Mileage and Turbo, no power.

[DieselDavey]

Hi again everyone,

I've had my 99 Burban (stock, no mods, 6.5, 1500 w/ 2500 suspension) for a week... I think I have a couple of issues.

I need to thank everyone for all the information on brake controllers. I performed searches on this board and found everything I needed to install mine. I learned a lot in the process. Thanks!

First of all, I towed my Travel Trailer for the first time. Just took it for a test run, about 15 miles. Handled great! I thought it did OK getting on the expressway, and getting up to speed (towed in "3" not overdrive).

I know the camper is overloading the Burban a bit... It weighs 7500- 8000 LBS. I did not expect it to perform like a powerstroke but...

How disappointing. Power very lackluster. Max speed was 65 (at 2000 RPM) I could hit 70 on a level grade (2500 RPM), and that is OK, but going up a decent grade I loose speed (5-6 MPH), even with the throttle floored.

My Ford F150 (5.4 gasser) kicks the Burban's Butt! I really expected the Burban to be at least the same as the Ford, or a bit better. The whole reason I bought the Burban was to get better fuel mileage than the Ford. The Ford gets 5 MPG pulling the camper.

No black smoke out the tailpipe, no turbo whine... I don't think the turbo is working. Is there a way to figure out if the solenoid for the turbo is operational?

I had the wife do a bit of a brake torque (revved up the engine with foot on brake) in the driveway while I watched the wastegate lever... Nothing. I don't know how many RPMs she got up too... I thought I should have seen something. I'll check the vacuum hoses today.

2nd... When unloaded and traveling on expressway on level grade I'm getting 2000 RPM's at 70 MPH... is this normal? I expected a bit less RPM. I'm afraid the lockup torque converter is not operating. Is there a way to check proper operation?

3rd... I'm only getting 10- 11 miles per gallon driving very conservatively (and unloaded). I know this could be related to a torque converter issue. Does a non-operational turbo effect mileage in a negative way?

I did perform searches on this board before asking questions... I did not find answers I needed. I appreciate everyone's time and effort. Hopefully someday I can contribute rather than just ask for help.

Thank you!

Dave

[DmaxMaverick]

The "symptoms" you describe sound normal. Your truck/engine may have issues, but nothing is screaming help. Your mileage should be better, and you should be able to pull that trailer at least as well as the Ford. Could be a number of issues needing addressed, and going through the system by the numbers is the best bet.

Black smoke is usually the first indicator the turbo isn't doing it's job. The absence of black smoke indicates plenty of air getting into the cylinders. It also may indicate some room for a little more fuel. Testing turbo performance during a brake stand is not a reliable method. It needs to be on a dyno or underway with a load. Boost pressure and EGT should be monitored (add gages!) to get a clear picture of what you are getting out of it. It could be just a matter of the timing being too conservative. The wastegate is held closed by vacuum. It will only open if the PCM sees the boost increase near the max preset, about 7-9 PSI stock. A brake stand won't usually get you there. If vacuum is weak, it can open early, but you will usually see black smoke under load.

2000 RPM's may be normal, depending on your gear ratio. No alarms here. You need to calculate your final drive ratio (tire size, diff ratio, gear selection, and torque converter state) to determine the RPM/speed relationship. You also need to confirm your tach is accurate. If the alternator has been replaced with the wrong pulley, it may be off significantly.

To start with, make sure you have a fresh fuel filter in it, and verify lift pump operation. If either of these are lacking, no amount of tuning will help. Even with a defunct lift pump, the 6.5 will work fairly well. Performance will fall off at higher power demands, but lower RPM's and demands may not notice it.

If you intend to depart from a completely stock configuration, get gages first. Boost and EGT. Without them, you will not be able to see what the mod is doing for you, and you won't be able to see the cautions if you cross a line. Fine tuning will help in the power department, and mileage increases usually follow.

[DieselDavey]

Thanks for the reply. I'll get a new filter, and do a search on how to verify operation of the lift pump.

This Burb had a new fuel pump and remote controller installed... are there more than one fuel pump?

Dave

[DmaxMaverick]

Yes and no (it's the terminology). One lift pump, which is what I was referring to. It's located inside the frame rail under the driver side door. It is where the same gasser truck would have its fuel filter, and looks similar (except it has a wire harness). For 99, the it is controlled by the PCM and a relay. The fuel lift pump is different than the injection pump (I think the fuel injection pump is what you referred to), and is located in the engine valley, under the intake manifold. The injection pump has an internal fuel transfer pump, which makes it capable of drawing enough fuel to allow starting and low power running.

