Can you help me diagnose problem 2001 8.1

[die hard]

How's every one doing today ?

I have a 2001 2500hd with 8.1 205,000 miles

Trucks idle is surging at low speed /rpm's it feels like it wants to stall most of the time and does stall occasionally when stopped moving . but will start back up? Today I was in reverse and it high idle for few seconds but came back down ? It only acts up when truck is in gear idles perfect in neutral ..I changed crank sensor few years ago had totally different symptoms than has now ..when driving down the road at about 55 mph truck will surge when in the passing gear ? And not build power like normally ..i put the scanner on it and is not showing any codes ....I've have tried plugs wires coil packs ? I know it's hard to determain problem over net but any suggestion would help ..I'm almost thinking throttle position sensor ,throttle body ?

[Formulabruce]

Take off the air tube in front that comes from the air cleaner, ( big) hose clamp) and clean the throttle body with throttle body cleaner, wipe it down well, and the throttle flaps. This should help. Good luck

[die hard]

Thanks that's what I've been thinking dirty throttle body .truck is no longer my daily driver letting anything sit is the worse ..do you think that would cause the stalling issue ? The high idle I can see caused by dirty flap

[Formulabruce]

I have a buddy with one , 2001 model, and was doing the same thing. Dealer wanted to make him buy a new Throttle and MAF, After a 220 dollar "test" . Cleaner is less than 7 bucks a can, just get the right stuff, Throttle body cleaner...The hardest part is the huge Clamp !

[die hard]

I cleaned it today had little carborn on it. Looks like new now .living in Maine this time of year my yard is all mud and snow so didn't test drive it yet ..I did find body ground strap from fire wall near master cylinder to engine is corrode and broke off .thatnks for taking your time and giving me help

[Formulabruce]

I live on the Maine border, Literally . Mud and mess is commin' !

[wingman]

I'd try repairing that broken ground led, grounds are a "free" repair, and can cure many nasties. Just my ten cents.....

A scan with a Tech 2 is always a good guide.

Good luck

[mjoekingz28]

Timing set (two sprockets, double roller chain, and associated hardware).

 

 

Shouldn't be impossible on a pushrod engine. Maybe the Chevrolet engineers made it to be open, available, accessible and meant to be changed with engine in chassis.

[die hard]

Wondering if anyone has any other input on my problem I just replace throttle body was a reman was only $130 with tps and throttle control motor. So I start it up to do the relearn process idles fine for 10 min then wants to stall idle races up for a second then goes back to normal .15 min idling it stalls but will start right back up ..took it for a ride still drives fine above 35 mph coming to a stop light it does same thing wants to stall idles up to keep engine running have to hold brake for few seconds till idle comes back down ? I'm lost no engine codes .somthing is telling computer engine is dieing and kicks up idle ? What does the maf sensor do ? I'm lost on what to try next ? ! I know it's hard to fix someone else problem online but I'm ready to try anything

[Formulabruce]

You can try to unhook the battery for 30 min, and see if it learns, that will reset the ecm, but you may still have to put a tech 2 GM tool on it to relearn. Sometimes a tech may do it as side work for some cash if you know one at a dealership. Good luck

[die hard]

Thanks I did disconnect battery over night and touch cable together before reattaching them ..the engine skips a beet for a second then the idle come up .i put it in neutral will drive and idle stays high .witch in the past when sometimes I come to top of big hill I put truck in neutral to coast down idle stays at what it should be for speed I'm traveling ..so has me wondering what the speed sensor has to do with idle control if that might be failing ? Telling engine I'm going faster than I am ? But then again no engine light/code ?

[Formulabruce]

seems like vacuum leak, but no engine misfire code. This will have to get on a diagnosis Tech 2, and a Forced rests and test of all sensors.. Idle should drop down going downhill in neutral to say 700 ... Good luck !

[die hard]

I've sprayed starting fluid all around intake ect but no change in idle I would think an intake leak would be idleling up all the time ..when is idleling high I put it in neutral idle stays high until truck has stopped moving ? Thanks again I hoping someone reads this post who has had simular problem

[die hard]

I don't have the best scan tool but does read codes second I un plug a sensor

[die hard]

I don't have the best scan tool but does read codes second I un plug a sensor