Opinions needed - Performed Optical Bump

[royunion]

Very good info, Thank you. I reached out to a couple of the local vendors to see if they can get one, if not it's online shopping for me lol.

I also wanted to post an update to how things are going. so far I have noticed easier starting and haven't seen any more air in the clear return line. Ive also noticed that now it has positive pressure on the IP from the LP, it's easy to press the pedal and hold 1k rpm. not sure if that's just a coincidence, but it feels and drives a lot better.

back to mentioning about the wastegate system, I do need to replace the vacuum solenoid still because it doesn't cut back on boost and sets a code, but I haven't done that yet only because I don't really drive it hard enough to get into an over boost situation under normal circumstances. at least I have boost now where as before when I bought the truck, there were so many boost leaks and exhaust leaks I think when I first got the gauge installed, the most I saw was 5lb. Now everything is all sealed up

I think now that I have a LP that actually is working, I may go ahead and replace the boost solenoid and then run through a tank of fuel to see how my mileage is before I do any more tinkering like trying to adjust the TDC-offset closer to -1.25 to -1.54, not to mention remove the optical bump at the same time ( or should I? )

A quick tip. You might consider using Cooper or aluminum tubing and only rubber tubing to connect the lines at the device. It won't melt or get brittle like those gm small plastic tubing. You might need to hunt down the small copper tubing at a good hardware store

Wasre gate solenoids get moisture in them and seize with rust. The waste gate actuator normal position is open. I believe the waste gate solenoid if bad sticks in the normally open position and will not let vacuum pass to close the actuator which closes the waste gate. A bad Wasre gate solenoid should let no boost be produced if you have a stock system.

You say you have thrown codes which is usually the MAP sensor registering an over boost condition.

Mine had two problems - the plastic tubing laying on the engine itself had melted flat and leaked vacuum when the engine was cold and when it got hot, the melt conditions caused a seal and boost came back, and two as a result moisture got into the waste gate solenoid and made it operate sluggish or intermittent.

You need to verify you have good strong spec vacuum first.

Once running you should not be able to move the actuator link by hand - obviously do this on a cold first start immediately before it gets hot.

The waste gate solenoid is a $40 to $60 part and it makes sense to replace it because they can seize or the solenoid fail

 

[royunion]

It seems that someone in here may have made a thread about replacing the faulty components in the PMD. Seems they replaced them two round things with two hold down screws and got them working again.
It seems he had a bear of a time getting enough sealer removed to get to the connectors and getting tje solder melted and them two units removed.

I repaired pmds for a while. You need a dremel type tool to route out the epoxy potting material on stanadyne units. There is none - as in direct access - once you pop the cover under the Chinese / Dorman pmds to the solder connection on the pins and to get to the Phillips head side of the bolts that hold them.

Then you need a heating soldering iron with a solder sucker built on and careful skill to heat and suck the solder away so you can get the power transistors out. You have to be careful not to burn the curcuit board foil so you can solder the new one in. Put some cpu heat sink transfer grease on when putting the new transistors in.

It took me fifteen to thirty minutes to repair one pmd.

The power transistors are only a few bucks mail order, but If you just put on a true powerful lift pump you will find you don't need to replace pmds if they are in a good airflow location cool away from the engine.

Truthfully the Chinese / Dorman pmds work just as good as the Stanadyne - because it is the lift pump pressure and volume which gives the performance and of course good fuel.

At $50 for a pmd and cable and heat sink kit - hey it works and runs. Sure I still keep a spare, but calibration resistors fail too and the power pin of the pmd weakens the temper and loosens the electrical connection too so it makes sense to just keep a spare new kit. I had an intermittent start condition and it was the power pin of the pmd had turned the connect socket blue and soft so the first time a small screwdriver wedged it tight and second time it broke off so it was new cable time. Still the pmd was fine.

I have not swapped a pmd for over five years on a daily driver. It is the lift pump not having enough real pressure and volume which causes them to overheat and fail because of how the throttle circuit works with the fuel pressure and solenoid.

 

[dbrannon79]

Wasre gate solenoids get moisture in them and seize with rust. The waste gate actuator normal position is open. I believe the waste gate solenoid if bad sticks in the normally open position and will not let vacuum pass to close the actuator which closes the waste gate. A bad Wasre gate solenoid should let no boost be produced if you have a stock system.

