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Diesel Master
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I am in the midle of chasing something down. I have an '02, built Mar of '02. It has about 22,000 miles on it and I have had it since June '02. From day one, it sometimes had a slightly lopey idle while warming up. Not when cold, not when warm, but while warming up. Now realize I have never had the hot idle surging those with bad regulators have had. Mine only happens sometimes when warming up then it goes away completely.


Last Spring I took it in and they reflashed the ECM. This almost compeltely fixed the problem. Also, the told me I had the later pump and regulator, not the earlier one they had problems with.


My mileage dropped a bit (1/2 mpg) after the reflash and I was getting more smoke at WOT with the Juice. This led me to believe the reflash "richened" the fuel delivery setting of the regulator a bit, though I am not sure.


Last Fall I installed the Mega pre-oem. My mileage went back to where it was before the ECM reflash and I started getting the slighly lopey idle while warming up again. None of this was a big deal, but I got to wondering if my regulator was going bad.


I messed around trying to bleed the Mega and wound up introducing air into the system. I immediatley got the lopey idle, more lopey than it had been. I disconnected the Mega. For the last four days I have been driving with just the stock fuel filter. I have had one momentary lope--lasted a couple seconds, but other than that the idle has been very smooth--though I can't help but visualize dirt getting to my pump and injectors!


I am beginning to think an ocassional, mild, lopey idle is not uncommon on the Dmax--at least my engine. I think it is due to air getting in the system. Though the stock filter does a pretty good job handling air, it must still let some through ocassionally.


It also seems to happen primarily when it is warming up. Perhaps as the fuel is warming up air comes out of solution at varying rates until it is at a stable temp then it slows down?


I think the secondary fuel filter just amplifies this air issue a bit. My next step is to install the lift pump I had had for 6 months. That will eliminated the air completely, and should tell me if my theory about the passing air being the cause of my lopey idle is valid.


Thoughts?


Blaine
 

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Hmm, didn't someone say our pump pulls a vacumn? Now, the additional restriction added by the second filter would seem to accentuate the relationship of fuel system components? My 'guess', as there are smarter people around, is its not an air issue and a lift pump probably would mitigate the symptoms.


BTW, my build was apr 02, have 8k, no box and no disernable lope ~
 

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Diesel Master
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Discussion Starter #3
Well, exept if it was due to pulling a vaccuum, then it would get worse as power was increased.............
 

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My 01 with 30k has had the lopey idle since 15k.I installed a post oem Mega at 18k and then a lift pump shortly thereafter.The lope now is the worst when in a half warmed up condition usually on the first start of the day.Did not see a big change in the idle with the fuel mods although it does seem a bit better since I changed the stock filter out with 12k on it.


My truck has not had any updates/ reflashes but will be going to the dealer soon for a look.


Blake
 

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Diesel Master
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Discussion Starter #5
Blake,


What is the build date on your truck, and please post what the dealer says when you take it in.


Blaine
 

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Blaine,


Build date is 05/01 and It'll be a month or so tii I get her to the dealer.


Blake
 

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Diesel Master
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Discussion Starter #7
I messed around with the Mega soem more today--I reinstalled it. of course, it was interesting because this time I had an empty (of fuel) EDU and two 2' sections of fuel line on either side of the Mega that were empty while the Mega filter itself was full of fuel. Priming was interesting, as I had three seperate pockets of air to pass.


I again noticed that air in the system will cause a lopey idle--the truck loped for quite a while. I also noticed that letting the air out of the Mega when it's installed pre-OEM requires you re-bleed the factory filter. I didn't do this one time and the truck died, making me reprime. When you have the Mega pre-OEM and you open tne Mega's bleed, the fuel in the line between the outlet of the Mega and the inlet of the factory filter drains back into the Mega and pushes the air out of the Mega. Yes, the Mega is now bled of air, but somewhere between the Mega and the EDU there is an air pocket that may cause the truck to stall. At least when there is air in the Mega it doesn't make the truck die.


I need to install my lift pump. I have some reservation because it is the higher pressure one and I am wondering if I should run a regulator. The again, the 6.5 didn't seem to have any problem with this lift pump.


Blaine
 

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Blaine,


Just install a needle valve and bypass back to the inlet side of the pump.Here is a pic of my install(copied A Bear and friends) and it dialed down to 1/2 pound and no air since.
 

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Diesel Master
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Discussion Starter #9
I have seen Jpblock's set uo, but am leery of cutting the factory fuel line. Kennedy's install is easily reversible in the case of a fussy service manager.................


