Just fired up my motor last night for the first time and it seemed to idle just fine. This morning i figured I'd let it idle for a couple mins to let it get to temp and see if the E-fans were working ok. Anyway it idles fine for about 7-10 seconds then starts to sound like crap and finaly shuts off. What do you think would cause this?? I'm thinking it could be a bad map sensor. Anyway heres a quick vid. Hope you guys can help. Thanks

VIC

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Don't try to tune your idle until you get the inlet piping done. Don't put your MAF there either. I forgot the exact length, but you need like ten inches of undisturbed airflow before and after the MAF. The wind off of your fans will screw up its readings, as will the air bouncing off the throttle blade.

 

Well I cant tune so thats out of the qestion. I have a mail order tune from nelson. It supposed to be good just to get the truck started and what no. I'll be taking it back to Nelson for a SD tune once everything is running right. I just figured out my 02 sensors are not even connected so i'm hoping that is the main issue. I scan the pcm and it came back with 2 codes P0443 and P1336. The first code is for the evap which is no biggie I would think but the second code is crank positioning scensor. I changed it out, erased the code and it sill came up. Any thoughts??

Vic

 

You need to do a crank position relearn when you get over to Nelson. Also, when he said that the tune he sent was good enough to get it running, I'm sure he didn't mean with the engine half apart and no oxygen sensors. That makes sense, that the engine runs OK cold, when it is in open loop. Then when it warms up and tries to go into closed loop, it doesn't work with no oxygen sensors. Get off the computer and get back to work!

 

LOL!!! You are correct!! I'm picking up a set of upstream o2's in the morning and well try it again!!

 

So same crap is going on. I put in new o2 sensors, fired it up and it still dies. Seems like it turns on fine, idles great for about 10 seconds and then starts shaking, sputters and dies!! Do you guys think there could be something wrong with the tune??

 

Security relearn?? If that was the case it wouldnt even turn on correct?

 

It takes awhile for the computer to learn. Mine would do the same. I held the throttle at around 1K rpm for a little bit and it helped it idle on its own.

 

Ok, ill have to try that in the morning. Thanks

It did seem to idle a little longer at times.

 

There are so many things that could be wrong with that setup, not intentially of course. Unless u have a scanner to see what's going on we will just be guessing. Remember the ECM only does what it's told to by the sensors so they all must be reading correctly.
It wouldn't run at all if the map was the issue.
Cold startup seems ok, then bad when in closed loop, sounds like a big vac leak or new bad o2's.
I'd get it all together put a smoke machine on it to test for vac leaks and be sure those o2's are toggling correctly.

Or just put it on a trailer and bring it on up. We're great at troubleshooting.