Finally fixed high RPM missing
Thread Starter
Team Owner
Joined: Feb 2006
Posts: 23,165
Likes: 117
From: San Antonio Texas
Finally fixed high RPM missing
After months of chasing what I thought to be an ignition or other electrical problem related to spark, I finally got a fix. I had changed the Opti because the old one cooked and was wet inside from a leaky W/pump. So I went all out and replaced wires, plugs, O2's,filter, injectors, coil & module...I was tearing my hair out over this. It ran just fine till I took the rpm over 5k and then it started to misfire like the key was being turned on and off! Finally took it in to Fuel Injection Specialty, here in San Antonio and they put it on a Tech scanner. We took it for a ride to log some data, and ran it up to the "buck-buck zone' a couple of times. Downloaded the info into a computer and gave it a close analysis. Well, everything was working just like it was supposed to, except the mass-air meter had a "dip" in it at the cut out times on both test runs. We pulled the sensor out and gave the little sensor wires a good electrical contact cleaner bath and checked the connectors while we had it off. It looked clean, but must have had some kind of booger on one of those little wires that you couldn't see. It will tear your head off now and runs much smoother and stronger in the mid ranges too. I would have never guessed the Mass air sensor would cause that much mystery and misdirection to my troubleshooting. It's like having a NEW LT4 now like it should have been all along. 
Race Director
Joined: Jan 2005
Posts: 10,641
Likes: 13
From: Slidell Louisiana
After months of chasing what I thought to be an ignition or other electrical problem related to spark, I finally got a fix. I had changed the Opti because the old one cooked and was wet inside from a leaky W/pump. So I went all out and replaced wires, plugs, O2's,filter, injectors, coil & module...I was tearing my hair out over this. It ran just fine till I took the rpm over 5k and then it started to misfire like the key was being turned on and off! Finally took it in to Fuel Injection Specialty, here in San Antonio and they put it on a Tech scanner. We took it for a ride to log some data, and ran it up to the "buck-buck zone' a couple of times. Downloaded the info into a computer and gave it a close analysis. Well, everything was working just like it was supposed to, except the mass-air meter had a "dip" in it at the cut out times on both test runs. We pulled the sensor out and gave the little sensor wires a good electrical contact cleaner bath and checked the connectors while we had it off. It looked clean, but must have had some kind of booger on one of those little wires that you couldn't see. It will tear your head off now and runs much smoother and stronger in the mid ranges too. I would have never guessed the Mass air sensor would cause that much mystery and misdirection to my troubleshooting. It's like having a NEW LT4 now like it should have been all along.
