well I'm at a loss

[eyepopn]

I've got an 03 envoy xl 4.2 was driving yesterday and all of a sudden reduced power light and check engine light came on and it started running like it was on 4 cylinders....... I got it home and pulled the plugs and changed them with the ac Delco iridium plugs and still seams like it's running on 4 cylinders. ......I've swapped coils and plugs between cylinders and when it's idling I've un plugged individual coils and the number 5 and 6 when unplugged make no change in how it's running........ I've tried different coils,cleaned tb and everything I can think of but it makes no difference. ...... and now only getting p0300 code...... any ideas would be greatly appreciated. ....

 

[Mounce]

Swap #5 and #6 coils to different cylinders and do the unplug method again. If again, unplugging those makes no difference, then replace them.

If it's still cylinder 5 and 6 that make no difference, it's time for a compression check on those cylinders. If that checks out ok, then the only other thing I think it could be is injectors or a random fuel system fluke.

Could be wiring issues though so if it's still cylinder 5 and 6 after swapping the coils, make sure their plugs/harnesses are getting power.

Welcome to GMTNation, btw.

 

[eyepopn]

Thank you for the welcome and I've swapped them coils from 5,6 to 1,2 and it's still misfiring on 5,6..... haven't checked compression only because it was fine all day then just poof started running like crap...... I played with the wiring and seams like I have continuity from the pins in the plug back a ways in the harnesses. ..... Which of the three wires in the plugs should have power I assume the black wire is ground but ...... could be wrong

 

[triz]

What's your mileage, any mods? Signs of overheating?

 

[eyepopn]

I just got it and the guy I got it from said the motor has 100,000 on it ...... the odometer reads 221,000..... no mods and no overheating. ......

 

[Tiggerr]

I just got it and the guy I got it from said the motor has 100,000 on it ...... the odometer reads 221,000..... no mods and no overheating. ......

That's not sounding too good. Id do compression leak down. Rule it out if nothing else..

 

[eyepopn]

I'll probably do that tomorrow...... I have noticed that the #5,6 plugs when I removed them were wet and smell like fuel......

 

[Tiggerr]

You definitely have either zero spark on those 2 or no compression. Something's not kosher for sure. Hope it's wiring issues, doesn't sound too good though.

Check that harness real well for the coils. They sell it by itself. I'm thinking there's a reason for that. GM isn't known for making life easy for things like that.

 

[djthumper]

What were the initial codes that you received when it went into limp mode? You could have a couple of bad coil packs.

 

[eyepopn]

The first codes I got were a p0300....then when it went in to " limp mode" it was a p1514 as well as a p0300,p0305..... and tiggerr is it a splice in harnesse or plug in ....... and we're can I find it ?????

 

[Tiggerr]

The first codes I got were a p0300....then when it went in to " limp mode" it was a p1514 as well as a p0300,p0305..... and tiggerr is it a splice in harnesse or plug in ....... and we're can I find it ?????

If I remember right it was in a GM parts site. I would assume it's a plug in harness. Didn't really look close as I wasn't having any issues, just browsing around. Might've been gm parts giant. One of those types of sites.

 

[eyepopn]

Ok.....cool.....I'll check in to that just in case....... thanks

 

[djthumper]

The first codes I got were a p0300....then when it went in to " limp mode" it was a p1514 as well as a p0300,p0305..... and tiggerr is it a splice in harnesse or plug in ....... and we're can I find it ?????

Looks like your coil pack on cylinder 5 went bad. I would order 2 of them. Have you cleaned the MAF and maybe the throttle body for the P1514.

 

[eyepopn]

There is no maf on an 03 and if I can swap the coil packs to different cylinders and the problem stays at 5,6 makes me wonder about the coil packs......

 

[Mounce]

Yeah, if you swapped both coils from 5 and 6 to two of 1-4 then there's a definite problem with cylinders 5 and 6.

Could still clean the throttle body though. You never know.

 

[eyepopn]

I've cleaned the throttle boy and disconnected the battery to reset pcm........ if the #5,6 injectors were stuck open would that (for lack of better words) flood them cylinders causing them to misfire????? the fuel filter looks old not sure when it was replaced.....or if it's been replaced

 

[Mooseman]

p1514 description talks about the throttle actuator, which is related to the throttle body. So you have two things close to each other that have come up at the same time that could be caused by damaged wiring. It doesn't sound like it's the coils because you swapped them out to other positions and the problem stayed with 5 & 6. Check the wiring for anything chaffed, burnt or broken.

 

[eyepopn]

A friend of mine has a parts car .....it's an Oldsmobile bravada...... would you recommend if I can get it to grab the engine harness and just swap the whole thing or just focus on the #5,6 coil wiring. ...... haven't had the p1514 code in awhile just down to p0300 now.......

 

[Mooseman]

Seems like a lot of trouble before checking out all options first. Check the wiring, then do a compression test on all cylinders. You never know, valves could have failed all of a sudden or a crack between those two cylinders. Check if those two cylinders are sparking by pulling the coils and putting a spark plug in them and grounding the outer casing. If spark and compression are good, then look at fuel.

