4g93t Runs Rough 90% of the time....

[rotated7]

Hey all,

I did some heavy searching on the forum prior to creating this post but couldnt find anything solid.

Anyway... story goes...

I have a CC GLXi coupe which was a stock Auto 4g93 SOHC and got bored so decided to convert the thing to GSR seeing as i had everything needed to do it. Car is now a manual 93t powered coupe. Everything is still standard - ECU, inj, AFM, Motor, etc. ECU i believe is a Japspec ECU. Still running a stock glxi fuel pump and have butted the original GSR dump pipe to the standard GLXi exhaust. It does have a Pod Filter but thats it.

When i first started the car after the conversion, i noticed it sounding mildly like a WRX and that the motor didnt idle steady - as in the motor rocked back and fourth but then it cleared up after 2 mins of idling. I could cleanly rev the engine fine and it sounded/idled fine. After taking the car to the local carwash to degrease the engine bay, ive gone to take it for its first drive but as soon as i gave it gas and got into boost, it farted, coughed and carried on and started running on what seemed to be 3 cyl. I thought it could have possibly been due to me giving the engine a degrease and wetting some components at the car wash so i continued to drive it in the hope that it would go away, but even after a good 30 min drive, it still idled rough and run like poo. So i took her back home and turned her off.

Next morning, Start her up, mild WRX idle but seemed to drive ok. Could rev it cleanly through the rev range but not flatten it. If i tried to give it gas it would fart and carry on, but, if i lightly got the revs up, she'd be fine. Let it idle and you could still feel it wasnt 100%, but was better.

This "dropping a cyl" problem seems to come and go.. its intermittent but even when its running at its best, its still not spot on where i can actually cleanly rev her on boost.

Things i have tried to rectify the issue:

Changed coilpacks with good working ones - no difference
Changed ignition module with good working one - no difference
Checked spark plug leads are in the right order - Yep
Changed spark plugs - no difference
Changed spark plug leads - no difference
Changed CAS to what i thought was a good working one - car wouldnt even start or idle. Put old CAS back in car starts?!?! (Although i know this CAS was working as i pulled it off the car around 3 months ago and sighted it working myself)
While on idle, i have removed each injector plug to see if the idle would change which it did on each injector.

Checked timing - set to approx 6deg btc on idle, but when trying to check if it advances by free reving the engine with a timing light, the light stops working until it returns to idle??!??!

Im leaning towards this being a dudd ECU that has leaky caps causing these weird problems.

Any thoughts/ideas would be great as im starting to run out of them!!

Sorry for the long post!!!

Cheers,
Chris

 

[MattL]

Pull the ECU out and take the cover off and have a look at the internals.

Failing that, you could have a bad ground on some stuff, so check your grounding points.

 

[EVO-00X]

Could be a variety of issues Chris. To totally eliminate what you've worked on so far can you answer the following questions:
1) What sequence have you got the spark plugs connected into the coil packs?
2) Is there any evidence of freying of the wires in the Cam Angle Sensor connection plug?
3) Is the back of the ignitor earthed down on the bracket its bolted to? (which earths out on your intake manifold).

 

[rotated7]

Could be a variety of issues Chris. To totally eliminate what you've worked on so far can you answer the following questions:
1) What sequence have you got the spark plugs connected into the coil packs?
2) Is there any evidence of freying of the wires in the Cam Angle Sensor connection plug?
3) Is the back of the ignitor earthed down on the bracket its bolted to? (which earths out on your intake manifold).

MattL: Thats the next thing im going to check...

Rob, heres the answers to your q's:

1. Sequence from top coil pack to bottom goes 4-1-2-3
2. I did notice that the CAS plug was alittle worse for wear. In saying that, the wires themselves seem ok.
3. Ignitor is in the original position mounted on the Coil Pack bracket, which this is then mounted on the inlet as standard.

 

[EVOCPE]

Is the CAS been put in right, i know if you go 180 degrees out it either wont start or will run rough

Is all the earths on? 2 near the ECU, 1 or 2 connected from firewall to the throttle cable bolts on the manifold

Have you checked the caps yet in the ECU??

 

[rotated7]

Is the CAS been put in right, i know if you go 180 degrees out it either wont start or will run rough

Is all the earths on? 2 near the ECU, 1 or 2 connected from firewall to the throttle cable bolts on the manifold

Have you checked the caps yet in the ECU??

