ok, I have talked about this before (last winter) and the truck is starting to do it again. In the mornings when the wait to start light comes on I start her up. wait for oil and everything to stabilize then kick on manual high idle to 1100rpm. when the grid heater cycles OFF the motor sounds like it backfires. It shakes the truck and usually only does it one time (NO CHECK ENGINE LIGHT AND NO CODES). I know what a backfire is, I am just using that as an example of what it sounds like. I have been shooting videos each morning to capture it on my phone so I can post it and show the dealer. It only happens when it has cold soaked usually overnight. Once it happens it usually does not do it again hence the PAI to get it on video. I will see if I can catch it on video and post it here to see what people think. Any help or ideas will be much helpful.

BTW- it was doing it long before I installed the bodylift (bodylift has a 3" spacer for the intake horn)

 

My truck did that the other day, just once. Kind of like a hiccup. My '03 never did that. My '03 had a much more rock-steady idle, too.

I'll be watching with interest...

 

THAT IS EXACLTY what mine does. I am glad it is happening to someone else and I don't feel like a freak! LOL!!

 

its in your heads

 

i will video it for ya JD!! LOL!! I aint just drummin it up! LOL!

 

Mine does it too. has done it to me three time in the 4 months ive owned it.

 

Yup, mine does it too. As soon as I set the high idle it does it, and with the jake brake on, you really can tell it does it, cause the jake actually turns off for a split second... Of course I always leave the jake on.

 

see JD, there are more of us out there!! LOL!! It did not get that cold last night so it did not do it this morning. will keep trying to video it.

 

1100 rpms IS A BAD NUMBER....

I do 1000 or 1200 plus... Some say its just the TST...others that it is voodo.

Try different high idle...see what happens.

 

1100 is the lowest it will go. will try 1200. why is 1100 voodoo?

 

Just is...who knows why...does not like that idle speed when cold.

 

Especially with TST... 1100 is a bad RPM.

I can actually feel my truck surging going down the road if I keep it right at 1100 RPM..

Just bump you idle speed up 100 or 150 RPM... Should go away.

 

it finally did it but it was not a loud one like usuall. About the 16-17 second mark is the backfire noise I have been hearing. I had the high idle set @ 1300 this time and still did it. I will keep trying to capture it on video so you can hear it really good. It is getting colder and will keep you guys posted.



http://s207.photobucket.com/albums/b...1109070740.flv

 

My ride does something like this as well, but it isn't a backfire, it is a missing injector cycle. I chased this thing for a year. It mostly happens during cold weather, but it can occur in warmer weather as well, but only when the engine is first started. Very occasionally, it will throw a crank sensor fault code, which of course was the clue. Then after 3 or 4 engine restarts, the engine light extinguishes and resets the code by itself. My experience is that I get the crank sensor code about 1 out of 10 misses.

I believe the fault is created by the timing box. I know of another guy that has the same symtom (different timing box). It happens very rarely and does no harm, so I live with it. I have called Banks and reported the fault, they deny any knowledge of such faults. I don't believe this and I think they just blew me off. I believe the problem is created by the close timing between the crank and cam timing pulses when the derived clocks are shifted by the cold engine sensor and the timing box together. These pulses bounce around a lot when looked at by an osciliscope in relationship to each other, which is caused by the backlash in the gear train linkage between them and every once in a while, timing pulse coincidence is lost and an injector cycle is dropped. However, I do not know this for certain, because you would not only have to have laboratory facilities with a logic analyser at your disposal, but a lot of luck to be looking at the right place at the right time to trap it, as it is very rare. Although this is an edjucated guess, I am satisfied with my analysis.
Steve

 

thanks for the insite Steve! but i must say that it did it LONG before the smarty or anything was ever installed onto the truck. If it is ok, then i will press on. It does get louder and more violent in colder weather so i will keep trying to capture it on video and post when it happens! Thank you again!