Knock Sensor??
05-13-2011, 08:32 PM
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Knock Sensor?? Ok, so a while back I installed Moroso solid motor mounts in my 97 Z28. Its my daily driver and even though many people said never do solids in a dd i did and I really like it. Anyways, one guy told me that solid mounts can drive the knock sensor crazy. He said this will retard the timing and cause it to run rich.
Well now my car is running really rough, it really sputters under a load or going uphill. Its worse at higher speeds too. Its the worst at low acceleration or once the car reaches its speed and slows up. Actual acceleration isnt bad. But I also thought I smelled gas several times. I checked some plugs (only 3, its a pain in the *** with headers) but none of them were fouled or very black. I thought maybe it could be my O2 sensors getting wet but I was gonna see what you guys think.
Well now my car is running really rough, it really sputters under a load or going uphill. Its worse at higher speeds too. Its the worst at low acceleration or once the car reaches its speed and slows up. Actual acceleration isnt bad. But I also thought I smelled gas several times. I checked some plugs (only 3, its a pain in the *** with headers) but none of them were fouled or very black. I thought maybe it could be my O2 sensors getting wet but I was gonna see what you guys think.
05-13-2011, 08:38 PM
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Have it scanned. Record the data while the car is running erroneously.
Sputtering under a load usually means it's something ignition-related, since the ignition system has to work harder under higher cylinder pressures. Plugs, wires, coil, ICM, etc.
Sputtering under a load usually means it's something ignition-related, since the ignition system has to work harder under higher cylinder pressures. Plugs, wires, coil, ICM, etc.
05-13-2011, 08:49 PM
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Haha ramair95ta, It was you that originally told me too!
So when you say have it scanned, do you mean the obd II scanner that you use to pull codes and stuff? Sorry Im kind of a Newb.
So when you say have it scanned, do you mean the obd II scanner that you use to pull codes and stuff? Sorry Im kind of a Newb.
05-30-2011, 10:07 PM
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Ok, so back to this issue now. I unplugged the knock sensor and cruised around today and I definitely still have the issue. I was hoping that after I unplugged the KS and ran it for a while it would clear up but it didn't. And i know for sure that it was running rich because I parked it for over a week and now when i started it up or revved it, it shot a ton of carbon and black **** out the exhaust. I said earlier that it was worse under a load, but it still does it on normal driving/acceleration so its not only under a load. I dont know if its the O2's, the KS, or some other random sh*t at this point so I am looking for some advice. Thanks guys.
Last edited by derekstl; 06-01-2011 at 12:27 PM.
06-01-2011, 12:51 PM
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As far as I know, Autozone can scan any OBDII car, so I would bring it there and get it scanned for any hidden trouble codes. It would be best to datalog it, but I don't think there's any cheap way to do that with OBDII.
The knock sensor wouldn't cause what you're describing and it looks like you've ruled that out anyway. Plug the KS back in. It seems to me that it's an ignition related problem....I would start at the plug wires, look under the hood at night for any arcing, then maybe remove one at a time to inspect. Are they getting burned on the headers?
If you have a temp gun, you can see if all cylinders are warming up evenly upon start up which could tell you if it's a specific cylinder acting up.
The knock sensor wouldn't cause what you're describing and it looks like you've ruled that out anyway. Plug the KS back in. It seems to me that it's an ignition related problem....I would start at the plug wires, look under the hood at night for any arcing, then maybe remove one at a time to inspect. Are they getting burned on the headers?
If you have a temp gun, you can see if all cylinders are warming up evenly upon start up which could tell you if it's a specific cylinder acting up.
06-01-2011, 01:41 PM
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Ok, I will take another look at that stuff. I replaced the opti, ICM, and ignition coils about 9 months ago so I hope none of that stuff is bad but I will double check my plugs and wires. The wires arent getting burnt since I tied them back with zip ties. Thanks for the input
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06-01-2011, 01:57 PM
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I tied mine with zip ties where there was no way they could get cooked, but they still got cooked. I eventually got them away from the headers, but then my problem was the passenger side where they go behind the a/c pulley & belt. I didn't have the factory plastic loom that bends around the acc bracket. Hopefully you have yours.
Hopefully it's just a wire, but I wouldn't rule out the new opti, ICM, and coil.
Hopefully it's just a wire, but I wouldn't rule out the new opti, ICM, and coil.
06-01-2011, 02:18 PM
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I only visually inspected mine and saw that they werent melted or anything. Are you saying they could have heated up enough to cook them but not show its melted??
06-02-2011, 12:20 PM
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But, I DID FIND SOMETHING. There is a spark plug wire that had the outer coat cracked when it was zip tied to the motor mount. I had electrical taped it a long time ago so it was covered. Could this cause the problem even though it was taped up??
I plan on doing new wires this weekend, (i got a free set with my opti a while back) and maybe new plugs while im at it.
06-04-2011, 11:17 PM
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So I started working on my car today. I didnt get all the way finished yet, but i did find some problems. All the plugs on my passenger side were extremely black and fouled out. The cracked wire I talked about was on the drivers side, so its not related. So i replaced all the plugs and wires. Obviously havent fired it up yet to see how it runs. But i still dont know what caused it to start running rich in the first place.
06-06-2011, 01:35 AM
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06-06-2011, 02:02 PM
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My money is on this:
Your Cat is "plugged" with the excessive carbon from you running rich,...probally due to a Opti malfunction.
This happened to my 1995 Z28 about a year after buying it new.
Opti replaced under warranty, Cat "punched out" by private mechanic on GM mechanics unofficial,"Bob's your uncle" opinion.
I loved it, the car immediately sounded better,a little louder with a rasp at certain decel rpm's.
I put another 180,000 miles on that car with no more issues,...when I went to rebuild the motor it looked MINT inside, could have prolly got away with just main/rod bearings.
Your Cat is "plugged" with the excessive carbon from you running rich,...probally due to a Opti malfunction.
This happened to my 1995 Z28 about a year after buying it new.
Opti replaced under warranty, Cat "punched out" by private mechanic on GM mechanics unofficial,"Bob's your uncle" opinion.
I loved it, the car immediately sounded better,a little louder with a rasp at certain decel rpm's.
I put another 180,000 miles on that car with no more issues,...when I went to rebuild the motor it looked MINT inside, could have prolly got away with just main/rod bearings.
Last edited by TIIMuch; 06-06-2011 at 02:08 PM.
06-06-2011, 02:25 PM
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What if I dont have a the cats on my car? I put headers and a y pipe on about a year and a half ago, and also replaced the opti about 9 months ago.
06-06-2011, 03:56 PM
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06-06-2011, 04:05 PM
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Haha well thanks for the input then. I will keep inquiring untill I can figure it out. I was just hoping that finding out that all the plugs on the passenger side are fouled, but the drivers side is fine would really help narrow down what could be causing it to run rich.
