I'll start off by saying the car in question isn't mine I'm just doing some research to see what I can figure out. A guy brought a 5.0 in a garage I hang out today with a miss. The car has a Professional Products intake, Pro Comp heads, he was unsure what the cam was, full exhaust, cold air, stock injectors and fuel pump and hes untuned. The car wasn't running for crap at first but he got to playing with the timing and got it running 10 to 1 better its just now in high gear it seems to load up with fuel and start missing and you can shove the fuel down it'll clear out. I myself am a LS1 person ( still like mustangs) and with those cars with just a bigger cam alot of them will barely start on the stock tune. Could this be his problem? The plugs have been changed, timings set and still has the high gear miss. He said it had some cam surge as well. Could the tune be the problem? Thanks

 

Compression check? Specifically #8.

 

what year?

what size injectors?

what size fuel pump?

could also be the coil giving up at higher rpms. when the coil goes bad( mostly when it warms up almost like the tfI) a symptom is the motor getting flat at higher rpms and under a load.

 

The car is a 92 and he said it ran alot better when it was cold but when I rode it wide open throttle was fine it was just when it was in high gear. Hes running the stock pump and injectors. It had a aftermarket coil on it but it still could have been bad. I'm sure they didn't check the compression.

 

the car has an H/c/i with stock 19lbs injectors, that is a problem they are running at 100% duty cycle that motor should be running min. 24lbs and a good idea would be 155 pump, then a tune for the injectors. I think she is fuel hungry for one.

 

also pull the plugs, check the vacuum, check the cap/rotor, check the timing, check the firing order, etc, etc. go through all the basics it sounds ignition based like the coil, tfi or even dizzy. Like i posted above he is really running those injectors flat out curious about the tune job now.

 

The mechanic set the timing with a light and hes had the cap on and off and he was pulling the chip in and out. That was one of the first things I asked the owner was injectors were in it and he said who or wherever he got everything told him he'd be fine with the stockers. I know with the LS1s anything over a cam you'll need bigger injectors. The car seems to run a bit rich but maybe getting it to a tuner will tell the tale.