Ok, So I got this 98 Camaro 3.8 dumped on me. Supposily the car was runing down the interstate fine when it started to miss, Bad enough that it had to be towed home. Guy tells me they replaced the coils, Ignition Modual, plugs( With NGK TR55) And wires. It still misses like crazy on cylinders 5 and 6 and 4 most of the time. 5 and 6 are more or less a dead miss and 4 is sometimes. Fuel pressure is between 46 and 52, plugs are getting fuel because they are wet, And I verified this though my scan tool by shutting down injectors. At 1000 RPM Cylinder 4 will cause it to stumble more but 5 and 6 will show no diffrence when shutting down injectors. Firing is good to the plug on all cylinders. Ive even pulled the valve cover to check for a broken cam but valve train moves normally. I did find when it came in that the MAF sensor didnt have voltage going to it and got that fixed. Any suggestions? Im out of them.
Thanks

 

I had broken pins on my ignition control module that caused a misfire on a 3800SC. Try to find an ignition control module and coils at a junk yard to change out and see if it changes anything, or borrow a known good one from someone with a 3800. Check the wiring to the ignition control module to see if 4,5,6 have a common ground or hot wire. might be a broken wire. Test the wiring from the computer to the ignition control module with a volt meter for continuity, that will tell you if the wires are grounding out some place in the wire harness.

 

Checked the ignition modual and wiring, All is good. i Did find a blown Engine sensor fuse blown and got the O2 and MAF working. Cylinders are firing. Replaced 4,5, and 6 with Double Platnum plugs. Now at idle Numkber 4 and 5 are a dead miss. Wen reved up to 2000 or so R's 4 starts firing and 6 starts missing. Rechecked injectors with noid light and my handheld injector tester that picks up on the injectors viberations. Im lost any more suggestions?

 

I know this is going to sound a little elementary but the 96 - 99 3.8L F-Body's came equipped with log manifolds. The Log Manifolds were NOTORIOUS for destroying plug wires in as little as a week after installation. Make SURE that the plug wires that were recently installed are routed AWAY from the manifolds and are not sitting on them and are not arched. Misfires were very common on these cars during these years because of that.

My 97 RS ate 3 sets of plug wires in about 4 months before I was finally forced to buy heat sheathing and boot protectors to protect my wires.

 

Yes, plug wires are good. Ive had them off, swaped around and checked them