TPS/Injection timing

[TomEichenberger]

I took the burb to my local trannie shop in order to service the 700R4, set the TV cable & the TPS(I had run it for ~3 month before I realised that that piece of electrical equipment in my glove box was a new TPS unit). I installed the TPS, but it ain't spec.

"You guys can set the TPS" I asked? Well they couldn't, as the weird shifting & black smoke demonstrated. They said "Take it to the dealer" . My dealer says that they got rid of the tools years ago.

So my question.How do you "field adjust" the TPS, relative to setting the injection pump.

Thanks

[BC Clark]

I would kind of like to hear the answer to this as well. Nearest I can tell from my service manual, just about everything relative to throttle adjustments requires the use of a .646 gauge block. J 33043-2 GM tool number. That maybe what the dealer threw away as the TPS is like any other computer sensor being used currently. Any computor sensor must be measured with a good Digital Volt Meter (DVM) or a really good high impedance analog meter (10 megohms/volt). The reason being, and the TPS is a good example, is that these sensors modify a 5volt carrier signal sent from the computer. The meter must be able to read the voltage without itself pulling the signal down and interfering with it. Of course the appropriate scan tool will measure directly. I use both depending on what I want to read.

Gas engines are easy, and have a low volt max. at idle and a high volt min. at WOT. The 5.7 isn't even adjustable, toss and replace. My diesel section lists a voltage ratio to be calculated with the throttle held against the .646 block between the voltage measured at teminals B to C divided by the voltage measured at terminals A to C. This is then compared to a value listed on your emissions label. Example given: 3.5 V B to c divided by 5.01 V A to C is .70, except on Sunday( ha! sorry). And then it must be below 2.2V at idle. Here is where I'd like to know if anybody has a quick rule of thumb check that doesn't take this .646 block.

The 6.2 injection is strictly mechanical and the TPS is only for your transmission (torque converter lock up as well) and EGR control. The black smoke is a pump/timing issue that for others to answer.

[TomEichenberger]

BC

Thanks for the reply. Your right about the injection pump; However, when I backed off the TPS, the amount of black smoke decreased considerably.

My suspicion is that someone futzed with the injection pump, while the TPS was off the truck.

Next question ,Where is the adjustment made on injection pump in order to "turn down" the fuel.
(Can't find it in The Haynes book).

Thanks

[TomEichenberger]

BC

Thanks for the reply. Your right about the injection pump; However, when I backed off the TPS, the amount of black smoke decreased considerably.

My suspicion is that someone futzed with the injection pump, while the TPS was off the truck.

Next question ,Where is the adjustment made on injection pump in order to "turn down" the fuel.
(Can't find it in The Haynes book).

Thanks

[ropinfool]

There are actually two places you can turn down the pump, If you do a search on this issue you will find all the info you need. It is also available in past issues. Good luck. John

[TomEichenberger]

John

Im in awe of you guys who have dealt with the 6.2 diesels and the associated accouterments.

Whoever, I am a neophyte when it comes to working on these things(thus the reason I joined The Diesel Page.)

Can someone, in very plain english('explain' it to me like I'm 5 years old')tell me how to turn down the amount of fuel getting to the injectors.

(I do have the cutaway diagram of the DB2 pump.)

Thanks

[ropinfool]

Well I'll give it a shot, I'm actually getting ready to turn mine up a bit. The "safest" place to adjust it would be on the drivers side down near the bottom of the lifter valley. There is a plug that can be removed. The engine will need to be cranked over until the allen head screw lines up in that hole. Counter-clockwise will reduce the amount of fuel metered. Don't go more than 1/8" to start. The other place is on top of the injection pump, much easier to access but you will be playing with the stop solenoid, if it is not re-installed (the cover that is) correctly you could have a runaway. Remove the screws holding the cover in place siphon the fuel out and look down in the bottom, there should be a hole, crank the engine over by hand until the screw lines up and adjust. (Thanks Arveetek!) Careful getting the cover back on correctly!!! Good luck! John