I have a pinging problem
Thread Starter
Melting Slicks
Joined: Mar 2008
Posts: 2,141
Likes: 76
From: Santa Maria, CA
I have a pinging problem
I have an 85. The engine has approx 40,000 miles on it. I have a significant ping under medium to full throttle. I use premium gas. This engine was bored .060 and has KB pistons running approx 10:1 compression. Engine has original cast iron heads. I did not do the engine work. This is not a heat problem. Coolant temp is under 180.
I have retarded the timing to 0 deg. Shop manual calls for 6 deg BTDC. I have tried octane boosters with no luck. Tried additives to clean the combustion chambers. I am wondering if the distributor was installed a tooth off. How can I verify it was installed correctly?
I have retarded the timing to 0 deg. Shop manual calls for 6 deg BTDC. I have tried octane boosters with no luck. Tried additives to clean the combustion chambers. I am wondering if the distributor was installed a tooth off. How can I verify it was installed correctly?
Le Mans Master
Joined: Mar 2004
Posts: 5,107
Likes: 171
From: Dublin CA
If you are not the original owner of the car and purchased it with the current engine, I would:
1) contact previous owner if possable and find out if a Hypertech chip was installed. I made the mistake and put one in my 85 and had the same pinging problem under various conditions. Turned out the chip was subtracting fuel as it advanced the distributor. So no matter what i did (timing, different fuel grades, octan boost etc) the chip ws the problem. If you can't find the previous owner, pull the chip and look at the label.
2) Not likely that you are off a tooth on the distributor.
3) What do the plugs look like?
4) Any chance that you have a big carbon build up on the heads?
1) contact previous owner if possable and find out if a Hypertech chip was installed. I made the mistake and put one in my 85 and had the same pinging problem under various conditions. Turned out the chip was subtracting fuel as it advanced the distributor. So no matter what i did (timing, different fuel grades, octan boost etc) the chip ws the problem. If you can't find the previous owner, pull the chip and look at the label.
2) Not likely that you are off a tooth on the distributor.
3) What do the plugs look like?
4) Any chance that you have a big carbon build up on the heads?
Melting Slicks
Joined: May 2007
Posts: 2,171
Likes: 1
From: Warwick RI
I have an 85. The engine has approx 40,000 miles on it. I have a significant ping under medium to full throttle. I use premium gas. This engine was bored .060 and has KB pistons running approx 10:1 compression. Engine has original cast iron heads. I did not do the engine work. This is not a heat problem. Coolant temp is under 180.
I have retarded the timing to 0 deg. Shop manual calls for 6 deg BTDC. I have tried octane boosters with no luck. Tried additives to clean the combustion chambers. I am wondering if the distributor was installed a tooth off. How can I verify it was installed correctly?
I have retarded the timing to 0 deg. Shop manual calls for 6 deg BTDC. I have tried octane boosters with no luck. Tried additives to clean the combustion chambers. I am wondering if the distributor was installed a tooth off. How can I verify it was installed correctly?
If at all possible you definately need to contact the original builder/owner. I am by no means an expert but if you covered octane, ign timing, and carbon build up the only place I would think left to look is compression and maybe cam timing( I am not experienced with cam indexing so this is a shot in the dark). You are looking at exactly what I would for the issue.
You may want to check your compression to make sure that it is 10:1, the combustion chamber size may not have been right for the pistons.
Thread Starter
Melting Slicks
Joined: Mar 2008
Posts: 2,141
Likes: 76
From: Santa Maria, CA
If you are not the original owner of the car and purchased it with the current engine, I would:
1) contact previous owner if possable and find out if a Hypertech chip was installed. I made the mistake and put one in my 85 and had the same pinging problem under various conditions. Turned out the chip was subtracting fuel as it advanced the distributor. So no matter what i did (timing, different fuel grades, octan boost etc) the chip ws the problem. If you can't find the previous owner, pull the chip and look at the label.
