Chevy mechanic in the house?

I have a 2000 Chevy Silverado 4wd 5.3 300k miles on it. Running very poor. Random misfire codes bank 1 & 2 running lean codes...

I could write 2 paragraphs of symptoms and what i have done to it. googled everything I can think of. My main problem is I have an ignition interlock device (breathalyzer) in it so I can't just drop it off at a shop and say fix it.

If there is a mechanic that can give some advice I will write more about my issues. I am leaning towards a ground issue???

Thanks in advance if anyone can help

a reply to: tinner07 Could have a vacuum leak, a dirty or defective mass airflow sensor (MAF), dirty fuel filter or weak fuel pump. although I have found that generally fuel pumps either work or they don't. ETA..Saying you lean towards a ground issue, have you checked the ground strap from the body to the engine for good connection?

a reply to: Justacasualobserver

Sounds more like a lack of fuel issue, does it do it all the time, or after the car has run for a bit, or randomly? I would think fuel filter, pump, or air leak like observer said.

If it is all the time, i would suspect fuel filter or air/fuel issue, ie: air leak, mass air flow

If it has to run a bit, i would suspect weak fuel pump

If its random, i would clean mass air, and see if it helps, then spray engine with starting fluid to check for vacuum leaks

Good luck!

Check your distributor cap and rotor. A hair line crack will allow enough moisture in to cause misfiring

I would start by swapping 1 and 2 coil packs with other cylinders and see ir the misfires fallow. That being said, you will notice that #1 and #2 are at the front of her engine. My experience is trash goes to the end of the fuel rail and dumps in the last injectors. Remove the fuel rail with injectors attached and pull #1 and gently tap it upside down on a block of wood with a sheet of white paper on top. Use grease on the injector orings when reinstalling.

This post was for information only.

a reply to: tinner07

It's a real good possibility that you have a intake manifold leak towards the front (cyl 1&2), probably needs a gasket and hopefully the manifolds not warped. It's a very common problem with 5.3's, especially with 300k.

a reply to: mtnshredder

Agreed. Lean code usually means vacuum leak versus low fuel pressure. Low fuel pressure will not make it past injectors. Look for intake leak or vacuum hose leak.

a reply to: tinner07

Have your alternator checked. GM vehicles can start throwing weird codes when an under-volt situation occurs. Happened to me twice, one Chevy, one Buick...

a reply to: tinner07
Double post

ok thanks guys.I have put new plugs and wires. cut off the catalytic converters. cleaned mass air flow sensor and new fuel filter.

Bought a spark checker tool. every coil pack showed an orange spark, not the optimal blue white. changed all 8 coil packs, checked #1 cylinder, still orange spark.

It seems to run rough in the morning, the check engine light will start flashing and looses power. I can get onto the highway and get it up to 70 and it runs ok, the check engine light may flash but it seems to run ok. After sitting all day at work it runs fine on the way home. check engine light is on but not flashing. Same thing the next day. Also it seemed to have these issues worse after it rains. That made me think a bad coil pack or two.

I was going to buy an obd2 code check device but they wanted 109 bucks. I can get one on Amazon for 40 and really that is not going to "fix" anything so I passed. But the guy said could be a ground issue,, also from what I have read online, ground could be an issue.

Do mechanic shops have engine analyzers that are more in depth at diagnosing problems than the code reader dude at auto zone?

a reply to: mtnshredder

It's a real good possibility that you have a intake manifold leak

Ok if that is the issue, would a rainy day let it draw in moisture and run worse? That kinda makes sense to me

a reply to: neomaximus10

If it has to run a bit, i would suspect weak fuel pump

So a weak fuel pump??? After running a bit what? enough fuel has started to flow or the pump itself picks up speed??? It does run worse intermittently, so obviously a fuel filter wouldnt only be clogged now and then, I did change that though. I want to get a fuel pressure gauge to test my fuel pressure or an actual gauge to mount on the hood to monitor fuel pressure when I am driving.

a reply to: neomaximus10

If its random, i would clean mass air, and see if it helps, then spray engine with starting fluid to check for vacuum leaks

Spraying starting fluid on the engine, if it has a leak will it suck it in and make the engine rev up? or be more like a gas pipe leak and bubble up? I suspect it will suck it in and rev...

a reply to: ttropia

My experience is trash goes to the end of the fuel rail and dumps in the last injectors. Remove the fuel rail with injectors attached and pull #1 and gently tap it upside down on a block of wood with a sheet of white paper on top. Use grease on the injector orings when reinstalling.

The #1 &2 cylinders being the end of the fuel rail? I really really don't want to pull the injectors out, although I am sure i can do it, It's putting it back together that gets tricky lol. That being said, what would I be looking for, any debris that actually comes out and lands on the paper? Is there an acceptable amount? and what if a small dirt pile does come out? can they be cleaned? I actually saw injectors are like $90 bucks each at auto zone, I am getting half way to a new engine at that point...

x2 for intake manifold gasket, especially if it's worse in the morning/cold. I would put money on it

originally posted by: tinner07
a reply to: mtnshredder

It's a real good possibility that you have a intake manifold leak

Ok if that is the issue, would a rainy day let it draw in moisture and run worse? That kinda makes sense to me

I think what your experiencing on a rainy day is most likely contributed to the air temp (rainy days = cooler temps). Metals expand and contract with temp which is why it's worse in the mornings. There's a few ways to check for a leak. You can use carb cleaner to spray around the intake, listening for a change in the motor (RPM increase, stumble, etc.) but be EXTREMELY careful that you don't have a plug arcing as it's flammable. You can also pressurize the intake system and then use soapy water to spray around the intake, looking for bubbles or they have smokers that inject smoke into the system. I would put money on a intake leak though. Chevy 5.3's are notorious for this.

a reply to: mtnshredder

Well I sprayed starting fluid around the intake and no change in rpm's whatsoever. I am glad it is not the intake gasket but I would have been happy to know the problem. Sitting at idle the check engine light started flashing. It is morning and a lot of condensation this morning. Going to let it sit all day and cook in the sun and see if any difference.

Going to look into the smoke method of checking for vacuum leaks as well as google how to remove a fuel injector...

FML.... went out to re-spray a little more thoroughly and the darn thing wont crank over now lol....battery is fine, nothing to the starter it seems... may be time to sell it ... but I love it...

a reply to: tinner07

Once the fuel pump runs for a while, the motor gets hot, just like any electric motor, if something is bad in the motor, when it gets hot, it can vause it to work improperly, have seen it many times, it is often a hard to diagnose also, since it only happens after the car has been running for a half hour or so.