I don't suppose you have any way to record data off the ECM? You could look at the command to the injectors and the engine speed and see if the ECM is trying to open the injectors again to stop the engine from stalling.

When you release the throttle, you've requested an engine speed of low idle but the engine is still up at something higher. The ECM should turn off the injectors to get the engine speed back down. As the actual engine speed approaches low idle, the ECM should start to turn the injectors back on. The rate that this happens depends on how the governor is tuned.

If you don't see any command or voltage to the injectors until the engine has dropped below low idle, or any command at all, then it's an issue with something electronic. If the command goes out, but nothing happens, then it's more likely a hardware issue with either the injectors reacting slowly, or a oil pressure/fuel pressure issue. You said the throttle was responsive, so hardware response might not be the issue.

Does it try to save itself from stalling or does it just die like you turned it off?

 

I don't have any way to record or monitor the chip instructions - but I think I'm going to have to find one pretty soon b/c this elimination process is getting a little old and not yielding the results I'm looking for. That said, I still need to check fuel pressure and will get that done by tonight or tomorrow morning. I'm going to put diesel in my V3 system and switch it over to that and see how it reacts - I'f I get a dip I'll know it isn't fuel pressure. One thing I have noticed is that when fully warmed up and driving down the road at say 35-40 mph if I punch it the amount of black smoke out back is pretty limited - so not out of the realm of possibilities that I have fuel pressure issues. My EOT sensor is a possibility too. Yes - it definitely tries to save it self and can more often than not. I believe my HPO system is in good shape and that it is actually compensating for the lack of sensoir info or fuel pressure. Thanks and keep the ideas coming.

 

I'm back - change my fuel bowl filter, seemed a bit overdue - there was gritty crap in the very bottom of the bowl. I washed that out and down the valve with diesel. put my new filter in - then I changed out the filter on my V3 system. Warmed up the truck and gave it a whirl. The idle still dips on rapid deceleration - but the behavior has changed a bit. When dips and then it comes back up, it bumps up over regular idle RPM and then settles down - it also happens less. This is more noticeable on the diesel fuel system - but is still present on the V3 system. I think this may be time to get a fuel pressure gauge.

What's the easiest way to install a fuel pressure gauge? Does anyone have a part number for the EOT sensor?

 

Fuel pressure gauge thread: LINK

Contact ED for the EOT part number.

 

Have you tested/checked your batteries? I've had a bad batt before and it would cause the truck to come close to stalling during idle. Also, if it's been a while since you changed the tranny fluid I would also do this. I've had 2 torque converters go and each time you can tell by the color of the fluid and the metal flakes in the bucket when you dump the pan that something was not right.

 

here's a couple of pics of my fuel press gauge setup. Got the electronic gauge & sensor adapter from ITP. Sensor with the adapter will tie right into the fuel bowl. Insallation is very simple.







[IMG][/IMG]

 

Robin - I have a DFA CCK installed from my V3 system - I noticed in the post link you sent you said "I personally have the sender reading the fuel pressure at a tee in a CCK sytem where the fuel return lines from each head join." - is this my best option?

WB - will check batts today - cold and running and will report back. I guess I didn't think of that b/c the truck starts so strong and fast even in old weather.

BTW - this is only a warm truck issue - it idles higher when cold ( I do mean pre-EBPV kicking in too). Thanks for all the ideas - I will keep chasing them down.

 

How about your CPS? It will do odd things to you!!!

 

I've got a spare in the glove box - may switch that out today too. The current one is a grey one and has about 20k miles on it.

 

Batts show 12.45 at cold, 11.65 with glow plugs on and 14.46 while truck is idling. That looks pretty good to me- yes? BTW it is about 32 degrees right now

 

Yes.
..............

Pop

 

I've got some new information to add to the puzzle. I took the truck into the shop Tuesday and just got it back - problem not solved. They did all the injector orings - some were disintegrating badly - some looked OK - didn't solve the issue. Bill said the only thing he could see it being was a weak HPOP - offered to put the pump in and if it didn't solve it take it out. It didn't solve it - so that is got to come out next week.

I know it is not a fuel pressure issue b/c when my Vegistroke system is on it still does it.

Bill was not in favor of the EOT sensor, but I'm beginning to believe that this problem is "data" related. Just as a reminder this does not occur when the truck is cold. When the truck is warm I can switch my DP Tuner from Jody's tunes to stock and make the truck stall - this makes me inclined to think that the HPOP is actually compensating for a low or stilted signal and when you switch it to the stock tunes the data needs to be re-evaluated and in the time it takes the new data to be assimilated the corrective measures of the previous tunes are no longer in place and the truck stalls.

Also - when we changed the IPR the truck was hot so we put a fan over the valley so we could reach in - when I cranked the truck after that the engine was still decently warm but the valley was very cool - the truck cranked/barked up really fast. In fact the truck starts faster at 30 degrees than it does fully warm.

I'm going to change the EOT this week - for the price and the limited time involved I have to. What other sensors impact the PCM's idle parameters?

Folks - Happy New Year and again - thanks for your intelligence on this.

 

Have you tried running it without the chip? You wouldn't be the first one who had a problem with a chip/tunes. Just to rule out any variables. Also, do you have a scanner or AE to monitor the ICP while this is happening?

 

I've been talking with Jody - am going to try that route next week. In fact this weekend I am going to ID all my potential avenues and poast in order and see what you guys have to say.

 

sound good, was the problem there after the chip install or has the chip been in for a long period of time and the problem jut started recently?

trying to get a better understanding.

at least you are getting alot of good upkeep & maintenence done.