2001 Tahoe 5.3 Runs Rough at times, At my ropes end!

[plsmith86]

Hey Ya'll,

I have a problem with my truck and I am getting close to my ropes end, and I just wanted to see if anyone had any ideas on what I could possibly do to fix my problem, or if anyone has had this happen to them..

About my truck:

2001 Chevy Tahoe LT, 5.3 Auto, 4x4. 285/75R16 Tires. 172k miles on her.

My truck started to run rough around 163k miles. Everything was original. I had a complete tune up done, with AC/Delco plugs and wires, cleaned out the fuel system, new fuel filter, air filter, changed the oil, changed all the drive line fluids, and did a throttle body cleaning.

Two months ago, out of the blue while I was stopped at idle, my truck skipped a few times, and then was fine. It than started to misfire, idle rough and shake bad. This went on for about two minutes, by the time I gave it gas, it jerked a little (to describe it best, was like teaching my wife how to drive a stick for the first time!) but it cleared up and was fine, and drove fine for the next two weeks.

It happened again, same issue. I noticed it only did it when it was hot. It cleared up. It started to happen more often. So I checked over everything that was done, plugs, wires, filters - all was fine. I put some high octane fuel in it, drove it through and it was fine for a while but did it again. At this point, it was more frequent and the engine light would flash (BUT IT NEVER SETS CODES, OR A LIGHT!!) So I decided it would probably be best to have the dealer use the TECH2 and figure out what the problem is, my DRB only does so much.

While not admitting defeat, while on the way to the dealer, it started to cut out bad on the highway and shaking bad. It never did this before. I am not sure what the problem was. I got to the dealer, paid 100 for diag, and they said that my muffler was making some noises; they suspect a baffle inside it was causing it. They wanted 700 for a new one. I took the truck, thanked them and had a flow master installed for around 200, cat-back. It ran great for a couple days, but did the same thing.

I took it back to the dealer, they said that they were finally able to get it to act up with them in the car, and that my EGR was throwing a code for getting stuck closed, and at the same time my engine has "multiple random misfire" codes. They then diagnosed it as a plugged converter and quoted me 1800, with a "cleaning" of the egr... "to start" I paid my 100 and went to a muffler shop. They disagreed and said there was nothing wrong with the truck but though from the exhaust it was maybe running "rich" I told him it was all original and it probably would not hurt... so we put on an aftermarket magnaflow stainless steel converter. It was about 500.

It ran great for about two weeks, but now it’s doing the same thing, and seems to get worse every time it does it. Now with that being said, I did check the EGR... its dirty, but not to the point where it could cause a problem (in my opinion) and it seems to be working. I cleaned it up some, and put it back together.

I don't have the slightest of ideas as to where to go next, the dealer seems to just be tossing parts at it, and I don’t really have the money to flush away on this thing. I love the truck to death, it’s in perfect condition, the leather does not have a single blemish in it, and every power feature works, including the rear air!

What I find strange, is that I cannot pin point where when or what causes this. It will happen with the AC on, AC off, steering hard over... nothing. It just does this randomly. It gets in my opinion great fuel economy... usually 14mpg city and 17+ highways. It never stalls out, and always starts right up, and does not really give me an issue there, however at times when I start it, it HAS acted up and cleared up after a few minutes.

I am not sure if I am chasing an intermittent electrical / sensor problem... fuel problem... mechanical?

In the last year, I have replaced the fuel pump, with a Delphi module, it failed while driving. That was about 14,000 miles ago. Since then the fuel filter was replaced 2 times with AC/Delco. The tune up was done. And all the filters seem to be fine.

As I said.. I am getting close to my ropes end, and nothing seems to be improving this issue... if you have any thoughts at all, it would sure be greatly appreciated!!

 

[MrFleming007]

When was the last time the MAF was cleaned? Do you have a scanner that will show your fuel trims?

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[bankswood]

I'm thinking like MrFleming007. My Yukon was doing similar things as far skipping / misfiring. It would clear up for awhile. It finally got bad enough to throw a code. I replaced the MAF and have not had an issue since.

 

[plsmith86]

The MAF has not been cleaned, no one has mentioned this, I think I might have to try that, and see what I come up with.. and as far as my scaner - it only reads codes, and monitors. So when the light does flash... I cant get codes because it wont set them. Its annoying!

 

[Vinniety]

I agree with others to first clean out the Mass air flow sensor, very easy to do. From there my thoughts are, o2 sensors or the ecm computer itself. The thing that worries me is that you get no code. You really should always get a code when sometimes goes bad even if the check engine light is not on sometimes there are codes stored. A ecm shouldn't be more then a hundred bucks and for what i see you spending money on i dont think its that bad of an investment if it comes down to it. Good luck!!

