• Welcome to The Truck Stop! We see you haven't REGISTERED yet.

    Your truck knowledge is missing!
    • Registration is FREE , all we need is your birthday and email. (We don't share ANY data with ANYONE)
    • We have tons of knowledge here for your diesel truck!
    • Post your own topics and reply to existing threads to help others out!
    • NO ADS! The site is fully functional and ad free!
    CLICK HERE TO REGISTER!

    Problems registering? Click here to contact us!

    Already registered, but need a PASSWORD RESET? CLICK HERE TO RESET YOUR PASSWORD!

Suddenly no throttle

Ok just replaced the APP sensor and it’s much easier to hold 1200 RPM in park. It’s not gradual tho. Slightly pressing the pedal send it to 1500 but then I back off a tad and it stays constant. Rechecked codes and all is good. I plan to go for a drive tonight and see how she acts

something I noticed out of the norm and probably has nothing to do with this issue is the fuel calibration number reading the data from GMTD. The number is sitting at 115 which it has been ever since I have bought the truck. Back in the summer I had gotten the PMD remount kit and used a #7 resistor on the PMD it’s been that way ever since. Recently I was able to remove the original PMD from the pump and keep it as a spare. When I pulled it from the pump I realized it had a #5 in it but I never changed it back. Shouldn’t that calibration reading have changed by now to somewhere around 145? I had read on Kennedy Diesel that those were some numbers set in the PCM using those two resistors.
 
It checks the PMD resister after like every 50 key on startups or something. I removed the bad injector blown engine on my 1995 I bought that way. Stone cold dead batteries with the WalMart receipt on em. 3 months after dropping in a replacement engine the ECM sets a code and turns on the light for a missing resistor. You would think it would check more often esp. with dead batteries.
 
dbrannon79 said:
yipes! they do show new Bosh and new AC Delco but they don't list them under application. I have to greb the GM part numbers to find them. which is a better one between Bosh and AC Delco? I looked on Leroy Diesel and Quadstar and both sites show Bosh. I've seen issues with the Bosh glow plugs breaking the ends off. are their injectors better?
Click to expand...

Bosch is the maker of injectors for a lot of diesel engine.
IIRC, the body is also made by Bosch originally.

There is no way of knowing what ACDelco source their injectors nowadays.
There are also different tiers of ACDelco: OE, Professional, etc.
So we have to be careful when buying.

Unfortunately, Bosch GPs have gone down in quality.
I still have them in mine, installed 12 years ago when it was still good.
 
Well guys I have to say I think the APP was the trouble. It’s 2am and I just returned from a 6 hour road trip to pickup a friend and there were no issues. No hesitation or miss, even low speed take off seems much smoother too! The engine light did come on but I’m sure it was for the wastegate solenoid. It always sets a code when I hit 70mhp. I’ll double check later after I get some shut eye. And go fill up to check the highway mileage. Thanks everyone for the help :)
 
Hey Guys, I wanted to check back in and give an update a full week of daily driving and give many thanks to you all for helping me with my truck :) . No problems and the only code I have on the ECM is for the boost control solenoid which I will replace sometime in the near future. now that this dilemma is behind me, I want to look into getting the best possible fuel economy possible. if anyone would like to point me in the right direction for some good reading material, I would be grateful. everything is still stock on the truck with the exception of me installing a Diamond eye 4" exhaust kit with muffler. but I really haven't seen much of any improvement in mileage since the install. I have seen better boost pressures, I can max out at 14 psi if I push it hard enough, and now usually cruise highway speeds at a constant 5 psi. Before I was doing good to get constant 3-4 and only maxed out at 10 without towing anything.
I have been reading up in the Diesel Place forums on water mist injection which sounds like something that is doable for me. at the moment I usually get 12 to 13 MPG with mixed driving, but of course I know letting the truck idle in the mornings for up to 10 minutes before leaving does have an effect on that during cool mornings.

Again a big Thank you to everyone :)
 
idi diesels take for ever to warm idling. Once it has idled for 30 seconds, the oil is warm enough to flow through the filter instead of check valve. So drive it to get it up to temp.

lower boost on hiway is less back pressure so better mpg.
The best improvements you can make for mpg is turbo. How you use it and how much you drive is how long it takes to pay off the turbo cost. Getting a tune to match that turbo is next inline.
 
Will L. said:
idi diesels take for ever to warm idling. Once it has idled for 30 seconds, the oil is warm enough to flow through the filter instead of check valve. So drive it to get it up to temp.

lower boost on hiway is less back pressure so better mpg.
The best improvements you can make for mpg is turbo. How you use it and how much you drive is how long it takes to pay off the turbo cost. Getting a tune to match that turbo is next inline.
Click to expand...
which turbo would you suggest going for, but without having to pull and install head studs and such? as far as a tune, I'm not sure how much of a tune is doable on OBD1 unless I missed something while reading forums. I do remember reading somewhere that using a turbo master actually hurt fuel mileage compared to the OEM vacuum waste gate setup. I still have the OE waste gate connected, but with the code on the ECM I think the solenoid just isn't opening to reduce vacuum to allow it to lessen the boost and to slow the turbo. the SES light only comes on when I hit 70 MPH and then let off the throttle.
 
