95 3100 with a #6 missfire...injector?

[alacran]

More info. I am working on a 95 3100 with a miss at idle. the SES is constantly flashing and i get a P0306 misfire in #6 (rear front bank cylinder).

My dad stated he had this problem before and paid $190 to replace #5 injector and sure enough it does look newer than the rest.

My question is can an injector cause a misfire code or am i missing something?

we pulled the plug wires on #4 and #6 with the engine running and there is no change in the engine tone when #6 is unplugged. we puled one wire at a time BTW we have spark.

Also, we checked the spark plugs, #4 looked normal and #6 looked darker (as if it was running rich). I could not check the gap b/c it is running bosch 4 plugs.

We swapped plugs still missing on #6.

Thoughts? I want to make sure it is an injector b/c the only deal i can find is an injector company out of state.

TIA
Nick

[bszopi]

First off, get rid of the Bosch plugs, especially the +4s, as these engines do NOT like them at all. Go with AC Delco platinums or NGK. I wouldn't want to start troubleshooting anything until this is done.

[alacran]

ok, is there a risk that the bosch 4 will throw off the timing? I agree and i told him on the spot that plugs were junk. We will see if puts the delcos back in. anything else?

Oh, the fuel pressure goes to 43 psi at idle with the vacuum line disconnected and plugged.

[Azrael]

43.5 psi with the regulator seeing atmospheric pressure is normal. Should be at mid to high 30's at idle vacuum. If you want cheaper copper plugs, the delco R44LTSM6's are good too.

[MidnightriderZ24]

ohm the injector from the harness by the alternator. also while its running, take a flathead screw driver and a wrench, and tap the injector..sometimes this frees the pintle on these older multec 1's. i actually had this same problem on a 98 3100. #6 is the last fed injector by the regulator, where lots of deposits sit, dirtying up the injector

[86FieroSEv6]

^^^ this ^^^ It is possible that the injector inlet screen is plugged with yuck that got disturbed by the previous injector replacement. Especially if the technician did not flush the rail. Whenever I pull a rail, I check all of the injector inlet screens and the o-rings usually get replaced . . . . because, after all....you're right there.

[alacran]

Is it possible to remove the regulator and look inside the rail by #6 injector? Also, what pins do i ohm out for #6? i will look for diagram.

[Azrael]

Regulator can be removed. It's held on to the rail by a single bolt or torx screw. You'll also need to free the fuel line from any brackets that secure it.

[alacran]

sounds like tapping on the injector worked the engine smoothed out but the SES is staying on now. perhaps we need to erase the code?