Got some crazy problem?!
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Got some crazy problem?! Ok, well last weekend we put a cam in my car. We also put an electric w/p, a new Delco opti, MSD cap and rotor. I also got a trifecta tune. It has been dead on except the idle which we had fixed as of yesterday. I drove it 200 miles this weekend without a single issue. Started it up yesterday morning and it ran fine. Until I lightly got on it. Then the craziness. The gauges went haywire. Pegged 260 on the temp like 8 volts, tach and speedo were jumping around and the car would cut off and buck and everything. But only if you got on it while driving. If you weren't moving you could rev it up all day long without a hitch. Any ideas. I checked all the obvious stuff. Grounds and what not. But never noticed anything. I tryed re-tuning it thinking it was a glitch. Negative on that helping. I can drive it just fine, if I don't get into it. If I WOT it, it goes all shitty.
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Okay. I tracked it down. Positive battery wire melted to header...wonderful. Ok so I fixed that. Now it backfires at idle and violently shakes when it does backfire. It acts just like it did when one of the wires were crossed. No one has fucked with any of the wires, and we checked all to make sure none were burned. Whats next? What can I test to find out why. I returned to pcm to stock and then re-flashed it to my current tune and to no avail. Seems to run fine (no backfire) at anything above idle. HELP!!!
What is the Idle RPM at? Sounds like it's idling too low and getting a Knock Retard off of something. I would bring the Idle up just a hair.
Mine has a pretty nasty Cam in it and I have it set at 1000RPM's for the Idle, and it will barely stay running with that, so a higher than the stock 600RPM's won't hurt..
Mine has a pretty nasty Cam in it and I have it set at 1000RPM's for the Idle, and it will barely stay running with that, so a higher than the stock 600RPM's won't hurt..
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The idle is 850. And it ran fine for 200+ miles and ~7 days. This problem didn't arise until the wire melted onto the header. Now it backfires under a load, or at idle. I'm ******* lost.
Maybe you've got a wire that is melted elsewhere, or a Fuse blown that you aren't seeing. You could have possible fried the ICM when that positive wire made contact and grounded on that Engine..something fried, I would look over everything.
It sucks man, I've been there before.. all that work some something ***** up..but it's got to be gone over. Take a break, drink a beer, and start going through it slowly.
It sucks man, I've been there before.. all that work some something ***** up..but it's got to be gone over. Take a break, drink a beer, and start going through it slowly.
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From: Georgetown, Texas
Thats what I think too. Something is fried. I don't want to start throwing parts though. I want a way to determine the exact cause. I have looked for burnt or melted wires while it was on the lift. We thought maybe the o2 sensors are or one at least on the passenger side because the Short Term Fuel Trim % is like on 0.00 and not moving. But We unhooked them both throwing it into open loop which should take of that. But no. It ran worse. Earlier it ran for 4-5 minutes at idle with no backfire...then started doing it alot. I took it down the road and it ran ok unless I put the clutch in and coasted, it not only tried to die but backfired. If I put my foot in it I would backfire. If I accelerated at a steady pace it was fine. And if I held it at a steady rpm it was fine. It was either WOT or idle.
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O'Reillys is coming to pick it up and test it for me and see if it is good. We will see here in a few minutes. But it definately is not a burnt wire. Something has to be shorted. ICM, coil, PCM, Opti...something.
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I had a similar thing happen to me and found out one of the spark plug wire wasnt pushed in all the way.
If everything you said checks out ok, do a fuel pressure test just to be sure its not fuel related.
If everything you said checks out ok, do a fuel pressure test just to be sure its not fuel related.
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From: Georgetown, Texas
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Ok. Well fuel pressure was 40+lbs. I don't know what else to do. Someone help me out. Y'all think it's the PCM or opti ? Any ideas would be greatly appreciated.
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Thats good at least you wont have to worry about it being a fuel issue.
Did you drop any of the spark plugs? any crack could cause a misfire. Over tighten the spark plug could crack them too. (just putting it out there just in case)
Is your opti making any kind of noise while its idleing? have you tried swapping a known good coil to see if it helped?
Theres still a lot to check if worse comes to worse get ready to check compression on each cylinder.
But like merv said, I think it might be something that got burnt out. Have you went threw your fuses?
Did you drop any of the spark plugs? any crack could cause a misfire. Over tighten the spark plug could crack them too. (just putting it out there just in case)
Is your opti making any kind of noise while its idleing? have you tried swapping a known good coil to see if it helped?
Theres still a lot to check if worse comes to worse get ready to check compression on each cylinder.
But like merv said, I think it might be something that got burnt out. Have you went threw your fuses?
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when my opti was going out the car would idle fine but as soon as i laid into it it would backfire so badly it scared the **** out of me!
Soon after the car wouldnt start anymore!
I think you said you checked the plugs and wires already. check the OPTI or maybe you fried the ECM. I think you can tell the computer is bad if you hook a scanner up to it and it doesnt respond to the scanner then its shot!
this is what im thinkin COIL, OPTI or fried ECM.
Soon after the car wouldnt start anymore!
I think you said you checked the plugs and wires already. check the OPTI or maybe you fried the ECM. I think you can tell the computer is bad if you hook a scanner up to it and it doesnt respond to the scanner then its shot!
this is what im thinkin COIL, OPTI or fried ECM.
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I have pulled a few of the plugs and they look fine. I haven't pulled all the plugs yet and I probably will tomorrow. Earlier I started it and it ran good. It idled for 10 minutes, reved it up some with no problems. Started to back out and bam. It started backfiring. Then it died and had like a whoosh of air of of the intake like it pushed all the compression out of the intake valves. I still think it is one or the other. PCM or Opti. I am not getting a connection between my scanner and the PCM. Well I take that back. Its intermittant. Some times it will read and then it won't or else it comes and goes. But that maybe the OBD-II port? I am going to check it tomorrow. My tuner has also suggested to check all of my grounds. But I looked and couldn't find anything. I am going to order a PCM tomorrow and install it and see what happens. Hopefully that cures all!? Any other ideas???
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Ok to address previous questions. No I didn't drop any of the plugs. I will change them tomorrow. It seems like a timing issue to me. Whether it be injector timing or spark I don't know. I do not have a MSD or like box on it. 100% stock except for a Delco opti and MSD cap and rotor. The opti is making no noises. I have checked the ignition system like 10 times . Today and the mechanic at my shop. We haven't found anything. And I don't have a "good" coil to use. Would a coil be a spark or no spark type deal? I get spark. It runs. Runs shitty. But runs. I am still going to try the PCM and see. I hate to have to pull the ******* opti off. Thats a bitch, especially after only like 300 miles. Ahhh ******* fuel injection and computers. I am about to rip all this **** off and put a carb. on it. I need another set of eyes. I am getting tired of looking at it. I'm off to bed for the night. Start again tomorrow. Thanks for the suggestions guys, keep em coming. If I am missing something simple someone lemme know...
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Well this is a whole fucked up thing. This morning we pulled the PCM out and took it apart to see if it was burnt or smelled burnt. We pulled the knock module out. No burnt smell. So we put it all back together put it back in and it runs fine. No problems. Driven 20 miles without a problem. I'm baffled.
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