please help me with car cutting out
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Joined: Sep 2000
Posts: 256
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From: indiana
please help me with car cutting out
ok heres the deal if i take car up to 4500 slow its not as bad but if i romp on it it cuts out really bad ive been told it is an ignition prob but ive check my msd,msd coil new cap,rotor,wires and its still there im at my ropes end its driving me nuts what else could it be? my fuel psi is fine "taped gauge to windshied" i have a 87 tpi with maf and custom chip can anyone help me???i would be eternally grateful if anyone can solve this prob thanks
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1992 camaro RS w/ 350tpi
195cc AFR heads with compition port work milled to 58cc
1 3/4 hooker long tube headers
4" mufflex system
custom ED Wright chip
eddelbroc intake base and runners and much more
new best ET 13.5 @104.66 on stock heads
no times with new afr heads hoping for 12's on motor
http://www.nav.to/badass355tpi
------------------
1992 camaro RS w/ 350tpi
195cc AFR heads with compition port work milled to 58cc
1 3/4 hooker long tube headers
4" mufflex system
custom ED Wright chip
eddelbroc intake base and runners and much more
new best ET 13.5 @104.66 on stock heads
no times with new afr heads hoping for 12's on motor
http://www.nav.to/badass355tpi
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Joined: Jan 2000
Posts: 19,656
Likes: 310
Bad RS,
There are a few possibilities that occur to me.
The fuel pressure might be perfect, but the fuel delivery might not. The ECM could be defaulting to the base lookup tables for WOT operation, and they may have injector pulse timings that are just too short for your particular configuration. If it were lean, however, you should detect a bit of backfire (not afterfire) and heating, with possible detonation. The ESC will catch the detonation and trim the timing curve, but you can usually hear a ping or two before the ECM gets the timing retarded.
You could have excessive initial timing, which would cause large steps of retard by the ESC in case of detonation. You could also have hot/fouled chambers that are causing preignition under heavy acceleration, again causing maximum spark retard and poor power.
However, your description of the symptom sounds a lot more like weak spark to me. Since you can slowly take your engine up to RPM, the high chamber pressures that exist during heavy acceleration would not be as prevalent, and might allow a weaker spark to accomplish its job of igniting the mixture. Under heavy acceleration, a weak spark can actually be blown out by the chamber pressure. With OBD systems, there is no good way short of an oscilloscope to determine if there is spark occurring in the chambers. The ignition system may be up to the task, but the plugs themselves need to be able to fire under the pressure. Clean spark plugs with the correct heat range and the correct gap are essential. Aftermarket plugs that are supposed to "work better" often don't have the correct heat range or tip projection to accomplish the assignment like the original plugs. (HINT: You won't find Accel or Bosch +4 plugs in the new LS1s).
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Later,
Vader
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"What a Day..."
Adobe Acrobat Reader
There are a few possibilities that occur to me.
The fuel pressure might be perfect, but the fuel delivery might not. The ECM could be defaulting to the base lookup tables for WOT operation, and they may have injector pulse timings that are just too short for your particular configuration. If it were lean, however, you should detect a bit of backfire (not afterfire) and heating, with possible detonation. The ESC will catch the detonation and trim the timing curve, but you can usually hear a ping or two before the ECM gets the timing retarded.
You could have excessive initial timing, which would cause large steps of retard by the ESC in case of detonation. You could also have hot/fouled chambers that are causing preignition under heavy acceleration, again causing maximum spark retard and poor power.
However, your description of the symptom sounds a lot more like weak spark to me. Since you can slowly take your engine up to RPM, the high chamber pressures that exist during heavy acceleration would not be as prevalent, and might allow a weaker spark to accomplish its job of igniting the mixture. Under heavy acceleration, a weak spark can actually be blown out by the chamber pressure. With OBD systems, there is no good way short of an oscilloscope to determine if there is spark occurring in the chambers. The ignition system may be up to the task, but the plugs themselves need to be able to fire under the pressure. Clean spark plugs with the correct heat range and the correct gap are essential. Aftermarket plugs that are supposed to "work better" often don't have the correct heat range or tip projection to accomplish the assignment like the original plugs. (HINT: You won't find Accel or Bosch +4 plugs in the new LS1s).
------------------
Later,
Vader
------------------
"What a Day..."
Adobe Acrobat Reader
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