Hey Mikey.. when i tried throwing on the other CAS it would only go 1 way.. if i tried to put it 180 out of phase it just wouldnt physically fit in place...

Earths, yep... i actually have 2 at ECU end, 2 at Throttle cable to Firewall and one from timing cover to chassis.....

Just about to pull ECU out and check... hopefully its something obvious in this ECU!

 

[rotated7]

OK guys.. ive tried some other things but she's still crap!

Things ive tried...

Checked ECU - Caps are fine.. no leaky obvious ones
Checked the Injector resistor pack and resistance accross all resistors are even - 6.7ohms IIRC

Car has been running "OK" for the past couple of days, but i still cannot floor it at all.. although, if i i lightly give it Gas, she has no problems getting up the rev range.

Im starting to run out of ideas!!

I guess my next thing to try would be fuel.. possibly not enough pressure at WOT? - Whats ppls thoughts on this??

Thanks,
CHris

 

[Missile]

Tried changing AFM?

 

[SIKWPN]

i reckon chris get your hands on to a compressor and blow every plugs you can find might be water in there..
yer try an air flow meter aswell got one here if u wanna borrow and your welcome to bring ur car down n i give ya a hand if you want too mate..

 

[EVOCPE]

Check the piping?? might be a vacuum leak.. still using the standard hose from intake to brake master (it has a 1 way valve)

Just read the 1st post better, it all happened after a car wash.. i had this prob before aswell

But mine went away after driving the car for a while so maybe the water dried out, to me it seems like theres water somewhere in the electricals, blow all the connections out

 

[CLuTZ]

boost leak

 

[rotated7]

boost leak

Hmm.. i think you could be right Clutz.. im going to have to check over the intercooler and piping. I just spent an hour changin the fuel pump with a known good pump and new filter and it feels as though it has improved but the problem of not being able to floor it is still there. Im not 100% if it actually has improved or if my minds just playing games on me now!!

I havent changed the AFM yet so thats next. Does anyone know if theres a difference between japspec and aussie AFM's?.. Everything else has been donated from a japspec GSR except for the AFM.

Lastly, is there anyone who's done a conversion to a CC coupe and butted the GSR front pipe up to the standard coupe exhaust?.. im thinking this could be choking the car causing it to fart and carry on at WOT... thoughts on this theory??

Thanks,
Chris

 

[CLuTZ]

Hmm.. i think you could be right Clutz.. im going to have to check over the intercooler and piping. I just spent an hour changin the fuel pump with a known good pump and new filter and it feels as though it has improved but the problem of not being able to floor it is still there. Im not 100% if it actually has improved or if my minds just playing games on me now!!

I havent changed the AFM yet so thats next. Does anyone know if theres a difference between japspec and aussie AFM's?.. Everything else has been donated from a japspec GSR except for the AFM.

Lastly, is there anyone who's done a conversion to a CC coupe and butted the GSR front pipe up to the standard coupe exhaust?.. im thinking this could be choking the car causing it to fart and carry on at WOT... thoughts on this theory??

Thanks,
Chris

The exhaust will just be a massive restriction, but shouldnt cause it to miss. Check the seal on the turbo outlet- it doesnt need it to be leaking much for it to cause all sorts of dramas, like making it run like its on 2 cylinders....

What piping are you using? Stock? Check for splits in the OEM hoses if you are- they are getting pretty old these days.

Rig yourself up a leak tester. Check this link:

http://www.mirage-performance.com/EclipseGSX/BoostLeaks/index.html

 

[rotated7]

The exhaust will just be a massive restriction, but shouldnt cause it to miss. Check the seal on the turbo outlet- it doesnt need it to be leaking much for it to cause all sorts of dramas, like making it run like its on 2 cylinders....

What piping are you using? Stock? Check for splits in the OEM hoses if you are- they are getting pretty old these days.

Rig yourself up a leak tester. Check this link:

http://www.mirage-performance.com/EclipseGSX/BoostLeaks/index.html

Thanks for the tip Clutz.. turns out it wasnt a boost leak causing the issue, but a combination of things...

1. on its way out fuel pump
2. Timing
3. spark plug gap
4. AFM* - this might not have any effect as i changed this at the same time i did the above.

Thanks guys for all your help. She's finally up and running great now and hopefully due to me running a Japspec ECU, if i throw in 98 or 100 octane fuel, it should stop the last issue of slight pinging when hard on the throttle.

Cheers,
Chris