Hey Guys, can I get some help on diagnosing a low load misfire condition.? I know this will be a stretch but, here is what I have.
New GN I just bought, I’ve put 100 miles on it. I don’t think I noticed this condition originally, however it has to be at a certain throttle position/load range to do it.
The misfire will start to occur at around 1.04-1.22 TPS voltage on Scan Master. It seems to be the worst most prevalent in the 1.12-1.16 TPS volt range. It will do this when accelerating normally, keeping up with traffic.... 2nd gear around 35-40 mph and 3rd around 45 mph. Steady throttle this does not occur, less throttle input, this does not occur. Heavy throttle this does not occur.. but If you catch right in that 35-40 mph range at 1.16 TPS, it will steadily buck/surge until you speed up slow down.
AFR is in the 14.0-14.2 range when this phenomenon occurs and doesn’t seem to change much...(no lean spikes or anything).
Today I changed the spark plugs, ohmed out the spark plug wires (all were less then 100 ohms). All vacuum hoses appear to be on. Just installed new fuel pumps, drained the tank completely so the gas is fresh.
Engine is 4 years old, 3k or so miles. Everything was new at that point...(cam sensor, crank sensor, ignition module, coil pack, MAF). Pretty much EVERYTHING was new and adjusted by very good Grand National tech.
Car idles good, revs smooth and clean in park. It’s only under light load/normal acceleration that this happens
I know this is a stretch but... any tips as to what to watch for, look for? There is no MALs on the SM, is there other channels on SM I should look at when this occurs to give me a clue? MV were all over the place as usual at that point.
Thanks for any help!
Just a new guy trying to get a new car lined out and it’s my first Turbo Buick. Thanks again!
New GN I just bought, I’ve put 100 miles on it. I don’t think I noticed this condition originally, however it has to be at a certain throttle position/load range to do it.
The misfire will start to occur at around 1.04-1.22 TPS voltage on Scan Master. It seems to be the worst most prevalent in the 1.12-1.16 TPS volt range. It will do this when accelerating normally, keeping up with traffic.... 2nd gear around 35-40 mph and 3rd around 45 mph. Steady throttle this does not occur, less throttle input, this does not occur. Heavy throttle this does not occur.. but If you catch right in that 35-40 mph range at 1.16 TPS, it will steadily buck/surge until you speed up slow down.
AFR is in the 14.0-14.2 range when this phenomenon occurs and doesn’t seem to change much...(no lean spikes or anything).
Today I changed the spark plugs, ohmed out the spark plug wires (all were less then 100 ohms). All vacuum hoses appear to be on. Just installed new fuel pumps, drained the tank completely so the gas is fresh.
Engine is 4 years old, 3k or so miles. Everything was new at that point...(cam sensor, crank sensor, ignition module, coil pack, MAF). Pretty much EVERYTHING was new and adjusted by very good Grand National tech.
Car idles good, revs smooth and clean in park. It’s only under light load/normal acceleration that this happens
I know this is a stretch but... any tips as to what to watch for, look for? There is no MALs on the SM, is there other channels on SM I should look at when this occurs to give me a clue? MV were all over the place as usual at that point.
Thanks for any help!
Just a new guy trying to get a new car lined out and it’s my first Turbo Buick. Thanks again!