OK I have a 99 gxe cal emission. In the last month I have replaced cyl 3 2x cyl 5 5x. All from the junkyard but from cars that have been wrecked. Run's fine for a few days then start to get a missfire back. Have checked my grounds and all seem to be good. I don't see how I could have pulled 7 bad packs, all 98 or older as I know the 99's are junk.
Also keep getting "pending" code's for a lean bank 1 or 2 pending on the day. Car also has an idle that is all over the place, will race at 2500+ rpms drop down to 750/800 rpm's nice and smooth then drop to 500 rpm's and lobe up and down. Don't know if this is related but....
O IACV and the EGR have been cleaned, 1st thing I did when I got the 500 miles ago. Replaced IACV from yard with no change in anything. Put mine back on. MAF has been cleaned replaced and back to stock to the car with no change. AT a real loss at this point!!!!

 

maybe it's time to buy them brand new?

 

< sarcasm > Ruin more expensive ones... great idea! < /sarcasm >

 

Grounds.

 

The coils ground to the intake manifold. There are two bolts with multiple ring terminals connected to the manifold between injectors 2 and 4. Remove those bolts and use scotch-brite to clean any metal surface that touches another metal surface. Also, you can try to measure the resistance between terminal 2 of the plug for the coils, and that spot on the intake manifold. Try to use alligator clips to make the connections to the multimeter so you can move the wires around to check for a bad connection.

 

Common sense says if you keep replacing the same part with the same results, then that's not your problem. Stop replacing your coils, the misfire is most likely coming from the lean condition. You may have a fuel issue, injector or vacuum leak somewhere. Make sure the egr isn't leaking into the intake either as that will cause a lean condition and rough idle as well. It's also one of the items you've previously worked on.

 

That dose sound like a good spot to look for the idle issue . How would I test or check to see if the egr is leaking? I am starting think I have 2 bad injectors but they test ok

Thank you !!!!