I don’t have a vacuum gauge to test but I have tried moving the waste gate arm while running and can’t move it. The code I get is 78 -Turbo Wastegate Solenoid Fault. I only see it when I’m on the freeway and go past 70mph although at the time I see the SES light up boost pressure is maybe at 10 psi or less. I haven’t really taken the time to try ohming the solenoid. But then again I also remember watching the live data on my laptop using GMTDscan seeing the pcm reading 14 or so boost pressure at idle. I’ll have to look at that again to see if maybe I was looking at the wrong sensor

 

[dbrannon79]

I repaired pmds for a while. You need a dremel type tool to route out the epoxy potting material on stanadyne units. There is none - as in direct access - once you pop the cover under the Chinese / Dorman pmds to the solder connection on the pins and to get to the Phillips head side of the bolts that hold them.

Then you need a heating soldering iron with a solder sucker built on and careful skill to heat and suck the solder away so you can get the power transistors out. You have to be careful not to burn the curcuit board foil so you can solder the new one in. Put some cpu heat sink transfer grease on when putting the new transistors in.

I was wanting to try my hand at repairing my recently failed Stanadyne PMD but sadly I can’t find it or remember where I put it to save my life!!
ive been running a cheap Chinese one that came with my relocation kit I bought off amazon. I just can’t bring myself to paying $300 for a new one from the local auto parts!!

the trouble with the one I got from amazon is with the resistor installed the harnesses plug won’t seat fully allowing the clip to lock! I ended up placing the resistor in the female connector on the extension where the plug is at the IP. Seems to work fine there.

 

[dbrannon79]

On the PMD note. If I could find a couple of dead ones to play with would be nice. If anyone gets ready to toss one in the dumpster, I’ll be glad to take it. Lol.

when reading up on the repair before. I had the thought of remote mounting the power transistors away from the actual PMD to isolate heat and experiment with the electronics. Several years ago when I was messing around with those Chinese mopeds. I had dissected a ignition control module and basically built another one. I cased it in one of those radio shack project boxes and mounted it’s transistors to a heat sink, adding a small computer fan for cooling and it worked until I sold the bike!

 

[Will L.]

Pretty sure Leroy sells the lifetime warranty pmd for around 150.
Ya buy and install it, and set up your old as the spare on its own heat sink or one sink big enough for two pmd. Drive on the lifetime warranty unit and eventually it dies. Move the cable to your current one for no down time other than the 1 minute it takes to get out of the seat and move the wire. Use an old plug with silicone on the back plugged in to keep connections clean until then. Remove and send off the warranty one when you get time. Then when the new lifetime warranty one is back, install it and move your current one back into the batter’s circle.

It is cool to fix a bad one though.

As to the low lift pump causing it- I believe it is a big factor, but in the fleet we had several trucks that lost the pmd while lift pump was still putting out good. We were convinced that some died from vibration breaking internal connections on many. Excess heat as well as dramatic heat cycles was what the engineers came up with as the primary cause.

 

[MrMarty51]

@royunion comment about the Stanadyne PMD power transistors not being glued in and @dbrannon79 on remote mounting the transistors remotely onto a heat sink, if this grey box PMD i am now running ever fails, I will be for sure experimenting with that idea. I do have some very nice heat sinks from some computers I scrapped.

 

[royunion]

@royunion comment about the Stanadyne PMD power transistors not being glued in and @dbrannon79 on remote mounting the transistors remotely onto a heat sink, if this grey box PMD i am now running ever fails, I will be for sure experimenting with that idea. I do have some very nice heat sinks from some computers I scrapped.

I did not say or imply the power transistors are glued down, I said use cpu heat sink transfer grease when replacing them. That is to assure the heat from them transfers to the pmd case and from there to whatever it is mounted on.

Remote mounting the power transistors is not likely to work well because transistor - because all transistors have a base, an emitter and a collector meaning the case of the transistor is part of the electrical circuit.

This is where cooling the transistor just does not matter if it is being over worked electrically. It suffers electrical fatigue and it will fail anyway. The key is to not work it as hard in the first place.

