Dtownbrown

OKay so iv been battling this cutting out for the past two weeks with no cure so far. Here is what the car is doing, It idles and drives just fine, but under a load it starting miss firing and cutting out. In neutral I can rev it up just fine, but as soon as it hits 5000rpms, it acts like it has a two step. I checked all wires, replaced plugs, checked wiring. Fuel pressure stays at 60# or more. We figure it could be a grounding issue so we hooked a volt meter to the passenger side coil pack wiring harness " The pink one" which I believe is the main hot wire, Revved it up and as soon as hit his 5000rpms, it had a big voltage drop. Checked the passenger side and it didn't lose any. So now im not exactly sure where I should go from here to trace down the voltage dropping issue? What would you guys suggest me do first? -Thanks.

This is on a 99 FRC.

Dtownbrown

Oh and im not sure if this ties into that harness but when I got my trans fixed and the car running again I kept popping the "injr1" fuse, I drove it about 6 miles and it popped that fuse atleast 5 times, I kinda messed with the wiring harness and it hasn't popped again so maybe there is something in the harness that's contributing to both issues?

neutron82

have you checked the coil/injector harness around the back of the manifold?... they are notorious for rubbing against the bracket where the harness goes behind the intake and chafing the wires which causes problems with the driver side coils/injectors

Dtownbrown

I looked them over when I had the intake off, didn't notice any thing from the norm. But I didn't separate all the wires so its still a possibility I may have missed something. Will look deeper into that tomorrow also.

Dtownbrown

The wire we checked voltage on while running is the Pink wire " PCM ignition supply" , I checked resistance and it was "0.01" on both sides. Not sure if that tells you guys anything more.

chaase

It may not be the problem but it can't help to look for missing insulation.

69

I noted your post here regarding the popping fuse,

http://forums.corvetteforum.com/c5-t...s-popping.html

Did you get this issue sorted out? We're there any codes?

Kevin

Dtownbrown

Well I never figured out why It was popping but it hasn't done it sense that day. The cutting out turned out to be a faulty Mass air flow sensor.

BadMedcn

Neutron82 is right on the money. This very issue had me chasing my tail several months ago. First, lost one injector on drivers side, then a second......intermittently on and off. Drove me nuts. Finally found the wire for the coil/injectors had a bad ground. Gave it a new one and voila! Not a code, or problem since. Mine began 3 years after replacing engine....as Neutron82 said, the harness rubbed on the back of the motor until it wore away enough insulation to give me an intermittent ground. Repaired it and gave it a new ground point that didn't stress the wire and that solved it. Wish I had Neutron82's input back then. So look closely. I believe the LS1 coil/injectors are grounded to the block on the driver side, rear. Good luck.

Bill Curlee

Ha,,,,,,,,,,,,, You sound like you have the EXACT same issue I I had. Under hard load i popped fuse 22!

Heres what mine turned out to be:





You have to start digging!

I could not believe that my car would run on FOUR CYLINDER!!!!!