Engine/Transmission (1998.5 - 2002) Need Some Help with 2 Issues

[Silver Ratler]

We are currently in the mountains of Colorado with our fifth wheel. On this trip I have had a couple of things occur that I am not sure about.



The first issue is my Isspro electric fuel pressure gauge, the needle bounces up and down over a range of about 6 psi. As the gauge is doing this there is no effect on the performance of the truck. Is the gauge going bad??



The second issue is a bigger concern. While driving without the trailer this past week, the engine "surges" on occasion around 1200 to 1300 rpms. By surging I mean the rpms will increase by about 200 to 300. It feels very much like what it feels like if you quickly push in the clutch and then release it while underway on a manual transmission. Could this be something to do with the transmission?? It did do it a couple of times on the 9 hour drive with the trailer attached, but over the last week while driving around it seems to be more frequent. Any ideas??

 

[rjrkihap]

By any chance does the surging coincide with the fuel pressure fluctuations? Are you still using the Carter style engine mounted lift pump? Are the fluctuations quick or does the pressure drop, stay low for a while (minute or longer) and then return to normal (this is what my Carter LP would start to do as it began to die).



If it were me, I would make sure my wire connections from the sending unit to the gauge and my ground wire(s) on the sending unit and gauge were all good. A bad ground will make these gauges act as you describe. Assuming the connections are good, I would get ahold of an inexpensive mechanical 1/8NPT fuel pressure gauge and watch what it does as the truck simply idles. Be patient and watch for similar fluctuations. If so, then you've identified a bad lift pump.



If it turns out to be a bad lift pump and you are using the factory Carter LP, I highly recommend replacing with an aftermarket system, FASS, AIRDOG. Good luck.



Ron

 

[JLandry]

Additional questions to help us try and figure this out…



How many miles are on the current Bosch VP44 fuel injection pump?



How long ago did you change the fuel pump?



Have you checked for DTC's (Diagnostic Trouble Codes)?



Best regards,



John L.

 

[Silver Ratler]

Let me try and answer your questions:



The original fuel pump died at about 65k while we were on the Interstate in Kansas. It was replaced with the in tank model. Truck now has 88k on it.



The gauge fluctuation is rapid, the needle just bounces up and down. The gauge bounces almost all of the time, so I have not seen any tie to the "surging"... ... . fuel pressure gauge may be at the low point, maybe the high point... ... does not seem to be related.



Have not checked for DTC's... ... . Will have to research to see what I need to do there.

 

[JLandry]

The gauge fluctuation is rapid, the needle just bounces up and down.

That sounds like a sending unit or gauge problem. As suggested earlier, you can verify what the actual fuel pressure is by connecting a fuel pressure test gauge to the fuel inlet on the VP44 fuel injection pump. There's a Schraeder valve there that a standard fuel pressure gauge will easily connect to.

Have not checked for DTC's... ... . Will have to research to see what I need to do there.

You can do that without tools by simply cycling the ignition key ON-OFF-ON-OFF-ON and then immediately watch the odometer window for codes. Be prepared to write them all down and post them here so we can help you.



Regards,



John L.

 

[cerberusiam]

The gauge fluctuation is rapid, the needle just bounces up and down. The gauge bounces almost all of the time, so I have not seen any tie to the "surging"... ... . fuel pressure gauge may be at the low point, maybe the high point... ... does not seem to be related.

You really should not get that kind of fluctuation out of the in-tank pump. The gauge should be fairly steady. As others said, sounds like a bad sensor.



Where is the sensor mounted? The lectric units do NOT like mounted on the engine at all. The harmonics kill them quite fast. The best mounting solution is off the engine with an isolator between the source and sending unit.



The rpm flare sounds suspiciously like the TC is randomly unlocking for some reason. Is there any pattern to when it does this? Certain speed, load, throttle position, gear?

 

[bromano676]

bad APPS. sounds just like my problems. TIMBO APPS fixed it.

 

[Silver Ratler]

Did the ignition sequence to check for codes... ... I don' believe any showed up. Here is what the odometer showed:



P-PCU

-------

P-DONE

P-ECU

-------

P-DONE

 

[SnoKing]

First item is most likely fuel pressure sender. Do you have it remotely connected with a hose away from the vibrations of the engine?



Second item sounds like Torque Converter unlocking/locking etc. Do a search of that. There are lots of different solutions. First is to clean all the different, and there are a lot of them, ground wire points under the hood. There are filters you can install, wire routing changes, new APS etc etc. SNOKING

 

[Silver Ratler]

Drove 9 hours today and made it back to Lubbock, TX from Colorado, towing the 5er so OD was off. Truck ran just fine, fuel consumption right where it usually is when towing, 11. 5 mpg. The fuel pressure gauge is still bouncing, but not as fast or all the time. The "surging" continued!



I checked the ground on the fp gauge and it was good. The sending unit is isolated from the engine, so... ... I'm assuming bad unit on that problem.



The surging continued while in the hills of CO and NM, but slowed way down..... almost gone when we reached the "flat lands" of TX. The problem seemed to coincide with climbing grades... ... cruise would have to accelerate to keep it at 60 mph. I was driving at about 2200 rpm, 62 mph and when the hill was short everything seemed fine... . cruise would catch up ok. On a longer hill... . the "surging" would occur and would also happen if I tried to quickly accelerate. No surging occurred on flat ground or going downhill.



Based on what I observed on the long drive home..... grounding issues would not make sense to me. Wouldn't it occur in all conditions if it was a grounding issue?



