Mystery miss

[margil]

I know I'm not the only one who has experienced this one. While driving, every once in a while my truck just QUITS. It's only for a split second not very obvious, but enough to notice. Maybe this is normal? Any advice is greatly appreciated.

 

[LSMITH]

margil, it has happened to a lot of us. This has been brought up several times. Scared the heck out of me the first couple times though. Mine has not done it in almost a year though, knock on wood. Mine has only done it in cold temps, a total of 5 or 6 times maybe. As far as I know no one knows what it is or how to fix it. I really don't think it is normal, but it happens. I quit worrying about it.

 

[GMcLean]

silly question, but did you take it to a dealer to check for any DTC`s?? This is my first day and my first reply to any posts on TDR . . I can tell by a lot of everyones attitudes towards dealerships that it is hard to find any that you can trust down in the good ol` USA. . That is really too bad!! At the risk of being shuned or black-balled right off the bat, I am a DC diesel tech.

 

[JR2]

GMcLean - welcome to the board, it is good to have DC diesel techs aboard. We have had several at different times, most of them got in trouble with DC for trying to help. We could really use you insite.



As for the miss, I know there were some instances of electrical interference with the ecm a while back. Some people reported that driving under certain power lines or by radio transmitters caused this... . just an idea. I think that there was a TSB for it.

 

[margil]

GMclean,



I haven't taken the truck in to the dealer for any sort of diagnosis. It has not happened in a while maybe, a couple of months and lately it's been sitting in the garage all nice and clean. I believe the last time it happened I was pulling my 10k 5er. It's one of those things that you know is not right but, you tend to forget about it until it happens again. I have had the truck for almost 2 yrs and it's happened maybe 5-6 times.



JR2,



I haven't paid too much attention as to the location where it has happened but, you can bet the next time I will be a little more aware of the surroundings.



Thanks for the replies it is really appreciated.



Margil

 

[margil]

LSMITH,



Thanks also for your answer it is nice to now that I am not the only one that this has happened to.



Margil

 

[GDouglas]

I posted a week or so ago about my 99 shutting down for about half a second at part throttle at times, but I also get the check engine light for loss of communication between the fuel pump module and the ECM. The last time it did it I disconnected the DDEZ and cleared the code and drove around for a day or so without any problem, so I hooked the box back up and have been driving problem free for 2 or 3 weeks now. I did take apart the MAP connector and the CAN connector to check for loose pins, etc. and didn't find any loose ones. My theory for now is that the DDEZ probably has to get power from two of the MAP pins to provide itself power with the third being the signal to the ECM. So while I had the connections apart, I sprayed some WD-40 in the connectors of the MAP and the CAN bus and reassembled. So far so good for now but stay tuned!

 

[Ram4Sam]

Miss/stumble-MAP sensor?

I went through just this scenario while towing last summer. Engine started to miss/stumble and truck went into a limp mode with very little power. Keyed up codes 1693, 0237, 0576. Checked all my connections which seemed fine and truck ran fine for the rest of the short trip I was on. Started to miss again so I removed the DD box and took it to dealer. (Mine has been pretty good so far) Repair order said that MAP sensor voltage was low and giving off erratic readinds. One of the work order lines reads"DRB tested-P0237 low voltage map sensor, checked freeze frame data, showed zero PSI at 1636 RPM" My truck has run fine ever since the MAP sensor was changed.



Another line on the RO says"Checked harness for short to voltage and short to ground per flow chart in powetrain manual pgs 88 to 92-checked ok-found map sensor showing erratic readings"



If the PCM/ECM is getting a zero boost reading from the map sensor and go pedal is pushed down a ways, could this be confusing the computer and cause the miss?



Sam

 

[LSMITH]

GMcLean, welcome aboard. It is really nice to have professional techs on the board. There is a lot of distrust toward the dealers but please do not take it personally, most everyone on here has had a bad experience or ten as you probably have too. Pipe up whenever you can, we value all input. Stay sort of stealth with your identity publicly on here so you have no chance of getting in hot water at work.



Mine has never had a code after the miss, and thinking back I know at least three of the times it has done it there are no power lines or radio/cell towers in the area. In each instance it has been cruising down the road at light throttle and cold outside (under 40). Those are the only common factors, and I have paid close attention. There is no box involved either so that is not part of what I have experienced. GDouglas, I hope yours does not do it again, maybe you found what was causing yours.



This is a problem that is going to have to get a lot worse for any realistic chance at finding the cause. Having made a living troubleshooting computer control systems I can tell you that with the frequency of the problem that most of us are seeing it will be blind luck if it is found unless it gets bad enough to duplicate regularly. The thought of ignoring it until it leaves us on foot is not pleasant, but I don't see a lot of choice.

 

[GMcLean]

Margil, unfortunately as you have likely heard many times from your dealer, an intermitant miss of this type which only happens whenever it so desires, is very hard to trace down to any one sensor or componant(inj pump). . Have you ever heard your dealer mention their "co-pilot"???? This is a very good tool for locating an intermitant concern as like yours. . It is up to them if they can do without their co-pilot for the length of time it may take to locate your problem but to me a happy customer is a good customer!!! In our shop, our customer comes first and in a small town like mine, we can not afford to tick somebody off by just pretending we cannot duplicate the problem and wait for them to come back when it does act up. .

Hope your dealer can maybe do without theirs for a while at least for you to try. .



GDouglas

In answer to your concern Loss of com between fpcm @ ecm,

it sure sounds as if your ddez is certainly contributing to your problem alright, but there have been a few cases I have run across of the fuel system relay not letting enough voltage through the circuit and setting that same dtc. . the repair was a new fuel system relay in the pdc under the hood. . Next time this happens, try swapping the relay with the horn relay to see if it goes away.



LSMITH



thanx for the warm welcome. No i do not take it personal. . I take my job very seriously and my customers rely on me to be honest with them and not beat around the bush so to speak. I did get in trouble one time when new dc guy came around unexpectedly and heard me commenting on the relyability of the lift pumps(that is another subject)to on of my customers.

Thanks for the advise about the stealth thing,,I wasn`t aware that dc would take offence to some outside help, even if it did come from one of theirs somewhere else

.

 

[chuck3]

TSB.# 18-24-99

Margil, Had the same thing on mine, it seems some of the Y2K trucks made between a certain date had this problem, took mine in for the Eng. reflash and its never happen since, that was over a year ago. Take it in for the TSB # 18-24-99 reflash that should take care of it.

 

[margil]

reflash

Chuck3,



thanks for that info. about the reflash 18-24-99.

 

[GDouglas]

GMcLean, thanks for the info on the relays. Next time I will try that first.