Engine misses but keeps running.....

[MinnAval]

Hi everyone.
I took my 2002 Avalanche (4wd,5.3liter Z71) on a wonderful drive from Minnesota to San Jose Del Cabo in the Baja about 3 years ago. This was about 3000 miles one way to our vacation home.

It ran perfectly and is an ideal vehicle for the bad mexican roads and offroads there. Its got approx 110k miles on it

It only gets used about 4-5 times a year for 1 or 2 weeks at a time. I was there this month. Leaving the ipod charger plugged in kind of fried the battery so I put a new one.

Everything worked fine for a couple days but then on a 1 1/2 hr trip to Todos Santos along the Pacific coast, the Engine began to miss and i thought it was gonna die in the middle of nowhere.

It did this about once every 20 miles or so and got us home without ever killing.

The check engine light never came on. I purchased a new fuel filter but have not put it in yet. So my question to you: Gummed up injectors? Bad Fuel Filter, Bad Gas. Any suggestions will be appreciated.

[MS03 2500]

A guess is, it may be the fuel filter, fuel pump or just need a tune up(plugs and wires).

You can have the fuel pressure tested after you change the filter. BTW not all problems will set the engine light on so you may still want to have it scanned. 

[ramonday]

Hi everyone.
I took my 2002 Avalanche (4wd,5.3liter Z71) on a wonderful drive from Minnesota to San Jose Del Cabo in the Baja about 3 years ago. This was about 3000 miles one way to our vacation home.

It ran perfectly and is an ideal vehicle for the bad mexican roads and offroads there. Its got approx 110k miles on it

It only gets used about 4-5 times a year for 1 or 2 weeks at a time. I was there this month. Leaving the ipod charger plugged in kind of fried the battery so I put a new one.

Everything worked fine for a couple days but then on a 1 1/2 hr trip to Todos Santos along the Pacific coast, the Engine began to miss and i thought it was gonna die in the middle of nowhere.

It did this about once every 20 miles or so and got us home without ever killing.

The check engine light never came on. I purchased a new fuel filter but have not put it in yet. So my question to you: Gummed up injectors? Bad Fuel Filter, Bad Gas. Any suggestions will be appreciated.

Sounds like a fuel delivery issue. Definitely check the fuel pressure. Should be about 54 on prime and about 48-52 on idle. If prime is okay, and pressure is lower on idle than 48-52, then you may have a vacuum leak or fuel regulator issue.

Of course, like MS said, it might need a tune up if never done. You're at about the right mileage for things like that to start crapping out.

[ygmn]

If it misses...
it would set check engine light as that is one of the codes..

ENGINE MISFIRE then which cylinder or random...

Have it checked out by dealer or knowledgeable mechanic..
as misfires are the worst to diagnose on these new trucks..

as it could be fuel, spark, air, exaust etc.. heck anything can make it misfire even bad fuel

[MinnAval]

Thanks for all the good suggestions.

I have a "Equus 3130 Innova Diagnostic Code Scanner with Live, Record and Playback Data Capability for OBDII Vehicles".

I have'nt used it much except to read and reset alarm codes.

Does anyone know if I can read fuel pressure while stationary with it  and whether I can leave it hooked up while driving to capture what the engine went through when my event occurs?

Also what is the best fuel additive to "clean" the fuel path?

Thanks in advance

[ramonday]

Thanks for all the good suggestions.

I have a "Equus 3130 Innova Diagnostic Code Scanner with Live, Record and Playback Data Capability for OBDII Vehicles".

I have'nt used it much except to read and reset alarm codes.

Does anyone know if I can read fuel pressure while stationary with it  and whether I can leave it hooked up while driving to capture what the engine went through when my event occurs?

Also what is the best fuel additive to "clean" the fuel path?

Thanks in advance

You have the Cadillac of scanners. I'm jealous. I don't think it will give the fuel pressure in this application. Not because of the reader, but because the ECU may not feed that info back to the ODBII port. I would leave it hooked up and do some driving and see what happens, though, regardless of whether or not it will send back a pressure reading.

As far as the best additive, I don't think you can beat a can of Seafoam in about 20 gallons of gas, and then do the Seafoam intake treatment. Of course, this is assuming the fuel pump is still good. If it's bad, then you just gotta replace it.

[ygmn]

I have that scanner.
It will not read fuel psi.

[ramonday]

I have that scanner.
It will not read fuel psi.

...and if you ever want to sell it...

[ygmn]

...and if you ever want to sell it...

they cheap on Amazon...