The less boost you run while under light throttle (cruising), the better your mileage will be. Synthetics in the transmission, t-case, and diffs(75w-90) won't hurt either.
 
Need more info how you use the truck.
If you have enough low end torque and are happy with the rate of acceleration up to freeway speed. Because if you are driving foot to floor because it is too slow, you need faster spool. If you are ok with Toyota Prius getting infront of you from stoplights then spool time being longer is ok.

Are you towing often? How much weight/ wind resistance if so?
Do you do much offroading where 0-15mph acceleration is way important?

Synthetic oils help, but so marginally. Proper tire pressure and tread pattern is far more important.
 
Will L. said:
Need more info how you use the truck.
If you have enough low end torque and are happy with the rate of acceleration up to freeway speed. Because if you are driving foot to floor because it is too slow, you need faster spool. If you are ok with Toyota Prius getting infront of you from stoplights then spool time being longer is ok.

Are you towing often? How much weight/ wind resistance if so?
Do you do much offroading where 0-15mph acceleration is way important?

Synthetic oils help, but so marginally. Proper tire pressure and tread pattern is far more important.
Click to expand...

at the moment I rarely tow anything. however I want to get a small to mid size camper for weekend get-away and fishing trips. I had been considering a slide in camper or the camper shell conversion but I think a trailer would be best.. never any off-roading, only has 2 wheel drive!

I normally use the truck commuting to work and as a daily driver. more in town driving than highway but trips to the coast are nice :)
And no I don't like the idea of a "coffin" car or rice burner blazing past me but I'm not a monster truck road warrior ether. I like to see the look on their faces after they've passed me up only to get stuck in traffic, when I catch up and keep chugging past them as the traffic lets up when I get there.

Basically I want the power when I need it but wouldn't use it all the time. I do love to hear the turbo whistle cruising through town and wish mine was slightly more noticeable.

for tires, I run a non-agressive all terrain 265-75-16 tire which even though is oversize, it puts my speedometer exactly with my GPS!
4L80E trans and 4:10 rear end gears. (been pondering the idea or 3:73 gears for mileage) the truck has the setup for a gooseneck hide-a-ball hitch and the standard receiver tow hitch with both the small 6 pin and RV trailer connections.
 
Get a vacuum gauge and check that the vacuum pump is putting out sufficient vacuum to satisfy the needs of the boost system.
I installed a Wicked Wheel compressor wheel on my stock turbo and it does sing so I can hear it.
On youtube, look up ginger snap customs. He does a lot of testing with different components. One of his later test runs was with the stock GM turbo on his OBD1 truck. The turbo drive pressure was about double to the boost pressure. The wicked wheel barely made a difference. I believe he is going to install a different turbo and make another run with it.
His very last video is installing the 4” exhaust system.
Most all of the components he tests is from Quadstar Tuning.
 
MrMarty51 said:
Get a vacuum gauge and check that the vacuum pump is putting out sufficient vacuum to satisfy the needs of the boost system.
I installed a Wicked Wheel compressor wheel on my stock turbo and it does sing so I can hear it.
On youtube, look up ginger snap customs. He does a lot of testing with different components. One of his later test runs was with the stock GM turbo on his OBD1 truck. The turbo drive pressure was about double to the boost pressure. The wicked wheel barely made a difference. I believe he is going to install a different turbo and make another run with it.
His very last video is installing the 4” exhaust system.
Most all of the components he tests is from Quadstar Tuning.
Click to expand...

I have thought about the Wicked Wheel but wasn't sure if that was a good route to take or what difference it would make. Ill have to lookup ginger snap on youtube and see how it works out. I just finished reading through a forum on the Diesel Place forums where a guy named PrivatePilot did a DIY WMI kit to run pretty much full time on his rig and seems to have boosted his fuel mileage a bit and gave a little more power. with some of the supplies I can source here at work and a cheap 15 gal sprayer setup from the local harbor freight, it wouldn't be too large of an investment for it to pay it's self off in a few months. even running a tiny bit of methanol in the water might even have more advantage over plain water.
 
If it is a Dually, then it is probably already good mpg?
Try to get the foot off the fuel pedal. LOL!!!

You cannot change the differential ratio gear to a lower ratio since it is a Dually and that is also expensive unless you can DIY.
 
JMJNet said:
If it is a Dually, then it is probably already good mpg?
Try to get the foot off the fuel pedal. LOL!!!

You cannot change the differential ratio gear to a lower ratio since it is a Dually and that is also expensive unless you can DIY.
Click to expand...
it's a single wheel. did mileage yesterday with about 80% highway miles this time around with a trip up to Austin and back getting 14.1 mpg.

all I would need to do on the gears is pull the pumpkin and swap out the ring and pinion. I have an extra set of 4:10's with the posi unit I got from a salvage yard, it still has the pinion housing installed (GM 14 bolt). all I would have to do is take to a rear end shop to have the pinion pre-load set if I were to buy a set of 3.73's. I wouldn't trust my hand at trying to set pre-load!!
 
You must log in or register to reply here.
Back
Top