Been having a problem ever since I went FI, once I start it up hot or cold, the engine will idle good for a few seconds then start idling rough for a few seconds.

When I hook a scan tool to it, I can see ALL cylinders misfiring when the idle starts to go rough.

Also, if I get on it a little and then come to an abrupt stop, the engine will almost die.

I have clean the MAF, fuel pressure is good (it use to show 58psi at idle, but now it is showing 60-65 psi) the change in pressure has nothing to do with it though because it has been doing it long before that changed


what do you guys think? warped intake gasket? bad fuel pressure regulator?

remember, all this started after I installed the turbo... idk what would cause ALL cylinders to misfire all at the same time every other few seconds at idle (only happens at idle, I can hold it at a rev and it is smooth, as soon as I let off the gas though it starts running rough/misfiring for a few moments, then runs OK then goes back to misfiring-- then goes back to OK and so on back and forth)

 

Got a wideband on it?

 

yeah, when the rough idle starts it goes down to about 12 then shoots up to a little over 15 while it idles rough. Then as it straightens itself out it goes back to 14.6-14.8

Could my spark plugs be causing this? NGK TR6 set to .035, unless I set them wrong

edit: I guess it couldn't be my spark plugs if it wants to run lean under the rough idle condition/misfires.. if plugs weren't firing it would cause it to go rich, right? unless the computer sees that first 12afr (from plugs not firing) and immediately cuts off fuel creating the lean misfires

 

I'm going to pull the plugs and gap them a little closer, been reading through threads of people having problems specifically with the TR6 spark plug

 

gapping the plugs smaller didn't do anything

also, I was wrong about the afr when it starts to misfire. it runs 14.6-14.9 and once it hits the 14.9 it starts misfiring and goes to 15.1

 

I have the same problem .....and a nelson tune.......i believe it is in the tune....when the fans or ac compressor is coming on it is drawing too many amps ans causing this......the idle ir related issues need to be fixed in the tune

 

Log engine voltage to see if it is causing the misfire. Incomplete injector data, along with a faulty alternator, can have a big effect on fueling. Do a scan to see if voltage drops just before a misfire occurs.

 

thanks for the info, I'll go and get that scan right now and post it up by tonight

 

here you go, the voltage does drop quit a bit (down to 12v) but I don't really see a relation to the misfires

you can see in one part I hold the rev at about 3k and all the misfires go away

The "misfire history" on this truck is ridiculous... every cylinder has over 800 misfires lol

 

I can't guess what your problem is from the info that scan an config shows (not that I could otherwise ), but it makes me wonder what your fuel pressure and ignition advance are like.