Can I check to see if the APS has gone bad?



Very frustrated at this point!!! Drove truck a little around town after dropping the 5er at home..... could not get it to surge!!

 

[wlowe]

I'm no expert but I would suspect the transmission/torque convertor is slipping. I say this because the surging happens more on hills and when towing or accelerating.

 

[dkoldno7]

surges

Hi, I've had the same surges on my 2002 &2001>I installed a navorne noise filter,to buffer the ecm,worked well on both trucks. there is lots of 411 on tdr,seperatering alternater wiring works also.

enjoy your efforts.

 

[SnoKing]

OK, if you are driving along on cruise control and RPM's go up 200-300 and speed does not change that is the torque converter unlocking. When RPM drop back down that is the torque converter relocking. It is a common problem on these trucks. You can try installing a manual lockup switch to prove it. On my truck I believe it does in towing for one of two reasons. 1. I am into the throttle hard and at a different area of the APPS pot.

or 2. The wiring to the trailer adds additional circuitry to the trucks base wiring. I am most likely going to buy a Timbo's APPS before heading to Arizona again in the fall.



I already have the DTT filter installed and tin foil on the alternator ground.



BTW, I would not call this surging, as vehicle speed is not changing.



SNOKING

 

[Silver Ratler]

Thanks to all for your suggestions and information.



This morning I downloaded the directions for the Suncoast re-wire and will do that tomorrow. I also ordered a filter from David Navrone to install..... Hopefully one or the combination of the two will correct my tc issue.



I will be contacting Isspro about a new sending unit tomorrow. Have to get these things fixed quickly..... Another trip to the mountains, this time NM is planned in 3 weeks!



Thanks again for all the input!

 

[cerberusiam]

The rewire and filter are useless if it is actually noise in the system causing a TC lock\unlock. You need to remove the source to implement a permanent fix.



Are you sure it is the TC unlocking at random times? Or is it an engine surge? Two totally different sources of problems.

 

[Silver Ratler]

The rewire and filter are useless if it is actually noise in the system causing a TC lock\unlock. You need to remove the source to implement a permanent fix.



Are you sure it is the TC unlocking at random times? Or is it an engine surge? Two totally different sources of problems.

As SNOKING pointed out, "surging" is probably not the correct term. Surging would be the engine calling fot more power, as in quickly hit the accelerator..... That is not what is happening. The TC unlocks for just a couple of seconds.



Your advice of "remove the source to implement a permanent fix" is well taken... ... . But, everything I have on this and other forums seems to believe that the "sources" are quite extensive. I had the same thing happen this morning while taking the 5er back to storage..... No trailer, no problem. When we were in Colo Sprngs, the problem occurred witha and without the trailer... . most likely due to the number of hills.



I would very much like to remove the source of the problem... ... appears that would cost a considerable amount of money, randomly replacing expensive components. That said, the first step seemed to me to follow the procedures that many others have followed. Hopefully this will stop the problem, if it doesn't, I'm only out $20 and an hour of my time.



If you have a solution, other than all those mentioned, I would very much appreicate your input. I do appreciate all of the comments and suggestions that have been offered..... This is a very frustrating situation!

 

[cerberusiam]

everything I have on this and other forums seems to believe that the "sources" are quite extensive. I had the same thing happen this morning while taking the 5er back to storage..... No trailer, no problem. When we were in Colo Sprngs, the problem occurred witha and without the trailer... . most likely due to the number of hills.

While the sources maybe extensive there are a limited number of ways the noise gets introduced. Eliminating the introduction points is the most effective as the sourcs generate noise new or old.



Take a look at the harness around the alternator and the ground for the passenger side battery. Both the ground wire AND the charge wire run thru the harness and to their respective end points. The bulk of the noise is introduced thru the ground wire due to its proximity to the charge wire and the fact it runs right thru the magnetic fields generated by the alternator.



As the wires age the protective wrapping deteriorates and they become more susceptible to chatter. What we have found most effective is removing both the ground wire and the charge from the harness completely and rerouting them to their respective end points seperately. Onoe around by the firewall and the other across the rad support.



Dodges fix for this was basically taking all the other wies out of the harness and running them seperately to the ECM. Go figure, they would do it the hard way.



Now, in certain cases that did not stop all the random issues. What did work was replacing the the TC with a triple disk. We never did figure out if the intermittent unlock was just a weak apply piston in the TC, or, the fact that the triple takes longer to lock\unlock and it mitigated the observed problem.



Couple more options to consider as you go. Good luck with it.

 

[cerberusiam]

Take a look here for problems and results. Good luck.



https://www.turbodieselregister.com...n-t-stop-transmission-hunting-out-lockup.html

 

[Silver Ratler]

May Have Solved 1 Problem

From testing this week end it seems that my TC issue may have been solved. I will know for sure in about 10 days when we hook up to the 5er and head for the mountains of New Mexico.



I received many suggestions on how to correct the TC issue and followed up on all suggested threads. I followed the advice of cerberusiam and seperated the ground and power wires from the alternator from the rest of the wire loom. I re-routed the wires and cleaned up all the ground connections.



I also installed the Navrone noise suppression filter as seen in the photos. I did both at the same time and did not test in between. Took the truck out on the highway this morning and could not reproduce the TC unlock/lock issue, so I am keeping my fingers crossed!



Thanks to everyone for their suggestions and help..... Oh... . The fuel pressure gauge must be bad..... No bounce when I checked fuel pressure with at the shraeder valve.

 

[Silver Ratler]

Photos of final install with air cleaner box re-installed.