My 93 has a 351W swap. Car runs very smooth for the most part. I have a studder/miss that happens at a specific RPM. Seems to be around 3500 or so. It smoothes out after that studder/miss zone. The tuner thinks its an ignition issue, but he couldnt nail it down. Any thoughts on what it might be? Maybe distributor or coil retlated?
Put a meter on your tps, slowly run it up to the rpm you have the 'studder' to see if there is a bad spot, do this key on, engine off. At least you will know if it ok or not, then move on to other things.
Ill try the TPS measurement. What is bugging me though is the tuning shop’s response..... they basically said “yeah, we noticed that miss/blip”. That was all they really said though. I asked if they could nail down the issue and they didnt seem to be very responsive. When I dropped off the car, I mentioned the miss. The car runs great otherwise. I figured maybe the tune would straighten it out.They basically said it was “tuned”, but the chip needs to be written. The miss issue is not resolved though. I think they use Moates Quarterhorse. Not sure what t do now. Im fairly certain that theyve already finished the dyno work and a tune I'm just waiting now for a new “chip” so the tune can be installed into my car, and not on their Moates tuning equipment.
So I just basically just rescued my car and gave up on that shop. It's a loooong story. Im not sure what the shop owners' problem is...... When I dropped off my car, I fully explained the situation. I wanted a dyno tune and for them to see what the "miss" or hesitation was at 3500 RPMs or so. He didn't even care or want to figure out that issue. I explained that I assumed they would corrddct the miss or at least let me know what path to go down. Nope. All he did was talk shift about how old and crappy Foxes are and that I should buy a Holley standalone system. I'm sure that the Holley is awesome. It's also big money. I'm sure that there are plenty of folks still using a Ford ECM. Old, sure. I think they still work though. I don't even have a FI car. Just a mild 351 swap. Rant over I guess.
A Miss under load is typically the TFI. The TFI is what actually fires the coil when they start to go badd or become weak they don't Saturate the coil enough and this causes spark loss or a miss under load