84 corvette bad hesitation tuned port converted
03-19-2016, 06:21 PM
#1
Cruising
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84 corvette bad hesitation tuned port converted
i have an 84 corvette with mass airflow tuned port,painless wire harness new computer hypertech chip accel injectors dui ign. reads 45 psi of fuel pressure. it hesitates like i has no gas after the engine gets up to operating temp. i just changed the filter and pump with no change. not real familiar with this old injection system any info would be much appreciated. also the engine was overhauled and a performance cam was also put in have no idea what cam it has as all this work was done before i got it and the guy gave up on the project.
03-20-2016, 05:34 PM
#4
Cruising
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The ecm part number in the car is a reman 7 6870 and the hypertech chip is 115 41 what I could read off em the computer appears correct not sure about the chip
Last edited by spivie; 03-20-2016 at 05:35 PM.
03-21-2016, 12:48 AM
#5
Race Director
Are you REALLY SURE?
I have heard of vacuum leaks on the bottom of the intake manifold runners, for example. I had a leak at the rubber coupling between the PCV tube and the intake manifold. They can be very subtle and really hard to find.
I have heard of vacuum leaks on the bottom of the intake manifold runners, for example. I had a leak at the rubber coupling between the PCV tube and the intake manifold. They can be very subtle and really hard to find.
03-23-2016, 09:14 PM
#6
Drifting
I had one drive me nuts related to the crank case vent...
Issue was that i installed a open vent on one side and then left the oem check valve vent on the other side for the evap...
Just saying it might be staring you right in the face like a fancy chrome breather...
Issue was that i installed a open vent on one side and then left the oem check valve vent on the other side for the evap...
Just saying it might be staring you right in the face like a fancy chrome breather...
03-23-2016, 11:35 PM
#7
Race Director
I found out recently that the reason the air from the throttle body goes to the passenger side valve cover is that it is metered because it has gone through the MAF. The air goes from the PCV valve into the intake manifold so it affects the AFR. Using a fancy chrome breather vent creates a vacuum leak.
03-24-2016, 03:29 PM
#8
Safety Car
Is the "performance" cam correct for an EFI engine? Cams designed for carbureted engines don't work well in EFI engines. Everything else can be perfect, but the engine still won't run well. What is your manifold vacuum at idle? Do you have a steady idle, and what is your idle speed?
03-26-2016, 11:39 AM
#9
Drifting
BLM (BLOCK LEARN MEMORY) is the ECM's ability to adjust for fuel. it runs from 108 to 160 with 128 being perfect. Counts above 128 is lean and below is rich. Also, base timing is 6 degrees. When adding a performance cam you should have 2 to 4 degrees added to the spark map in the idle area. Simply adding it to the base is a grave error. Find someone who can help you such as Alvin at PCM of north Carolina after you know your BLM counts at various points of operation.
