What did you do with your GMT400 today...or yesterday....

[Will L.]

Boy did they mess that up!! Can’t even see the turbo sticking through the hood!

 

[dbrannon79]

Pulled out the pressure washer today. soaked the 93's engine compartment down with some degreeser and gave it a good bath. Man there was a lot of crap in the driveway!!

got it all cleaned up now, I might try to pull the oil dipstick tube from the pan and seal that up since it's blowing oil from there. Now that I have case vents on both the oil fill and the valve cover, it might not blow so much out other than the oil mist from those two vents.

 

[dbrannon79]

In other news, I've driven the 95 here and there the last couple days and noticed right away of how much LOUDER the 93 is now with the newly rebuilt injectors in it. it's noise level I think now exceeds that of an old 12 valve cummins!! I wonder if I need to revisit timing adjustments since the injectors are all set to 1950 rather than what the old ones were at around 14-1500 psi.

Wish there was a way to put a timing light on it without needing a special one or a sure fire way to check if adjustments are needed.

 

[dbrannon79]

Did some other minor repairs on the 93 prepping for the trip next weekend. my blower quit working on medium speed. checked all the relays and finally deemed the resistor at fault. got that fixed.

while I was in there I found this little grey long box of sorts with two pins as if something slides in there and plugs in to it. it located in the harness down by the blower motor. anyone know what this thing-a-mobob is or what it was used for?

 

[MrMarty51]

On the fuel pressure gauge setup.
I jumper wired from the front, IP, wire in the gauge pod to the gauge wire and the sending unit still was acting up.
Swapped the LP sending unit around with the IP sending unit but needing to take the truck out for a drive so that possibly faulty sending unit will warm up and thats when it starts the gauge to bouncing.
The now LP sending unit was reading a steady 12 pounds and the IP sending unit was holding right on 11.
Should the pressure regulator be bumped up any more than the 11 PSI at the IP ? I set it at 11 just in case something went wonky and the pressure would climb to over the 12 at the LP.
Planning on church tomorrow so we shalt see.

 

[MrMarty51]

Did some other minor repairs on the 93 prepping for the trip next weekend. my blower quit working on medium speed. checked all the relays and finally deemed the resistor at fault. got that fixed.

while I was in there I found this little grey long box of sorts with two pins as if something slides in there and plugs in to it. it located in the harness down by the blower motor. anyone know what this thing-a-mobob is or what it was used for?

View attachment 93499View attachment 93500View attachment 93498

I believe that is referred to as the vent box.
When it becomes necessary to let smoke out of the wiring then You open that lid and let it flow.

 

[MrMarty51]

 

[dbrannon79]

Found it. did some searching on the innerwebs and apparently it was for a diode back that has something to do with 4x4. one wire comes from the brake switch and another to the 4x4 switch, rear ABS and TCM. all the wires are there but no diode back inside. this truck is a 2x4 so I guess that makes sense the box is empty

Strange Grey Box

Hey everyone, I'm back from the dead! But my truck sadly isn't. Got a wiring short somewhere, and I think I found it in my engine harness. Currently removed and exploring options to have it rebuilt, but I wanted to ask about this strange grey box I found amongst the wiring. I've never seen this...

www.gmt400.com

 

[dbrannon79]

Strangely enough while I was replacing the blower resistor, the LP randomly decided to turn on. I had just finished up washing off the engine with the power washer so I pulled the connector to the OPS and sure enough there was moisture on the pins. blew out the sensor and connector. the connector was missing the little rubber seal so I scrounged though an old GM harness I had in the garage (can't remember what it came off of) found one on a connector that looked similar. plopped it on the OPS plug, fit like a glove. hope I didn't damage the OPS. time will tell...

 

[dbrannon79]

Drove the 93 out into town tonight... it did fine.

had to make a late night run to the grocery store.... ran out of TP!!!!

 

[MrMarty51]

Here is live DATA from the AUTEL reader.
Anyone see anything that needs attention ?

 

[dbrannon79]

Looks good to me

 

[MrMarty51]

Looks good to me

Just wondering if possibly increasing the advance about 0.50 would help, bringing it to about -1.30 offset.

 

[dbrannon79]

you'll get slightly more performance and more clatter, but the performance is negligible afaik. not sure how it would effect mpg's

 

[MrMarty51]

you'll get slightly more performance and more clatter, but the performance is negligible afaik. not sure how it would effect mpg's

Probably not enough to go through the intense work of getting the pump adjusted just right then going, once again for several times, the relearn process.
I’ll leave it.

 

[dbrannon79]

My 95 is set at -0,70 or somesuch and does fine. iirc GM spec is -0.45 to -0.75 but you can go as far as -1.94 without setting the SES light. I honestly don't know what that gives you, but supposedly better "off the line" performance and louder clatter. I personally prefer not so loud clatter.

I want folks to hear and know it's a diesel, but not sound like a "Come-A-Part" as I've heard others call a Cummins LOL

 

[ak diesel driver]

The obd1s would get stuck and be hard to get unstuck once you hit -2.02 IIRC. The obd2s don't seem to have that issue.

 

[MrMarty51]

The obd1s would get stuck and be hard to get unstuck once you hit -2.02 IIRC. The obd2s don't seem to have that issue.

What do You run the timing offset on Your 6.5s at ?

 

[Big T]

My ‘99 I settled at -1.30 TDCO and called it good. ‘94 is is at -1.94 TDCO

 

[MrMarty51]

My ‘99 I settled at -1.30 TDCO and called it good. ‘94 is is at -1.94 TDCO

I’ll bump mine up some.