newbie needs help

[red coupe89]

hey everyone, having a problem with ignition in cyl 4 of my 91 TT. i have power, ground and signal in the harness and out of the coil pack and a brand new plug on the hole. had compression and fuel, but no ignition, not sure where to look and its driving me crazy, anyone ever run into this or have any ideas on where to look?


thanks!!!!!!

[NXgear]

are you sure you're getting spark? hold the spark plug tip to the block or somewhere with bare metal that is grounded and turn the car over to check for spark. Also, have you ruled out a bad injector? Check this by removing distributor from engine (crank angle sensor harness connector should remain connected). Disconnect ignition wires. Turn ignition switch ON(but do not start). Rotate distributor shaft slowly by hand and listen for operation of each injector.

[NXgear]

I ment to tell you to test the spark plug with a known good one. Leave the one in the engine or you'll loose compression. Also the injector check might not work on your car so if you have good spark just try unplugging the injector while it's running to see if there are any changes. If not, most likely bad injector.

[red coupe89]

yes, the plug works in another whole, and when gounded lights up. I was unsure how to check to see if the injector was fouling the plug out as the old one was soaked in fuel. i unpluged the pack connector and the idle didnt change, still had the same misfire.

[red coupe89]

bump for some other options, injectors seem good.

[NXgear]

so no change when you unplug the injector??? ...this would make sense if the injector is bad. Any chance you could swap injectors to see if problem follows to a different cylinder? not sure how hard these are to pull out. Are you getting a check engine light? did you happen to check the gap on that new plug? wrong gap would cause miss fire also.

[Ace2cool]

No change when he disconnects the coil pack. Z32 is coil-on-plug. How are you verifying that the injectors seem good? Here's an option: mark the CAS with a scribe, take it off, turn the key to run (don't crank it over), and listen to each individual injector with a mechanic's stethoscope or a long screwdriver while slowly rotating the CAS shaft. If you really want to get into it, hook up an inline fuel pressure tester, and with each injector pulse, the fuel pressure should drop. If it doesn't, you have a clogged injector.

Same thing with spark plugs. If one of your plugs isn't firing, then chances are the PTU, CAS, or wiring is shot.

You have checked codes at the ECU, yes? ECU diagnostics are there specifically for times like this. CAS and PTU don't throw a CEL, if I'm not mistaken. EDIT: just verified this. They will not throw a CEL.

[red coupe89]

yea dont have a CEL, and plug is gapped correctly at .044. i will have to get to the injectors to check the pulse. the wiring checked out, i had power, ground and signal on the connector and the pack zaps when the neg test light is added to it, also switched packs and hole 4 remained the problem.

[red coupe89]

injectors a firing correctly after pulling the CAS amd rotating. switched the coil packs again to no avail. check all wiring with a test lite again and no dice.....losing my mind!!!

[red coupe89]

ttt still on 5 cyl!

[BigTDogg (MA)]

PTU, swap with a known good unit to test.