My sig has most of the truck details, the most recent changes to the truck was a reprogram on my DP tuner about 2-3 months ago, and an adrenaline HPOP last week. I recently moved and there is a long hill that I coast down from about 60mph to 40mph in 5th gear (manual tranny), so you can imagine this is minutes of coasting decelerating for the 40mph zone. The truck will turn off when I depress the clutch pedal. It has happen both times I have taken this road home.

It is scary hitting the red signal as the truck dies with everyone stopped in front of me, I never had so much time finding third to get her going again... I tried decelerating this evening around town and it seems that the rpms will dip lower the longer I decelerate, sometimes dropping to around 400 rpms before recovering...

I do have AE to help troubleshooting, can anyone help point me where to start... Most of my truck troubles are usually created by yours truely, so if anyone has ideas on how an HPOP install could create this type of problem I imagine you would be on the right track to solving my issue.

 

Did it again today, at least I was expecting the loss of my steering and brakes this time. I am going to try removing the DP tuner and see if I have the same results on the stock PCM. It seems like the easiest place to start.

 

When was the last time you changed the CPS?

 

I had a similar problem with my 1990 bronco. Under certain drive --> stop conditions (the first stop sign coming home from work) the engine would die if I let off the gas and depressed the clutch.

It turned out to be the exhaust gas recirculation valve would get stuck open and basically act like a huge vacuum leak and kill the idle. It only happened under certain conditions where the engine was making more particulate matter to clog up the EGR (guessing). I disassembled the EGR valve and used a healthy dose of carb cleaner. That fixed the issue (for as long as I needed it to work).

-the Goat

 

Thread moved to the 7.3 forum.

 

Check with Jody on your tuning. If he hasn't yet, he may have to tweak something. You're on the right track going to stock. I'm assuming you don't have a stock tune or it's doing it in his "modified stock" tune as well.

 

Good point, I can try the stock tune on the chip, but I am not sure if the chip is still in action even when on the no.1 setting. I will report back with the results on the PCM tests.

The CPS is about 2 years old, I do have a spare, may try the spare if the tuner removal route does not produce any solutions.

 

Update: I tested the truck on the stock setting and could not duplicate the problem. Now after switching back to my 80E settings I have not had the same problem ...

 

I doubt it would effect someone in CA, but if the air is really cold and you removed the intake heater, it's possible to cool the cylinders down enough during long decel that the fuel won't ignite when the injectors start spraying. That's the whole reason the exhaust valve closes at light throttle in cold weather is that there's too much cold air rushing through the cylinders at low load, and can cool the cylinders to the point that you lose compression ignition. Start a diesel without working glowplugs in the cold and you know how hard it is to compression ignite diesel without enough heat already in the cylinders.

 

I thought the intake heater was only used during long periods of idling, to help with wet stacking in cold climates?

How steep is this hill that shut off on you? Might try a steeper hill also(i know not the smartest idea but keep the speed down) to try and replicate it.

Could be a fuel problem/fuel pickup?

 

I had the truck shut down on my again after decelerating and braking while coming down the grapevine. Of course I was exiting to get fuel and the truck died right as I was exiting. Brakes and power streering are gone and I almost missed the curve.

I was lucky I was not towing at the time, I would have lost control in the corner for sure. I am ordering the orginal black CPS just in case, and will send a note to Jody. I think I really need to monitor the truck with the AE program to figure out what is happening.

Here is another thread that is slightly related...

https://www.ford-trucks.com/forums/8...tall+%2Bclutch

 

When I had a bad injector leaking HPOP oil internally, the idle would dip down like you are describing and in exactly the same circumstances.
Coasting up to a stop after a long decel.
Idle would dip way down, then recovers.
Replacing that injector cured several things, including that dippy idle.

 

wow, nice to know, that may explain my dipping idle too. When I hit the clutch from about 1500 rpm or more the idle will dip as well.
Man, my list keeps getting longer of things to fix, my pocket book can't get any shallower.

 

Thanks Kwik, Do you think that pulling the covers and checking the oil spurt from the injectors would diagnose this type of problem? Or any ideas on checking for problems.

It seems strange that the other 7 cylinders (assuming only one injector is bad) can't keep the truck running. Seems like it should just burn that oil from the chamber...