uh oh!!

[GF7PE]

Ok today I went out on the beach. Started the truck up this am went and filled up at the gas station, drove down to the orv entrance about after about 40 min of drivin. Got out on the beach and was crusin at 15-20 for about 30 min when all of a sudden when I went over the dune and hit some soft sand there was this "knocking, slapping, ticking" coming from the valve train. Every time I hit the gas it, it does it again pretty bad, even in neutral. No power and vibrates pretty bad too. So i get to the camp and pull out my recipt from Mobil and make sure I did put 93 octane in, and I did. SO, I park it and hang out for a few hours. When I go back out to leave its fine and hasnt done it since.

 

Any ideas?

[LikeaRock14]

Sticky valves???

[snoman]

Maybe some sand got in some sensors and threw timing way out of whack or you had a momentary power spike from a power conection to ECM that scrabbled working memory of ECM until it was "rebooted" (shut of and later restarted.)

[GF7PE]

follow up

 

so i read this stuff and say screw it. I go out and decide to run it hard. First light I floor it and it doesnt move but it revs up. I look in my mirror and there is smoke all over the place from the rear tires. I say wtf!!! This truck has had low end issues for a while now and when I got the westers tune it helped a little but not much. But now all of a sudden the low end/hole shot is amazing. What do you think could have caused this.

 

never thought the 6.0 would be able to roast the 35's off the line

[8100HD]

Must be Lyndon's new time release programming.

[1BADHD]

Hmmm.....interesting. When I had the 93 tune and 35's I could put a a$$ whoopin on the 35's. I dunno why it would all the sudden run so much better.

[Butch 02 Denali]

The trip in the dunes might have reseated a loose conection, maybe on one of the 02 sensors or grounds for the engine? Or the posibility that the load on the engine from driving in sand burnt some built-up deposits off the 02 sensors, making them respond better. The noises could be the engine retuning for the changes?

 

Or it's Lyndon's new time release programming like 8100HD said!

 

Butch 02 Sierra Denali

[GF7PE]

d**n it!!!! looks like I spoke too soon. This am it was great but now its back to the way it was before the "knocking". You guys think its bad O2 sensor?

[snoman]

d**n it!!!! looks like I spoke too soon. This am it was great but now its back to the way it was before the "knocking". You guys think its bad O2 sensor?

Have you changed fuel type?

[GF7PE]

nope always Mobil 93 and the same station

[Butch 02 Denali]

Take a ride over to an AutoZone parts store and have the codes read (for free).

It will be interesting to see what is in there!

 

Let us know!

 

Butch 02 Sierra Denali

[GF7PE]

Take a ride over to an AutoZone parts store and have the codes read (for free).

It will be interesting to see what is in there!

 

Let us know!

 

Butch 02 Sierra Denali

a friend of mine has auto tap. what do I want to look at?

[Butch 02 Denali]

Any error codes that are stored in the PCM. There has to be at least a couple in there!

[GF7PE]

I went to auto zone and all it said was "PASS"

[snoman]

I went to auto zone and all it said was "PASS"

Have you rechecked all of the computer harness and sensor connections? YOur ECM has two types of memory in it. The ROM where the programing is stored and the RAM were it is "executed" so to speak and were it stores data as it "learns" your engine and driving habits. It is almost like you are have a power spike and is reseting or corupting you RAM or working memory and your ECM has to relearn everything again, over and over. take apart and reseat all electrical conectors in the ECM circuit (Engine Control Module though some call it somethin else) and senor hook ups.