1995 7.3 PSD, manual glow plug mod

[Kevin 007]

My 95 is subject to many stops and re-starts throughout the day, and the factory glow plug setup cycles the plugs every time the engine starts, no matter how warm it is and will afterglow for the 30 seconds or so after the engine has started. So, pretty ******* the alternator, relay and glow plugs.
Question is, can I trigger the factory relay (or whatever relay/solenoid is in its place) with a low amp momentary ON switch from inside the cab like you can like on older non electronic diesels? Will it screw up the ECM or any electronic systems? I don't want to be cycling the plugs when its not necessary, for obvious reasons.

 

[direwulf23]

My 95 has this setup, but the PO had it installed so I really don't know how it was done. my truck operates fine, and for the most part I prefer the manual glow plug relay. Sometimes it sucks.
Now, I do have a ZF so I've no idea if there might be a problem with the automatic electronics, but all of my gauges work fine.

Sent from my LG-D850 using Tapatalk

 

[greenskeeper]

The easiest way would be to put a toggle on the pcm ground wire that activates the GP relay.

I wonder why your truck acts like this? My 97 will not cycle the GPs when the truck is warm as evident by the LED I put on the GP relay to monitor operation.

 

[79jasper]

Yeah, you may have a bad temp sensor or something. When mine is warm, they hardly cycle.


Sent from my SAMSUNG-SM-G935A using Tapatalk

 

[trackspeeder]

Once the engine is up to temp the glow plugs do not cycle. The PCM will run the Wait To Start lamp and that is it. Most likely the oil temp sensor is bad causing the glow plugs to cycle. I would fix this before tampering with the wiring.

 

[Kevin 007]

Ok, good thoughts. I will try the EOT sensor as iv'e been wondering anyways. Yeah, they defiantly do cycle. And every time to, as I watch the voltmeter on every start up and you can tell when they shut down the needle goes way back up.

 

[79jasper]

And I wouldn't say it's that ******* the glow plugs. It took 200k for the stockers to go in mine, had two still working.

Sent from my SAMSUNG-SM-G935A using Tapatalk

 

[greenskeeper]

And I wouldn't say it's that ******* the glow plugs. It took 200k for the stockers to go in mine, had two still working.

Sent from my SAMSUNG-SM-G935A using Tapatalk

I'd want my glowplugs to cycle often just so that when they do fail I don't have to fight the carbon when removing them.

 

[79jasper]

Are you saying cycling more often burns off the carbon?
(Wasn't sure if there was a word left out)
All of mine were real easy coming out.

Sent from my SAMSUNG-SM-G935A using Tapatalk

 

[greenskeeper]

Are you saying cycling more often burns off the carbon?
(Wasn't sure if there was a word left out)
All of mine were real easy coming out.

Sent from my SAMSUNG-SM-G935A using Tapatalk

Yes. A healthy glow will burn off any carbon buildup between cycles.

 

[Kevin 007]

Ok so according to Autoenginuity, my oil temp input was quite realistic, about 44 degrees F when I started the truck (about 42 degree ambient air temp outside) and as the truck warmed up, the EOT rose to about 190 degrees and stayed around there, where I think it should be. But my coolant temp was way high right off the bat, about 270 degrees and after about 15 mins down the highway, it goes down to about where the engine actually is, 120 degrees or so and then rose to 302 or something like that at stayed there. The engine is not running that hot obviously.

I have been having an extreme low power and rough running situation when the truck is cold and it doesn't smooth out until it warms up after about 15 mins of driving, the same time as the coolant temp input drops down from its initial high reading at startup. Then the truck starts to run very well and all power is back, but the temp input rises to 302 shortly after that.

So im thinking that the coolant temp may input issue may be throwing something off here...What are your thoughts on that?

Sorry, I have yet to figure out how to get the Autoenginuity graphs uploaded onto the forum

 

[79jasper]

Should have a option to screen shot.
I'm really not sure what to tell you on coolant temp. Far as I know, we don't have a coolant temp sensor. It uses oil temp and maybe has some algorithm to make up a coolant temp.
Have you watched the timing?

Check everything, ambient/IAT, MAP, EBP, baro, etc.

Sent from my SAMSUNG-SM-G935A using Tapatalk

 

[Kevin 007]

Hmm, maybe there is no coolant temp input and that was screwing with the Autoenginuity...causing it to give strange numbers

I have not watched the timing...yet

 

[79jasper]

Of course, gummed injectors can do the exact same.
Start off running crappie then get better as it warms up.

Sent from my SAMSUNG-SM-G935A using Tapatalk

 

[madpogue]

There is no coolant temp sensor input. There's no "algorithm", and there's nothing wrong wrt. it; the number reported is simply meaningless. This book - http://www.forddoctorsdts.com/download-2.php?f=949873DITDirectInjectionTurbochargedDiesel.pdf - pages 24-33 describes the sensors and regulators/actuators connected to the PCM. That's what you'll be able to see with AE.