 

[eyepopn]

Ok..... I was wondering if I could check for spark that way or not.....I'll check that when I get home from work and I'll see if I can find my compression tester and check that as well..... thanks by the way everyone all this help is greatly appreciated. ........

 

[eyepopn]

Ok........ update...... I have spark on all coils..... so I checked compression and sure enough no compression on number 5...... now what?????

 

[triz]

Check your oil. Sometimes when you have two cylinders next to each other like that it can mean a blown headgasket, loss of compression. That is why I was wondering what type of mileage and if it was overheating.

 

[eyepopn]

Oil looks good no milkyness...... and since I've owned it it's never overheated. ......

 

[Mooseman]

A leakdown test would tell where you are losing compression.

Do you trust the guy you bought it from? Is there proof that it was swapped and it has only 100k miles?

 

[Tiggerr]

A leakdown test would tell where you are losing compression.

Do you trust the guy you bought it from? Is there proof that it was swapped and it has only 100k miles?

I would assume they guy is full of it. Usually the case without receipts. And go under that assumption. Figure it has 220k. If it was me I'd just swap the engine for a low milage unit(good luck finding one).. Or major that one and be done with it.
Unless you can get away with a head gasket. But with that milage, I'd just do it all.

 

[ChrisinVictoria]

I found a good used engine on www.car-part.com . They seem to have a lot of them for$8-$900 with low mileage.

 

[eyepopn]

Update on my situation...... I contacted the guy I bought the envoy from yesterday and told him what I found and when I talked to him today he's gonna make it right..... he's got a different motor on the way and gonna do the motor swap for me.......

 

[Sparky]

Wow that's pretty good that he's doing that then!

 

[eyepopn]

Now when I get it back what can I do to try to keep anything from happening again....... I love the envoy and want to do whatever I need to to help with its longevity. ........ I'm gonna put the new plugs I have for it in and probably clean the throttle body and do an oil change. .......but any other suggestions? ??????

 

[Sparky]

Probably didn't do anything wrong. Just treat it well like you would expect. I've done nothing special with mine and have 210k on it.

 

[Tiggerr]

Update on my situation...... I contacted the guy I bought the envoy from yesterday and told him what I found and when I talked to him today he's gonna make it right..... he's got a different motor on the way and gonna do the motor swap for me.......

Impressive! Can't beat that with a hammer lol! Glad to hear he'll make it right!

 

[Mooseman]

That is awesome, especially since it's a bitch of a job to swap an engine in these (got the t-shirt).

Just do your regular maintenance, good quality oil and filter. Initially, maybe clean out the CPAS, change the transfer case fluid, change the oil in the diffs, flush the power steering fluid, replace the tranny oil and filter, flush the brake system and replace the coolant, unless you know for a fact they have been replaced.

 

[Tiggerr]

That is awesome, especially since it's a bitch of a job to swap an engine in these (got the t-shirt).

Why are these in particular a PITA to do a swap. Haven't seen anything out of the ordinary on mine that would suggest that. Granted any swap is a bit of work. I usually jerk motor and trans all at once and reinstall that way too. When I can. Curious. Doing a swap is in my future to do list.

LS3 if I have my way. Can you say Rainier GS? lol

 

[Sparky]

Well yours being 2WD means you don't have that front drivetrain to mess with. That's part of what makes it irritating to do.

 

[Tiggerr]

Well yours being 2WD means you don't have that front drivetrain to mess with. That's part of what makes it irritating to do.

I can see where that would be a pain the way they set that up in these yeah.

 

[Mooseman]

I missed the 2WD part. Yeah, that's the irritating part when you have 4x4. In fact, you can see where it mounts on the oil pan. Anyway, not your problem.

 

[Tiggerr]

I've seen the setup yeah. PITA.

 

[eyepopn]

I'm just happy he's doing what he can to make it right ....... wish there were more people like that in the world.....

 

[eyepopn]

Update sorry it has been so long but been really busy........anyway got the envoy back and found out that a throttle body bolt had made its way in to the intake on the last motor and got lodged in the #5 valve making the valve not shut all the way........but the new used motor is running great only thing I'm noticing is randomly the rpms will drop and it shuts off...... happened to my girl once and just happened to me ....... other than that it runs and drives great......any thoughts on what would make it do that ...... no check engine lights when it does happen .......

 

[Tiggerr]

Update sorry it has been so long but been really busy........anyway got the envoy back and found out that a throttle body bolt had made its way in to the intake on the last motor and got lodged in the #5 valve making the valve not shut all the way........but the new used motor is running great only thing I'm noticing is randomly the rpms will drop and it shuts off...... happened to my girl once and just happened to me ....... other than that it runs and drives great......any thoughts on what would make it do that ...... no check engine lights when it does happen .......

If it happens when warm out with AC on... It's common phenomenon, no-one ive seen yet can solve. My rainier does it. My better halfs Malibu did it too. Never solved it on that or the rainier. Tried just about everything you can think of. Seems like a GM quirk idk... Good place to start is cleaning TB and resetting PCM. Love to see a solution, it's annoying. I even went to GM with mine...with both of these vehicles actually.(which I never do). They had no answers. Much luck to you!

Glad they made things right for you swapping the engine!