[Robyn]

Make sure you have good vacuum to the waste gate actuator.
If the vaccum is at least 15-20" and steady this is a good thing.

Be sure the air filter is unrestricted.

The next thing I am suspect of is the EGR not working properly and or leaking constantly.

Now the final issue I am concerned with is the Catalytic converter.

If the cat is plugged up and most will be if they have many miles on them.
This effectively plugs up the exhaust and will slow if not stop the turbo from working well and with that goes the boost, power and mileage.

This rig driven easy without a load should easily get 20+ MPG

My 94 2500 4x4 Burb with 4.10 gears will run happily all day on the highway getting 21-22 MPG and 16-17 around town in stop and go traffic.

Put a vacuum/pressure gauge on the intake and rig it up with a hose and place the gauge under a wiper blade so you can view it.

Run the rig and see what shakes out.
Hard pulls should see about 7PSI and cruising at freeway speeds with light throttle should see about 2 psi

Best

Robyn

[rustyk]

I had somewhat similar issues (see:[URL="http://www.thedieselpageforums.com/tdpforum/showthread.php?t=31767"]; it may not be only the fuel filter, but also the air filter. It was, anyway, on my 8-ton motorhome...

[DieselDavey]

Thanks for all the information!

I have much to check out. I'm glad I have a starting point.

The mechanic at the General Motors Proving Grounds seemed to think the problem was from the solenoid that controlled that vacuum to the waste gate actuator. He said that he had to replace the solenoids often, even on brand new vehicles, and that it was a common problem.

Everyones reply made sense, and I'll start step by step beginning at the lift pump and fuel filter... although I do hear a motor running under the drivers seat when I turn the key before starting... I think thats the lift pump, but that don't mean its actually pumping any fuel (does it?)...

I'm encouraged by Roybn's statement about fuel mileage... I hope to get the mileage up to where I originally thought it would be!

Rustyk, How is the fuel mileage with your 8 ton beast? I thought about a motor home... I've got 28,000 into my camper and 6,500 (sounds like I'm just begining) into my Burban.... Should I have gone the Motor Home route?

Robyn, How do I check that Cat?

Thanks again DMAX!

Dave

[Robyn]

Pet it and see if it purrs, No purr BAD CAT :D:D:D

PM me and I will give you the recipe for a cat fix.

This sort of fix may require some testing, possibly long term.

Best

Robyn

[DieselDavey]

Just starting to get my hands dirty and my knuckles bruised on this Burban...

Checked the air filter today... black as night, could barely see any white at all. Also had a nice collection of insects.

I think the filter I removed was a K & N, it used a hose clamp to secure it to the intake.

If this is a life long filter, and is designed to be cleaned (and oiled?), is black the normal color after oiling?

The change filter indicator was still green.

I put in a new disposable filter, took her for a 22 mile run, mostly expressway. Fuel gauge barely moved a needle! Hopefully I'm seeing around 20MPG! Did not notice any increase in power. Its seems to do ok... nothing really impressive.

Bought a new fuel filter too. I'm doing the searches for instructions on changing... Will change tomorrow... This will allow me to check the lift pump at the same time. I can't find the water drain... Hopefully can find it in better daylight conditions. Where the heck is it? Do all of you have to kneel on the radiator to reach the darn things? I read about Robyn's (relocation) solution, sounds good to me!

I still need to find a vacuum gauge, local shop did not have one.

Going to try to drop the Catalytic Converter this weekend. What do you use for pipe? Muffler pipe? I am a pipe fitter and have access to sch.40 and sch.10 piping of all different diameters.

Thanks again!

Dave

[daustin]

Most people just straight-pipe out the soot trap/converter for "testing", some test for many years gathering information. :D Also, if you think you may have tranny converter issues, count the shifts. You should have 3 (1-2, 2-3 and 3-4) THEN you'll feel the torque converter lockup (feels like another shift). If you're getting those it's working. Many people also shed the vacumn controller for the waste-gate, and install what's known as "turbo-master" which is a mechanical / spring waste gate controller. There's also some good computer upgrades and of course the 3" downpipe upgrade and exhaust crossover upgrade which many people do when shedding the "kitty".
lol Good luck, let us know how your going with it.
Don