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My 08' GMC has been backfiring and hesitating pretty bad the past few days... I have no idea whats going on with it. I have tried HEAT fuel treater in the tank thinking I had water in there... no change. Its been down to 18* or so recently, when the cold weather hit is when the truck started running poor. Today the sucker backfired and blew my CAI off. All I have is a tune and CAI, no major mods.
:tantrum:
How do the plugs look?
I haven't pulled them, the truck only has 40k miles
Well pull them, spark plugs will tell you more about how your engine is running than any electronic gadget. My guess is it's too lean or too much timing.
I was planning on checking them out as soon as the temp here gets over 20*.... I don't have a shop or anywhere to work out here. Thanks for the input.
Same thing is happening to me in this ridiculously cold weather. It's a single damn degree outside right now lol! Plugs are a good place to start.
Pulled plugs, they look fine. Now the truck only mis-fires and cuts out under WOT. I plan on putting in 48lb injectors soon but would like to fix this beforehand.
Not to start nothing, so don't take it this way, I just think it's funny to come to this conclusion right off the bat. I would have started out with - history on the truck, any parts changed out, any ses lights maybe?Quote:
Originally Posted by Frenchy
Now why would you say there is too much timing? The only way it could be too much timing is by the tune right? I would think I would know better to set the tune up with too much timing lol.
He would have known this right away after the initial tune install, he would hear detonation going on.
Seriously though, I'd like to know how too much timing could have happened or caused this?
Now running too lean, that could be anything, so I won't say you were blaming the tune on that one.
It could be lean, maybe a bad fuel pump?
Steps:
Did you change anything recently?
Get fuel pressure checked.
Maybe get the pcm read regardless of ses light illuminating, see if there is something in history.
Check to make sure the O2's are toggling correctly. O2's don't set right away, maybe it's a semi-bad O2.
Get the truck scanned and view all cylinder misfire data. See if any of the cylinders are misfiring.
Those are some of the first steps I'd take.
I'm thinking a bad o2 sensor.
lmk,
allen
Quote:
Originally Posted by BigMac
I just saw this, only WOT? Check fuel pressure under a load/wot.
I'm running my gauges for the turbo setup so I'll go ahead hook up the fuel pressure gauge. Dealer replaced an o2 sensor today and it fixed the mis fire, it still cuts out under WOT, feeling like no fuel so I'm thinking low fuel pressure. Nothing wrong w/ the tune, it just feels like its not getting enough fuel. Thanks for the help!
Allen, Devin wasn't bashing your tuning at all. He said nothing about the tune. You know as well as anyone that vehicles can develope a rich or lean condition from many factors other than the tune. I'm not trying to start anything either... just clarifying on Devin's behalf.
I am having a similar problem. At WOT it feels as if a governor is kicking in, especially right before a shift. So I am curious to see what comes of this.Quote:
Originally Posted by BigMac
I'm looking for a fuel pressure gauge to see if thats my prob, the cutting out is even worse under tow/haul mode... but thats making it run up higher in the rps's before shifting. Are you in the Midland area Ruffneck?
Yes I live in the Midland area.
That's perfectly understandable and trust me, I'm not trying to start it, lol, but he said TIMING, that is only related to tuning, and too much timing can't cause the issues his truck is experiencing.Quote:
Originally Posted by pl4yboy
I also was perfectly clear that I wasn't including lean or rich in that remark, just the TIMING, then I asked him to explain how timing can cause that and how else could too much timing be applied besides with tuning.
I know he didn't say it, but Timing and Tuning go hand in hand.
It's just remarks like that from someone towards another who is trying to get his truck running right, causes the truck owner to call and question the tune every time!
You wouldn't believe how many calls we get like that.
btw, we're tuning up a 6.2L to run your truck at the race track, it's all stock, but still should be fun.
Damn... I better throw some more at this one then because I'm sure its an ECSB 2wd that weighs 600+lbs less! GDI... why do you have to make it hard on me?!
it's just stock, so i'm sure you can take it, stock exhaust, everything, just hoping to get some good times from it.