What/where should i check my coil pack for faults?
I just completed a spring cleaning, and my car still has horrible idle, pops under WOT, detonates under full boost, and hesitates under load.
I readjusted TPS, IAC, replaced fuel pressure regulator, replaced cracked vaccuum hose on turbo, plugs are nice & tan. Fuel pressure is 30psi (vac on) and 38PSI (vac off). Under full boost It goes to 43psi, and under simulated boost using a compressor to force 25psi my fuel pressure stays at 62psi..pump seems fine. Or is it?
I'd like to troubleshoot the coil pack since i cant think of anything else that would cause this. What resistance should i see? Where do i measure it? Car on/off? What should the resistance be with 8mm standard plug wires?
After verifying fuel operation (seems okay) the only thing i can think of is maybe injectors need cleaning (have injector cleaner in tank as well as octane boost). Soon to use a pressurized inj. cleaner this week.
Also - the wastegate "thingy" where the rod goes into the round bell-like device (actuator?) is really grimy and corroded. The wastegate rod actually looks like it's worn out the bell-like device it's connected to into an oval-opening. I cannot move the arm for the life of me - should I be able to? I dont see any boost problems whatsoever, but should this be so corroded, and worn-looking?
Often, when going 30mph, i'll floor the gas, and the car will pop, hesitate for a second (myself and a buddy actually moved forward in our seats when it hesitated), then starts boosting and accelerating normally. I thought it was no fuel pressure, but the pump and regulator test fine with those values. I have to gently accelerate from a stop or else the car will pop and probably die (haven't tried it, but it does stutter). When cruising, i can hear the exhaust stuttering as well, and at idle the engine/car shakes from side to side almost as if it were missing. Exhaust seems to be hiccupping to describe it bluntly.
Am i looking into the corect areas? The car is an 87 GN with 12K original miles on it, 100% stock, and it's sat for about 3 years before i just bought it off of a collector. I've eliminated bad gas as a possible cause.
Please help me troubleshoot this baby so i can get her running perfect and start my mods for a 12-sec daily driver
Hooked up Diacom to the ALDL, and it doesn't show anything abnormal, but im not at all familiar with these cars at all, and am at my wits end for fixing this problem. Thanks guys.
Coil pack test. Buick TAC found the ohm testing coil packs did not work well. They came up with a test thats easy and works.This was never published to my knowledge. You need an AC "test" spark plug Delco # ST-125 and one new plug wire. The ST-125 is a dummy plug with an alligator clip attached. Snap-On makes them but they don't seem to work as well, don't quite know why. This combo I will call a test tool.
Attach test tool to one coil tower at a time. Start engine and listen for a nice even ticking noise. Let engine run for thirty seconds on each tower. If the ticking is interupted or skips replace the coil.
Phil
Phil,
More detail on this tool, please.
Where to buy. Does the tool get screwed into the cylinder in place of the regular spark plug? What does the alligator clip do? I've never seen one. Can you take us throught it step by step? Does it work on other ignition systems?
THX! Don WE4
Or... just go to http://www.casperselectronics.com and order their coil pack tester. Tests the entire coil pack in one shot...pretty slick!
The ST-125 can be purchased from any "DELCO" dealer. Most new car dealers have acess to Delco as well as many auto parts stores. It was introduced in 1975 to test spark voltage on the HEI system.
You leave all your plugs in engine.There are no threads on the ST-125. The alligator clip goes to good ground.
Simply remove one wire from coil and hook the set up to it. Ground the ST-125 and start engine. Do this on all six cylinders one at a time. If the tick noise is even and steady the coil is good.
Phil
Wow - awesome! Thanks a million guys..i've never heard of that test either. This forum and it's members are more valuable than gold! If I could buy ya's all beers I would..
Thanks again. I'll see what happens.
A few years back an ex GN owner and now mechanics shop owner told me how to do it even cheaper than that. Take a piece #12 solid wire and bend it so it fits around the tower snugly. bend the other en so it is about 3/4" to 1" away from a good ground. the rest of the test prcedure applys to the delco tester. A good coil will throw a healthy spark with a snap. Hope this helps.
Brent,
84 T-Type
86 GS
65 GTO
94 Suburban 454
99 GMC
if you are having them problems under wot it is ur coil pack i had the same problem and that was wut it turned out to be.
hey
i posted a message titled missing a couple of days ago about my gn missing and it turned out to be the coil pack. i brought it to a shop instructing them only to do a diagnostic test on it and get back to me in order to keep costs down, but they decided to fix it and boy did it cost although it is fixed.
it was missing real bad
just my 2 cents(as if i had any)
chad 86 gn
Awesome. Well - my coil tested kindof weak, so i ordered a new one from www.kirbanperformance.com
(along with a bunch of other goodies!) It was only $49 ! For a brand-new GM coil-pack. I hope it's gonna work okay.
Hopefully it does the trick. I'll post back after i get it installed this weekend so you know if it worked. Hey - i really appreciate the effort guys..awesome tips!!
Whelp..I ended up ordering more than a coil pack
I got a heated o2 sensor, engine ground kit, 160 degree thermostat, TPS voltage regulator (works WONDERS!), and coil pack.
I put them all on, and nothing..it still did the same thing. So, my buddy and i decided to re-analyze the plug/wire situation. First off, the coil boot for my #6 cyliner dumped about a half-teaspoon of rust/corrosion when i pulled the boot off. Yikes. Then we checked all plugs again, and the white parts looked black, so we replaced all of the stock R44TS plugs with R43TS plugs, and gapped at .035
Thing runs like a maniac now! I dumped $300 and it turned out to be my spark plugs, and crap wires! I couldn't believe it - but man im a happy camper now! One thing else we noticed..bone-stock factory plugs were gapped at .045! It says to gap them at .035 right on the engine sticker! I dont know if it was the plugs or wires or both together, but my car runs like brand-new. No hesitation, rought idle, popping, and it boosts a heck of a lot quicker (thanks to the TPS). Before the TPS regulator i could only get .45volts low and 4.1 volts at full throttle. Now i can get .44 volts low and 4.79 volts full throttle..it made a BIG difference on my car at least.
I just though i'd let ya's know what the problem was. Thanks for all the help folks - see yas at the track :P ..now for that 12-second recipe...hehe