Well I thought that I should share my story as it seems to be everyone elses also. My truck would stall and stall. It seemed more frequent if the temp was hotter. When it stalled sometimes it would go into the "default" fuel mode and run like crap. Sometimes just turning the key off and re-starting and there would be no problem (For a while). I borrowed a scan tool (From ace mechanic brother) and checked the codes. First I got a crankshaft sensor code so I figured this was it. Replaced it (Had a fun time at that! Broke= long story) problem still came back. Checked codes again and had optic sensor come up. After lengthy investigation and almost having dealer change IP I found out the the dealer had just changed the IP for the previous owner and I was just out of warranty. So I pulled the optic sensor and visually inspected and tested electronically (I know electronics) I was fine! Before all of this I had bought a brand new PMD as I read on another site(The wrong site) that to change this and remote mount it (With their kit) and it will solve all your problems including marital! Well after all this and a few other things; Lift pump, OPS, praying to diesel gods with a sacrifice of the neighbors dog ( Not really but I did think about it) I finally broke down and asked my even more busier than me mechanic brother.(wanted to do it without bothering him) I explained what was going on. He immediately told me to pull apart my ignition switch and clean and/or make a relay board for it. Ignition switch? How could this cause all of this? Well after looking at the schematic and thinking about it it made sense. GM seems to like to run a lot of current up through this switch. After a while the contacts get hot and carbon up! I pulled mine apart and this was exactly how mine was. After cleaning and re-assembling my truck has finally ran for more than few hours. (A week now with no codes or problems. 90+ degrees outside) I will eventually make a relay board to carry the current so the ignition switch doesn't have to but at least now I can finally dirve it and work on my projects that have been on hold. (PMD and external mounted optic sensor)


On the same note: After fixing this and taking the wife & kids to Disneyland I don't think I'll be seeing divorce court! Of course when she sees how much I want to spend on it (New exhaust, etc..) I might be back in the doghouse!http://www.dieselplace.com/forum/smileys/Big Smile.gif


I'm keeping my fingers crossed!

MDhorban,


Glad to heard you fixed it!


In the archives there's a few ignition switch/ stalling stories. I replaced mine when I had a stalling problem but it was the WG solenoid and a failing fuel solenoid that caused it.


Keep us up with your PMD thoughts, I'm very interested, as are countless others. If you posted a schematic poeple could make their own. I also like taking the optical out of the pump.

P.S One thing that I forgot to mention was that in each case of stalling, the truck would still crank over fine (Just no start) which made me not even suspect the ignition switch as the problem.

I think this relates to isolating the electrical, becuse now you've isolated the electrical load on the ignition switch, not to dissimiliar to what's done with the OPS for the lift pump.

mdhorban, how's that PMD redesign coming along ?

external mounted optic sensor? is this a typeo?

No, It's a solution to expensive pump replacement. An external optical sensor wouldn't be sensitive to water in the fuel. besides the current optical sensor seems overpriced.


and here's another idea. the pump will run on just the crank sensor in limp mode. the truck runs poorly(no advance/ boost), it is running on the limp program GM gave it. What if the limp program had more advance/boost in it? You could run your truck in limp and not care.Edited by: quantum mechanic

YEAPPER it sure does

how would that work? externally i mean, not just forcing it to run in limp.

HEY YA


Any one have a lead on where to buy the plug ends(both) for the PMD wiring extension. I have seen a link but it doesn't appear that they sell them there all I can find is infomation on that site. Thanks

Can't talk long as I'm at work. Anyway Iv'e been on vacation so i'm just back in the swing of things. If you look at the oil fill it is right in front of the IP. This would be the ideal spot to mount a external optic sensor. The sensor does not have to be the same type (Magnetic or optical) or even the same diameter encoder wheel as long as it has 8 and 512 slots (Could be 2 wheels?) The stepper advance motor is the only real hard part and that should not be to hard. I would take care of this electronically. That is have a delay from when the sensor picks up the pulse to when it actually outputs it. Then advance or retard electronically. (Get pulse delay 500ms, need advance then delay output only 300ms and so on.) This could be done with a microcontroller set to read the stepper advance signal coming from the ECM. All good in theory but for ease I think i'm gonna first try it with a actual stepper motor.


As far as the PMD I've had some delay's but i'm on it. Got it mapped out about 80 to 90%.

Oh and as QM stated. You could just re-program the ECM to not run in limp mode and run just off of the crankshaft sensor.(Which is a magnetic hall-effect sensor) You would not have the advance from the ECM but it would probably run fine.(Or re-program the ECM to do its own electronic advancement as I stated earlier.)


Don't the Dodges and/or Fords use only one sensor?

My 96 Ford PS only uses a Cam Position Sensor.