Alright I need some help

[edd112]

Just thought I should seek help here before I go to a mechanic.
Lately my 04 tahoe has been backfiring, in one instance, it felt like my engine was gonna stall, so I gave it a little gas and it did nothing but backfire and then the truck went forward. Happened again about a minute later while pulling into a parking garage. It's been happening on rare occasions but now it's becoming more frequent. The check engine light comes on sometimes but not all the time. Just wondering if anyone has been through this, I've heard it could be bad catalytic converters.
My tahoe has no mods other than a magnaflow bullet exhaust I installed about a year ago.

 

[cmc76]

not trying to be a smartass, but im sure everyone who has looked at the thread is asking.... what code is it throwing?

 

[drew4216]

Bad cats, leaking intake gaskets, fuel pump, chances are your cats aren't probably that clogged, I have even seen a loose battery in the side post design that made that happen I would check that first, for the intake gasket run your engine at idle, spray brake clean around gasket, if you have a leak your engine will rev. Any auto parts store should be able to check your fuel pressure the 5.3 should idle between 52-55psi I think. I would be surprised if it wasn't one of those.

 

[edd112]

not trying to be a smartass, but im sure everyone who has looked at the thread is asking.... what code is it throwing?

Honestly haven't had time to run codes on it. I work almost everyday and my days off are busy, but yeah ill get to it asap. I took it to autozone a while back and they said it could be either a bad fuel pump or vacuum leak, or even a faulty sensor. I was just wondering if anyone on here has had the same problem.

 

[edd112]

Bad cats, leaking intake gaskets, fuel pump, chances are your cats aren't probably that clogged, I have even seen a loose battery in the side post design that made that happen I would check that first, for the intake gasket run your engine at idle, spray brake clean around gasket, if you have a leak your engine will rev. Any auto parts store should be able to check your fuel pressure the 5.3 should idle between 52-55psi I think. I would be surprised if it wasn't one of those.

Yeah man, we'll at 127k miles it could be anything. Got the truck about a year and a half ago so I don't know how well the previous owner took care of it. (Only one previous owner)

 

[about20ninj45]

Order a Bluetooth scanner from amazon. Bafx elm327 scanner. It's 25 bucks and it works, that way you don't have to second guess your codes

 

[edd112]

Order a Bluetooth scanner from amazon. Bafx elm327 scanner. It's 25 bucks and it works, that way you don't have to second guess your codes

Dang honestly I haven't even thought of that. Will look into it, thanks!

 

[ccapehartusarmyINF.(ret)]

i have a bafx elm 327 and its awsome theres two main apps to get i actually recomend obd doctor over torque
ive also used the expensive 1200 dollar snapon scantools in school and im able to accomplish the samethings with this 20 dollar adapter and a 10 dollar app

 

[SLCHOE]

The flashing Check engine light and then off would almost certainly mean you have a PENDING code so we need to know what that is.

Autozone guys are there to sell parts NOT to fix cars. Keep that in mind. Why do you think they offer the free code read? P0420 code? Ah yes, yo need a catalytic converter. That's $700. A vacuum leak could set off a P0420 and the fix would be a $5 gasket but they're not in business to fix your car. They're in business to sell you parts.

Anyway...

The symptoms could be a failing fuel pump but with failing fuel pumps, they don't usually let up after they quit. I'd check your MAF sensor for dirt. Next time it acts up and doesn't want to accelerate, shut it off and disconnect the MAF sensor. Then crank it. It may take a couple of cranks because the PCM is confused as to why there is no airflow during cranking and procedding to falling back on stored data values for MAF (default). If it runs well after that, clean your MAF with MAF spray or Carb/Brake cleaner. Just make sure you blow it dry before you plug it back in.

