I went to go have the final tune put on my car today at ProDyno. Its a 99 cobra, prodyno built motor, aluminator block 9.2:1cr, 04 cobra heads, 01 intake cams, D1SC, lightning maf and mafia. I have the divisionX/lethal budget return fuel system on the car with 60lb injectors as well.
This is the 5th motor that has been in the car and I dont want to lose another. I found out the car already had a reman'd motor in it after it started knocking. Put in a NA aluminator, then 2 motors built by pro dyno. I had a p1 on the aluminator and first pro dyno motor, now a D1.
Essentially we made 13 runs on the dyno today. The first run after we loaded a tune to make a full pull was rich starting around 4700 to ~6000 rpm. He pulled some fuel in that area and and the second run looked closer to a flat 11.7A/F. He began working on drive-ability and some more WOT. He noticed when he pulled some more fuel in that same area (and i think this is where the problem began to rear its head) and the A/F rode nicely on 11.7 until 5500 when it began to go lean, stopped the pull. Dan loaded the previous adjustments from the second run, but the fuel trims did not follow suit, they again began to run lean unlike the 2nd pull which had been slightly rich. We started looking through the tune and noticed when he had commanded more fuel in the third run the alternator voltage began dropping, the 4th run the voltage values were under 13v and fluctuated from 12.4 to 12.8. We changed the alt on the dyno and made another run, the voltage was worse. Replaced the alternator with the previous one and voltage never dropped below 13v again. Runs 5-9 had problems either running too rich, too lean, or blowing off the elbow at the TB.
Every time we made a run, things would look great until 4750rpm then it would either go rich or lean with the same exact fuel commands in place. When the runs were cut short, there were 2 occasions in which the car felt like it had a bad miss and he let out and the car ran rough a couple seconds and he shut the car off. When restarted, it seemed like a cylinder had starved for fuel and knocked for a few seconds, then cleared up and went away.
We then checked the plugs and everything checked out fine, not detonation, no fouling. We tried brainstorming on what could be effecting the A/F to consistently change at 4750rpm, but it would be random whether it would run rich or begin to tip in to the lean side. It seems heat related, although iats were around 100. By this time the car cooled down some and we were on run 10 on his dyno, we loaded the tune from the second run and laid a beautiful 611/540 hp/tq but was the richest run by far. Since the problem seemed to be heat relate we made 3 more runs not changing a single item, again running into the same rich/lean at the same 4700rpms. Im stumped as to whats causing this guys. Is it the computer, injector driver module, a bad ground?
The GOOD:
fuel pressure is 50-54psi WOT
MAF signal is smooth
Timing is constant at 17* and not being pulled
Plugs looked good @ .032
Max boost 16# only fighting a tiny bit of slip with my 8 rib
Made sure the tune file was not corrupt, (deleted, started a new file and even deleted the factory binary just for shits and giggles)
injectors are brand new
The BAD:
Random A/F starting @4700 with no changes to fuel trim
Seems heat related, after cooling down the car will make a solid run with decent A/F then get worse each run
Seems like it starved for fuel on pass side on 2 runs, knocked for a very short time on start up after those runs
During some of the later runs, after 4250rpms, no data would be logged other than the A/F and live readings on the dyno
Are the injectors closing when they get warmer, although they are new?
So im in need of some direction, has anyone had this problem? What can i do? What can i test? How do I fix this issue? Does this seem like a specific computer, wiring harness, or fuel component problem?
This is the 5th motor that has been in the car and I dont want to lose another. I found out the car already had a reman'd motor in it after it started knocking. Put in a NA aluminator, then 2 motors built by pro dyno. I had a p1 on the aluminator and first pro dyno motor, now a D1.
Essentially we made 13 runs on the dyno today. The first run after we loaded a tune to make a full pull was rich starting around 4700 to ~6000 rpm. He pulled some fuel in that area and and the second run looked closer to a flat 11.7A/F. He began working on drive-ability and some more WOT. He noticed when he pulled some more fuel in that same area (and i think this is where the problem began to rear its head) and the A/F rode nicely on 11.7 until 5500 when it began to go lean, stopped the pull. Dan loaded the previous adjustments from the second run, but the fuel trims did not follow suit, they again began to run lean unlike the 2nd pull which had been slightly rich. We started looking through the tune and noticed when he had commanded more fuel in the third run the alternator voltage began dropping, the 4th run the voltage values were under 13v and fluctuated from 12.4 to 12.8. We changed the alt on the dyno and made another run, the voltage was worse. Replaced the alternator with the previous one and voltage never dropped below 13v again. Runs 5-9 had problems either running too rich, too lean, or blowing off the elbow at the TB.
Every time we made a run, things would look great until 4750rpm then it would either go rich or lean with the same exact fuel commands in place. When the runs were cut short, there were 2 occasions in which the car felt like it had a bad miss and he let out and the car ran rough a couple seconds and he shut the car off. When restarted, it seemed like a cylinder had starved for fuel and knocked for a few seconds, then cleared up and went away.
We then checked the plugs and everything checked out fine, not detonation, no fouling. We tried brainstorming on what could be effecting the A/F to consistently change at 4750rpm, but it would be random whether it would run rich or begin to tip in to the lean side. It seems heat related, although iats were around 100. By this time the car cooled down some and we were on run 10 on his dyno, we loaded the tune from the second run and laid a beautiful 611/540 hp/tq but was the richest run by far. Since the problem seemed to be heat relate we made 3 more runs not changing a single item, again running into the same rich/lean at the same 4700rpms. Im stumped as to whats causing this guys. Is it the computer, injector driver module, a bad ground?
The GOOD:
fuel pressure is 50-54psi WOT
MAF signal is smooth
Timing is constant at 17* and not being pulled
Plugs looked good @ .032
Max boost 16# only fighting a tiny bit of slip with my 8 rib
Made sure the tune file was not corrupt, (deleted, started a new file and even deleted the factory binary just for shits and giggles)
injectors are brand new
The BAD:
Random A/F starting @4700 with no changes to fuel trim
Seems heat related, after cooling down the car will make a solid run with decent A/F then get worse each run
Seems like it starved for fuel on pass side on 2 runs, knocked for a very short time on start up after those runs
During some of the later runs, after 4250rpms, no data would be logged other than the A/F and live readings on the dyno
Are the injectors closing when they get warmer, although they are new?
So im in need of some direction, has anyone had this problem? What can i do? What can i test? How do I fix this issue? Does this seem like a specific computer, wiring harness, or fuel component problem?