2) Not likely that you are off a tooth on the distributor.
3) What do the plugs look like?
4) Any chance that you have a big carbon build up on the heads?
1) contact previous owner if possable and find out if a Hypertech chip was installed. I made the mistake and put one in my 85 and had the same pinging problem under various conditions. Turned out the chip was subtracting fuel as it advanced the distributor. So no matter what i did (timing, different fuel grades, octan boost etc) the chip ws the problem. If you can't find the previous owner, pull the chip and look at the label.
2) Not likely that you are off a tooth on the distributor.
3) What do the plugs look like?
4) Any chance that you have a big carbon build up on the heads?
Thanks.
Melting Slicks
Joined: Jan 2002
Posts: 3,293
Likes: 79
From: Jackson MI
Is this something that just started happening? Or has it been doing this as long at you have owned the car?
I would look into the things above, but also think about your fuel system. I would double check the fuel pressure for sure. If you have replaced the injectors then you can mark those off of the list. When was the last time you replaced the fuel filter? If its clogged it will cause issues on the quick throttle changes and high rpm. If the exhaust is comming out this weekend then that would be the time to change the fuel filter.
As far as the timing, I would get a timing light out and verify it is exactly where it should be, then you can mark that off the list.
I would look into the things above, but also think about your fuel system. I would double check the fuel pressure for sure. If you have replaced the injectors then you can mark those off of the list. When was the last time you replaced the fuel filter? If its clogged it will cause issues on the quick throttle changes and high rpm. If the exhaust is comming out this weekend then that would be the time to change the fuel filter.
As far as the timing, I would get a timing light out and verify it is exactly where it should be, then you can mark that off the list.
Last edited by mn_vette; Jan 13, 2009 at 01:23 PM.
Burning Brakes
Joined: Feb 2002
Posts: 804
Likes: 5
From: Fresno CA
I second what was said about the Hypertech chip. I installed one of their Thermomaster chips in my 85 A/T along with a 180 stat and 180 fan switch and the car ran at the temps I wanted but had a terrible spark rattle at all points throughout the RPM range. Removed it and had a custom prom done and the problem was gone. Take a look at the chip first and if your base timing is a 6* it will most likely be the prom.
Thread Starter
Melting Slicks
Joined: Mar 2008
Posts: 2,141
Likes: 76
From: Santa Maria, CA
Is this something that just started happening? Or has it been doing this as long at you have owned the car?
I would look into the things above, but also think about your fuel system. I would double check the fuel pressure for sure. If you have replaced the injectors then you can mark those off of the list. When was the last time you replaced the fuel filter? If its clogged it will cause issues on the quick throttle changes and high rpm. If the exhaust is comming out this weekend then that would be the time to change the fuel filter.
As far as the timing, I would get a timing light out and verify it is exactly where it should be, then you can mark that off the list.
I would look into the things above, but also think about your fuel system. I would double check the fuel pressure for sure. If you have replaced the injectors then you can mark those off of the list. When was the last time you replaced the fuel filter? If its clogged it will cause issues on the quick throttle changes and high rpm. If the exhaust is comming out this weekend then that would be the time to change the fuel filter.
As far as the timing, I would get a timing light out and verify it is exactly where it should be, then you can mark that off the list.
I have been through the whole fuel system. Replaced injectors, fuel filter and recently the pump died. My fuel pressure is right where it should be.
Thread Starter
Melting Slicks
Joined: Mar 2008
Posts: 2,141
Likes: 76
From: Santa Maria, CA
I second what was said about the Hypertech chip. I installed one of their Thermomaster chips in my 85 A/T along with a 180 stat and 180 fan switch and the car ran at the temps I wanted but had a terrible spark rattle at all points throughout the RPM range. Removed it and had a custom prom done and the problem was gone. Take a look at the chip first and if your base timing is a 6* it will most likely be the prom.
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