Our Community is 940,000 Strong. Join Us.


2001 2500HD 8.1L Idling


AnchorJoe
02-06-2013, 03:34 PM
I have a 2001 2500HD P/U with the 8.1L V8. I have owned the truck for ~5yrs and used it with everything towing. For about the last three years, I have noticed that when the truck is in gear (Either Rev. or Drive) the engine idle almost acts like it is missing. It doesn't do this at higher RPM's (say over 1K) while driving.

Last spring I did a tune up (Plugs and wires) and a few of the plugs had quite a bit of build up so I figured that was what was causing the issue. For about 1wk after the tune up it seemed to clear things up (at least I didn't notice it), but then resurfaced.

My question is: should the "Coil" parts that feed each spark plug need replacing, or could they cause this symptom? The ignition system on this truck is a bit different that what I am used to seeing, so I am not sure where I should start looking for the problem. Thanks for any guidance anyone might have.

Also, there are no error codes being thrown.

j cAT
02-06-2013, 03:50 PM
I have a 2001 2500HD P/U with the 8.1L V8. I have owned the truck for ~5yrs and used it with everything towing. For about the last three years, I have noticed that when the truck is in gear (Either Rev. or Drive) the engine idle almost acts like it is missing. It doesn't do this at higher RPM's (say over 1K) while driving.

Last spring I did a tune up (Plugs and wires) and a few of the plugs had quite a bit of build up so I figured that was what was causing the issue. For about 1wk after the tune up it seemed to clear things up (at least I didn't notice it), but then resurfaced.

My question is: should the "Coil" parts that feed each spark plug need replacing, or could they cause this symptom? The ignition system on this truck is a bit different that what I am used to seeing, so I am not sure where I should start looking for the problem. Thanks for any guidance anyone might have.

Also, there are no error codes being thrown.

idle should be 600 rpm. replace the pcv / use some injector cleaner with 4OZ of marvel mystery oil in the fuel. clean the throttle body /IAC....

check fuel pressure/replace the fuel filter.

AnchorJoe
02-07-2013, 08:27 AM
Thanks for the quick reply. I did actually also change the fuel filter last spring when I did the tune up (forgot to mention that part). I will try the injector cleaner in the fuel and see how that improves things, and then go from there. Thanks again.

j cAT
02-07-2013, 09:21 AM
Thanks for the quick reply. I did actually also change the fuel filter last spring when I did the tune up (forgot to mention that part). I will try the injector cleaner in the fuel and see how that improves things, and then go from there. Thanks again.

the fuel filter can get dirty fast . the more fuel used the shorter the life. only use ac delco or purolator fuel filters. wix is also recommended.

the PCV and hoses need replacing if cracks or poor fitting. also the valve is a part most forget, gm recommends replacing less than 20,ooomi. I have found 30-40,ooomi is when this should be replaced ...it has nothing to do with getting dirty or restricted. with a clean well maintained engine the pcv wears out . this then causes idling/fuel management issues.

AnchorJoe
03-19-2013, 05:37 PM
UPDATE: So I ran a bottle of injector cleaner through the system (Tank full), and the truck still seems to have little flutters when sitting at an idle in gear (Rev/Fwd) at stop lights, intersections, etc. I don't seem to notice the flutter when in park or neutral.

What is the possibility that something is wrong in the transmission, and could a fluid/filter change help correct the problem. The truck has 148K mi on it and I purchased it at 88K and have not done a transmission fluid change. Last information I read on transmission fluid services was every 100K.

Anything else I should check/look into?

Thanks for any guidance.

sa200
03-21-2013, 06:29 AM
Put in new sparkplugs, thats what I have to do every 30k.

AnchorJoe
03-21-2013, 09:36 AM
I did replace the plugs and wires last spring and I haven't put more than 12K on the truck in the last year. I am also wondering if the plug coil components on each cylinder might need replacing. Still trouble shooting.

sa200
03-21-2013, 10:37 AM
Put new plugs in... At the very least pull all and check for buildup. Those engines are oil burners.
My 2001 will start missing while idling in gear when it wants new plugs.

j cAT
03-21-2013, 10:44 AM
I did replace the plugs and wires last spring and I haven't put more than 12K on the truck in the last year. I am also wondering if the plug coil components on each cylinder might need replacing. Still trouble shooting.

what plugs did you use ? the ac delco iridium plugs work best.

measure the plug wires resistance should all be very close OHM readings. new wires can be bad !

the idle being not smooth is vacuum leak/hoses/fuel pressures /injectors/low compression.

bad wires wrong wires can do this along with the use of some plug manufacturers. what is the idle in gear ? in neutral ? could be dirty maf/IAC.. map could also be bad or the gasket that it seats into the manifold.

j cAT
03-21-2013, 10:54 AM
UPDATE: So I ran a bottle of injector cleaner through the system (Tank full), and the truck still seems to have little flutters when sitting at an idle in gear (Rev/Fwd) at stop lights, intersections, etc. I don't seem to notice the flutter when in park or neutral.

What is the possibility that something is wrong in the transmission, and could a fluid/filter change help correct the problem. The truck has 148K mi on it and I purchased it at 88K and have not done a transmission fluid change. Last information I read on transmission fluid services was every 100K.

Anything else I should check/look into?

Thanks for any guidance.

the transmission fluid/filter change should be done every 40,ooomi if you do not plow or tow large trailers. only use dexronVI DO NOT USE DEXRON III. this fluid is no longer recommended by GM. causes transmission failures.

the 100,ooomi fluid /filter interval you see in the manual is for fairy tale land stuff. not the real world. GM view on the vehicles they manufacture is 100,ooomi is the life of the vehicle . they used dexron III in that transmission and with that 100,ooomi stated interval many got screwed real bad.

our country bailed out these crooks.

toyota has used for many years a low viscosity synthetic transmission fluid designed to go 150,ooomi. this is possible also because there is no filter only a screen just in case a chunk of metal breaks off. gm uses clutches these wear out. the debris then eats at the valves. you must drop pan and clean up this mess .then use the dexronVI which you will see faster smoother shift and I found better MPG.

AnchorJoe
03-21-2013, 11:41 AM
Thanks for the insight. I will check the plugs and wires per your suggestion. I do recall last spring when I did the tune up there were three plugs that looked rediculous with build up, and not knowing when the previous owner did a tune up I assumed it had been a while. Also, I used standard AC Delco plugs, so maybe upgrading to the Iridium grade would be good.

I am also planning to drain the transmission and change the fluid/filter. With that regard, is this something a DIY'r can handle or should it go to a transmission shop. I have done transmission fluid and filter changes before, but from what I understand the Allison is a different beast so I am not sure if there are special needs that have to be considered.

Thanks again for the insight.

j cAT
03-21-2013, 12:42 PM
Thanks for the insight. I will check the plugs and wires per your suggestion. I do recall last spring when I did the tune up there were three plugs that looked rediculous with build up, and not knowing when the previous owner did a tune up I assumed it had been a while. Also, I used standard AC Delco plugs, so maybe upgrading to the Iridium grade would be good.

I am also planning to drain the transmission and change the fluid/filter. With that regard, is this something a DIY'r can handle or should it go to a transmission shop. I have done transmission fluid and filter changes before, but from what I understand the Allison is a different beast so I am not sure if there are special needs that have to be considered.

Thanks again for the insight.

I never have worked on your transmission. check up on the procedure. my guess is it should not be that different.

Add your comment to this topic!