Chevy truck owners I have a problem question

[wdswtr]

EGR valve or the pipe coming into it may be rusty and have an air leak in it.  If its electric EGR valve you can unplug it, you will get an instant check light but if the truck runs smoother you will know its bad.  Listen for an air leak in that pipe, if you find one and put your finger over the leak you will instantly notice your engine run smoother, careful though the pipe will be hot if its been running for a bit.  I would tend to guess its not your cylinder since you unplug the battery for 30 minutes and things ran smoother, from my understanding all that did was zero out the computer until you went through a complete drive cycle and it self adjusted again.  EGR valve, air leak, Mass Air Flow sensor, Map sensor, throttle body or electrical short are all suspect to me.  Luckily all fairly inexpensive parts.

Edited June 8, 2015 by wdswtr

[Jeremy K]

Truck is running rough again. Went on a few forums and said to clean the air man agent system and throttle body. I did both but no luck. Now I read it could be the body modular sensor or the accelerator sensor. I think I will bring it back to my mechanic and let hime do the compression test on#7 and look at the lifters. Don't know what else to do…..frustrating for sure.

 

I should clarify that it runs rough at a stop lights, foot on the brake and when you rev the engine and it hits 1500 rpms. 

The problems associated with lack of compression will not come and go. Im not sure how much you want to wrench on this truck yourself but if it was mine i would get it up to operating temp and hit the exhaust manifold with a quick shot of wd-40 a properly running cylinder will just vaporize the wd-40 and a poorly running cylinder will leave a wet mark . Determine which cylinder is running bad . Switch the coil with a good cylinder and repeat the spray test . If that doesn't work then swap an injector with a good cylinder and do the spray test again. If nothing makes a difference then you can start checking further down the line . Did you happen to notice it running poorly after it rains out ?Possibly could be a moisture problem.  

[jjb4900]

yeah, unfortunately the unhooking the battery trick only fools it for a little while and you're back to square one in no time..........been there done that.

[First-light]

yeah, unfortunately the unhooking the battery trick only fools it for a little while and you're back to square one in no time..........been there done that.

Yes that is what I found out . thanks

[First-light]

First Thank you to all the folks that chimed in on my truck problem. Seems like there are some knowledgable people on this forum. Again thanks! Just got the truck back from a day at the shop. It ended up being a defective plug. My original plug was replaced with a defective new one. They ran all the tests all passed except for the miss in #7. Last resort he pulled the plug and put in a new one and the truck ran great. The miss is gone at idling and at 1500 rpms. At the tune of $125 bucks for two hours of diagnostics and a new plug I'm a happy camper!!!!

[jjb4900]

First Thank you to all the folks that chimed in on my truck problem. Seems like there are some knowledgable people on this forum. Again thanks! Just got the truck back from a day at the shop. It ended up being a defective plug. My original plug was replaced with a defective new one. They ran all the tests all passed except for the miss in #7. Last resort he pulled the plug and put in a new one and the truck ran great. The miss is gone at idling and at 1500 rpms. At the tune of $125 bucks for two hours of diagnostics and a new plug I'm a happy camper!!!!

good to hear it wasn't anything major.......like I said earlier, my last tuneup produced 3 brand new Champion plugs that were bad right out of the box..............what brand?

[First-light]

I'll find out.

[ants]

Glad it was something simple & cheap. I once spent a week thinking I needed some major engine work over what turned out to be bad plug wires. In the end I think it ended up only  costing me about 100 bucks or so, PHHHEEEW!

[wdswtr]

The bad plug confuses me a bit, when you did the battery unplug and things ran fine till the computer reset the bad plug still would of been a problem, but instead it ran fine for the short time.  Dont want to be negative as I hope its been permanently resolved but I am wondering if the garage reset the codes when the plug was changed.  Guess you will know when you complete a drive cycle on it.  Im just scratching my head on the diagnosis.

[First-light]

Ok I see what you're saying. Yes it did run fine for a while. I need to drive it for a while tomorrow to see what happens. 

 

All I can say is when I left the shop the first time it was running worse than when I brought it in. Maybe I felt it was much better but really it was back where I was originally after the battery disconect. Hard to follow I know…….

Edited June 10, 2015 by First-light

[wdswtr]

Well if the problem comes back at least its not detrimental to the wallet to fix.  Have you seen the prices of new trucks these days??????  YIKES drive it till the wheels fall off and weld them back on and keep driving it more lol.  My truck I bought in 2004 is now double the price today for the basic same damn truck.  Makes a person sick to his wallet.

[Five Seasons]

First Thank you to all the folks that chimed in on my truck problem. Seems like there are some knowledgable people on this forum. Again thanks! Just got the truck back from a day at the shop. It ended up being a defective plug. My original plug was replaced with a defective new one. They ran all the tests all passed except for the miss in #7. Last resort he pulled the plug and put in a new one and the truck ran great. The miss is gone at idling and at 1500 rpms. At the tune of $125 bucks for two hours of diagnostics and a new plug I'm a happy camper!!!!

Really sucks when new parts don't work. Happened to me plenty of times. A diy troubleshooters nightmare.