 

[plsmith86]

I am going to try the MAF cleaning today. I was concerned about the check engine light not setting or keeping codes, however when I was able to use a friends scanner, all computers were communicating properly, however I have learned that when your working on cars, the last thing the computer will blame is its self!
Dodges are nortorious for sending you on a wild goose chase, but then again I am not working on a dodge so all my trade tricks are out the window on this one!!
on the oter hand, If I get a good scanner there may be stored codes that my scanner is not picking up. I can't bielieve that a ECM is only around 100$ I had to replace one on my impala and it was around agrand with program from the dealer. If thats the case, its almost worth replacing just because!

 

[M3PO]

You could use a temp gun and take the temps at the inlet and outlet of the converters, if the temp is considerably cooler on the outlet, there is a good chance it is plugged. If exhaust was free flowing through it, the temps should remain fairly consistent.
I would also try another dealer, they all have alleged techs that simply want to throw parts at it. If you do have to take it to a dealer, give them less info, simply tell them to diagnose the problem and provide a fix. When they quote you that fix and before you approve the repairs, reiterate to the service writer that you expect a guarantee the suggested repairs will solve the problem. Not knocking you, I can understand wanting to save money, but my buddies that are dealer techs see this all the time. If the customer proceeds with the suggested repairs and the problem is not fixed, the tech/dealer is on the hook. Now, they might not fix the truck for free, they might give you $x in credit towards the actual fix. Sometimes there is more than one problem, so they have to fix one thing to get to another.

 

[Vinniety]

I am going to try the MAF cleaning today. I was concerned about the check engine light not setting or keeping codes, however when I was able to use a friends scanner, all computers were communicating properly, however I have learned that when your working on cars, the last thing the computer will blame is its self!
Dodges are nortorious for sending you on a wild goose chase, but then again I am not working on a dodge so all my trade tricks are out the window on this one!!
on the oter hand, If I get a good scanner there may be stored codes that my scanner is not picking up. I can't bielieve that a ECM is only around 100$ I had to replace one on my impala and it was around agrand with program from the dealer. If thats the case, its almost worth replacing just because!

A scanner to read codes are all the same unless you need to read logs like downstream o2 codes and other fancy things. The issue that i see is unless someone is going to lend you there advanced and expensive scanner to use for a few weeks then good luck but i think it has something to do with ecm. Also as for the ecm i did a google search and i find them from 145 up to 250 reman. Thats not bad. Here is one site, never used them but thought i give you an idea.
http://www.lowmileageparts.com/2002-chevrolet-tahoe-electric-engine-control-module---ecm-55056.aspx

Good luck !!

 

[Rivieraracing]

If you are cleaning out your MAF, hope you know to only use MAF specific spray cleaner, to never use an air compressor to dry it all out after spraying the MAF cleaner (it will air dry on its own), and to never touch the little wires in the MAF at all with anything!! Otherwise, if you've never cleaned in out it would be a good cheap try for a fix for sure!! If you run a K&N, then it's a good thing to do at least once a year anyways!! My can of MAF cleaner has lasted me 5 years so far and I have a few more cleanings left in it still!!

Good luck!

 

[DCT]

I had a similar issue. No check engine lights. Engined stalled a few times too. I have a 2001 suburban with the 5.3L. 140k miles. All I did was clean all the dirt build up in the throttle body. Removed only the intake boot and wiped clean with a rag. Idle is smooth now.

 

[MrFleming007]

What the flashing CEL is usually telling you its that the system thinks that catalytic converter damage may occur if you keep driving. Misfires are a sure way to set this off. Here's my thought process. You say that the exhaust system is pretty much new, so I think we can rule that out. I also think we can rule out air delivery and vacuum leaks. Cleaning the MAF is a good maintenance item and might solve this, if not, you know its clean (I clean mine every other oil change). A vacuum leak would do this, but not at highway speeds when pressure in the intake would be near barometric pressure. Ecm getting hot and acting up? Maybe, but I would think that once it got hot it would do it all the time, the act normal when it was cooled down. It sounds like some misfires going on, which should set a P0300 code. With misfires, I would suspect the fuel delivery and ignition system. With new plugs and wires, I would just check to make sure they are seated correctly and not chaffed, then rule them out. This leaves coil packs. If you could narrow down misfires to certain cylinders, then you could take the coil packs for those cylinders and move them to a non mis-firing cylinder. If the problem follows, you've got a bad coil pack. If it doesn't, suspect ecm or fuel delivery.

To be honest, I cheaped out with my data reader. Since I already have an Android smart phone, I just got a cheap obd2 Bluetooth reader and bought Torque from the Android market. Data refreshes might be a little slower that a quality dedicated reader, but it does do everything that the quality readers do. For a total investment of around $40, its already paid for itself in diagnosing my fuel trims and p0171 and p0174 codes. Good luck!

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[Vinniety]

Everyone has great ideas and i would like to contribute a few more of mine. As we are talking about the Catalytic converter i would recommend to look at it when the problem happens and see if its RED or like someone said get a infrared temp and see what the temp is on the exhaust before and after the cat. The catch there is when that cat gets hot and is bad the truck will continue to ride bad it wont happen to ride bad then 2 minutes later run good.......unless the o2 sensor is getting the heat and going haywire. Also if the coil pack has a misfire you have to get a code. If you dont then the item which im thinking is the ecm is not working well and that why your not getting the code. You never know it might try to put you in safe mode i think that's what its called. Thats when you get a check engine light on and the ecm makes the vehicle run lean in the sense to get to a safe spot or to a mechanic. I remember reading something like that. Thats why when that check engine light is on you waste more gas. Anyway just more thinking keep this thread posted on what you find out and how it gets fixed!!

