94 Suburban Cold Start

[69ra3ta]

When I go to start my 6.5 TD Burb in the morning, it starts right up with very low idle and belches black smoke. When depressing throttle I get very little response. I need to keep feathering the throttle to keep it running for the fear of it dying. After a few minutes, I floor the pedal and the motor literally snaps to life. The motor runs decent after that with no smoke. I do however have an SES light that illuminates on and off. I have not pulled codes since I don't have a code reader. I have recently replaced the Glow Plugs, Glow Controller, Injectors, Lift Pump, Oil Pressure switch, Coolant Switch, PMD and IP. Now that doesn't mean that I could have a bogus part though. Any help would be appreciated.

Doug

[a5150nut]

94 doesn't need a code reader. Paper clip or jumper wire in the upper right corner under the steering column, OBD1 connector. Turn ignition on and count the blinks of the dash lights.

[69ra3ta]

So I now have the codes. There were 2 as follows:

DTC 25 - Accelerator Pedal Position 2 Circuit High
DTC 45 - EGR Vent Error

Is the DTC 25 the throttle position switch at the pedal?

Is the DTC 45 the can that is in close proximity to the Turbo and above the valve cover? It looks like a breather. I have not been able to locate anything that resembles an EGR Valve yet.

What parts do I need to replace? Can anyone clarify the codes for me?

I am on a road trip with the Burb right now. Of course it decides to throw trouble codes while away from home. But 1200 miles so far and it's still running but tough to start in the morning. I hope I can fix before I go too much further.

Thanks a bunch!

Doug

[69ra3ta]

I don't understand the DTC 45 code. My truck has an "F" in the VIN so I believe that my truck doesn't have an EGR valve. So then why is this code appearing? Any help out there?

Thanks,
Doug

[JohnC]

WAG:

the EGR vent performance is monitored by the Baro sensor. Maybe you have a problem with the Baro sensor.

The Baro sensor and the APP sensor both run off the 5V supply. Maybe there's a problem with the 5V supply...

[69ra3ta]

Thanks John. Where can I find the Baro Sensor, How do I test the Sensor itself?
Doug

[JohnC]

On the firewall above the brake master. Try unplugging it?

[69ra3ta]

Thanks for the reply John. I found a small "box" up and inboard of the master cylinder with a plug that fits from the bottom side. Does it sound like I found it? Should I unplug it while running or not? If I unplug what should happen?

Thanks for the help.
Doug

[Kick Ass Matt]

I would replace the pedel switch first. I've been told that the codes come as they occur, so meaning the pedel switch might also cause the computer to THINK the baro sensor is bad.

It wont be a bad idea anyways since the pedel switch's been doing 200K

Matt

[69ra3ta]

Kick Ass Matt,

Thanks for the reply. I came up with the same conclusion except when I priced out a new switch. $299.00 (ouch!) from SSDiesel Supply which is a far cry less than the dealer wants. I hate to experiment with such a high $$ part unless I know for sure.

Anyone out there with a loner to test with (LOL)

If I thought it would solve the problem,

"When I go to start my 6.5 TD Burb in the morning, it starts right up with very low idle and belches black smoke. When depressing throttle I get very little response. I need to keep feathering the throttle to keep it running for the fear of it dying. After a few minutes, I floor the pedal and the motor literally snaps to life. The motor runs decent after that with no smoke"

I would go ahead with the purchase.

But in my mind, I cannot reason that the pedal position sensor would fix the problem as stated. Keep in mind that the above scenario only exists for the very first start in the morning only. It's fine otherwise except for the on and off SES light.

[Warren96]

I haven't heard anyone mention the ground on the passanger side causing wacky throttle pedal codes, clean that first.