My symptoms have been for the 3 weeks that I've owned the car is a diesel sound and some power loss. I though it was the timing, but adjusting that only helped a little bit.

Before I set the timing 2 weeks ago I put in some low octane fuel and lost all power and came up with a code 43. I put 92 octane back in and it solved the power and overheating problem. I've only been runing 92 since then.

This weekend I replaced the fuel filter and no improvement. Today I was booting around and my SES light came on and I lost all power. Its a code 43 again. Can anyone diagnose the problem from these symptoms?

Thanks guys.

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89 GTA - L98, Black on Black Leather, T-Tops

RIP: 87 Camaro Sport Coupe

 

please help

 

Check the ground On the electronic spark control box. Its the box against the fire wall on the drivers side beside the brake booster. Thers a bunch of wires coming out of it. One is a ground, and one goes straight to the knock sensor. It is possible to swith the wire from the fan switch to the knock sensor cause there the same connections. Check continuity of that wire. I think its a brown wire. If the connections are reversed or the ground is bad the problem you have will happen. Let me know if you need diagrams on that cause I have them

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1987 T/A GTA 5.7L, Bored .020 and ported for .202 valves, edelbrock headers, flowmaster exhaust, JET STAGE II chip, Comp CAM, Adjustable fuel pressure, Airfoil, K&N filter, B&M stage 2 shift kit, and a home depot ram air(Hey it looks good and it works)

 

By the way I think the code 43 is a message saying that the ECM is not recieving input from the knock sensor. Definetly check the wiring. Could be busted or the knock sensor may not even be connected. Let me know if you need help with locations and such Ive been there before. I know its a pain in the ***


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1987 T/A GTA 5.7L, Bored .020 and ported for .202 valves, edelbrock headers, flowmaster exhaust, JET STAGE II chip, Comp CAM, Adjustable fuel pressure, Airfoil, K&N filter, B&M stage 2 shift kit, and a home depot ram air(Hey it looks good and it works)

 

Thanks for the reply. It looks like a plethora of wires in that location near the brake booster. I think I may need to be babied through this. And where exactly is the knock sensor located on the L98? How do I check the ground? I have a digital ohmmeter but how do I connect it to the wire?

I just drove my buddy home and the SES light didnt come on at all. However I do think it is still hurting my performance because the car has a diesel sound to it and it seems to be chugging gas.

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89 GTA - L98, Black on Black Leather, T-Tops

RIP: 87 Camaro Sport Coupe

 

Chugging gas? Im almost sure the ecm is not recieving a signal. The sensor is near the bottom by the motor mount on the right (passenger side) od the block. Its just above the oil pan. Its screwd right into the block. There should be one wire going to it. Careful if you take it out. Youll lose all your coolant throught that plug. Around the fire wall where I said it was plugged in, you should see a few relays. Its around there. Its the biggest unit attached to a braket. With a plug containing six or so wires. I think its the brown wire you need. Get DVOM and set it to continuity. Conect a lead to the wire right at the sensor, disconect it from the sensor first. Then conect a lead to the conector at the fire wal. Disconect it here to. You should have continuity between these to points. Meaning the wire is ok. If not, you found your problem. The fan switch is on the same side but higher up screwed into the head. They have the same connection. If there crossed youll have no knock reading. Check that firs and let me know. The knock sensor could very well be hooped. Its easy to change but messy

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1987 T/A GTA 5.7L, Bored .020 and ported for .202 valves, edelbrock headers, flowmaster exhaust, JET STAGE II chip, Comp CAM, Adjustable fuel pressure, Airfoil, K&N filter, B&M stage 2 shift kit, and a home depot ram air(Hey it looks good and it works)

 

Are you getting this problem right off the bat or when you give it a fair bit of throttle. At idel you probably wont see a SES light. When you hit the throttle it should come on and your performance will suffer

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1987 T/A GTA 5.7L, Bored .020 and ported for .202 valves, edelbrock headers, flowmaster exhaust, JET STAGE II chip, Comp CAM, Adjustable fuel pressure, Airfoil, K&N filter, B&M stage 2 shift kit, and a home depot ram air(Hey it looks good and it works)

 

It doesnt come up at all. It only did it today when I was booting past a mustang. Then after that I had like no power whatsoever. When driving my friend home later I was nicer on the gas pedal so maybe thats why the light didnt come on during the 30 minute trip. I'll try checking that wire tommorow. Unfortunately its dark out now Thanks.

 

I think the reason you losing power when that light comes on is because the computer is seriously retarding your timing cause your not sending a knock signal. By the way that box with all the wire coming out of it I told you about is called the ESC or electronic spark control in case your interested. Keep me posted

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1987 T/A GTA 5.7L, Bored .020 and ported for .202 valves, edelbrock headers, flowmaster exhaust, JET STAGE II chip, Comp CAM, Adjustable fuel pressure, Airfoil, K&N filter, B&M stage 2 shift kit, and a home depot ram air(Hey it looks good and it works)

 

I'm sorry edge but I can not seem to get my SES light to come back on again. This is a good thing and a bad at the same time. My car still has a diesel sound to it and it doesnt accelerate that hard. However the performance is still decent. I can spin the tires in 1st even from a rolling 30mph and it chirps 2nd every chance it gets.

I located the ESC sensor and the connection looks okay, however I can not locate where the ESC module ground wire goes to.

Also if anyone can tell me.. does it work to view the total timing by leaving the EST bypass wire connected and checking the timing? When doing that the timing mark isnt too far ahead than when the bypass wire is disconnected and its at 6*. The timing mark is probably around 12-14* with the EST not bypassed. Maybe this signifies theres still a problem. Thanks to anyone that can leave some feedback.

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89 GTA - L98, Black on Black Leather, T-Tops

RIP: 87 Camaro Sport Coupe

 

I have an Idea. Im working the next couple of days so youll have to be patient with me. But I have the GM service manual. Ill copy the test page for the ESC and email it to you. That module could be hooped. Also I wonder it the TPS has anything to do with this. Ill have alook at the troubleshooting section to give me some ideas. Just be patient ill get it to you

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1987 T/A GTA 5.7L, Bored .020 and ported for .202 valves, edelbrock headers, flowmaster exhaust, JET STAGE II chip, Comp CAM, Adjustable fuel pressure, Airfoil, K&N filter, B&M stage 2 shift kit, and a home depot ram air(Hey it looks good and it works)

 

Thanks man, that would be great. No big hurry cause my car runs decent, but always good to have an f-body running in top shape