I got a spark-knocker!
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Junior Member
Joined: Jun 2001
Posts: 21
Likes: 0
From: North Carolina
I got a spark-knocker!
My '87 305 TPI auto is one heck of a spark-knocker. I never really noticed it when I bought the car about 3 years ago. As soon as I got it I started putting 93 Octane strictly in it. Now when I went to the coast this past summer, the spark-knocking got worse. I live at altitudes of 3000 and up so I figured the car was not used to the lower elevation. I'm sure it was knocking before the trip to the coast, but here lately it seems as if it is getting worse. I have been running 87 Octane fuel for about the past 3 weeks, hoping that was the problem. It seemed to help for the first few days, but then it came back. I don't buy the cheapest gas in town. I have 2 other vehicles that I use the same brand of gas in. My '68 SS and my '81 GMC Jimmy. Both 4 barrells and built to run. They both run just fine off of the same gas.
I know that my IROC is getting old, over 143,000 mi. but it just runs too good and smoothly. It'll still light up the rear end (posi) whenever you punch it in first, dead stop or not. But its when it shifts into the other gears and it is under load that the spark-knocking is noticable. The fuel don't seem to affect it any great deal. I've not checked the timing, but neither has it ever been tampered with. It is a COMPLETELY stock car. Virgin engine and tranny, no mods, still smog legal even the GM muffler and catalytic converter. It does have K&N filters. AC Delco R43TS sparkplugs, 7MM wires (custom length), new cap and rotor. Very well maintenanced and regularly serviced.
I'm suspecting the Knock sensor, but how exactly do I go about testing it? The ECM has no codes present, and the past code it threw about 4 months ago was about the ignition module, but was a freak code I think. No problems or codes since.
I'm going to store my IROC and my '68 for the winter, so I'll have plenty of time to troubleshoot them. Please help if you possibly can. Thanks in advance.
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1987 IROC,305 TPI Slush box G80,G92,143K+:Mint condition,K&N Filters, ADS Superchip, Stock Exhaust, Virgin Engine and transmission.
1968 SS Camaro, 350 built and shaved, Holley 750 Dual line double pumper, TH-400, 3.73's
Two other Thrid Gen Camaro's for parts ('84Z and '85Z TPI)
I know that my IROC is getting old, over 143,000 mi. but it just runs too good and smoothly. It'll still light up the rear end (posi) whenever you punch it in first, dead stop or not. But its when it shifts into the other gears and it is under load that the spark-knocking is noticable. The fuel don't seem to affect it any great deal. I've not checked the timing, but neither has it ever been tampered with. It is a COMPLETELY stock car. Virgin engine and tranny, no mods, still smog legal even the GM muffler and catalytic converter. It does have K&N filters. AC Delco R43TS sparkplugs, 7MM wires (custom length), new cap and rotor. Very well maintenanced and regularly serviced.
I'm suspecting the Knock sensor, but how exactly do I go about testing it? The ECM has no codes present, and the past code it threw about 4 months ago was about the ignition module, but was a freak code I think. No problems or codes since.
I'm going to store my IROC and my '68 for the winter, so I'll have plenty of time to troubleshoot them. Please help if you possibly can. Thanks in advance.
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1987 IROC,305 TPI Slush box G80,G92,143K+:Mint condition,K&N Filters, ADS Superchip, Stock Exhaust, Virgin Engine and transmission.
1968 SS Camaro, 350 built and shaved, Holley 750 Dual line double pumper, TH-400, 3.73's
Two other Thrid Gen Camaro's for parts ('84Z and '85Z TPI)
TGO Supporter
Joined: Jan 2000
Posts: 1,861
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From: In your ear. No, the other one.
Car: '89 Trans Am WS6
Engine: 350 TPI
Transmission: T5WC
Axle/Gears: 3.08 posi
I've had a similar knocking problem.
Check the timing first (dont look for a zebra when you see hoove prints. look for a horse).
Next check for air leaks. Get a sensor-friendly can of carb cleaner and spray around the intake. If the engine jumps a little, its sucking air from someplace it shouldn't be and is therefore running a little too lean.
If you have access to a scanner:
Check the knock sensor reading and make sure its in spec. If its bad, the computer can't retard the timing. Its cheap and easy to replace (you dont even have to drain the coolant if you don't mind getting a little on you. Plug the hole with a finger while you swap them out. Do it quickly!).
Check the O2 sensor reading and make sure its in spec.
Basically you're looking for reasons why the spark is off or why the engine is running lean, the two things that cause knock!
Hope this helps,
M
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'89 TA - 5.7 TPI (L05, was originally a 305TPI), T5-WC, 3.08 Posi (Drum)
Check the timing first (dont look for a zebra when you see hoove prints. look for a horse).
Next check for air leaks. Get a sensor-friendly can of carb cleaner and spray around the intake. If the engine jumps a little, its sucking air from someplace it shouldn't be and is therefore running a little too lean.
If you have access to a scanner:
Check the knock sensor reading and make sure its in spec. If its bad, the computer can't retard the timing. Its cheap and easy to replace (you dont even have to drain the coolant if you don't mind getting a little on you. Plug the hole with a finger while you swap them out. Do it quickly!).
Check the O2 sensor reading and make sure its in spec.
Basically you're looking for reasons why the spark is off or why the engine is running lean, the two things that cause knock!
Hope this helps,
M
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'89 TA - 5.7 TPI (L05, was originally a 305TPI), T5-WC, 3.08 Posi (Drum)
