New Distributor installed, now has an unwanted "rev limiter"
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Supreme Member
Joined: Sep 1999
Posts: 7,072
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From: Philly, PA
New Distributor installed, now has an unwanted "rev limiter"
Hoping somebody has expereince with this exact problem, because it's a weird one. Replaced the distributor in my brother's heavily modified 87 GTA that now has a 409 and a Miniram, etc. It is still run by the stock ECM, sensors, wiiring harness and a custom chip. He had a rough idle which we traced to an OEM distributor that was physically worn out and causing a rough idle (lot's of slop in the shaft in all directions).
Dropped in the new Delco stock replacement distributor and hooked it up just like the original one. Simple. Fired it up, set the timing. Idled perfect for the first time ever. We were stoked. Then we took it for a spin. All is good except the thing falls on it's a$$ at WOT above about 4000 RPMs. At 3000 the power falls off, 3500 it starts to miss, and by 4K you're popping and coughing to the point it won't rev any higher. It free revs in neutral all the way to redline just fine. It NEVER had high RPM problems before we installed the new distiributor.
THinking we got a bad distributor, we put the original one back in. The rough idle returns but the high RPM ****-fest remains. Obviously, we scewed up SOMETHING during the INSTALL of the new distributor but what?
All the simple stuff has been checked 3 or more times by now (wiring, coil, timing, wires, cap, rotor, etc). We're not novices at this stuff. What did we blow out? The ECM? Did we screw up the wiring somehow without knowing it? Absolutely NOTHING else was touched when we installed the new distributor. Diacom readings are all normal even while the engine sounds like it is coughing up a lung at high RPMs.
Somebody has had this happen to them before. I just hope they read and respond to this post.
Dropped in the new Delco stock replacement distributor and hooked it up just like the original one. Simple. Fired it up, set the timing. Idled perfect for the first time ever. We were stoked. Then we took it for a spin. All is good except the thing falls on it's a$$ at WOT above about 4000 RPMs. At 3000 the power falls off, 3500 it starts to miss, and by 4K you're popping and coughing to the point it won't rev any higher. It free revs in neutral all the way to redline just fine. It NEVER had high RPM problems before we installed the new distiributor.
THinking we got a bad distributor, we put the original one back in. The rough idle returns but the high RPM ****-fest remains. Obviously, we scewed up SOMETHING during the INSTALL of the new distributor but what?
All the simple stuff has been checked 3 or more times by now (wiring, coil, timing, wires, cap, rotor, etc). We're not novices at this stuff. What did we blow out? The ECM? Did we screw up the wiring somehow without knowing it? Absolutely NOTHING else was touched when we installed the new distributor. Diacom readings are all normal even while the engine sounds like it is coughing up a lung at high RPMs.
Somebody has had this happen to them before. I just hope they read and respond to this post.
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Joined: Jul 1999
Posts: 607
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Your old HEI may have a better coil or ignition module in it. The new replacement one, may just have stock stuff which really doesnt do much after 5000rpm. The stock coil is good for 48kV...most aftermarket coils are 50kV or better.
Upgrade to a better (higher voltage) coil and/or module, and your high rpm performance should improve. Or as a test, put your old module and coil on the new distributor.
Upgrade to a better (higher voltage) coil and/or module, and your high rpm performance should improve. Or as a test, put your old module and coil on the new distributor.
Thread Starter
Supreme Member
Joined: Sep 1999
Posts: 7,072
Likes: 13
From: Philly, PA
My question turned out the be a curve-ball, although I didn't mean it to be. As it turns out, the distributor was just fine. The fuel pump relay decided to take that exact moment in time to take a dump. What are the chances?
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