GM Techs - Issue with 2003 Suburban - Injector?

[spankis]

My parents have a 2003 Suburban with 150k miles on it, and it's a 1500 4wd, with the flex-fuel 5.3L. The check engine light was on it when I took it fishing this past weekend, and it was idling pretty rough. By the time I got back home Sunday it was still running poorly but the light was out. Even so, Autozone was able to pull the stored codes for me and there was a dirty MAF/ vacuum leak code, and another code for a misfire on cylinder #1.

 

I cleaned the MAF and checked for vacuum leaks but found none. The plugs and wires are only 2 months old ( I changed them myself) but I also pulled the cylinder 1 plug, and replaced it for good measure. It looked a bit white, like it had been hot/lean, but just barely. I also swapped coils 1 and 3 to eliminate any possibility of a bad coil. Drove it around a while, and the light came back on - Same code, cylinder #1 misfire. I suspect now that it's a dirty or sticking injector causing it, as the noid light shows it getting good signal.

 

The dealership will do an injector cleaning for $149, and that's what I told my dad he should do. Does this sound right? Or is this a common indicator of some underlying issue? Also, do the flex fuel injectors tend to foul up if you don't run E85 ever?

Edited June 23, 2010 by spankis

[BradyPPC]

Swap injectors with another cylinder that is good and see if the problem follows. If it does, the injector is your problem. If not, it may be an intake manifold gasket. They like to lay over on and cause a leak. Alot of times, they will run poorly when cold and once some heat comes into it it will expand and seal up.

[spankis]

Sounds reasonable, too. I will suggest he try that tonight. If it does follow with injector, would the dealership cleaning generally clear it up, or should I just replace it? Autozone shows a $90 direct replacement, and a $140 "revised design" model. I guess I'm wondering if it might be wiser to replace it and skip the system cleaning.

[BradyPPC]

Just replace it

[Dave1647545494]

intake gasket

[BradyPPC]

intake gasket

 

That is my bet as well.

[spankis]

Thanks guys, I'll look closer at the gasket tonight, and swap the injector at the same time.

[STEVE-O]

I would also not pay a dime for a injectore cleaning cause it almost never cures the problem and a new injector is like you found out as much or less than the cleaning that it will do.

[spankis]

I think it was AJ who directed me to a TSB for the flex-fuel motors regarding a rough/low idle without a check engine light a while back. It fixed the issue right away then, but that was quite a few miles ago and it was different than this current problem, so I was definitely hesitant to assume it was the same.

[SinisterSS]

with it being a flex fuel car I'm not 100% sure but when I had this issue with my camaro it was the o2 sensors, also if you have another maf swap it out and see if anything changes

[AJ]

I would also not pay a dime for a injectore cleaning cause it almost never cures the problem and a new injector is like you found out as much or less than the cleaning that it will do.

 

you don't know what your talking about or not useing the correct tools or a good cleaner.

 

 

O2 doesn't cause a single cylinder misfire normaly, it can though.

 

what kind of plugs did you put in it when you replaced them?

 

also i would swap the coil first because its easier then an injector.

 

spray carb cleaner all over the intake on the bank that has the problem, smooths out then you need to replace the intake gaskets with the updated style.

 

answer those questions and we'll go from there.

[spankis]

AJ:

 

Plugs are AC-Delco Iridiums from Autozone, which if I recall is what came in it factory? I could be wrong. When I pulled the cylinder 1 plug I replaced it with a new one for good measure anyway. I also swapped coils 1 and 3 and it still threw the cylinder 1 code. Didn't try the carb cleaner trick, but I went ahead and installed the updated gaskets tonight....

 

 

Unfortunately the gaskets didn't fix the problem. I did not swap injectors as Brady suggested, even though I had planned to. Alldata shows that you are NOT supposed to re-use the injector clips, and I didn't have a replacement so I had no choice but to skip it. I do feel like it's definitely a fueling issue at this point though.

 

I would have liked to verify that the code is at least still the same, but I didn't get it back together early enough in the evening to go have it ran again. My dad and I dropped it off at Bob Mcdorman for the injector service in the morning, hopefully that solves it.

[spankis]

In summary, I have so far:

 

- cleaned the MAF

-verified good injector signal with a noid tester

-checked and replaced cylinder 1 spark plug ( looked very slightly whitened )

-replaced manifold gaskets with the new updated style

 

Would still like it some more input, pending the outcome of the injector cleaning service...

[spankis]

Soooo Mcdorman says it's a valve issue in that cylinder, which makes sense I suppose. Not sure whether it's intake or exhaust, and I'm not entirely sure what work my dad has authorized yet, but I guess they're going to pull the valve cover and see what they can see in the morning.

 

It seems likely that we'll soon be looking for someone cheaper than the dealership to replace a valve....I'm not sure I trust myself that deep.

[Dave1647545494]

if your comfortable pulling the head I have all the tools to change the valve out you can borrow them or bring the head over and I'll just do it for you....

 

you can go reman head also if you want but if it just needs a couple valves and a lap job I'd just fix it and put it back on

[spankis]

I'm not sure I am that comfortable to be honest, but I appreciate the offer Dave. I've never had the heads off one of my own cars, the deepest I've been is valve covers.

[AJ]

let me know if you want it replaced i can get it handled for you. knowing the guys that work at mcdorkman i would have it looked at again by another shop or i can help you.

[spankis]

Yea I know nothing of their service department, it was just the closest to their house in Canal. I appreciate the offer though AJ, I'll let you know once he decides what he's doing.