New parts, still a rough idle? (1 Viewer)

[concretejungle]

Thanks to CDan i now have a new intake hose, new plug wires, new dizzy cap, new rotor and new belts. Also replaced the exhaust gasket after the last cat because i could feel a slight exhaust leak and i threw a CEL PO420 which is insufficient cat. I cleared the codes and so far no codes. I also noticed a much improved driving experience with the new parts. Shifts are firmer and seem to be at the right spots, more power, quieter idle (new belts ), BUT, she still is pretty dang shakey at idle. I just can't seem to figure this one out because the truck is running like a top until i come to a stop light and the thing shakes enough to cause the side mirrors to vibrate. This is frustrating.

 

[KliersLC]

Well, I tried to help before but I am afraid I didn't do very well so here goes again. If you no longer have any exhaust issues, (did you fix the hanger ) then your problem sounds remarkably similar to one that I had on my 81 mini. Now, keep in mind that I haven't bothered to take a look at the mounts on this rig so I don't know if this is a potential problem but when I collapsed the tranny mount on my mini it showed the exact same symptoms you are describing. Does it shake in park? If so get a floor jack and lift the tranny about 3/4 inch, if there is play in the mount and the shaking stops this could be your problem. If it only does it in drive then set the ebrake, chock the wheels and do the same thing. While you are at it you might check the motor mounts too. If one of them broke it could have shifted and made contact between the perch and the block. I hope this helps
Good luck,
Dan

 

[concretejungle]

Thanks Dan, i did swap out my nice trusty clothes hanger for a large hose clamp and tightned that down, so yes the exhaust is fixed.

It does feel almost as if the motor mounts are smashed or something, like the motor is sitting on the frame. It's not as bad as before, much better, but still vibrates more than it ever did to begin with. But, now that i think about it, it gets the girls excited so i may just leave it alone and use it to my advantage.

EDIT: oh, and it only vibrates under load, IE if i put it in neutral, no vibration.

 

[IdahoDoug]

You didn't mention plugs? Also, a bit more on the problem as it sounds like this has been visited before? IE - it sounds like you guys are discussing a drivetrain/frame interference shake, not an engine shaking issue as even a healthy engine will vibrate the mirrors if the block's against the body somewhere.

So, lots of confusion as to whether this is a problem with your engine running rough, or a normal engine but it's against the body somehow.

DougM

 

[Arya Ebrahimi]

He replaced his plugs less than 10k miles ago.

No, alex, I'm not stalking you.

Ary

 

[concretejungle]

Doug, i just tried to search and for some dang reason couldn't come up with my past thread that started this.

Basically about 2 weeks ago i went wheelin' at Uwharrie with a local board member. I used my sliders a few times and once on the exhaust side. During that time i know i smacked my exhaust once. Some time soon after on the trail, the truck just started vibrating pretty bad when i was stopped at an idle with my foot on the break. I guess i'm not really sure when it started on the trail because i was concentrating on driving. On the way back home i noticed at every stoplight, the rig would vibrate pretty bad, enough to shake the mirrors and rear view mirror to make everything look blurry in them. Came home and found an exhaust leak where the rear cat mates to the down-stream exhaust. Next day threw a CEL---PO420 - insufficient cat.........was told that could be from my leak, so i replaced that gasket with a new one from Toyota, reset the light and so far no light and i felt around it and no leak..........then felt i was running lean because of a crack in my intake hose from the airbox to the TB. Replaced it, along with other said parts, unhooked battery to reset computer, now it is slightly better but still rougher than it was before this ordeal.

Thanks,

Alex

 

[patpend2000]

Have you looked for a vacuum leak? Rough idle sounds like a vacuum leak, check all of the small hoses, one may have come loose or dried out and developed some cracks.

Kelly

 

[IdahoDoug]

Definitely sounds like you've deformed the exhaust a bit and it's coming in contact with something. Basically, there should be no contact between the drivetrain or exhaust, and the body. When it's cold, you should slide your hands the entire length of the exhaust to see where it's touching, also looking for contact between the sliders and body (next on the list IMHO).

DougM

 

[concretejungle]

I was planning on taking the sliders off tomorrow to see if they were the culprit.

 

[ElJefe]

Concretejungle... Just wondering if you have had any luck with this. Mine has been doing the same thing for nearly a year now... not quite bad enough to shake the mirrors, but definitely not silky smooth like before. Mine started after a road trip from Cali to Colorado. Threw a code en route that turned out to be an EGR VCV. Fixed the VCV + full tune-up and it just hasn't idled as smooth since. Checked all the usual suspects... vac leaks, exhaust leaks, wires, O2, PCV. No more codes in over 10k. Finally just gave up. Runs silky smooth off idle but at idle in D it will vibrate noticeably through the seat and steering wheel. Smooth as silk in N. It's funny that mine will also idle dead smooth for about 2-3 seconds after coming to a stop and then the vibrating will quickly build. Just like a vac leak or lean miss but for the life of me I can't find a damn thing. The other thing that I noticed is that it vibrates much less on warm days. The warmer it is outside, the smoother it idles. Anyway, just seeing what you found...

Chris

 

[CPJONES1231]

you may wanna try chekcing your TPS too. Sometimes it can get moved a little bit and it will cause the same symptoms.

 

[ElJefe]

I checked it as per the FSM... OK. God only knows how it is supposed to work right when there are such huge ranges for all the values. I'm due for another weekend of troubleshooting this sometime this month. Hmmmmm... what HASN'T been checked yet...

 

[concretejungle]

Just saw this post, sorry i'm a little slow. I have fixed the problem. I felt dumb when i found out what it was, but i'm sure that all the things i replaced helped also. What had happened is i had hit really hard on my transfere case skid plate (the stock weeny one) and the plate was mashing against the Tcase. When the truck was in gear the tcase would transmit the vibrations onto the skid plate, through the crossmember and throughout the truck. I climbed under there and pulled the skid plate away from the Tcase and no more vibes. But, the new plug wires, rotor, rotor cap and exhaust gasket made the truck run like a top.

 

[Digger276]

Wasn't there past posts about the wire running to the IAC was too thin and replacing it also resolved a rough idle at stop lights? I've searched but could not locate it.