LT1-LT4 Modifications 1993-97 Gen II Small Block V8

need help lt1 boltons-cam problems!

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Old 02-15-2009, 01:00 PM
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Default need help lt1 boltons-cam problems!

full bolt ons, thunder racing 230/236-112lsa. the car ran like ****, i change plugs, wires, lots of sensors, radiator,t-stat, header gaskets, put stock balancer back on no more underdrive. the car ran very good after all that, it didnt break up or rpms hang up anymore. after about am hour of driving rhe problems came back but not as bad. any info? its got pcm4less tuned for the cam
Old 02-15-2009, 01:08 PM
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Explain "ran like ****." You need to be more detailed. Is it when the car is warmed up? All the time? Certain RPMs? More info please.

Perhaps your ICM is bad. Once they get hot, they tend to fail, as do most electrical components. Have you changed that?
Old 02-15-2009, 01:36 PM
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Originally Posted by RamAir95TA
Explain "ran like ****." You need to be more detailed. Is it when the car is warmed up? All the time? Certain RPMs? More info please.

Perhaps your ICM is bad. Once they get hot, they tend to fail, as do most electrical components. Have you changed that?
+1. Need much more info, like "lots of sensors", that could mean anything.
Old 02-15-2009, 03:24 PM
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sorry, i changed-both temps-tps-iac-map-iat. the car runs good untill about 3 grand. if you pull in any gear around 3 grand it breakes up-sputters, i dont know how to exsplain.

i changed the plugs, wires, header geskets, t-stat, radiator, balancer. i drove it for a while and it was fine now all problems are back, rmps hang up around 2grand when stoped, if you give it a lil gas it will come down to about 900 and jump from 500-900 and almost die. it hesitates bad when you get on it likes it missing. its hard to start after hot, cranks and you have to give it gas..
Old 02-15-2009, 03:33 PM
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Sounds like you replaced everything except the ICM (ignition control module). Like I mentioned, they are prone to heat-soak.

Also, if it hesitates to reach higher RPMs, might want to take a look and make sure your cats (if you have any) are clogged.
Old 02-15-2009, 03:41 PM
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no cats lts and dumps. so try the a new icm?
Old 02-15-2009, 03:53 PM
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Originally Posted by sohc19974.6l86
no cats lts and dumps. so try the a new icm?
I would.
Old 02-15-2009, 04:08 PM
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Do you have any dtc codes showing up? Meaning is your ses light on?
Old 02-15-2009, 04:20 PM
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yes a.i.r-o2's. no egr or air pump on the car. rear o2's are tuned out. the car is very hard to start after being hot....
Old 02-15-2009, 04:22 PM
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Originally Posted by sohc19974.6l86
yes a.i.r-o2's. no egr or air pump on the car. rear o2's are tuned out. the car is very hard to start after being hot....
That's a clear-cut symptom of a bad ICM. Hard starting when hot.
Old 02-15-2009, 04:27 PM
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what are symptoms of a bad icm?
Old 02-15-2009, 04:27 PM
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x2 agreed, i bet your icm is thermally breaking down.
Old 02-15-2009, 04:28 PM
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Hard starts when hot, sometimes wont start it all untill it cools down. This is common symptoms of a failing icm.
Old 02-15-2009, 04:30 PM
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they normally shut off ignition signal once heated up. but it is electrical so it can cause the engine to have a misfire tupe situation too.
Old 02-15-2009, 04:32 PM
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similar to a burnt-out light bulb you can shake it,tap it etc. and it may come back on again but how long is undetermined time to replace it.
Old 02-15-2009, 04:40 PM
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were should i get one from, how are msd optis and coils? that whats on there now
Old 02-15-2009, 04:42 PM
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stick with ac delco!
Old 02-15-2009, 04:45 PM
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I'm going to guess that you have a 97...10474610 is the GM part number. Don't settle for anything less than the Delco. Additionally, you will want to move the ICM farther away from the cylinder head, as that is the hottest part of the engine. Do a search and you'll find some information.

IMO, stick with the OEM optispark. The opinion is split on the MSD. Some people have problems with them while others have success. I am sticking with the OEM.
Old 02-15-2009, 04:50 PM
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how do i know if the opti is good?
Old 02-15-2009, 04:53 PM
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From what you have explained thus far, the ICM is what you should target first - not the optispark. It's relatively inexpensive. It's easier to diagnose a failing optispark if you know that the ICM is good.



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