Fastlane wrote:Okay cool, will do.
Want to take it to Gary, but he's a bit of a distance away from me, so have to arrange to have car dropped off with him.
What about Poizen?
And chec your plug gaps
Posted: Tue Mar 22, 2011 5:23 pm
by Caveman
Had/Having the sad problem, it's my shitty UNICHIP system. Anyone know about the Spitronics system? thinking of using it.
Posted: Tue Mar 22, 2011 5:44 pm
by poizen
He has my number but I'm further from gary
Posted: Tue Mar 22, 2011 5:44 pm
by aep886
Caveman wrote:Had/Having the sad problem, it's my shitty UNICHIP system. Anyone know about the Spitronics system? thinking of using it.
spitronics are XXX rather go for gotech if you have to!
Miss
Posted: Wed Mar 23, 2011 9:00 am
by Fastlane
Ja, Poizen is much further away.
Car did have a Dastek Unichip before the previous motor fried, but got rid of it.
I wonder if the mechanic connected all the wires back to the ecu properly?!?
I heard that std boost is 0.5 bar?!? Anyways I am using a t25g with t25 actuator. What should my boost then read?
Strangely, I have noticed that the car idles fine (actually quite smoothly) when I first start it. Only after driving it (obviously placing it under load) does it start its nonsense.
Also suspecting the eight port head having something to do with it. Maybe ''butterfly flaps'' not open enough.
What about sticky valves (or too deeply seated valves) ? What would the symptoms be?
Miss
Posted: Wed Mar 23, 2011 9:03 am
by Fastlane
@P3g4sus : I thought that the plugs came pre-gapped.
I didn't adjust gap, just fitted them on. Was I supposed to adjust gapping?
Posted: Wed Mar 23, 2011 9:54 am
by djtreble
Those plugs are pre-gapped, but check to make sure they haven't been knocked closed or somehow wider open