96 6.5 with a miss

[KrisL]

Ok this is my parents truck, 96 suburban with 101,000 miles. Staring about 4 weeks ago the truck stall several times over a 30 minute period while my mom was driving it. Truck was towed home. So the first thing I tried was changing the fuel filter, truck seemed ok. Then my dad had to use the truck for work for a week and he noticed that it was progressivly getting lower on power and had developed a miss in 1st gear/lite throttle. SO they take it to a dealer who says the ip is bad, so they change it(under warrenty). Ok now we have the truck back a few days and notice that the miss is very noticable, hard to start, smokes alot on start up(grey smoke, never used to), and truck has had a big loss in power. So they take it back to the dealer who has it for three days drive 150 miles and they find NOTHING WRONG, idots.:mad: Now I get involed and my first thought is that the timing isn't set right. That should help the with loss in power, hard start, smoke at start up, right? The miss I'm not sure it might be timing or possiblely an injector problem. Injectors only have about 40,000 miles on them.
So the question is if the timing is off what is the best setting for increased power?
On a side note the product at www.obd-2.com can that be used to set/adjust the timing with?
Thanks in advance.

[rjwest]

Car code works well.

Easy to read TDCO ( timing ),
and do keyon/keyoff procedure to clear TDCO, and let Truck reset timing
by it self...

You need to do a search on forum ., lot's of data on TDCO and
carcode..

[moondoggie]

Good Day!

"...he noticed that it was progressivly getting lower on power and had developed a miss in 1st gear/lite throttle." Unusual - 6.5TD misses usually occur under heavy load at highway speeds, most often tracing back to LP (lift pump) system. I'd be tempted to check it anyway, but maybe after other leads don't produce results.

"...smokes alot on start up(grey smoke, never used to)..." Does this clear up after the engine reaches normal operating temp? Take a look at the marks where the IP attaches to the engine - are they in line? Seems like after some wear, these usually wind up with the IP mark 1/16" or so towards the driver side, probably to compensate for timing chain wear. Can you get them to tell you where they set TDCO when they timed it? -1.94 makes the most power; I think spec is something like -0.50 - -1.50, which will give better starting. I got rid of the grey smoke on startup on my daughter's 89 (below) by tweaking 'er a little towards the driver side (advancing the timing); I figure I'm safe, it's still the quietest 6.2 I've ever heard, but properly timing is of course the best & safest route.

"...and truck has had a big loss in power." I suppose it depends on how retarded it's running.

Let us know what you find - it will help others.

Good Luck & Blessings!

[KrisL]

OK the lift pump was changed back in december 06 at about 98,000, so it should be good.
The smoke does clear up once temp is reached until you do wot run then you get a countious stream of black smoke. This truck very rarely had black smoke.
Timing chain is still the factory one so its possible but that usually doesn't happen that suddenly. As for the marks on the engine I have to go check.
On edit; I didn't see any marks but I was looking in the dark with a flashlight so I might of just missed them.

[moondoggie]

Good Day!

"...until you do wot run then you get a countious stream of black smoke." Black smoke = insufficient air (99% odds) or too much fuel (1% odds). Rig up a boost gauge, even temporarily. (I've been monitoring my boost temporarily for years now with an old vacuum/pressure gauge. :D ) Cruising at highway speeds your likely to see 1 or 2 PSI; start adding footfeed & the boost should climb; as you approach max footfeed, you'll notice boost climb then the PCM will actually pull back boost (for reasons no one has been able to explain to me) - it might go as high as 10 PSI, but will likely drop back to 5 or 6 under PCM control.

With a stock truck, you'll usually see NO black or gray smoke during the daytime; you'll notice gray smoke in your mirror at night under heavy load, from the headlights of vehicles behind you.



Blessings!
(signature in previous post)

[rjwest]

OK; 1st , you really need to review old posts, I can't retype all the info on
the unique problems of the 6.5.

2nd GAGEs gages gages, SE avatar...

Major items , come to mind.

Boost controller solenoid, clean with wd4,

LP bad again, without fuel pressure gage, can't be sure , never assume.

Timing could be screwed up . but if way out of wack, would set a code..

Check waste gate actuater, should not be able to move when idling,

also check if stuck open, [possible but not lickly.

Bad vacuum pump, affects boost also,
need vacuum gage.

Use any coolant, make any oil, loose any oil???

DO YOU HAVE A CHECK engine light???? ( read codes)

Do you have a scan tool, get parts store to read for codes...

If you are going to be a 6.5l guy, Learn, Read the forum posts , do search,
Hard to tell with limited info you have posted...eliminate some of the above, report back, you will get help

I have become convinced that the 6.5 is a reliable engine and not to bad to maintain, just need to be knowledegable, OR PAY BIG BUCKS.
Dealears Don't know squat, and you pay for there learning. OH and there
very happy to take your money...

AND, Do you have a remote PMD, If you are going to keep vehicle,
You Absolutly need one

[KrisL]

Ok I'm not a newbie to the 6.5 or to this forum I changed my screen name so the web site considers me one, it used to be 82beast, so I not a total idiot just sometimes.
The truck does have gauges(boost,pryo,trans), kennedy boost controller, k&n filter, full 4in exhaust, cooling mods, gm-8 turbo(formally a gm-5).
When accelorating boost used to jump up to 12 or 13 lbs then settle around 9lbs, now its luckly if it hits 10lbs before settleing at 5 or 6 lbs. while cruising at 70mph used to hold about 3lbs, now 1lbs MAYBE 2lbs.
Coolant level unchanged, oil level also fine, no check engine light, wastegate moves freely(engine off).
Timing is going to be checked by a different shop, non-dealer, weds or thurs.
Pmd has not been moved yet but it is on the list of things to do, right now my dad would be happy if it just ran right.

[gmctd]

Hey, '82\KrisL

Several things -

Dirty air filter - black smoke, lower power

Load(s) of bad fuel - seems to be everywhere, lately - black smoke , lower power, missing, stalling
Including load of gasoline put in by somebody on a cell phone:eek:

Battery connections, cables, grounds, etc - stalling, missing

PMD\FSD going south - stalling, stalling, stalling

OPS - missing, stalling

Ign switch - stalling, missing

[rjwest]

May have a air leak into fuel system, : Hard start , smoke,

Again; Need to be sure LP is working with correct pressure/flow.

Rereading the initial post , it appears that the problem appaered imediatly
after IP changed, There work has a warrenty...
May want to ride with service manager and show him problem..