TPM

96 GMC Suburban, 7.4L K2500, Engine code J on the VIN.

Changed plugs - same NGK plugs as before. Gap set to .o45 per Chilton manual for engine code J 7.4L.

Changed wires, same Belden set as before.

Idles ok, bit of a rough spot, not bad. Won't drive. Sort of feels like a miss or a few cylinders missing. but not quite.

Very sure all wires are routed correctly. Only thing I have for a possibility is the note I had from Napa Auto Parts said gap at .60 .

Another question - its an SLT with rear air conditioning - how do you get the rotar cap out. I can barely get the plug wires in to the rotor cap.

suzuki-guy

You really should Acdelco spark plugs! Its what they came out of the factory with! Just a suggestion!

TPM

It was AC Delco - I don't know why I wrote NGK. Is the .045 gap correct?

tm4hammer

i have the same year here are the specs. for that year on the 7.4 Ac delco plug type 41-932(1.52mm) set at .060" is the set up for your rig
Air cleaner-ac-type A1300C
OIL FILTER- AC TYPE-PF-1218
PVC- AC TYPE CV-774C
FUEL FILTER -AC TYPR-GF-626
COOLING SYSTEM -DEX COOL CAPCITY WITH AIR 27.5 QTS.
CRANKCASE OIL10W30 7 QTS.
AUTO TRANS.4L80E - DEXTRON 111 7.7 QTS.
TRANS. CASE NV243 DEXTRON 111 4.5 PTS.
FRONT AND REAR DIFF'S 80W90 /W GM PIN 9985010 ADDITIVE
these are the factory specs and parts recomendations and not my own
The miss might be related to a spark plug boot not seated on the spark plug they can be decieving some times an cause misfire and crossfire and the di cap LOL i wont let ya suffer i went and got a flex carb adjustment driver about 12' long with interchangable bits they are cheap and save your ribs some bruising a couple of hex screws on the cap and a couple on the rotorI remove the coil to get a better shot at it good luck and a great truck

TPM

TM4, it was a loose boot at a spark plug and a not seated coil wire. Thanks. I gapped it at .045 and it runs, it seems, fine. I have to drive it this morning and I'll regap the plugs later. Thanks.

pltk2

i got a friend of mine with small hands to help me with mine. the gap is .60 and you need to loosen the wire looms on top of the engine and move them to get to the wires not a 5 min job.

Loryder412

I just did full tune up to drove 100 miles check engine light came back on. Code was random miss fire. Everything is tight and in place what else can it be

pltk2

okay, I did a complete tune up on my 1997 suburban, new wires new plugs and cap and rotar, I also changed to an accel super coil 45,000 volts. now I have developed a hesitation when I go up hills or inclines. can this be caused by a malfunctioning injector or a fouling plug.i run exxon gas all the time can this be the problem, I heard they put a dye in there gas. please let me know what you think.lease reply to my email pltk2@hotmail.com thanks.

pltk2

does anyone know what the correct hr rate is for fuel injectors on a 1997 suburban with a 7.4 vortec engine