Found Dead Truck on the Road

................and it is MINE !! Was returning from delivering a load with the wife and those problems I've been having the last 3 weeks finally came to a close. Three scanners and four mechanics couldn't find the problem plaguing the old GMC 6.0 with engine misfiring and frequent hard starts, but something will be done now. Have to take the Dodge Cummins and haul it in tomorrow morning...hope the thieves don't run off with everything meanwhile. It's gotta be a ground problem somewhere. My ratchet come-alongs powered by armstrong will have to pull it on the trailer. Where's that winch I've been dreaming of? No, not wench....WINCH !

I could see a bad ground cause a hard start, but a bad ground cause a misfire ? either way, good luck with it man

My truck was having hard starts and misfiring. It was the injectors, but didn't show up in a scan.

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Originally Posted by Bear

I could see a bad ground cause a hard start, but a bad ground cause a misfire ? either way, good luck with it man

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I was told a bad ground at the computer would cause some power/resistance issues and not allow it to send/receive signals to the functions that make it FUNCT !!
Something like that :mad:

And this is why I hate the vehicles now with all the computerized crap. everything has a computer or a sensor. Sensors for your tire pressure, sensors for all the mechanical stuff, sensors for your hood if its not latched. One sensor goes bad and the whole thing is kapooey.

I remember when the high beam button was on the floor by the pedals and you had to add air to your own tires and park your car by yourself and headlights didn't have 17 lightbulbs in em and brakes were just brakes.

Now, if your brake sensor goes out your whole computer system is flooey and your doors won't open. ok, not really but it sure seems like it.

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Originally Posted by newattitude

And this is why I hate the vehicles now with all the computerized crap. everything has a computer or a sensor. Sensors for your tire pressure, sensors for all the mechanical stuff, sensors for your hood if its not latched. One sensor goes bad and the whole thing is kapooey.Now, if your brake sensor goes out your whole computer system is flooey and your doors won't open. ok, not really but it sure seems like it

I remember when the high beam button was on the floor by the pedals and you had to add air to your own tires and park your car by yourself and headlights didn't have 17 lightbulbs in em and brakes were just brakes. .

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i miss them days too ,..... funny thing is ...,with all the new fangled self diagnosis stuff the things have ,...usually some old school troubleshooting finds the problem easier ,....every now and then i get to have fun and fix them when the computer ,efi gurus are left headscratching.....i learned from my pops who grew up in the days you had to smell the exaust ,pull the plugs ,listen ,look and change the cheapest part first

Haha New, you nailed that one for sure! I just feel sorry for the guy trying to air up the tire while you're driving ; P

I was having similar trouble with a 2000 Chevy with 5.7...they thought injectors but ended up being mass air flow sensor.

New, back when my grandpa started teachin me how to drive on the farm, them ole trucks had the starter on the floor. and I wanna bring back the manual choke! I hate all this automated, need a sensor, to sensor the sensor, crapola!!

don't scrap that motor!

that is a very desirable motor for an LS swap. worth at least $500 with accessories.

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Originally Posted by KzScrapper

I was having similar trouble with a 2000 Chevy with 5.7...they thought injectors but ended up being mass air flow sensor.

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I weighed that option and had to consider that the MAF sensor couldn't possibly cause starting problems (and I think they're related) so had to discount that possibility. BUT..........whatever it is, IS going to be interesting and I'll let y'all know IF we get it fixed. Thanks.

With the price for a computer analysis, the last time I had probs that could require one, I decided that every part included in the test would cost little more. I started replacing the most likely ones first, and had it fixed before reaching half of the test price

UPDATE:

Now that I've gone and bought a Dodge Hemi, inherited an old 94 Chev diesel from the grandson and have my son's Dodge Cummins to use....oh ya, the wife got a new truck that we've been hauling with also, well anyhow a mechanic tore into that engine (I thought I gave an update somewhere) and found a bent push rod and a burned valve. Replaced those and it runs but with a miss at low idle. The scan tool kept saying "Oxygen sensor" so he replaced THAT and it made it worse. It's a 6.0 gasser. So now I haven't used it for 6 months but still own it and it has an eternal miss. New plugs and wires and MAF sensor is good, oxygen sensors test okay, timing chain is okay, intake gasket is new.....the only thing that isn't new is that it MISSES !!! Grrr

two easy ways to find out where a skip is coming from:

1: get ahold of a handheld temp gun, pop the hood and within the first minute or two of the engine running, take a reading at each individual exhaust port on the exhaust manifolds. get the heat gun as close as you reasonably can to ensure accurate readings. your looking for all cylinders to be within 70-80 degrees temp wise, abnormally cold means weak spark/lean fuel on that cylinder, abnormally hot means way too much fuel/ late spark.

you have to be kinda quick for this method to work as the exhaust manifolds heat soak quickly and makes accurate readings harder to obtain.

2: (be careful use insulated tools) have someone pull one plug wire at a time and listen for changes in the idle speed, whichever coil(s) make little or no difference in running quality is were your problem lies.


once you have it isolated to 1 or 2 troubled cylinders, measure the resistance on the injector and the primary and secondary side of the individual coil for each cylinder that is weak, do it cold and then again after the motor is at operating temp, also ohm check the plug wires themselves, if all ohm check good; and you have good plugs then check compression on the cylinders.

if you find a cylinder with low compression, put a tablespoon of motor oil in the cylinder and spin the motor 2-3 revolutions and re-test compression, if number improves dramatically then you have a broken/collapsed piston ring, if the number stays low then the head gasket or valve seat is leaking.

if you have a cylinder w/ less than 90 psi it will never run right, lower than 90psi and the cylinder cannot achieve complete combustion.

and FYI i have personally seen a dead/ shorted coil or injector cause a miss, and the computer never catches it, never set a code or anything.

If you bent a pushrod you may want to inspect the cam also. It could be in the ignition, distributor or a sensor. If you just put new plugs in I would pull em and see what they say. It could even be your fuel pump was going out maybe.