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View Full Version : Suburban acting up need 6.5 Tech in NH or MA



bl78ljb
08-05-2007, 08:46
Well, my Suburban had been running quite well after going through some suggestions from this group to get my "bucking" problem under control - I replaced the locking gas cap with a diesel cap, and while the truck was in the shop at the dealer they replaced the OPS for me free due to a screw up on the job they were actually working on (can't complaint about that apparently it took the tech about 5 minutes with the right tool). Our family just went on a road trip out to Chicago (from Maine), and the truck ran fine on the way out getting about 16-17MPG. However, on the way back it started to act up again. About Rochester, NY in the evening it started to buck again on a rare occasion, stopped for the night and fueled up in the morning and the bucking continued for a while and then seemed to go away for about 150-200 miles. When we got into MA it started to happen again and regularly and by the time we were about to leave MA it became unbearable. It was losing power on the highway the RPMs would suddenly drop and it would not really respond to throttle and then would suddenly come out of it and drive a bit further. At that point I made the decision to leave the truck with my father in the Nashua, NH area and borrow his 2000 Excursion to finish our trip home. When in his driveway with the truck in Neutral it coughed and dropped to about 300 RPM again (I thinks this eliminates the TCC someone had suggested earlier), and this also occurred in Drive with the brake on but not when I just stopped I had been sitting for a while and a TCC should act like a manual tranny and die when you stop - right?? I do have a remote mounted FSD on the DSG cooler, but attached to the intake, however, during the 95+ degree weather in the mountains on the way out to IL no problems at all, and the problems got worse as the temperature was cooler and didn't seem to be as bad during the mid-day (don't know if that is cause-effect or coincidence due to driving distance). My wife also noticed some black smoke during acceleration up the mountains, don't know if that is related or not (Air filter looks good and the indicator is still green so I don't think that is bad). The LP is new and with this happening at idle I don't think that should be contributory?. These same symptoms have occurred only since my new engine was put in and never before the new engine and has occurred across three fuel filters in about 4-5K miles with this filter only having about 2.5K on it. This leads me to believe it has something to do with the fuel system which is under warranty. However, as it is a warranty issue I have to have a shop do the work, and as the truck is in NH 4 hours south of me I will have little luck getting there to do the work anyway, so I would like to get a suggestion for a good shop in Southeastern NH or Northeastern MA that would be a safe driving distance given the problems with the truck. Also, any further suggestions as to what may be wrong would be helpful, and anything I haven't clarified I can do that as well.

Thanks in advance

JoeyD
08-05-2007, 18:20
I have a friend at Liberty Chevy in Wakefield MA, right off rt 95, that knows the 6.5's good.

rameye
08-06-2007, 19:10
I'll be in Stoddard (1/2 hour west of Concord on Rte 9) this weekend I have a tech 1..your welcome to use it.

Just give me a heads up, I'll make sure I pack it up.

Only good for OBD1..not sure what year yours is..

E-mail rameye@optonline.net

rameye
08-06-2007, 19:13
I just read the by-line on your post...I think your OBD2... not gonna work.

If you want a second head scratcher...offer is still there.

Gotta tell you....it kinda sounds like low fuel pressure.....or possibly a dead or dying PMD....any codes??

bl78ljb
08-07-2007, 09:27
I just read the by-line on your post...I think your OBD2... not gonna work.

If you want a second head scratcher...offer is still there.

Gotta tell you....it kinda sounds like low fuel pressure.....or possibly a dead or dying PMD....any codes??


No codes. This has happened despite documented adequate fuel pressure, and across 2 PMDs and the remote FSD currently on the truck. When I sent the info to the company I bought the engine from they have seen similar symptoms with a cam position sensor and apparently that will not throw a code until it dies and you are on the side of the road - but can be diagnosed with a Tech- II (yes I am OBD-II). I also appreciate the offer, but I am in Bangor, ME and my truck is in my parent's driveway in Windham, NH and long-distance head scratching is a terrible thing which is why I figure as it is covered under the engine warranty I will have someone with the knowledge and tools fix it.

Thanks again

bl78ljb
08-07-2007, 13:19
I have a friend at Liberty Chevy in Wakefield MA, right off rt 95, that knows the 6.5's good.
I would like to contact your friend, as that might be the best option. I sent you my contact info by personal message. By any chance is Liberty Chevy the same place that Smyly Chevy used to be??

Bryan

JohnC
08-08-2007, 14:54
Ignore anyone who suggests it's the cam position sensor. There isn't one. There is, however, a crankshaft position sensor...

When the new engine was installed some of the grounds may not have been reconnected or left loose. Sounds like an electrical issue to me.

bl78ljb
08-08-2007, 18:07
Ignore anyone who suggests it's the cam position sensor. There isn't one. There is, however, a crankshaft position sensor...

When the new engine was installed some of the grounds may not have been reconnected or left loose. Sounds like an electrical issue to me.
JohnC
Thanks for that bit of info. I agree it does sound electrical to me as well, especially as it is so random, which makes it much harder to diagnose as well. However, hopefully it will not spontaneously fix itself before I can get it to someone to fix it. BTW anyone know how to contact JoeyD as his friend sounds like my best option thus far.

JoeyD
08-08-2007, 18:23
I just sent you an e mail with my phne number, call me and I will call him to see when he can take it in.

rgrowan
05-13-2008, 12:37
I just had an optimized 6.5 installed and have experienced the bucking during acceleration mostly. What did they determine the problem to be??

bl78ljb
05-13-2008, 14:06
I guess I forgot to add it to this thread. I found that the ECM harness coming out the right hand firewall has two potential positions, one correct and one incorrect. Basically the turbo heat shield rubs against the harness when it is installed in the incorrect position and if I remember correctly shorts out the harness to the IP (OPS wire I believe). See this thread here: http://www.thedieselpageforums.com/tdpforum/showthread.php?t=29697&highlight=bucking for more details on this problem.