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2006 GMC Envoy XL
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I have a 2006 gmc envoy xl sle with 198,000 miles on it. Drove it to run some errands and parked it in the driveway. Next day it would not start. The engine turns over but does not start. When I turn the key on I can here the pump in the gas tank priming. I'm thinking I have a fuel or spark issue. To see if it was possibly a fuel issue I tried using starter fluid but it still did not start. Since the starter fluid didn't help I'm thinking maybe its something with the spark plugs or coil packs?

I tried connecting a code reader but no codes were found. What other test(s) can I do to isolate the issue?
 

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I believe that if you continue cranking for over 20 seconds, a code WILL set.

But, if no code comes up, the thought that all 6 of your coilpacks can fail at the same time is one of those "Zebra Moments" where you hear hoofbeats and make a bad assumption.

Three things need to be present to make an engine run;
  1. Fuel
  2. Spark
  3. Compression.
It's kinda like the Golden Triangle that if you remove any ONE of them, the fire goes out. Same's true with an internal combustion engine.

You need to do this: POINT #1 ---> CRANK the engine and LISTEN to the cranking rhythm!
Then if that's OK, go to POINT #2 ---> Make sure that you have fuel - although you said that you tried starting fluid and got a ZERO. This will move you to POINT #3.......

You have to confirm (both) the injector action and ignition activity, as they are related because of TDC and #1 cylinder signals that need to co-ordinate the ignition with the injection.
  • Since Vortecs don't allow for a NOID Test, you need some sophisticated way to test the injector distribution head for electronic signal to actually fire each injector.
  • AND -- be warned! RESIST the urge to stab the unit with a 12V test light - the kind with the ground wire and a sharp spike to probe the circuit: ECMs don't like surprise faults-to-ground at all!
I'm leaning over-the-internet to a failure of a spark/injector signal, although I think that ignition is the bigger-slash-related problem.... but not ALL the coilpacks died at once... so don't go there.

It's more likely an ECM issue/or a TDC (CMP/CKP-EDIS type) failure or a timing chain failed ---- >something easy like that!

I hope I'm wrong here and it's just a bad ignition switch.... lol.


FWIW ---> MOST electrical failures are in the GROUND circuits; 99.4% of the time, anyway!

You have some testing and probing to do..... that's YOUR part, since I am not there and you are.

PS - I make service calls - Barn-to-Barn, + meals, gas/motels, etc. let me know.
 

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Discussion Starter #3
Thanks for your feedback and suggestions.

when I was trying to start the cranking rhythm sounded normal and consistent.

I talked with my neighbor down the street who mentioned I should try my other ignition key which I hardly use. He said some keys actually have a chip in them, not the fob, but the actual key which maybe went bad. I tried it and it started first try. I didn't have to keep cranking it. It started slow initally but got running at normal speed. Tried using the same key a couple more times where I turned off the engine and started it back up. Also tried the other key I normally use again and it started up. I don't know why it started today.

My neighbor mentioned possibly changing out the ignition switch which I saw in some videos and posts mention that those were a common thing that goes bad. I've never replaced it so its still the original one. Should I replace it?

Not sure if my environment had anything to do with it but the gmc normally sits outside and I live in Colorado. we had some cold weather around 10F and lower with wind chill when the issue started. It has since warmed up and was in the low 60s today. Had a similar issue couple years ago where it was in the winter time and it would crank but not start. tried again the next day when it was warmer, maybe 20 degrees or so, and it started.

I'll try starting it for the next couple days in the driveway and drive it around the block to see if it fails to start again. Maybe also check codes again to see if there is anything since it was running . I'll have to read up on spark/injector signal, ECM issue/or a TDC (CMP/CKP-EDIS type) as I'm not a mechanic and not very familiar with them.

I believe all envoys use a timing chain and they typically never need to be replaced but mine still has the original with 198,000 miles. Will I possibly need to change mine soon? when it started the engine sounds like its running smooth and normal, its not rough. If its the timing chain I was thinking that the engine wouldn't sound good when its running.
 

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The timing chain uses a hydraulic compensator/adjuster to take up the slowly developing stretch as the link rollers and pins wear. In constant oil and no actual dirt getting into the bearing surfaces, it should last a very long time.

One of the biggest reasons for premature wear is oil that needs a change to remove carbon and microscopic particles of metal from other reciprocating/rotating parts in the engine. Scheduled oil and filter changes mitigate that contamination and it's abrasive characteristics by replenishment with unpolluted lubricants.

Timing chains have come lightyears away from the original multi row bicycle chains of yore. Going out on a sturdy limb here.... I'd say IF religiously applied oil changes are carried out.... modern chains should last over 200K miles. I'm also totally cognizant there will be anecdotal oaths invalidating and staying my opinion.... so be it.... but those are usually in the 2% zone.

Your key may hold the answer to your mystery.... and my TB possesses it's own arcane personality that I am homing in upon....and any day now I'll decide if it's an intermittent battery ground (most likely) or a dying ignition switch (less likely, but still on my diagnostic horizon).

I getZERO lights, the radio goes black with total loss of preset radio memory, no starter action ...not even a click... and this happens when it feels like it.... and of course when I am NOT paying rapt attention... and I miss the moment by my being in a non-diagnostic mode. Ah well..... I'll find the reason... but not today.... nor tonight.

If it's gonna be sporadic... I'll ignore it to make it mad and then I can find the problem instead of playing whack-a-mole with it.

Let's home in on both our vehicle's peculiarities.... er, problems....I'll keep an open mind for your-.... and my- ultimate diagnosis.

Mechanics are their own worst customers..... but RETIRED MECHANICS are worse!
 
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