NEED HELP 03 sounds like its "dieseling"

[redline customs]

My 03 just did something weird 3 times in a row. I got in to drive home from work. Started fine, nothing out of the ordinary. Drive home(like 2 mins) shut the truck off and it sounds like it was dieseling( trying to keep running after I shut it off. At first I thought it was my amp shutting down or something. Didn't think much of it. I drive to the store to get dinner and it does the same thing. So I start it and it does the same thing again. It just goes maybe 1 sec but then it dies. When it finally stops, it torques the car sideways, like I was revving it. Everything seems normal, temp, oil pressure, no see. Not sure what to think. Anyone have any suggestions?2will

 

[freddyboy61]

First thing that comes to mind is carbon buildup in one or more cylinders.

 

[redline customs]

Any way to remedy this? Any major problems that can be caused?

 

[littleblazer]

I don't think it'll really hurt anything unless it's doing it for prolonged periods of time...

 

[Sparky]

Probably not. It is usually more a symptom than a problem in of itself.

I'd probably start with simple stuff - dump a can of seafoam in the next tank of gas and see if it makes a difference. Wouldn't hurt to clean the fuel system out anyway.

 

[redline customs]

OK thanks. Was just worried something was going wrong. No like I said it maybe lasts for a second. At first I was kinda thinking it was my ignition switch acting up again, but its not like it takes a sec to shut off. It shuts down fine, just seems like it has enough rotational mass to keep turning itself. This was the first time this has happened to me and the first time I've ever seen it happen on a efi vehicle. I've seen it happen on carbed cars but that's just because of the fuel left in the cylinder and the distributor being turned by the crank.
Oh and was gonna ask, do you think that cleaning the throttle body would help any? I will try the seafoam but figured might as well spend my day off this weekend doing more than just laying around.

 

[Sparky]

Doubt it would affect this in particular, but if it hasn't been done for a while it can't hurt!

 

[SnowBlazer]

Interesting video from Eric the Car Guy. He doesn't use Sea Foam in his cars, he uses this little trick that'll do the same thing for free.

 

[Sparky]

I just am very, very leery about introducing non-combustible liquid into my engine...

Plus, on a FI engine how to get it in there decently?

 

[djthumper]

Spray bottle

 

[redline customs]

Honestly, I think I'd rather use sea foam. In a vacuum line. Knowing my luck I'd mess it up and hydrolock my engine. Sea foam isn't that expensive.

 

[mrrsm]

I'm in full agreement with not using anything that can accidentally bend your connecting rods. During the tear down phase of an engine head R&R... I was really shocked at how much carbon had steadily accumulated inside my son's 2002 TB engine. (Before and After Cleaning Images follow and many more are available at the link below...)

During the subsequent efforts at cleaning up this mess.. I discovered from @Mooseman that the only effective method for dissolving this dreadful material from within the combustion chambers and on the tops of the pistons and top rings... was a heavy application of GM Top Engine Cleaner. The stuff is quite foamy and remarkable in how it dissolves all the Carbon like nothing else can.

At the time I was using this on the 'wide open engine" it occurred to me that since this engine's spark-plug holes open up into the upper most area of the combustion chambers.... that on a fully assembled engine...it would indeed be laborious... but after removing all of the spark plugs... an intrepid mechanic could use a long spray nozzle and after bringing each piston to Top Dead Centre ...one after another following the correct Firing Order of the GM Atlas Engine... it would be possible to fill up the cylinders with the spray foam and leave the engine sit for 10-15 minutes...one after the other...again with no spark plugs installed...and after stuffing paper towels down into the spark plug wells to absorb the carbon-soaked excess fluid in each cylinder, rotating the engine in a clockwise direction very gradually to allow the liquid to be absorbed or pushed out and around the exhaust valves.

You could also use compressed air attached to a compression tester hose to slowly pressurise each cylinder and evacuate the foamy Carbon laden fluid before re-installing all the plugs and hand-turning over the engine very slowly a few times to ensure no hydro-lock of the cleaning fluids would occur. It follows that because of the serious penetrating power of this stuff... it would be wise to perform a Mobil1 Oil and Filter Change as the contents of the crankcase will have been contaminated during this cleaning effort. It is important to mention that NO SCRUBBING WHATSOEVER WAS NECESSARY TO ACHIEVE SUCH CLEANLINESS!

