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Discussion Starter · #1 ·
Hey guys,

Ive been trying to get this straightened out for 4 months now and am really getting frustrated, hope someone can think of some new suggestions.

Out of the blue one day my car started running very poorly. Limped it home and after some testing it appears to only be firing on cylinders 1/4. I got some help on another forum and started trying things out, most people were certain it was a spark issue so i changed out the coils, power transistor and ecu and none of them helped. At that point i did a bit more troubleshooting, got ahold of a spark testor and all 4 are getting spark but it appears that injectors 2 and 3 arent working for some reason. I had the injectors cleaned and even swapped them around a few times and still the same issue. You can start the car and let it idle(barely) and you can unplug the plug wires and injectors from 2 and 3 with no change. If you unplug anything from 1 or 4 it dies immediatly. Today i recieved an injector resistor pack to try and also no change, we also checked continuity from the injectors to the ecu and there is a complete circuit so there doesnt seem to be any broken wires to 2 or 3. No engine codes are being thrown at all so nothing is showing up in my pocketlogger as well. I also checked the connections at the ecu from my safc2 and they seem fine, i am considering removing it to see if there is some issue there. Anyone have some new suggestions, im not sure what else to do!

Thanks for your time,

Blake

Some brief car info...

95 gst
1g engine
fp big 16g
550's
large greddy fmic
safc2
 

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My first question would be how long ago did you get the car and was it sitting for a long period of time?

I witnessed something identical to your problem recently and to my suprise the injectors where getting fouled out because of rust in the gas tank... Just a thought but it could be a lot of things.. I assume you checked compression??
 

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Discussion Starter · #3 ·
Turbolover,

Thanks for the reply. I have had the car for 9 years and built/blueprinted the engine from the bottom up at that time. It is my project/weekend driver and it only has 60k miles on the chassis, engine only has about 7k on it in all that time as well. It has always ran great, ive slowly added mods over time so there hasnt been any drastic changes. The rusty tank thing could be a possibility but i did swap the injectors around a few times and it seems to be isolated to 2 and 3 only no matter what injectors are in those spots. Also, since i can unplug both of those injectors with no change while the car is running it makes me think it something controlling them, a sensor etc, but i am not sure what controls them other than the ecu and injector resistor pack.

Blake

P.S. I havent checked compression, the engine has so little time on it, and honestly i dont run it hard, i sure hope that isnt the issue.
 

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A bad mas will make it seem like its only running on two cylinders.

Lets give an example of what the ignition system composes of.

Crank sensor/ cam shaft position sensor.
Transistor
coils
sparkplug wires, sparkplugs
ecu.
If those check out the its NOT the problem.


I guarantee its the mas.;)
 

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Discussion Starter · #7 ·
Thanks for all the suggestions guys, i just tried something with the mas. Started the car up and held it at about 1200 rpm, running really bad of course. Unplugged the mas and there was no change in the way the car ran at all, bad mas? I would assume unplugging it would change the way the car runs if it were normal?

Blake
 

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blakesgst said:
Thanks for all the suggestions guys, i just tried something with the mas. Started the car up and held it at about 1200 rpm, running really bad of course. Unplugged the mas and there was no change in the way the car ran at all, bad mas? I would assume unplugging it would change the way the car runs if it were normal?

Blake
I see why you would assume this but actually, look at it a different way. If the MAS was bad, i.e. sending no voltage, then unplugging it would not change anything as there would still be no voltage. I would try to borrow another MAS to swap in there, or perhaps you could use a blow dryer on your current one and watch the air count on the SAFC to see if it is measuring anything (I'm not sure if that works, maybe someone else will know? Seems logical thinking about it but I'm pretty inexperienced under the hood).

Aside from all that, did you check the plug wires for arc holes? It's a long shot but maybe some moisture got in there and your plug wires to the 2 and 3 cyl's are arcing out now.
 

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I had the same problem with my car a week ago but i was only getting spark on cylinder 2 and 3 .Did everything just like you ,end up being the cam angle sensor.
 

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Discussion Starter · #10 ·
Well i guess its time to try the MAS and CAS. If anyone has one or both lying around please let me know, i live in a small area on the west coast and its hard for me to get used dsm parts so shoot me a pm. I need a 1g cas and a 2g mas btw, not sure if i mentioned i have a 1g engine in my 2g.

Thanks for your time guys and ill post an update asap,

Blake
 

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turbolover said:
I don't think hes checked the compression but it would probably be a good idea before he goes spending money on stuff he might not need.
Me too.

If I have an issue with the mas the car ussually idles better with it unplugged, but not always.
 

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I was just reading through again and saw you have a 6-bolt in that 2g. I'm assuming no DSMlink since you have a SAFC.

So, that makes me wonder if you're experiencing the "limp mode" problem (it usually throws a CEL, but mine sometimes didn't). Do some reading on "limp mode" and "barometric sensor wire mod/potentiometer mod" or "6-bolt pot mod". Since I was too broke to buy DSMLink for my 6-bolt in a 2g, I did this popular cheap way out and it actually works.

I'm not sure what exactly limp mode does, but it feels exactly like running on 2 cyl's, so maybe it cuts off two injectors like you are experiencing. Not really sure but certainly someone here knows. Anyway, read on it, and if you try it it will set you back a half an hour and a couple bucks at most.
 

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Discussion Starter · #16 ·
Ssearles,

I think you are refering to the random misfire issue that can pop up? I use a pocketlogger to clear that code but i also installed an adjustable resistor a couple years ago to one of the ecu pinouts(cant remember what one off the top of my head) to fix that problem.

On another note someones thread got bumped up today (xuberantz) and it sounds like he has/had the exact same issue as me. This is exactly what my car is doing at the moment... "It sounds exactly like a damn subaru, with no check engine light." An injector change solved the issue for him so i might give that a shot this weekend. I tried a new mas and the car still has the problem, i have a cas on order, not much left to try after that!

Blake
 

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Yes the random misfire is what I was referring to, so I guess you have eliminated that problem already. Too bad the new MAS didn't work, but I thought that was kind of a long shot.

It doesn't make sense to me that new injectors would fix the problem because you said you swapped them around and it still did the same thing. You moved injectors known to be good into the 2 and 3 spots and they didn't work, and moved injectors you thought were bad into the 1 and 4 spots and they did work.

Something is either telling the ECU not to signal those injectors, or preventing the signal from getting to them. The only thing between the ECU and the injectors is just wire, so if the wiring is fine then you have a problem with something else which is causing the ECU not to signal the #2 and #3 injectors.
 

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Discussion Starter · #18 ·
Just wanted to post an update, still no good news. I tried a new CAS, no change. I bought a noid light kit to check the injectors and all 4 are getting signal, i also swapped em around one more time to make sure it wasnt just 1 or 2 bad injectors. So now it looks like the injectors are getting signal, the plugs are getting spark but the car is running so damn rough it really seems like its only really running on 1 and 4.

Once again with the car at idle i am able to unplug injectors 2 and 3 with no change but as soon as i unplug 1 or 4 it dies, here is what i have tried so far....

Coils
Power Transistor
Injector Resistor Pack
ECU
MAS
CAS
New plugs and Wires

I will do a compression test tomorrow, any other ideas? I installed the AFC2 a few weeks before this happened, could something strange have happened with it out of the blue? Also i just wanted to mention that it smells like its running super rich.

Blake
 
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