 

[Sprayed99]

If it were 1 bad coil, plug, or injector it would isolate that and give you a known misfire code by bank (side). A P0300 is a random misfire code and flashing CEL means that is requires immediate attention because it is a high risk for catastrophic failure. The flashing CEL only means that GM programmed the PCM to flash when it detects certain codes... the random misfire being one of them. I have dealt with this damn code many many times. Most times it is a wiring issue. I have seen the following.

Wires rubbing and shorting to cause injector failure
Ground wires corroded or loose
Battery voltage low (either battery or alternator)

The MAF should be cleaned just to rule it out and it is a cheap job.

---------- Post added at 10:06 AM ---------- Previous post was at 10:04 AM ----------

Thats why when that check engine light is on you waste more gas. QUOTE]

 

[MrFleming007]

Also, check for corroded/ loose engine grounds. I suppose its possible that the crankshaft position sensor is going out, but I doubt it, though I've heard of them cracking and doing all sorts of wierd stuff.

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[plsmith86]

Hey Yall,

Today I went to the parts store, and purchased some MAF cleaner, Throttle Cleaner, and for giggles a new air filter, along with a new EGR gasket. I pulled off my intake, and did find a kink in the rubber boot.. I doubt that would have anything to do with this, but I re-formed it and set it aside. Took off the MAF sensor, sprayed it down several times, and let it air dry. I took off the air box cover and removed my filter... it was not bad, but was dirty, so I put in the new one anyhow. I then took apart my EGR. After closer look, it did have some carbon, but I can not see any manufacture name on it anywhere, Usually GM has GM on it, AC/Delco, Delphi or Valeo. So, I am not sure if it is junk aftermarket but I did bench test it and the solenoid does work... Any way I douced it with TB cleaner, several times, scraped the old gasket off, and cleaned out as much carbon with Q-Tips as I could, and used a 20MM Hex driver and made sure the valve was seated and moving freely. I then sprayed down the TB, it was not dirty by any means and very little carbon came out of it, but everything was apart, so I figured I might as well do it. I let it all dry, put it back together. When I started the truck, it cranked over for a good 10 seconds, I stopped and did it again, when it kicked over, it ran rough for a few seconds and cleared right up. I suspect that it was doing some sort of calibration. I was able to get a friends scanner and pulled history - It had multipul misfire codes but nothing else. I do have a lazer thermometer and did check the exhaust, everything is fine there. I really hope I find some slack in my rope! I will keep every one posted and let them know how it runs. I sure hope this fixes it, the truck gets great fuel economy, and is in excelent condition. Thanks for all the input everyone!!

 

[Bedore]

I suspect when you first started it, it ran rough because it no doubt had a bunch of TB cleaner to digest. When I cleaned my TB my truck did the same thing. I wouldn't worry about that in particular since it eventually cleared up.

As for the rest of the issues, it's hard to tell. My truck ran great, but would occasionally flash the CEL. I ended up needing a crank relearn done at the dealer, and it was fixed. My brothers 03 GMC Sierra 1500 ran like you describe, and it finally got to the point that it was not drivable, but his ended up being plugged up cats. Wish I could help you more.

 

[plsmith86]

Well, I am not going to say its fixed, but knock on wood it has been running fine all week. I drove close to 400 miles this week and it has not given me any problems. I really dont know what else it could be, if this did not take care of the problem, but so far so good. I thought about the crank sensor, but I dont know of any 5.3's having any problems. I know on the 6.0 and 8.1 they would heat up and crack and do all sorts of weird crap. I suppose this is possible, but normally when they crack, the engine would just cut out all together with no warnings. While working for GM, I seen this at least a dozen times. But I never came across this problem that I am having which is why I was / am stumped. I have 22 chrysler techs working for me, and I have stumped every one of them as well! It's such a stupid problem and I knew it would be something easy, but the wild card is "something" Hope this one can be put to rest, Thanks Yall.

 

[shelyjo13]

help is here

it could be the fuel pressure regulater or the egr

 

[NavyVet1]

I have a cold air intake with a K&N oiled filter on it. would that cause problems with my throttle body? I also used a fuel system cleaner (Royal Purple) in my fuel tank. About a month later the problems started. I have replaced the MAF sensor, catalytic converters, spark plugs, plug wires, the computer and the o2 sensors. Which did not solve the idle or cutting out issues. Tomorrow, I am going to try cleaning out the throttle body (again) and replacing the idle air control valve, crank position sensor, & cam position sensor. Hopefully that does it!!! Any other suggestions would be welcome.

 

[JoeM5952]

Maybe TPS sensor?