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icecats87
12-12-2010, 07:44 PM
Car;s in the shop after ive tried everything i could think of to find out why it was mis firing. so heres what happened, in august the car was mis firing, had it code read and it was throwing a mis fire code and a open fuel injector circuit. after many things, (new plugs,wires) took the injectors out one by one put new O rings on them cleaned the outside of them and even swapped number 6 with a different cylinder to see if mis fire would change cylinder but no luck

Me and my auto lab teacher at school looked at it test the connection from the harness to each injector everything was within spec, even tested it from the PCM to harness everything was fine. i Bought a PCM from mpracing.org and it stopped the misfire untill 2 weeks ago it came back, i swapped injector again and checked wires everything is fine, is there a possibility the PCM went bad again? and if it did is something causing it to go bad or what? or maybe did i get a bad PCM? i dont know what to do next,

Thanks for the help i would love to fix this, tried giving all info if you have any questions feel free to ask

Also the shop can't figure it out, they tested injectors there fine and all wires are good there saying it is probably a bad PCM, i emailed mark and he says its not

01GPGT
12-12-2010, 10:25 PM
did you try swapping coils too see if the miss fire changed cylanders?

all i see you you messing with the injectors but have not even messed with the ignition

icecats87
12-12-2010, 10:32 PM
did you try swapping coils too see if the miss fire changed cylanders?

all i see you you messing with the injectors but have not even messed with the ignition

i didnt mess with one i think the shop i took it did, but all codes were either misfire on number 6, open fuel injector circuit, and something about being lean, and rich (due to the misfire)

gtjoshua1
12-12-2010, 10:57 PM
Thats so weird,sounds like a bad PCM though.

icecats87
12-12-2010, 11:01 PM
Thats so weird,sounds like a bad PCM though.

Yeah its been at the shop for 5 days everyones looked at it, maybe i got a bad PCM for mpracing

01GPGT
12-13-2010, 01:37 AM
get a stock one at the junk yard and swap it in to see if it goes away.


the shop proably messed with the coils though if it's been there for 5 days

AaronGTR
12-13-2010, 07:23 AM
Could be a bad coil, but it could also be a bad ignition control module.

[ChaosweaveR]
12-13-2010, 08:01 AM
Could be a bad coil, but it could also be a bad ignition control module.

Possibly...or he could have issue I had back in May...

Bad valves. I'd check for compression in the misfiring cylinder.

icecats87
12-13-2010, 09:15 AM
Thanks for all the replies, i think i get the car back today, the shop thinks its a bad PCM, and when i get it ill check all that other stuff with ignition, and compression test, but if it was those wouldn't it throw a code for them? the codes are all about mis fire and open fuel injector circuit that's why everyone looking at fuel injector related stuff.

[ChaosweaveR]
12-13-2010, 09:17 AM
Thanks for all the replies, i think i get the car back today, the shop thinks its a bad PCM, and when i get it ill check all that other stuff with ignition, and compression test, but if it was those wouldn't it throw a code for them? the codes are all about mis fire and open fuel injector circuit that's why everyone looking at fuel injector related stuff.

Still, check the compression. When my valve floated on cylinder #3, the PCM only picked up a misfire, that's it. The LA1 is known to float valves in older age.

icecats87
12-13-2010, 09:23 AM
;1145127']Still, check the compression. When my valve floated on cylinder #3, the PCM only picked up a misfire, that's it. The LA1 is known to float valves in older age.

Ill do one when i get the car back, about a month ago the dealership had it in looking at the tranny and did one and everything was good, also in class about 2 weeks ago we were doing them and did my car and it was fine i cant remember exactly what it was but it was about 10 pounds lower then what mitchell on demand said, and it was because of the elevation, but i will do another one when i get the car back

icecats87
12-13-2010, 12:38 PM
So the the shop i took it too (close family friend owns it) they tried everything and think it could be a bad PIN connecting that the PCM connects too so there putting a drop of some special liquid in on it and in the harness, don't know the specifics but it should fix it and if it doesn't then it is a bad PCM

AaronGTR
12-13-2010, 05:05 PM
;1145120']Possibly...or he could have issue I had back in May...

Bad valves. I'd check for compression in the misfiring cylinder.

Yeah, I already told him to get a compression and leak down test done though PM's. I guess he doesn't want to listen to me though since he keeps insisting it's the PCM. lol There are still several things it could be and they need to be ruled out one at a time.

Malaclypse
12-13-2010, 05:29 PM
Are you still setting an injector code? If so, for what cylinder?

Also, spark and compression are not to be overlooked even if you DO have an injector circuit code. Its always a good idea to check just to be sure.

icecats87
12-13-2010, 05:34 PM
Yeah, I already told him to get a compression and leak down test done though PM's. I guess he doesn't want to listen to me though since he keeps insisting it's the PCM. lol There are still several things it could be and they need to be ruled out one at a time.

I was going to do a compression test if they couldn't find anything out haha but turns out the connecting pin the goes into PCM wasn't getting a connection, so they used a drop of some liquid i don't know the name of it exactly if you want i can get it, but its suppose to make the connection better and it fixed it.

Are you still setting an injector code? If so, for what cylinder?

Also, spark and compression are not to be overlooked even if you DO have an injector circuit code. Its always a good idea to check just to be sure.

it was number 6 but found out what was wrong

AaronGTR
12-13-2010, 05:40 PM
I was going to do a compression test if they couldn't find anything out haha but turns out the connecting pin the goes into PCM wasn't getting a connection, so they used a drop of some liquid i don't know the name of it exactly if you want i can get it, but its suppose to make the connection better and it fixed it.

And you know this for sure? Or that's just what they told you they were going to do? I'd wait until you actually drive it for a while with no misfire codes. But anyway, probably all they did was put a d ab of dielectric grease in there. Kind of a band-aid fix, but sometimes it will work on connection problems. What they should really do is replace the faulty pin in the harness, if that's what ends up being the problem. most places don't like doing that though because it actually takes work. lol


Anyway, with all the problems you've had and the mileage on the motor, I'd still have those tests done. Just for peace of mind. It shouldn't cost much.

icecats87
12-13-2010, 05:43 PM
And you know this for sure? Or that's just what they told you they were going to do? I'd wait until you actually drive it for a while with no misfire codes. But anyway, probably all they did was put a d ab of dielectric grease in there. Kind of a band-aid fix, but sometimes it will work on connection problems. What they should really do is replace the faulty pin in the harness, if that's what ends up being the problem. most places don't like doing that though because it actually takes work. lol


Anyway, with all the problems you've had and the mileage on the motor, I'd still have those tests done. Just for peace of mind. It shouldn't cost much.

Not sure exactly what it is but they said its some expensive liquid thats worked on 3 previous cars, and i drove it home from the shop and no codes or mis fires, had a coolant leak before i went in so i gotta find that now haha, and ill do those test this weekend

01GPGT
12-13-2010, 08:05 PM
;1145127']Still, check the compression. When my valve floated on cylinder #3, the PCM only picked up a misfire, that's it. The LA1 is known to float valves in older age.

this is what happend to the old engine. i had #6 vlave was not sealing. other then that it was fine