WillL at end offered other ways the transistors fail at https://www.thetruckstop.us/forum/threads/opinions-needed-performed-optical-bump.49575/post-609999 but testing IP's on a bench stand at 5 psi they get hot and failed even in testing the IP. Turning the pressure up to 16 or 18 psi Inlet they ran cool and could run not mounted to the IP and the pmd could be held in a hand.

It is always heard how people believe the lift pump is good, when it is not and the rest said doesn't matter. That is "dirty diagnosis". People breeze past the problem in the first few words.

The DS4 is meant to be run best at 16 to 18 psi because that puts the least amount of strain on the pwm system which is FSD (PMD) and Fuel Solenoid to act as a throttle.

On the DB2 over 5 psi screws up the timing and it may not function well, but on a DS4 5 psi is bare minimum. 16 to 18 is best on a DS4 for lond FSD circuit life.

As WillL pointed out in post 162 - basically at the time gm screwed the pooch trying to make a junk OEM solenoid pump solution work when Cummins told Dodge better. It has a 55 gph 30 psi capable lift.

It is a loosing proposition to buy what is needed to repair the pmd. On eBay $25 for the desolder, at harborfreight $10 for the hobby tool set, the transistors $10, $10 for cpu heat sink grease, and at least $20 for a pointed soldering tip to swap out the solder sucker device so you can solder them in, solder of course, Flux, and the nut driver to get the nuts loose. Then you will need needle nose vice grips to pull as you desolder, and a small philips screwdriver for electrical work if you spin the screws under the potting material and have to route down to them to hold them while you unscrew the nuts.

That is more than the cost of buying a whole Dorman relocation kit on eBay.

Lastly, stanadyne does not make electronic components. Where do you think they are made??

Like WillL said you could buy a lifetime pmd from Leroy or just like I say just use the Chinese / Dorman pmd. But trust me if you run 14 to 18 psi real pressure and volume to the IP you won't be swapping pmds and you will feel the difference in acceleration.

I am attaching pics of the two main tools you need.

 

[royunion]

Pretty sure Leroy sells the lifetime warranty pmd for around 150.
Ya buy and install it, and set up your old as the spare on its own heat sink or one sink big enough for two pmd. Drive on the lifetime warranty unit and eventually it dies. Move the cable to your current one for no down time other than the 1 minute it takes to get out of the seat and move the wire. Use an old plug with silicone on the back plugged in to keep connections clean until then. Remove and send off the warranty one when you get time. Then when the new lifetime warranty one is back, install it and move your current one back into the batter’s circle.

It is cool to fix a bad one though.

As to the low lift pump causing it- I believe it is a big factor, but in the fleet we had several trucks that lost the pmd while lift pump was still putting out good. We were convinced that some died from vibration breaking internal connections on many. Excess heat as well as dramatic heat cycles was what the engineers came up with as the primary cause.

The last paragraph you wrote is 100 percent correct. Mounting an axternal cooler in a hot place does not help. A heavy foot driver does not help. Sometimes the pmd does not fail but the connectors loose temper and electrical contact. See my post at https://www.thetruckstop.us/forum/threads/opinions-needed-performed-optical-bump.49575/post-610005

 

[royunion]

On the PMD note. If I could find a couple of dead ones to play with would be nice. If anyone gets ready to toss one in the dumpster, I’ll be glad to take it. Lol.

when reading up on the repair before. I had the thought of remote mounting the power transistors away from the actual PMD to isolate heat and experiment with the electronics. Several years ago when I was messing around with those Chinese mopeds. I had dissected a ignition control module and basically built another one. I cased it in one of those radio shack project boxes and mounted it’s transistors to a heat sink, adding a small computer fan for cooling and it worked until I sold the bike!

Depends where you live as to heat and moving or sta ding still a lot. My pmd is in cool airflow right at the front of the hood. But still standing still the pmd does not get HOT only warm. See my post at https://www.thetruckstop.us/forum/threads/opinions-needed-performed-optical-bump.49575/post-610005

 

[royunion]

I was wanting to try my hand at repairing my recently failed Stanadyne PMD but sadly I can’t find it or remember where I put it to save my life!!
ive been running a cheap Chinese one that came with my relocation kit I bought off amazon. I just can’t bring myself to paying $300 for a new one from the local auto parts!!

the trouble with the one I got from amazon is with the resistor installed the harnesses plug won’t seat fully allowing the clip to lock! I ended up placing the resistor in the female connector on the extension where the plug is at the IP. Seems to work fine there.

