This morning truck ran fine, Took my wife to work then headed out to get a new tire on her wheel she blew out last week. I filled up with gas and usually get 100 miles before the needle moves. Well I wasn't paying attention to anything as I'm looking for tire shops Ive never been to before. Got the tire replaced, went and put it on her car and hopped on the highway.
I happened to look down and 1/4 tank is already gone and only 33 miles on the clock since fill up and reset ( I reset the odometer trip every fill up )
Then HOLY HELL I noticed my tach is running 40k at 62mph when its normally around 17k on the tach. slowing down gunning it a bit... nothing lowered on the tach. Got off the highway and looked over the TB and cables, all seem fine, trans fluid is clean and full....
I replaced the plenum gasket about a week ago and no issues since til today, and new TPS as the old one broke trying to unplug it so that's new....
Got back on the highway and it was normal again? Ill be picking up my wife after work and driving home ( about an hour drive) so I will see if it does it again.

I noticed a couple times this past month, when I got on it to pass someone, the truck seemed like it cut in and out, kinda bucking almost misfiring type of deal but not with the motor,,,the trans.... What could be a possible issue with the trans? I ran my code reader and all systems are OK and no codes?
Any ideas greatly appreciated, Thanks.

 

Don't have O/D turned off do you? Might try and cycle the switch a couple times, just to be sure the PCM is paying attention.

Also, have a look at the coolant temp sensor by the thermostat housing.... that not having a good connection will positively tank your fuel mileage. (I can't bring myself to call it fuel 'economy'....... as there is nothing 'economical' about these trucks. )

 

Coolant temp works, just changed out a 160 thermostat with a 192 , shows the difference on guage. Since doing the plenum Ive went from 200 miles a tank to 350 a tank of gas... but today everything is nuts on it? Ill check the overdrive as I never mess with it but double checking it later... Wonder why it was fine after stopping then got back on

 

May have bumped the button. It's on the end of the shift lever on your truck......

 

Ill check it, Thanks for the info. Ive never used it so very possible it was accidently bumped handing stuff out to my wife ( her bags and purse ) hopefully nothing major with the trans, cant afford it right now after the new tires and shocks as well as all the small crap lately Ive done to it lol.

 

Ok , The OD was never turned off as theres a light on the dash that I would have seen, so that's not the issue.

The RPMs and MPH seems to be ok for now EXCEPT when I come to a stop or park or whatever....it stays idling high a 10000, normal is 6500. If I tap the gas it revs and comes back down to the same 10000... If I stomp on it real quick it will fall back down to 6500 just fine.

Could the TPS that I replaced is bad (new part) or could it be a spring/cable issue a I had the whole top of the motor off to do the plenum gasket? I'm going out to tinker a bit with it, Ill check back from time to time today... I still have no codes or lights for anything and just put a tank of gas through it yesterday ( 300 miles) constant stop n go, just the higher idle is bugging the hell out of me.

I'm Deaf, so had a few friends check it out (listening) and they said everything is fine, no pinging, knocks, hisses ... nothing, sounds great, runs drives great... just a funky idle now. (smooth idle, just higher than normal )

 

Throttle cable (or TV or cruise) hanging up?

 

I checked all the cables yesterday, Just checked again and they are all free...
I am betting on the IAC as I did not change that ( just cleaned the carbon off and also cleaned the TB before re-installing...
I disconnected it and there was no changes in idle , reving and all, the idle stayed the same ( didn't bog like it should ) so I think that's my issue.

I was thinking the TPS was bad but it is new and the throttle response and everything is great so that cannot be the issue. The IAC seems to be stuck open or due to the tip having some wear ( I noticed when I cleaned it during the plenum repair ) just didn't get a new one as it was running fine, but guess I should have anyways now.

 

IAC was the culprit. Changed it out, gave it a romp ...it idled up higher around 20000, then slowly dropped down to 10000, then dropped rather quickly to 6500 where it normally idles. Doesn't stick and stay at 10000 like it did before. I'm assuming it will start idling and all that with the RPMs once I drive it a bit so the PCM can get itself back in the groove with the new IAC.
Everything Ive replaced on this truck so far has been factory original parts, some still have the tags/labels on them with the date stamp and production dates of the parts. Crazy, but I'm loving this truck more and more as I get things fixed.
After new tires, shocks and alignment, its handling hella better but still that little play and I know exactly what it is, even tho inspections passed everything and says its all within specs, The tie rods are loose enough to wiggle with one hand ( done this with my 97 in the past) so once those are changed I know it will be a stiff ride with no play. Track bar was the only thing they failed during inspection along with 1 ball joint, so all ball joints were done. My only real issue to get done is a front axle seal leaking after they did the ball joints...which of course they deny, I figured Ill just get the whole front axle rebuilt later ( New seals, lube, joints, maybe the hubs? ) I'm sure its all original.

 

Ok, went out today and its still idling up a bit... Heres whats going on.
Cold start revs and holds at about 15000. Punch the gas a few and it will drop to about 7500 and holds... still not dropping to normal where its supposed to sit around 6500?

When you rev it ( tap the gas ) it jumps to 20000 on a light tap, holds for a few seconds then slowwwwwllllyyyyy comes down to 10000 then drops suddently to 7500 . So whats causing this? Vacuum leak? something else?
This was a sudden thing after driving for almost 3 weeks after doing the plenum gasket. I checked the plenum and tested it, so it is not blown or anything, no vacuum on the pcv valves as a Mopar Mechanic told me to check. I'm a bit baffled at this latest issue, its a throttle issue it seems and needs to be addressed since when driving it has a "pull" when stopping due to the higher rpm. I'm probly going to tinker with it a bit more tomorrow, so I will check in from time to time... I don't want to get caught in the snow with it like this.