What would cause a miss?

[DASH]

Hey guys, I have something going on that is very mysterious! As I am driving down the highway with the cruise set, the Cummins will miss or stumble. I has only happened twice since in 9500 miles. It's nothing drastic, kind of a little chug, and the cruise always stays put. Is this a cruise control problem? It has never happened with the cruise off. I just changed my fuel filter about 200 miles ago, could it be an air bubble in the fuel system? Beats me, just thought I'd see what everyone else thinks! Thanks!

Mark

 

[MidwestMotorman]

more info

Need some more info... You are saying this only happens with the cruise working? If so, it is probably just the cruise keeping the speed the same. You have an auto, so you only would feel the jerk or miss when the TC is locked up. My 99 is a stick and you can noticeably feel the cruise let off and resume to keep the speed the same.



I believe the "chug" is normal. My truck did not seem jerky with the cruise on, but as the motor broke in, the power went up. I think I notice the cruise working more as my motor broke in and got more power. I have 42k miles on the clock.



Also, any small vacuum leak would affect the cruise too. Maybe someone else has experienced the "chug" feeling as well?



Forgot to add: Do you feel the chug on a flat stretch of road, or just on the hills and slopes? If it chugs on the flat roads, I would suspect something else other than the cruise.

 

[DASH]

The Chug

Hey Nathan- Thanks for the response. I think it is only happening on a flat surface. It seems like it just cuts out, but for only a very slight bit of time. When it does this it always does it twice about 3-5 seconds between chugs. Who knows? The cruise always stays glued right on where ever I had it set, I guess I'll just keep running it and see what happens. Thanks for the insight. Take Care.

Mark

 

[work2muchplay2little]

DASH, I realize you haven't BOMBed yet, but I have experienced a similar miss ( it happened to be accompanied by lighting the check engine light) but the point is it was related to a less than perfect connection of the harness to the MAP sensor. Others have reported finding loose connectors under the dash, and the PCM and ECM in prior posts. Might be worth just giving all the connectors a little push just to make sure.

 

[DASH]

Many thanks!

Hey Kurt- Many thanks I think I will give that a try, at least that is something I can do myself. To me this sounds like a very possible problem. When it does this, it seems like it could be a loose wire just losing a connection momentarily! I'll give her a shot. You are correct, the bombing hasn't started- Yet- !

Mark

 

[MidwestMotorman]

miss

DASH



When I used to be a GM service manager, we experienced a problem like yours. Customers would report a miss, and everything would be fine with the ignition and fuel system. I had to send a tech out with a scanner hooked up and watch the data while the customer drove. We discovered that the valve body was causing the transmission to slip at cruising speeds.



This turned out to be a common problem with certain newer front wheel drive GM vehicles. We ordered a new or rebuilt GM transmission for the first couple times, but found out that they still had the faulty valve bodies in them. We had to order just the valve body to finally get the good ones.



Long story short: Being you experience it twice, it could very well be the lock/unlock of the trans or momentary slippage. If you are still under warranty, I would have a tech and computer ride with you and monitor the vitals to determine if you do have a trans problem. The ride would also tell you if anything else is amiss.