stroked and stalling
Thread Starter
Registered User
Joined: Apr 2003
Posts: 382
From: Green Bay, WI
stroked and stalling
383 was built, broken and now repaired. I have:
6" eagle H beam rods
-16cc SLP/JE pistons
Scat9000 stroker crank
comp cams 306
Comp 10308 valve springs
58mm TB
42lb injectors
The car ran fine before the valve float problem (although way too rich) and now that it is rebuilt, runs smoother, with one hiccup.
After the engine is under load or partial throttle, and the clutch is put in or the car is in neutral, it will sputter and die. There was a problem w/ the IAC sensor, but after adjusting, the IAC at idle is now around 110-120, not pegged at 160. The car starts fine, idles fine, and only has a problem when not in gear/clutch depressed. I have to keep my foot slightly on the gas to keep it from stalling. What should i be looking for ?
6" eagle H beam rods
-16cc SLP/JE pistons
Scat9000 stroker crank
comp cams 306
Comp 10308 valve springs
58mm TB
42lb injectors
The car ran fine before the valve float problem (although way too rich) and now that it is rebuilt, runs smoother, with one hiccup.
After the engine is under load or partial throttle, and the clutch is put in or the car is in neutral, it will sputter and die. There was a problem w/ the IAC sensor, but after adjusting, the IAC at idle is now around 110-120, not pegged at 160. The car starts fine, idles fine, and only has a problem when not in gear/clutch depressed. I have to keep my foot slightly on the gas to keep it from stalling. What should i be looking for ?
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Joined: Nov 1998
Posts: 71,094
From: Hell was full so they sent me to NJ
Re: stroked and stalling
This should be in "LT1 Engine Tech".
How did you adjust the IAC? Are you sure the IAC is functioning (the PCM "counts" is just what the PCM is telling it to do, not what it is actually doing)? How good is the programming - who did it? What is the target idle speed? What was your "valve float problem"? How did you fix it? How does the IAC counts respond to increaing speed/rpm?
How did you adjust the IAC? Are you sure the IAC is functioning (the PCM "counts" is just what the PCM is telling it to do, not what it is actually doing)? How good is the programming - who did it? What is the target idle speed? What was your "valve float problem"? How did you fix it? How does the IAC counts respond to increaing speed/rpm?
Thread Starter
Registered User
Joined: Apr 2003
Posts: 382
From: Green Bay, WI
Re: stroked and stalling
Injuneer:
IAC was maxed to 160. Turned the idle screw on the throttle body and IAC dropped to 120. That allowed me to use the power steering without the car stalling. The programming is crap, i'll be getting a Herder tune shortly, but am concerned because i dont think a new tune will fix it. this was not a problem before the rebuild. The valve float was immediatly followed by a smash that dented a piston, bent the valve and broke a spring. I would test the IAC, but am not sure how to do that. IAC inversely proportionial to rpm.
IAC was maxed to 160. Turned the idle screw on the throttle body and IAC dropped to 120. That allowed me to use the power steering without the car stalling. The programming is crap, i'll be getting a Herder tune shortly, but am concerned because i dont think a new tune will fix it. this was not a problem before the rebuild. The valve float was immediatly followed by a smash that dented a piston, bent the valve and broke a spring. I would test the IAC, but am not sure how to do that. IAC inversely proportionial to rpm.
Administrator
Joined: Nov 1998
Posts: 71,094
From: Hell was full so they sent me to NJ
Re: stroked and stalling
Why are you looking for a vacuum leak? That would cause the IAC counts to move toward "0". At idle, the counts approaching "0" would indicate the engine is getting too much air = too high an idle speed. Counts near "160" would indicate (in addition to bad tuning for the cam) that the RPM is too low and the motor is supposed to open up to let more air in/raise RPM.
When you start moving, the PCM uses a "follower" table to increase the IAC counts and avoid stalling when the throttle is allowed to close. Again, doesn';t sound like yours is actually letting air in.
On a stock cam, you would look for idle counts in the range of 20-40. As you started to raise road speed/RPM, the IAC counts would increase to the range of 70-110 counts. How yours responds would depend on what the target idle speed was and how they set up the follower table.
The PCM scan just shows you what the IAC motor is supposed to do, in terms of "counts". It doesn't indicate if the IAC motor is actually moving. Shoebox has a test procedure on his website, if I recall correctly. If for example, the IAC motor wasn't moving, or the IAC passages were plugged up, you would have stalling.
When you start moving, the PCM uses a "follower" table to increase the IAC counts and avoid stalling when the throttle is allowed to close. Again, doesn';t sound like yours is actually letting air in.
On a stock cam, you would look for idle counts in the range of 20-40. As you started to raise road speed/RPM, the IAC counts would increase to the range of 70-110 counts. How yours responds would depend on what the target idle speed was and how they set up the follower table.
The PCM scan just shows you what the IAC motor is supposed to do, in terms of "counts". It doesn't indicate if the IAC motor is actually moving. Shoebox has a test procedure on his website, if I recall correctly. If for example, the IAC motor wasn't moving, or the IAC passages were plugged up, you would have stalling.
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