 

[Rocket Man]

I had similar problems with my '02 Denali. Codes pointed to MAF sensor, throttle body sensor, then multiple cylinder misfires. After replacing a few parts and cleaning the throttle body, it kept getting worse until one day I floored it and suddenly lost a LOT of power and the CEL started flashing. I knew what it was right then- clogged cats. A mechanic confirmed it at no charge and I had a muffler shop replace them.
Edit: this was at 130 k miles.

 

[SLCHOE]

Lets stick to THIS vehicle.

Get some codes for THIS vehicle if you can.

Past experiences with OTHER vehicles DONT MATTER in this case.

 

[Rocket Man]

Past experiences with similar symptoms on other people's vehicles is exactly what helped me diagnose mine. Just trying to help so there's no need to be like that. There's no exact code for a bad cat. My point is that you might see codes pointing to other issues but those issues MIGHT be caused by plugged cats, as was my case. The MAF, TBS, and misfires were all acting up BECAUSE of plugged cats. If your engine can't exhale it shows up in other areas. So I'm just saying it MIGHT be the problem. Calm down and don't be so critical of someone with similar experience trying to be of help @SLCHOE ! Sheesh.

 

[ccapehartusarmyINF.(ret)]

past experiences with similar vehicles do help
as long as people dont start chiming in with similar expereinces with an 88 ford f-150 and we happen to be discussing an 06 tahoe

 

[Rocket Man]

Exactly; my '02 Denali is definitely a similar vehicle to the '04 Tahoe being discussed and my problems were similar. Mine felt like it was backfiring as well but that was after throwing several codes over a period of time.

 

[SLCHOE]

Not what I was getting at Red Rocket.

On these trucks those symptoms can come from a bunch of different issues. What I was getting at was that codes/data are needed for THIS VEHICLE to determine the direction to go with THIS VEHICLE. But nevermind that I guess... Carry on.

 

[Rocket Man]

That's exactly what I was saying. My problem pointed to several issues but ended up being one. I just advised him that if the codes pointed to things that have to do with intake problems, it may actually be exhaust problems. Of course he needs to read his codes. That's only obvious. But your CAPITAL LETTERS ARE THE EQUIVALENT OF SHOUTING. Please stop SHOUTING at me! We are both trying to help, I understand that. Maybe you could have just started to the OP that he needs to read his codes instead of directing a message towards me stating in capital letters that I was wrong to share my similar experience. It felt like an attack on me as opposed to being helpful to the OP.

 

[SLCHOE]

That's exactly what I was saying. My problem pointed to several issues but ended up being one. I just advised him that if the codes pointed to things that have to do with intake problems, it may actually be exhaust problems. Of course he needs to read his codes. That's only obvious. But your CAPITAL LETTERS ARE LIKE THE EQUIVALENT OF SHOUTING. Please stop SHOUTING at me! Thanks.

Ok is this better? Does this feel better Red Rocket? Soothing even? LMAO

Chill the **** out. Nobody is shouting at you over the keyboard. You can relax now.


I fix these cars for a living. A simple misfire can be one of MANY issues not just a simple bad spark pug is all I am saying. I tell my apprentice the same thing. Go in with an open mind. Don't let past vehicles symptoms/final resolutions dissuade you from doing a systematic diagnosis. Doing that can waste tons of time going in the wrong direction.

Look at the data you have for the problem you have and go from there, ALWAYS (oops... didn't mean to "shout" again).

 

[Rocket Man]

@SLCHOE Happy Thanksgiving. Keyboard etiquette isn't your thing, I get it. Typical

 

[FamilyTruckster]

pull the vacuum line off the fuel pressure regulator and see if fuel is passing through (coming out of the line when you pull it off... meaning ruptured diaphragm in the regulator)... could be a number of things, but if you dont have a scan tool or a whole lot of time, thats a quick check diag...?

 

[SLCHOE]

@SLCHOE Happy Thanksgiving. Keyboard etiquette isn't your thing, I get it. Typical

Please save me your passive agressive non-sense.

When you know what you are talking about, chime in. Otherwise stay quiet.