95 GSR 4g93T miss fire

[Skineo73]

95 GSR 4g93T missing under load.

Replaced spark plugs/Leads/Coils/ DAS dwell angle sensor/ changed the ECU. Cleaned up every plug and contact no vacuum leaks cylinder compression is good and even no smoke.

Idles fine, cruises fine on the road as soon as you give it a little gas it feels like one of the cylinders is not firing right. Foot down Under load when the turbo comes on it misses really bad one cylinder still makes 8psi. No miss fire when the cars whining down trough the revs. Apart from changing the injectors which is what I will do next any other idea's? or anything I can check?

 

[Liberoz]

Try pulling out spark plug leads and see if you can isolate which one is not firing. just went through very similar shiite and it was in my case CAS crank angle sensor. Replaced with known working vr4 one and presto
Ran on that one till a new cas sensor ordered for mine and just rebuilt with new electrical sensor and new bearing at the same time.

 

[Richard]

How many K's are on it?
It is quite posibly your fuel pump not delivering enough fuel if it is the stock item and has quite a few K's on it.
My car has exactly the same issue as you have just described, it doesnt do it quite so much after I put a really good set of spark plug leads in it, however I am doing a course at trade school and we tested my fuel pump (300,000km's) and under load it drops to about 1.5 litres per min and when the current was connected to an ociliscope one of the sections on the armature in the fuel pump motor was found to be not working.
I am putting in a Walbro very soon and expecting to see my problem dissapear.

 

[Skineo73]

Can't idls fine I can free rev the car to red line it only miss fires underload on the road.

 

[Skineo73]

Good point the car has had a replacment motor but has done wll over 300.000 Ks still the same fuel pump. I do have a new larger one here ready to go on one of them Walbro and I'm waiting on 510cc injectors to arrive in the post.

 

[Liberoz]

hook up with one of the guys on here from toonsville and data log your car all your question will be answered after logging it.

 

[3zercrowd]

hook up with one of the guys on here from toonsville and data log your car all your question will be answered after logging it.

You're a TOON

Yeah as Simon said we have changed everything around on the bastard! :evil:

Even did a compression test this arvo and it was good.

Changed the CAS and no change, ALTHOUGH it was one from the spares that was in the garage so real condition unknown.

The only thing he changed before this started to happen was the Evo8 MR BOV, then he said it was going great guns on 12psi and then the next day it just stalled at the lights, then it went to shit? :evil:

Ill wait till jason gets back with the tail sniffer and AFR and we will test that. Maybe the fuel pump has shat itself but we are going to change it anyway and add the 510cc's and Evo MAF with Meek chip when Simon rings Chris

I think josh might have the datalogger at home too...

 

[Liberoz]

Dane did you check the ecu for caps acid melting the board as my old gsr 5years ago did same thing very intermittent then old day just wouldnt fire back up.
When the caps leak acid the first part of the board to go is the fuel sender circuit!

 

[3zercrowd]

Dane did you check the ecu for caps acid melting the board as my old gsr 5years ago did same thing very intermittent then old day just wouldnt fire back up.
When the caps leak acid the first part of the board to go is the fuel sender circuit!

I havn't opened the ecu up...but simon says ( :lol: ) that he pulled the unichip out and cleaned the contacts up and it ran better (and swapped the normal gsr chip). He also has changed the ecus between the 2 he has also.( series 1 & 2 Gsr's )

 

[Liberoz]

Dodgy leads maybe! I'm now just taking a stab

 

[CLuTZ]

boost leak

 

[Dean]

fuel pump as richard said.
i also had very similar symptoms...

 

[GSR94T]

i agree with the datalog idea

 

[Skineo73]

Boo ya the 510cc injectors are here

 

[3zercrowd]

Boo ya the 510cc injectors are here

Rang Meek yet? :wink:

 

[Skineo73]

Ah nope I thought I would fix the miss fire in the car first

 

[Liberoz]

Ah nope I thought I would fix the miss fire in the car first

So what your plan of attack then?

 

[3zercrowd]

Come over tomorrow and ill check for boost leaks in the system with the tester.
Ill also check the J pipe gasket and maybe the manifold bolts and turbo bolts too.....

 

[Skineo73]

-Negative Thought I would try and get rid of the miss fire first

 

[Skineo73]

I'm usless at posting on forums