Engine rpm drops
Thread Starter
Staging Lane
Joined: Mar 2008
Posts: 57
Likes: 0
From: Stockholm, Sweden
Engine rpm drops Hi !
I have now completed my engine swap and everything works fine except one crucial thing. When I hit the trottle and release it immediately the rpm drops significant and if I do this with the transmisson in drive the engine stops. I know that the engine worked fine before the swap. I wonder if I have missed something. I have changed from cast exhaust manifold to headers, should I tune the PCM? I dont have a scanner tool yet but the MIL does not lit. Anyone have a clue what is wrong ? / Magnus
I have now completed my engine swap and everything works fine except one crucial thing. When I hit the trottle and release it immediately the rpm drops significant and if I do this with the transmisson in drive the engine stops. I know that the engine worked fine before the swap. I wonder if I have missed something. I have changed from cast exhaust manifold to headers, should I tune the PCM? I dont have a scanner tool yet but the MIL does not lit. Anyone have a clue what is wrong ? / Magnus
Thread Starter
Staging Lane
Joined: Mar 2008
Posts: 57
Likes: 0
From: Stockholm, Sweden
Engine will not run when warm No, I will check that to day. The engine runs fine when it is cold, the problem occurs when it reach the working temperature (185-190 degree F). Is the engine sensitive to minor changes such as delete of catalysators or adding headers, since this is what I have done. M
TECH Regular
Joined: May 2005
Posts: 406
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From: Bay Area, CA
Hi !
I have now completed my engine swap and everything works fine except one crucial thing. When I hit the trottle and release it immediately the rpm drops significant and if I do this with the transmisson in drive the engine stops. I know that the engine worked fine before the swap. I wonder if I have missed something. I have changed from cast exhaust manifold to headers, should I tune the PCM? I dont have a scanner tool yet but the MIL does not lit. Anyone have a clue what is wrong ? / Magnus
I have now completed my engine swap and everything works fine except one crucial thing. When I hit the trottle and release it immediately the rpm drops significant and if I do this with the transmisson in drive the engine stops. I know that the engine worked fine before the swap. I wonder if I have missed something. I have changed from cast exhaust manifold to headers, should I tune the PCM? I dont have a scanner tool yet but the MIL does not lit. Anyone have a clue what is wrong ? / Magnus
Thread Starter
Staging Lane
Joined: Mar 2008
Posts: 57
Likes: 0
From: Stockholm, Sweden
Hhmm ! What is TPS ?
I will try to drive it more and see if PCM recalibrates.
When I release the trottle the engine rpm drops to about 900 rpm and after less than a second the rpm drops to 200-300 rpm and if I am lucky the engine does not stop. Then after 1-3 seconds the rpm goes back to 800 rpm. It is not a problem to rev it up to like 4000 rpm. M
I will try to drive it more and see if PCM recalibrates.
When I release the trottle the engine rpm drops to about 900 rpm and after less than a second the rpm drops to 200-300 rpm and if I am lucky the engine does not stop. Then after 1-3 seconds the rpm goes back to 800 rpm. It is not a problem to rev it up to like 4000 rpm. M
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Thread Starter
Staging Lane
Joined: Mar 2008
Posts: 57
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From: Stockholm, Sweden
I have now tried to find if I lose vacuum somewhere. I found that the MAP-sensor in the back of the intake is little loose ! should it be like this ? It is a LS1 (Corvette) intake. M
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It could be the problem, but the TPS went out on my ls1 and it when it shifted to OD at very low speed it almost died. Same for comming to a stop. RPMs would go down to like 250.
also, where is your maf mounted? if it is too close to the throttle body it can super sensitive.
just learned this the other day. my friend an i did an ls swap in his s-10 and to get it running (temporary) we just used a short (like 2 inch) connector to connect the maf to the throttle body and once it warmed up (entered closed loop) if you put it in gear (or came to a stop, we took it around the block like that) it would just about die. connected the maf like 10 inches away and solved the problem.
just learned this the other day. my friend an i did an ls swap in his s-10 and to get it running (temporary) we just used a short (like 2 inch) connector to connect the maf to the throttle body and once it warmed up (entered closed loop) if you put it in gear (or came to a stop, we took it around the block like that) it would just about die. connected the maf like 10 inches away and solved the problem.