Ok, you know how it is, whenever you are working on your own stuff,. nothing seems to go right. Well, that is sooooo true here.
My GN with a Speed-Pro 72 lb injectors, champion heads, houston headers, 3.5" DP etc... etc... has a problem.
It misses and pops through the exhaust on full throttle acceleration. It seems to have gotten alot worse lately. Here is the history..... It seemed to have a slight miss/surge at the top end 5500 RPM+ ........ I then had a cam sensor failure that caused some MAJOR backfires.... after fixing that, I decided to test my coil/module with the Caspers tester. I had a breakup at higher rpm, I swapped the coil wires around at the module and dertermined that it was a module failure. At this point I decided to go and switch to the Type II ignition.
Well, things after this are just down hill. With NEW GM module, MSD coils, new plug wires, plugs, just for a tune-up and the new cam sensor, it misses and pops through the exhaust worse than ever.
So, ok, possibly an intermittant crank sensor? Put a new one on. No change. Checked fuel pressure, seems to hold under acceleration. Dropped timing back, no change. Excessivly richened up the map, no change. Leaned it out, no change. Then I talked to Lonnie Diers about the situation. He said to try Valvesprings, sounded like valvefloat. New tool-steel valve springs, possibly better, now seems like a surge but then the more I drive the car the worse it gets. I''s not the same everytime I get on it. Sometimes it's a clean 1st gear and then sputters slightly in 2nd. Sometimes it's just a miss or two followed by a sputter.... and depending on how pissed I am will depend on how long I stay in it.
Questions:
Injectors? Possobly faulty under a load?
Speed Pro ECM has anyone ever experianced a failure?
Fuel problem that doesn't show up on a gauge? I have a Walbro 340m with a bosch external. What about cavitation?
I'm searching for any help.
Thanks!!
Pat
My GN with a Speed-Pro 72 lb injectors, champion heads, houston headers, 3.5" DP etc... etc... has a problem.
It misses and pops through the exhaust on full throttle acceleration. It seems to have gotten alot worse lately. Here is the history..... It seemed to have a slight miss/surge at the top end 5500 RPM+ ........ I then had a cam sensor failure that caused some MAJOR backfires.... after fixing that, I decided to test my coil/module with the Caspers tester. I had a breakup at higher rpm, I swapped the coil wires around at the module and dertermined that it was a module failure. At this point I decided to go and switch to the Type II ignition.
Well, things after this are just down hill. With NEW GM module, MSD coils, new plug wires, plugs, just for a tune-up and the new cam sensor, it misses and pops through the exhaust worse than ever.
So, ok, possibly an intermittant crank sensor? Put a new one on. No change. Checked fuel pressure, seems to hold under acceleration. Dropped timing back, no change. Excessivly richened up the map, no change. Leaned it out, no change. Then I talked to Lonnie Diers about the situation. He said to try Valvesprings, sounded like valvefloat. New tool-steel valve springs, possibly better, now seems like a surge but then the more I drive the car the worse it gets. I''s not the same everytime I get on it. Sometimes it's a clean 1st gear and then sputters slightly in 2nd. Sometimes it's just a miss or two followed by a sputter.... and depending on how pissed I am will depend on how long I stay in it.
Questions:
Injectors? Possobly faulty under a load?
Speed Pro ECM has anyone ever experianced a failure?
Fuel problem that doesn't show up on a gauge? I have a Walbro 340m with a bosch external. What about cavitation?
I'm searching for any help.
Thanks!!
Pat