Two questions. Where did you install the oil pressure switch, and what gauge wire did you use form the relay to the pump?


Blaine
 

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The pics show my air compressor lines etc so hope there is no confusion.


I wired the pump into the fuse block to an unused terminal that comes on with the key and shuts off after you shut off the key and open the door.It also shuts down after a short delay so its the same one thats used on the radio.I've got an inline fuse and don't remember the gauge of wire but I think I used 12.Someday I'll do the oil pressure activated circuit but you know how that goes.



Blake
 

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Diesel Master
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Discussion Starter #11
Thanks
 

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Diesel Master
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Discussion Starter #12
Got it installed, though I still need to add the oil pressure switch, and the bleeder switch. I don't know if I'll add the regulator or not. I don't have it permanently mouned yet--just cable tied--so I need to decide on it's final mounting location. I also want to cover the hoses with a braided hose cover.


The difference in how the truck runs is significant. I was still waffling today about putting in the pump when it died right after I started it--I just hadn't got the Mega fully bled. After I installed the lift pump and turned on the "ignition", it took a while to get all the air out. Even then, it took a few seconds of cranking before it started. It surged for a couple seconds, then settled into the smoothest idle it has ever had. I drove it "around the block", and got to fully lay into it a couple times. It didn't miss a beat, and it turned the tires over (285s) at around 30 mph, so I know the Attitude likes the lift pump too! All during the warm-up and run it continued to idle very smooth. i'll know for sure in a day or so, but I think I have my lopey idle solved.


Blaine
 

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I have and '02 built in Jan '02. Have an occasional lopey idle, that only shows up about 3 to 5 minutes after the first start in the afternoon. Goes away within a minute or two. Never notice in the morning, as no time spent idling. Has done this pre-Mega, and pre-lift pump.


I had bad Mega air issues prior to lift pump, and have none now. Even had an air issue prior to Mega.



In my case, I don't think this lope is related to air.


Have noticed no difference in mileage from before Mega, to after, to after lift pump. Really can't judge from seat of the pants differnce in performance, as I had Juice before all of this. I don't go to the track, and have never been on a dyno. Ran great then on the street, and still does. Now, upgrading Juice from original, to hot, and then to hot attitude, there was a difference I noticed!



I will just keep on driving it, and worry about it if it starts to get worse. Oh, I almost forgot, the lope was much worse before I started using Total Power.
 

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My 01 had the lopey when warming up syndrome.

Than it progressed to when hot. I do have a secondary post-OEM filter.

I have since had the RPCV replaced and it now idles perfect at all times.
 

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hoot said:
My 01 had the lopey when warming up syndrome.

Than it progressed to when hot. I do have a secondary post-OEM filter.

I have since had the RPCV replaced and it now idles perfect at all times.

Did you get the RPCV done under warranty or did you just do it yourself? If so, how much? Was it on advice of others or some other reason? Just wondering since I have developed a warmup vibration/lope. I have a lift pump on and it ran great for months when I first put it on. I wonder how many things can cause the lope?
I am about 300 miles from the end of the 3/36 (the 36 part) and am planning on getting it in this week. I was going to ask for any reflashes, injector and regulator check out. I could put the RPCV on it as well if you think it is worth it.
 

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Following SoMNDmax's lope on his 2001, he found that Total Power helped mask it quite well for a while, then it intensified. He then discontinued TP and it was bad enough to get the RPCV replaced...
 

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Diesel Master
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Discussion Starter #17
I guess all our trucks are different. Hoot has the beta version--an '01--and IIRC, GM changed the style of regulators late in '01/early '02. There is a good chance that Hoot now has the same regulator as the '02's and on.


I have been told the "warming up lope" lope on '02s is characteristic of the DMax by a service manager, but I'm not entirely convinced. Mine was pretty much fixed the first time after the ECM reflash, and didn't really start agan until I installed the Mega. When I disconnected the Mega, the lope went away--except for one very short episode. During the process of disconencted and reconnecting the Mega, as well as installing the lift pump, everytime I got air in the system I got a lopey idle.


I installed the Mega pre-OEM last Sep. After I in intially bled it, I was never able to get any more air out of it. However, I imagine air was building up and ocasionally passing--as per my intermittant lopey idle.


I too run Total Power. I started with it a couple months after the ECM flash, when the lope was gone. However, I was running another additive before that.


I guess time will tell if air is my issue..................


Blaine
 
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