Missing at idle
 

Ok so all cylinders are missing at idle cylinder 1 getting hit the most. When I apply throttle misfire disapear but when I release throttle cylinder one misfires a bit. At the same time im running "lean" on bank two but I suspect a vac leak. At idle bank one runs rich as much as -5% while bank two is at 4 to 6% and rises slowly to 10 if I let it idle a bit. When I apply throttle both banks indicate -4% ltft. When I release throttle bank two at times spikes up to +20%. I have new o2s opti from chandler, coil, taylor wires and acdelco plugs. TIA.

Re: Missing at idle
 

I forgot to mention I keep getting codes p1351 and p0300

Re: Missing at idle
 

Been a while since I've messed with OBD2, but I think that the p1351 code is the ICM circuit, and P0300 code is misfire. Correct me if I am wrong though. If it is, I would start by asking if it does this when it's both hot and cold? If it only misses when hot, I would think that you have a heat sink problem in the ICM. It may already be out though, causing it to run like crap all of the time. I think most auto parts stores can test the ICM if you can get the car there.

As far as the lean condition goes. Have you checked for exhaust leaks in the manifold? Had this problem on my car, and was giving a false lean. Could be the case, but would start by solving the misfire first, and work my way though the problems one step at a time.

Hope this helps.....

Re: Missing at idle
 

Ok well it does seem to miss more when its in closed loop. Changing the icm didnt help I keep getting p1351. Today i'll check fuel pressure and diagnose if I have a bad opti, coil or wires. P1351 usually sets at a higher rpm around 2000 and up. Thanks

Re: Missing at idle
 

Fixed the missing issue. The high resolution wire was stripped and about to break. I used shbox opti and spark test which led me to the problem. I also cleaned the iac motor and did the icm cooling mod. Car runs alot smoother and have no problems so far. Only problem i have is the false lean condition i have on bank 2. Checked all vacuum hoses for leaks and found none. Checked header flange before it warmed up and felt no escaping exhaust. Seems like the false lean condition grows even bigger when car is up to temp. Could it be valve guides seals that slipped off valve guides? Incorrect valve lash?