I have been having power surges for as long as i've owned the truck, didn't think much of it until i found this place. You can feel a power surge and hear the turbo whine kick in for a couple secs and then its gone from 2000 to probably 2300 rpm, this will continue until you move your foot on the accelerator or your above 2300 rpm. The truck will pick up speed rapidly during the surge and then loose it rapidly between the surges, its alot more evident when towing. You can hear the turbo whine at different rpm's and the truck won't do this. I've checked for good vacuum, replaced the vac pump, selonoid seems to be working fine. I also seem to get a little more power from the beast when i unplug the egr valve but it still has the surges. Can i remove the egr or keep it plugged (the vacuum to it) permanently without any engine damage? I have a clean K&N in the truck, also pulled the adapter off the back of the filter box to allow for more air flow. New stock injectors around 200,000 km, doesn't seem to miss.

do you have good, unaerated supply pressure while the truck is running? Do you have any codes? as for the EGR, put new manifold gaskets underneath, leaving the EGR circulator holes plugged, or just plug the line, as long as you get good vacuum to the BARO you wont have a problem and it will do nothing but good for your motor. Could be the optic sensor starting to go, it loses count on the high res tracks and can no longer effectively meter fuel, or air could be causing a bad reading/erratic advance movement.

Have you checked your tranny fluid, or if mannytranny clutch plate?
could it be slippage?

Tranny fluid is good (auto). I feel the truck surge forward and gain speed at those rpms not just gain engine rpm. Unaerated supply pressure? Fuel? No leaks from front to back, just checked. What about the IP screen i read about on here some where, could it be dirty and how do i find it and check it, can i do that without any air bleeding or priming of the system? If its the optical sensor wouldn't it do it at the higher rpms under load also? So many questions, so little time. Sorry about the silly questions but i'm trying to save some $$$$. Any time you take it to the mechanic you end up going home a little poorer with the same problems. Engine light comes on once in awhile but doesn't do it at the same time as the surge, haven't had codes checked, shops are always closed when i need them.

use the paper clip trick to read the codes...makes troubleshooting a lot easier when you know what the computer says. it could also be your wastegate solenoid, it works at idle 100% vac just fine, but when you get to about 2000 the computer will try to adjust your boost and if the solenoid is sticking, the computer will over compensate and cause a surge.


The Screen your referring to is on the inlet fitting of the pump, just behind the ESO, you will need to remove the inlet line, and with a deep 3/4 socket you can remove the inlet fitting and transfer pressure regulator together, or sometimes a 9/16 on the inlet will pull them both out. There is a tiny screen on the bottom of the inlet, this one can be removed and done without, the large one around the body will indicate any trash in the incoming fuel, and can be slid off the body, cleaned and replaced.... but I dont think this is your problem.Edited by: Texas Diesel Guy

Thanks for the info TDG. I will check the screen before my next post. I checked the codes once i found the link to the paper clip idea. Here's what i got, 16, 31, 32, 33, 78. All the help is greatly appreciated.http://www.dieselplace.com/forum/smileys/Big Smile.gif


How do i clear the codes to start over?

vehicle speed sensor buffer fault,EGR pressure low,EGR curcuit,EGR control pressure,and waste gate system fault.

well speed sensor is causing your surge for sure then, loose wire somewhere possibly right where it plugs in at the tranny tailshaft or at the PCM. as for the EGR stuff sounds like there is a lot of vacuum leaking to make the EGR and wastegate solenoid throw codes, start at the supply line coming from the vacuum pump and check to make sure all the lines are plumbed properly too, there should be a vacuum line map under the hood right in the front of the truck, but if not... I'm going to steal this graphic from quantum, thanks man!


http://www.dieselplace.com/forum/uploads/631_emissions1.jpg


just be sure the lines coming from the vacuum pump are in the ports toward the front of the truck, and that the line from the EGR, tees to the Baro and that they all fit snugly together.Edited by: Texas Diesel Guy

The screen going into the pump was fine although i didn't find the little one inside, nothing there. All vacuum lines are good and in the right position, used the plug and suck method.....lol. Not sure what plug your talking about TDG. Had a fast look at the one coming out of the tail shaft of the transfer case and it was great. Fast check on the PCM appeared to be ok too. One thing that was done a couple years ago is a high idle switch put in the truck, jumps something in the PCM to get high idle @ 1000 rpm but its not on while driving. All the codes may have came up while i had the vacuum hoses off and the truck running to check a few things. How can i clear the codes and start over?

you need a scanner to do that, which would help, you could watch it while your driving (maybe a passenger instead) and might get some clues as to whats going on.

Well i drove home from work tonight and its blowing black like no tomorrow, it quits for a bit and then black again. I kept it pinned most of the way home (100 kms - 60 miles). When i was on the gravel road it seemed to take off like a jack rabbit when i was going over washboard, not sure if thats a faulty wire or the wheels leaving the ground but it only did it a couple of times. One other thing, there was a chip replaced in the comp from the dealer to get the speedo to read correct for the tires i installed (that was shortly after the lift kit, 200,000 km ago), it was from the dealer so i thought it shouldn't interfear with anything. When i do get the time i will be replacing all 3 of the selonoids just in case. I"m going on holidays in a few days and will be pulling a 5th wheel through the mountains for a couple thousand miles so i would like to have her up to snuff to do that.


Thanks again you guys for trying to help me out here.


Does anyone know of any good 6.5 TD diesel dudes here in Alberta?

Well i drove home from work tonight and its blowing black like no tomorrow, it quits for a bit and then black again.


My '97 was doing the same thing. A $30 wastegate solenoid cured everything in 5 min flat, got it from Lordco, piece of cake to changehttp://www.dieselplace.com/forum/smileys/Big Smile.gif.

You can clear the codes by disconnecting the battery for a few minuites or
when checking codes step on the fuel peddle or smoething like that.
You can eliminate some of that l56 egr stuff, but someone whose done it should tell you how.
I'm L65.

if you can't shake the code 16 (vss low) it is worth the $60 (30x2) for the two speed sensors on the tranny. input and output. also it takes 10 min to replace both. with what we know about sensors on these trucks its more than $60 worth of piece of mindhttp://www.dieselplace.com/forum/smileys/Big Smile.gif

Ok, i think i've cleared the codes (key off, paper clip in, fuel peddle depressed, key switched on) only code i get now is 12. Dunno if thats an all is good code or not but will make the assumption. I will take it for a drive in a bit and see what comes up. I will have the egr hooked up before starting it again.


Does anyone have a list of all of the codes so i know what they mean.


These 2 speed sensors, where are they located on the tranny, i don't have a problem in buying them if i can replace them. Pics?

Ok thanks everyone. After clearing the codes and driving 60 miles i only get code 78. Have put on a new wastegate selonoid ($46 Canadian). Will take it for a run to work in the morning and see if all is ok.

60 mile drive today - Code 12 only, assume all is ok. Truck ran great with no surges. Next.... Want more power. I will start a new post for that!


Thanks everyone! http://www.dieselplace.com/forum/smileys/Clap.gif

code 12 means the engine is off, only see this when there's no othr codes.