New and need help

[Kenny D]

Did you clean the engine bay? A full tune up wouldn't hurt (plugs/wires/cap/rotor/filters). Check and clean all electrical connections as they might have corroded while sitting for 9 months and when you drove it for that short time while running good, it might have vibrated just enough to break the connection somewhere. In my experience, even the most unbelievable can be the culprit. I could be possible that if you dislodged some debris in the fuel system that an injector could be clogged.

 

[crammit442]

Thanks for the info. My gut says ignition as well. Very generous of my Grandmother indeed. Sadly it's 2WD. Only has 105,000 miles The biggest benefit for me is that its heavy as lead and has a big motor. My lawn trailer loaded is around 5500 lbs and while my 4runner pulls it, it doesn't pull it well. Quick question. If I do go ahead and replace the plugs, it seems like I've read that there is definitely a preferred brand for this motor. Any idea which it is? I'm normally an NGK only kind of guy, but if there's a general consensus on a certain plug, I'll use that. Oh yeah, it will ONLY start w/o any accelerator. Usually takes several short spins w/no gas to start. Thanks again.
Charles

When i went to pick it up I put a battery in it and it fired right up. Ran well as usual. Obviously, 9 month old fuel is OLD.


Charles, welcome to the forum. Can you start the Tahoe without touching the gas pedal ? If so, fuel pressure is probably acceptable. Two important things make the engine run, Ignition and Fuel. A fuel problem is erratic ( runs good and bad ) Ignition will run bad until you find the problem.
Give this a try, pull the spark plugs one @ a time and check for a small piece of carbon in the gap, my guess is one or more will have the same problem. Just take a small knife blade and clean out the gap. This often happens when a car sets and not driven.
Nice that Grand Ma is passing it to you. Is it 4wd and how many miles ? Post some pics when you have time, and let us know what fixed it. Good luck.
David g...................

 

[Kenny D]

For the 5.7 I always used the AC Delco plugs and Autolite Iridium once.

 

[crammit442]

I went out at lunch and pulled all the driver's side plugs. I was a bit disappointed to see that all four looked quite good. I'll probably be able to pull the others later this afternoon. Hopefully I'll find a couple of REALLY bad plugs. It sure would make things easier. Unless I find bad plugs and it fixes the problem, I guess I'm going to go ahead and pick up plugs, wires, cap, and rotor. I've checked all the electrical connections I could find and dried and sprayed with CRC. They've all looked clean and dry so far. I just asked my buddy if he had the codes he pulled yesterday and all he remembered was P300 misfire, MAF sensor error, and TP sensor error. In the expert "group" opinion, should I start with the above mentioned parts or look elsewhere first. Those seem like just good maintenance, even if it doesn't fix the problem. Thanks.
Charles

For the 5.7 I always used the AC Delco plugs and Autolite Iridium once.

 

[Kenny D]

I know it sucks to diagnose issues in this year range, I hate to have to throw parts at it and not solve anything but it wouldn't hurt to have a tune up. My son had issues with his 90 TBI 5.7 and he threw sensors and parts at it and it ended up being a bad wire to one of the injectors. It's always the ones that pop up out of nowhere that leave you scratching your head. I find it odd that just parking on an incline would cause any issues at all.

 

[crammit442]

For spark plugs, am I correct that I need the A/C Delco platinums or is copper OK? Does anyone have the exact correct plug part number? I appreciate the help.
Charles

 

[crammit442]

A little fresh info. I went out to pull the passenger side plugs. The first plug I pulled (#8) came out with the insulator broken off right at the hex. I don't think I broke it. I think it was at least cracked. The other three were quite clean just like the first four. I was hopeful that a cracked insulator might be responsible for a lot of arcing and could be the whole problem. It runs noticeably better, but still has a pretty decent stumble. I went ahead and got new wires, cap, and rotor. Once I get everything out of the way and off I can take a good look at the cap and rotor. I'm definitely changing the wires. If the cap and rotor are good I can return the unused new ones. I'm probably going to change them either way just for good measure. Hopefully I'm on the right track. Any more good ideas would be appreciated. Thanks again.
Charles

 

[RED TAHOE LS]

Sounds good, after you change out plugs/cap/rotor/wires, go to WalMart and get you a bottle of fuel injector cleaner and dump in the tank and a full tank of fuel @ least 89 octane, go for a ride and let her breathe.
David g...........

 

[east302]

For spark plugs, am I correct that I need the A/C Delco platinums or is copper OK? Does anyone have the exact correct plug part number? I appreciate the help.
Charles

Factory platinum plugs are Delco 41-932 at 0.060" gap. They usually come pre-gapped, just double check them. Torque to 11 lb-ft.

If you've already bought a cap and rotor (Delco?) then I'd just put them in since you don't know how long the old ones have been on.

I've had better luck with Delco wires.




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[crammit442]

So I installed a new rotor, cap, and wires. Runs like a NEW car! I even managed to get the firing order right the first time for once. Looking at the cap, I probably could have just replaced it and the one cracked plug and it would've likely fixed it. You would never have been able to tell there were eight pieces of metal in it. Every single contact was completely black. I think with good oil and fluids, an occasional can of freon, and a set of tires I should hopefully have a decent truck to tow my lawn trailer. If I remember right, the tires on it are 235/65R/16's or some similar weird size. They look awfully small. Looking at my 4runner, I'd think 265/75's would easily fit w/o issues. Anyone know what's actually supposed to be on it? It rides REALLY low to the ground. I appreciate everyone's help with this. It sure picked a really odd time to start running poorly. The whole parking on the hill with year old gas thing could easily have had me going in circles for a long time. Thanks again so much!
Charles