Injector/hp question
02-16-2010, 06:46 PM
#22
Thread Starter
Join Date: Jan 2010
Location: Florida
Posts: 21
Not sure, but i think that includes this handheld tuner. This is what the e-mail said :
"We charge $100.00 for an tune if you already have the tuner or $375.00 for an SCT X-cal 3 with two tunes loaded in it specific for you."
"We charge $100.00 for an tune if you already have the tuner or $375.00 for an SCT X-cal 3 with two tunes loaded in it specific for you."
02-17-2010, 09:50 PM
#23
Thread Starter
Join Date: Jan 2010
Location: Florida
Posts: 21
Started it up for the first time today! No tune yet just wanted to hear it run and iron out any issues first.
It started right away. After a couple mins it begam "loping". Reving up and nearly stalling. It seemed to happen when the motor began to get warm about 70 degrees C. Or when it went to its closed loop. I'm hoping its just a vacuum leak i've overlooked, or it needing a tune. Not quite sure yet.
It started right away. After a couple mins it begam "loping". Reving up and nearly stalling. It seemed to happen when the motor began to get warm about 70 degrees C. Or when it went to its closed loop. I'm hoping its just a vacuum leak i've overlooked, or it needing a tune. Not quite sure yet.
02-18-2010, 12:43 PM
#26
TECH SAVANT
Join Date: Dec 2006
Location: Saint Augustine, FL
Posts: 10,938
To elaborate, there are two scalar values in the tune that tell the PCM how much fuel the injectors can inject, and these are all the PCM knows about that vital information...
They are the low and high fuel injector slopes, and they represent the lb/h capacity of the injectors at low and high injector pulse widths--two values are need because as the pulse width narrows (less fuel needed) at some point the time it takes for the injector to open and close becomes larger proportionally to the time it is open, and becuse fuel flows during the opening and closing the injector's capacity is effectively increased.
This point is defined by a certain injector pulse width called the injector breakpoint, and is also programmed in the tune.
The high injector slope value is generally set to the rated injector capacity, the low slope to a 15% to 20% higher value to allow for the fuel that will flow during the opening and closing of the injector, for narrow pulse widths.
With 30lb/h injectors installed, and the PCM thinking they are 19lb/h units, the PCM will end up injecting 30/19, or 158% of the proper amount of fuel = "pig-rich". In closed loop mode the O2 sensors will report this rich mix, and the PCM will try (via the short term fuel trims) to compensate--however it can only pull about 30% max of the calculated fuel requirement, an STFT of -30%. Sustained STFTs of over +/-25% will trigger a DTC.
One other comment, if you have cats's running that rich for any significant time (50+ miles) will kill them--they will burn themselves up from the high unburned fuel content...
They are the low and high fuel injector slopes, and they represent the lb/h capacity of the injectors at low and high injector pulse widths--two values are need because as the pulse width narrows (less fuel needed) at some point the time it takes for the injector to open and close becomes larger proportionally to the time it is open, and becuse fuel flows during the opening and closing the injector's capacity is effectively increased.
This point is defined by a certain injector pulse width called the injector breakpoint, and is also programmed in the tune.
The high injector slope value is generally set to the rated injector capacity, the low slope to a 15% to 20% higher value to allow for the fuel that will flow during the opening and closing of the injector, for narrow pulse widths.
With 30lb/h injectors installed, and the PCM thinking they are 19lb/h units, the PCM will end up injecting 30/19, or 158% of the proper amount of fuel = "pig-rich". In closed loop mode the O2 sensors will report this rich mix, and the PCM will try (via the short term fuel trims) to compensate--however it can only pull about 30% max of the calculated fuel requirement, an STFT of -30%. Sustained STFTs of over +/-25% will trigger a DTC.
One other comment, if you have cats's running that rich for any significant time (50+ miles) will kill them--they will burn themselves up from the high unburned fuel content...
02-18-2010, 06:50 PM
#27
Thread Starter
Join Date: Jan 2010
Location: Florida
Posts: 21
Thanks for elaborating. No cats.
Ok, in closed loop it would compensate for the rich mixture and lean the engine out. Im guessing that the mixture in the CL would still be too rich, because it seems to run better in OL. I gave up on running the car any more until I can get the tune done. Hopefully early next week.
B.T.W I pulled my plugs (old ones, because I didnt want to foul out the new ones) and they where black as black can be.
Also, I noticed a vacuum line broken, not sure where it is supposed to go? Passenger side engine compartment coming off a small canister. It comes off the TB too a sensor then to this small canister, then the other side of this canister had a broken vacuum hose on it.
Ok, in closed loop it would compensate for the rich mixture and lean the engine out. Im guessing that the mixture in the CL would still be too rich, because it seems to run better in OL. I gave up on running the car any more until I can get the tune done. Hopefully early next week.
B.T.W I pulled my plugs (old ones, because I didnt want to foul out the new ones) and they where black as black can be.
Also, I noticed a vacuum line broken, not sure where it is supposed to go? Passenger side engine compartment coming off a small canister. It comes off the TB too a sensor then to this small canister, then the other side of this canister had a broken vacuum hose on it.
02-18-2010, 07:03 PM
#28
TECH SAVANT
Join Date: Dec 2006
Location: Saint Augustine, FL
Posts: 10,938
It will TRY to compensate in open loop, however it will not be able to fully compensate, as it it will hit the limit of it's ability to compensate. With 30lb/h vs. the 19lb/h injectors it expects it will still be pig-rich at -30% STFT.
I.e. the 30lb/h will really mess with the PCM's mind. The PCM will try to make things right, but try as it might, it will nor be able to do it...
I.e. the 30lb/h will really mess with the PCM's mind. The PCM will try to make things right, but try as it might, it will nor be able to do it...
02-23-2010, 09:17 PM
#30
Thread Starter
Join Date: Jan 2010
Location: Florida
Posts: 21
Anyone still reading this thread....
I Broke down on the way to work today.... a loud rattle sound coming from somewhere. I havent been able to diagnose it yet but I'm thinking I broke a valve spring? The passenger side exhaust was smoking bad and the car was missing. I pulled over and just shut it off for now. I hope I didn't bend a valve. Still got plenty of oil pressure.
The heads had stock valve springs, retainers, followers and cams, is there any reason I should have "upgraded" the springs because of the ported heads?
I Broke down on the way to work today.... a loud rattle sound coming from somewhere. I havent been able to diagnose it yet but I'm thinking I broke a valve spring? The passenger side exhaust was smoking bad and the car was missing. I pulled over and just shut it off for now. I hope I didn't bend a valve. Still got plenty of oil pressure.
The heads had stock valve springs, retainers, followers and cams, is there any reason I should have "upgraded" the springs because of the ported heads?
