Ok, I will describe this as well as I can. Look at my mods, I can start this car up and leave the driveway, go down the road 1st thru 3rd, normal driving, stop, turn left then from 1st to 2nd then to 3rd, the engine will kinda backfire and pop for just a second very lightly then it smooths out. I can also sit parked and put the rpms up to 4K and this may sound crazy but the engine gets a different tone to it like its leaning out or something. The car pulls stong as hell, I have tried to find a vacuum leak but no luck, could this be doing this because my mass air meter is calibrated for a Non supercharged application?
Car seems to lean out, popping/misfire
- Thread starter 1993SSP
- Start date
Hmmm, sorry for all the questions, but I forgot to ask what size injectors your running, and if you have had the car dyno-tuned. Sometimes my car will "lean-pop" and stumble a little when it is cold too. It can usually be fixed with some minor tuning changes. You might try increasing your fuel pressure by 2-3 psi and see if it makes a difference. Unfortunately a good tune usually has to be a compromise between power and good driveability. As for the N/A calibration on your mass air meter, on a supercharged car there has to be a way to add fuel linearally as boost (read: power) increases. There are different ways to do this. Most common is with the FMU, which increases fuel pressure in proportion with boost. Then there is a chip ,PMS, etc., in which you can go in and change your fuel curves at different RPM. Then there is the mass air. The s/c calibration on the Pro-M basically provides a richer fuel curve in the higher RPM range then the n/a. So basically if you run and FMU or if your car has been properly dyno-tuned with a chip, you should be fine with the n/a meter. When all is said and done, you just need to make sure your air/fuel ratio at high rpm is safe, usually below 12:1 somewhere.
I have the EXACT same problem. It has been doing it ever since my H/I/C swap last winter. I have Edelbrock performer heads + performer intake, e-cam, 24# injectors, and a C&L 76mm maf/pipe. When the motor has been sitting for a while and is cold, I get slight pop/misfire at times, especially when accelerating below 3000rpms in 2nd and 3rd gear. However as soon as the car warms up a bit it goes away. My timing is set at 14* initial and my fuel pressure is at 40psi w/vacuum off. I've tried playing around with the timing and fuel pressure, but no luck. My car has not been dyno tuned yet, but it will be after this winter when I ad a supercharger. However then I will be changing to 42# injectors, and a better MAF.
Dyno tune would be a very good idea, especially on a supercharged car. It is very important to know where your air/fuel ratio is so you don't blow head gaskets or torch your pistons. 1993SSP, the 24lb injectors might be a little on the small side, depending on whether you are using an FMU, and depending on how much boost you're running.
I have the same exact problem. However, it started after I added a larger throttle body (No power adder). I have discovered that it only pops and idles badly when it is warm outside (60+). When it is cold everything drives great and no hesistation.
I have searched around for an answer to this problem for several months now. No one seems to have a definite solution. I am thinking it might be a sensor such as the Air Charge Temperature sensor or Coolant Temperature sensor
I have searched around for an answer to this problem for several months now. No one seems to have a definite solution. I am thinking it might be a sensor such as the Air Charge Temperature sensor or Coolant Temperature sensor
RMODEL65
Member
mine was doing this on cold days i was getting a rich code the engin was trying to lean out and with the extra dense air when it was cold it was running very lean.i put new o2s and the problem went away also my tps was low i replaced that maybe u just got some bad o2s out the box??