I will agree that most of the time... this kind of complicated combustion chamber relief will not be practical and most people will have neither the experience nor the confidence in doing something that seems so drastic. But FWIW...look at the Before and After images of the Pistons and Cylinders on an engine with 240,000 miles and you'll see why doing this over a long weekend when your certain not to need the vehicle... with patience and care...it will get rid of an enormous amount of Carbon build-up that only serves to cause pre-ignition...changes the "quench" dimensions inside the CCs ... and robs the engine of power and smoothness:

http://s557.photobucket.com/user/60...NEREPAIR/TRAILBLAZEREPAIRTOOLS?sort=3&page=11

 

[Sparky]

Dang those pistons are disgusting lol. Wonder what mine look like in my truck?

I might have to give that stuff a shot, although with my engine in a V it likely won't clean the whole thing since I'm not tearing the heads off my truck's engine. But who knows, it might.

 

[redline customs]

Thanks. I may have to do this when I have a couple days off.

 

[littleblazer]

The water trick only works on carbuerated motors...

 

[mrrsm]

@Sparky ... about doing this in a V8 configuration... This GM TEC actually expands rapidly into a dense, super-fine foam that SHOULD be able to reach all of the areas inside ANY combustion chamber...but the trick is to narrow that space as close to TDC as possible. Then as the cleaner expands outward on contact with the air inside the cylinder...it will reach all over the interior spaces...and after adhering to the Carbon Deposits... will slowly loosen and pool on the top of the piston and cylinder space. With the V8...that might prove very advantageous if you were to use this following technique to vacuum out all that "Black Mung". By the way... you might think that the stuff would simply drain down around the gaps in the piston rings...but instead... this stuff will remain their semi-filling the top of the piston for a very long time...and so it acts very nicely in quantity to dissolve so much Carbon Build-Up and MUST be either absorbed somehow or be vacuumed out. The cool thing also is that there is a huge amount of Carbon that gets dissolved off of the "Sticky" Piston Rings, too.

OP... I was thinking about your report of "Dieseling" and in the context of the presence of so much carbon inside the combustion chamber... what happens is that those flakes of Carbon and any thickened build up of the stuff on the tops of the pistons... act like "Glow Plugs". And once they get hot enough in there to incandescence... when the pistons are on the upswing on the compression stroke in each cylinder... pre-ignition is the result that can also keep the engine sputtering and trying to run even after the ignition is turned off.

I was pondering a simple way to get this GM TEC stuff in and out of each cylinder either at or near to TDC with the least amount of fanfare. I think the best way to accomplish the task is to get a cheap Compression Tester Kit from Harbour Freight and use the threaded Spark Plug Adapter Hose as the means to guide in a slender, clear plastic vacuum hose that come with the MityVac Kit...a small but powerful hand vacuum pump that can be used to evacuate all of the Carbon Goo that will dissolve and pool on the tops of the pistons if enough GM Top Engine Cleaner Spray enters and fills each cylinder.

http://www.harborfreight.com/compression-test-kit-8-pc-62638.html

You would be able to monitor your progress during the evacuation procedure because the Mity-Vac comes with a small, opaque Drain Container that you will be able to see inside of as the "Black Mung" gradually fills it up with each squeeze of the handle. If enough of the GM TEC spray is induced using the MityVac Plastic Hose guided using the Compression Tester Hose to dissolve all that Carbon and then soon sucked clean away... you would not have to be concerned with the Carbon and Chemicals affecting the innards of either the O2 Sensor in the Exhaust Manifold...or settling into the CAT and damaging or contaminating anything inside. These procedures would also minimize the chances of the Plastic Hose getting either caught upon, shaved off or stuck in and against the sharp threads inside the Spark Plug Holes. EZ---> PZ...

(Don't Forget to Change your Oil and Oil Filter...)

http://www.harborfreight.com/mityvac-vacuum-pump-39522.html

 

[redline customs]

Cool thanks I'll try that. Would it be a problem if I didn't get all of the chem stuff out? Ill do my best but then again I won't be able to see everything soooo. Ya know. I don't want to harm the engine or anything and seems like you said it won't but I just want to be sure. Thanks again for the tips guys I appreciate it.