Putting a higher wattage calibration resistor permanently in the cable actually better

 

[royunion]

I don’t have a vacuum gauge to test but I have tried moving the waste gate arm while running and can’t move it. The code I get is 78 -Turbo Wastegate Solenoid Fault. I only see it when I’m on the freeway and go past 70mph although at the time I see the SES light up boost pressure is maybe at 10 psi or less. I haven’t really taken the time to try ohming the solenoid. But then again I also remember watching the live data on my laptop using GMTDscan seeing the pcm reading 14 or so boost pressure at idle. I’ll have to look at that again to see if maybe I was looking at the wrong sensor

Does it move by hand when cold back and forth without the engine running by push and pulling at the actuator shaft?? It might be mechanically stuck closed which also allow an ovrrboost situation.

 

[dbrannon79]

Does it move by hand when cold back and forth without the engine running by push and pulling at the actuator shaft?? It might be mechanically stuck closed which also allow an ovrrboost situation.

no, with the engine off you can move it freely. I've already replaced most of the vacuum lines with rubber hose, as you said those hard plastic lines GM used get very brittle with heat and age.

 

[royunion]

no, with the engine off you can move it freely. I've already replaced most of the vacuum lines with rubber hose, as you said those hard plastic lines GM used get very brittle with heat and age.

Then it is likely the waste gate solenoid or the map sensor - both five to ten minute replacements.

 

[Rockabillyrat]

I did not say or imply the power transistors are glued down, I said use cpu heat sink transfer grease when replacing them. That is to assure the heat from them transfers to the pmd case and from there to whatever it is mounted on.

Remote mounting the power transistors is not likely to work well because transistor - because all transistors have a base, an emitter and a collector meaning the case of the transistor is part of the electrical circuit.

This is where cooling the transistor just does not matter if it is being over worked electrically. It suffers electrical fatigue and it will fail anyway. The key is to not work it as hard in the first place.

WillL at end offered other ways the transistors fail at https://www.thetruckstop.us/forum/threads/opinions-needed-performed-optical-bump.49575/post-609999 but testing IP's on a bench stand at 5 psi they get hot and failed even in testing the IP. Turning the pressure up to 16 or 18 psi Inlet they ran cool and could run not mounted to the IP and the pmd could be held in a hand.

It is always heard how people believe the lift pump is good, when it is not and the rest said doesn't matter. That is "dirty diagnosis". People breeze past the problem in the first few words.

The DS4 is meant to be run best at 16 to 18 psi because that puts the least amount of strain on the pwm system which is FSD (PMD) and Fuel Solenoid to act as a throttle.

On the DB2 over 5 psi screws up the timing and it may not function well, but on a DS4 5 psi is bare minimum. 16 to 18 is best on a DS4 for lond FSD circuit life.

As WillL pointed out in post 162 - basically at the time gm screwed the pooch trying to make a junk OEM solenoid pump solution work when Cummins told Dodge better. It has a 55 gph 30 psi capable lift.

It is a loosing proposition to buy what is needed to repair the pmd. On eBay $25 for the desolder, at harborfreight $10 for the hobby tool set, the transistors $10, $10 for cpu heat sink grease, and at least $20 for a pointed soldering tip to swap out the solder sucker device so you can solder them in, solder of course, Flux, and the nut driver to get the nuts loose. Then you will need needle nose vice grips to pull as you desolder, and a small philips screwdriver for electrical work if you spin the screws under the potting material and have to route down to them to hold them while you unscrew the nuts.

That is more than the cost of buying a whole Dorman relocation kit on eBay.

Lastly, stanadyne does not make electronic components. Where do you think they are made??

Like WillL said you could buy a lifetime pmd from Leroy or just like I say just use the Chinese / Dorman pmd. But trust me if you run 14 to 18 psi real pressure and volume to the IP you won't be swapping pmds and you will feel the difference in acceleration.