[MinnAval]

Hey Everyone,

Here is the follow up on my Avalanche Saga.
During my Jan trip to Cabo i did the following:

Fed the Seafoam via the vacuum line as previously discussed by various people.
Surprisingly the engine would not kill as I fed the can. I finally had to pour the last oz in to make it kill.
I waited a few minutes and then started the car.
It smoked like hell for a few minutes but then cleared up.
Took it for a test drive at various speeds on highway and viola...no missing no clunks....
The engine ran perfect and I was impressed.

Subsequently I have changed the fuel filter, put new Delco plugs and new cables.

By the way the old fuel filter was totally shot. There was something rattling inside.
There was a fair amount of brown rust and/or dust (The Cabo environment is like Arizona and red clay/dirt is everywhere)
around the pump some of it might be inside the fuel line also?

Also with the fuel line disconnected from the gas tank air pressure was used to blow the fuel line clean.
This was done from the engine side to the tank side with the fuel filter off.
Question comes to mind as to the state of the injectors and their filters.
The car runs fine...better than it used to by a long shot....

but

The fuel pressure reads 30psi.

During idle and normal running, I can hear the fuel pump "whine" constantly.
Not too loud but still audible. This might be normal but I don't remember.
I am back in the US now.
Is the fuel pump about to die?
What is the best course of action?
The local Cabo  GM dealer wants US$1200 to put in a new fuel pump.

[MS03 2500]

At 30 PSI the pump has one leg in the grave, it should be a least 50 PSI.

Depending on how conformable you are working on the AV some folks have cut a hole in the floor and changed the pump themselves.

[MinnAval]

Actually i would do the cutout if the car was at my house where i have all the tools and even a Car Lift in my garage.
But the car is in Cabo and i have very minimal tools there.

So I am planning to take a Delphi pump from NAPA with me the next time i go to Cabo and have a local guy put it in while I watch.

The Cabo GM dealer wanted $1200 to do it and I did not know if that was a reasonable charge or not. Basically, the pump itself is $350 here in Minnesota
so I guess that dealer wants $850 for labor to put it in and service the Injectors.

Does it sound like its a resonable charge?

Funny joke about this is that my son's friend works on cars locally as a profession and he said to my son..."Tell your Dad to fly me to Cabo for a week and I will replace the pump for free.."........lol

[MinnAval]

Hi Everyone,

Follow up on my saga.
I had bought the fuel pump in Minnesota and was gonna bring it out to Cabo.
In the mean time the fuel pump did crap out before I got there (wife and couple of girl friends had to get the car towed a few blocks home).

Now the new fuel pump is in car runs like a million bucks.
So it now has new fuel pump, fuel filter, new plugs, new plug wires and clean injectors.

Question for all is that to be proactive what else should I change.

How about front/rear differential work, tie rod work....etc

[MS03 2500]

Just go though all the system or have a mechanic do it. There is not a easy way to tell you what might be wrong.

[MinnAval]

Actually there is nothing wrong with the car now.
What all has been done to it seems to have fixed the original problem.

My question actually was for suggestions to pre-empt possible problems in the future because of the 100k+ miles on the car.

[ramonday]

Actually there is nothing wrong with the car now.
What all has been done to it seems to have fixed the original problem.

My question actually was for suggestions to pre-empt possible problems in the future because of the 100k+ miles on the car.

Wouldn't hurt to check the front hubs at this point. Make sure there is no play while grasping the top and bottom of the tire and rocking to and fro. Also, check the oxygen sensors and cats. I'd suggest replacing the sensors (Rockauto.com has them cheap) and just take a rubber mallet and lightly tap the cats to check for anything rattling around. They should be okay, though.

Maybe have the front rotors checked and cut if needed. If so, go ahead and replace pads, too, even though you'll probably have 50-60% left on them.

Front shocks should be around replacement time. It's a 30 min job and not too expensive. Might even get the front end aligned afterward.

Flush radiator and replace thermostat.

Plugs and wires.

You can change the diff oils, but they are probably fine.

Ball joints: I'm touchy on this, but my suggestion is to have a reputable shop that you trust check them. It is possible to check them while you are inspecting the front hubs, but you have to know what to look for and how much to stress. I've found that it is deceiving on recirculating ball steering setups. At least to me.

That would be my suggestions. You can debate on a transmission flush, but I do them every 30k since I had a good one put in mine. Probably overkill on that.

[MinnAval]

Thanks ramonday,
These are good suggestions.
I already have put new plugs and wires but will give carefull consideration to the rest on your list.