I hope someone out there may be able to point me in the right direction, because i'm fed up with this car....

I'm gettin multiple misfires on the driver's bank 1,3,5,7. The "misfiring" is intermittant. I have been on the interstate, and had the car stumble, then after a few miles of driving with the ses light blinking, the car straightens itself out.

Went for a drive today, got to a stop light, and the car just falls flat on it's face. It was missing so bad that i thought it was gonna shut off. Well i try to make it home. Get about halfway there, the car "straightens" itself out again. Travel another mile, car begins to miss once again. SES flashing indicating multiple misfires.

I get home, put the car on autotap. ONly two codes thrown are PO300 (multiple misfire), and PO303 (misfire on #3). It says my drivers bank is running lean, and the pass. rich. Everything seems to be out of whack from one bank to the other.

Since that time, I've been testing coil packs, and what not. It seems as though i am gettin the correct voltage at the packs, but i really don't know what to look for. I'm just going off a "haynes manual" which is really worthless.

The car is also running at 221 at idle according to atap, and it climbed to 235 ont the highway last night. I don't hear my fans coming on at idle, but i read in a previous post that the "low side" fan doesn't come on until coolant temp. reaches 227. What is strange is that when all these misfires occur, the car runs a lot cooler. I haven't had the chance to have it on atap when the car does this at speed, but the temp hand falls from 210 to approximately 175.

Any advice at all would be helpful.

1998 Trans AM ws-6
160 stat
free ram air mod
flowmaster
a/f, fuel press gauges

those are the only mods.

 

Besides taking a hard look at #3, you need to get some data when this happens.

Bank 1 running lean is indicative of a miss-fire or cyl not firing at all (O2 sensor sees the oxygen that wasn't burned).

Mark

 

What would you recommend that i "log" with autotap exactly? Thanks.

Cory

 

Since you know for sure the problem is on #3, you should be able to issolate it pretty easy. Try swapping the coil, wire, and plug with another cylinder and see it the problem moves with the parts or says on #3. If the problem stays on #3, then you have either a fuel or compression problem on that cylinder, so try swapping the injector with another cylinder. If the problem is still on #3, do a compression and leak-down test on that cylinder and one other cylinder and compare them. If it is a lack of compression, you will need to determine whether it is a ring or valve problem. Also could be a collapsed lifter on #3, but I would think you would hear a clicking sound in this case.

 

Whole bank of misfires & a lean driver's side
would make me think about the injector harness
ground for that side. A poor (loose) connection
can easily produce the intermittent good/bad
over each bump & jerk. There's also a (slim)
chance it's in the fuel plumbing but I'd bet on
electrical meself.