I am attaching pics of the two main tools you need. View attachment 65727View attachment 65728

How exactly does 16-18 psi of inlet pressure help the fuel solenoid work less? Inlet fuel has no direct flow to the fuel solenoid. It only feeds the transfer pump. Then fuel under transfer pump pressure is directed into the pumping chambers. The fuel solenoid controls the fuel volume leaving the pumping chambers. So the fuel solenoid never sees inlet pressure directly. And at 600rpm transfer pump pressure is already at 45psi. I could see inlet pressure under 5psi starving the transfer pump being an issue. And I understand cooling the PMD with fuel, but I don't see how 16-18 psi of in let pressure helps the solenoid work less. I read that Sure Cure Lift Pump description. seems like a big sales gimmick to me...

 

[smokymtn65]

I would buy into the theory it will run cooler.. higher pressure , more flow will help keep temp down..

 

[Rockabillyrat]

Right I get that part. But he said in a previous post that with 16-18 psi of inlet pressure the solenoid doesn't have to work as hard because of the increase in inlet fuel pressure.... but the fuel solenoid is controlling fuel under pumping pressure. So unless your starving the transfer pump the solenoid will be unaffected by the increase in inlet pressure. Also return fuel volume has a set flow rate that is controlled by the condition of the pump, the vent wire, and the return fitting. your not going to increase flow rate through the pump by increasing inlet pressure. I'm just not seeing the point to 16-18 psi of inlet pressure.

 

[dbrannon79]

I'm also curious on that Sure Cure Lift Pump system, I found one website online that describes it but absolutely no pictures of the setup.
it did sound like a sales gimmick too, but maybe it's something new out on the market that not many people know about.

as for the fuel solenoid being controlled by the PMD with it overheating while controlling it, I would venture to say the electronics in the pmd are under rated to handle the current load the fuel solenoid demands without the pressure from the fuel helping open and close it. under rated parts sounds like the way GM and others try to redesign things for their use when manufactures like Stanadyne already have the tried and true design. if makes any sence.

 

[Rockabillyrat]

But the solenoid doesn't use inlet pressure to open and close it.... it controls the volume of fuel under pumping pressure. two totally different things. That's the point I'm trying to make.

 

[Will L.]

Ok, so the one person here that knows about this “sure cure lift pump” carries a spare pump with him. Again I go back to my earlier statement that ANY part to make an engine run that SUCKS SO BAD that it is logical to buy 2 and carry a spare- is a total piece of crap and in no way should be introduced to a truck. If you are dead broke and scavenging parts from a junkyard (which I been through) then yes, get 2,3, even 4 of the junkyard parts that cost $3 each so you can make it to work and earn enough money to buy something worth while instead of worth less.

PMD- best reliability mod we did in the fleet was adding a second one where the driver could easily swap over and continue his route, mounted off the dash in front of the a/c vent worked well until winter and the heaters were on DUH! Haha. The couple thousand trucks I saw go through that outfit all going to junkyard after crashes or sold in excess of 200,000 miles, with many that were attempted being pushed to the 500,000 mile mark with a dollar limit of when to cut it loose of course like any fleet would have.
So now MOST everyone has learned heat soak from the engine bay after engine is shut off drives the temperature north of 140f and does damage to the pmd even with engine off. And a heat sink works both ways- it sheds heat when pmd is hottest, and when pmd is colder the ambient engine heat goes right into that heat sink and nicely warms the pmd - Hence my DUH moment of pmd infront of vent. So we learned outside the cab and engine compartment was the best option. BUT STILL THE PMD SUUUCCCKKKKSSSSS!!! Thats why you need 2. If someone made a pmd that was $300 and never any more money need be spent, most would do it. Yeah- thats 2 lifetime warranty units...
So $400 later a sure cure kit really isn’t a cure because if one pump dies, and they are so sure it will die that it comes with a spare- the next will die. Then you get to buy more. SMH

spend the $400 on a pump like the fass even if that is only most the price- buy once and cry once. Choosing to add an expensive but not top shelf part makes no sense to me. Fass and airdog at least are world wide known suppliers that have good reputation and guys that have ran half million miles plus with 1 pump.

And Yes Rockabilly- you are on point. And 2 degree colder fuel doesn’t help the ip.