 

[mrrsm]

You are Welcome, Brother... As long as you get most of the material out you should be Okay... I would still recommend rotating the engine several times after vacuuming out all of the cylinders prior to re-installing the Spark Plugs. Then rotate the motor a few more times after the plugs have been installed just for good measure. You will notice how much harder turning over the engine becomes because of the Compression Cycles inside each closed cylinder when the Spark Plugs are inside... this will be normal and you will hear the hissing of the air escape as you go slowly around.The important thing to remember is that you only Spray Clean with the GM TEC and then Vacuum completely... One Cylinder at a Time!

Trust me... if you were to encounter an actual Hydro-Locking condition while doing this very slowly by hand... you would feel it instantly. Going nice and slow with a Large Socket, a Long 1/2" Breaker Bar and some patience... will ensure that no lock-ups will occur. But don't be persuaded to "key" the engine over until this process has been completed.

All liquids are incompressible... and so even strong Connecting Rods will bend all to Hell and gone if surprised at high speed...and hence the slow "Hand-Made" method will do the trick. THIS is the goal in mind... when the Piston Heads are so clean...you can read their Orientation Arrows and Manufacturing Sequence Numbers with crystal clarity...without using any abrasives or harsh chemicals to do the job:

 

[mrrsm]

One way or another ...you will need something to help in finding TDC without losing your mind in the process... 6 Times in a Row. So something like this easy to use TDC "Warning Whistle" is inexpensive... but may require the addition of a 6"-8" long 14MM Tube Extension Tube with Spark Plug Threads to work on the GM Atlas 4.2L Engine deeply recessed Spark Plug Holes:

https://www.amazon.com/dp/B000TQ16HG/?tag=gmtnation-20

Alternatively... THIS device is a fairly expensive... but indispensable tool that will be long enough to lightly thread inside of each Spark Plug Hole and still sit high enough above the top of the I6 Engine to read and anticipate the approach of Top Dead Centre. In my opinion, this is the only one worthwhile considering AND WILL NOT WORK ON V8 ENGINES UNLESS THEY HAVE HEMISPHERICAL COMBUSTION CHAMBERS AND DEAD CENTRE SPARK PLUGS:

Make Sure you REMOVE this Tool from any Cylinder Before Closing The Engine Hood!

https://www.amazon.com/dp/B000FMSU9Q/?tag=gmtnation-20

 

[gmcman]

1 can of BG44K to a full tank of fuel, in your case, I would repeat the dose.

You can do the top engine cleaner but I would suspect a very dirty intake manifold. If that were mine, I would pull the intake, clean it out real good and install an oil catch can.

Once cleaned, then I would run the 44K.

That stuff is pretty much the best you can get. Top engine cleaners work also, BG is much easier.

 

[Mooseman]

We're all missing the one element missing that would cause an engine to have dieseling or "run-on" and that's fuel. This used to be a common problem with carburetor equipped engines but was eliminated with electronic fuel injection. An engine cannot run-on without fuel so unless you have a leaking injector, it can't happen. Carbon could be an ignition source if there was fuel but on its own is nothing except a possibly elevated compression that could cause knock while running, which would be controlled by the knock sensors and PCM.

What I think the OP is experiencing is the vibration from the engine as it spins down after shut off. I have that and I know why it's doing this... the engine mounts are shot. Mine vibrates while idling and also shakes the whole truck as it stops.

 

[redline customs]

Once again thanks for all the info guys I really appreciate it.
@Mooseman, I was actually thinking about the mounts. I noticed it was shaking pretty good while at a stop sign earlier. I might as well go ahead and replace anyways. 169xxx plus my driving is bound to have some effect. At this point I may as well do everything short of a full tear down. Just to be sure. Is there any posts around about good tips for some high quality "complete maintenance" basically? I'd search but have no clue what to type. Basically I just want to find info on all the dos and don't when buying one of these used. Normally idda had it done by now but I work about 80 hours a week so the time tree has been less than fruitful. Thanks again guys.

 

[mrrsm]

When the Time and the Tides Align (...AND the contents of your Wallet) ... These are the "Pricey" but necessary OEM AC-Delco Motor Mounts you want ...always recommended by @Mooseman that the other "Cheapy-Leaky" flavours cannot compare with. And even though you are lucky to have the 2WD flavour of this vehicle that simplifies things, there is a very contemporary thread on the MM Replacement with some added technical information that can be viewed here:

http://gmtnation.com/forums/threads...replacement-passenger-side.15720/#post-506710