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View Full Version : rough idle randomly



Alterocks
01-28-2008, 07:17 PM
49164.1

starting thursday i believe, my truck would run rough. i would be criusing along and then i could feel it run a lil rough and i would lose power, i could maintain my speed but i could speed up.... well since then it seems to happen randomly... sometimes i'm at a light and it'll just start idling rough... but usually comes out of it quickly... well today i was driving from lunch and it just got really bad... if i floor it it runs fine... but when i let my foot up it runs rough agian... and when i have the bad idle and shut my truck off it smells like a two-stroke LOL...

i pulled these codes from the dash..
152- 2/1 O2 sensor shorted to voltage
455 Large evap leake detected
420 1/1 cat efficiency
432 1/2 Cat Efficiency

i dont have cats so thats the two codes.... not sure what the large evap leak is... and i assume theother one means that i need a new O2 sensor....

what do you guys think? where the best place to get a sensor? dealers ship?

Danno, whats your price on a sensor? my zip is 33469 so are the saving worth it?

BTLFED R/T
01-28-2008, 07:28 PM
Upon first reading, I would have said cats. But you don't have any. HMMMM

The evap leak could be the gas cap. I'm not sure if the gas cap was a small or large leak though.

00RedRT
01-28-2008, 07:30 PM
Mine did this. I replaced the O2 sensors twice and it kept happening. Turned out to be a vaccum leak and the O2 sensors were never even the problem.:mad:

Alterocks
01-28-2008, 11:01 PM
Mine did this. I replaced the O2 sensors twice and it kept happening. Turned out to be a vaccum leak and the O2 sensors were never even the problem.:mad:

vacuum leak.... rough idea of where at? ugh.. i hate vacuum leaks...

00RedRT
01-28-2008, 11:10 PM
vacuum leak.... rough idea of where at? ugh.. i hate vacuum leaks...

Mine happened to be the back of the M-1 intake manifold.:(

Alterocks
02-01-2008, 10:42 PM
so it seems that this happens when my trucks warms up... i've never had it happen all week when i start the truck... but after driving for 15-20 minutes.. it'll start... any ideas?

are pre cat O2s and post cat O2s the same?

machine351
02-13-2008, 12:39 PM
you have to have that cat. the truck will not run right without them. anything 1996 or newer has to have them. they use 2 ho2s that measure the diff between the in and out of the cat and adjust accordingly the air and fuel. another thing do ya keep your pcv changed. I bet if you pull out your plugs that they are either running real hot or carbon fouled. comes from hot comes from running lean, fouled from running rich. checkum out man. you will see. put the cat back on the way it is supposed to be. you will get the power back. you might have to change the plugs though. hit me back man.

John
02-13-2008, 04:34 PM
are pre cat O2s and post cat O2s the same?

i believe so. you going to try swapping the old rear into one of your fronts? They should work the same, but the connectors might be different so you might have to swap those. I never looked to see if the connectors were identical.


you have to have that cat. the truck will not run right without them. anything 1996 or newer has to have them. they use 2 ho2s that measure the diff between the in and out of the cat and adjust accordingly the air and fuel..

not true, you can run without them if you use a sim; or most people have the luck of just being able to remove the rear o2 sensor and tie them to the frame rail.

BryanRT360
02-13-2008, 04:39 PM
the front and rears have a different clip

John
02-13-2008, 04:40 PM
well there we go, thats our answer. so if you do that, try swapping the connectors.

slvr03dakrt
02-13-2008, 04:53 PM
i'm all for taking the cats off i picked up .5 in the 1/4 by going to a true dual setup with no cats and o2 simms.

tcuillier
02-13-2008, 11:22 PM
you have to have that cat. the truck will not run right without them. anything 1996 or newer has to have them. they use 2 ho2s that measure the diff between the in and out of the cat and adjust accordingly the air and fuel. another thing do ya keep your pcv changed. I bet if you pull out your plugs that they are either running real hot or carbon fouled. comes from hot comes from running lean, fouled from running rich. checkum out man. you will see. put the cat back on the way it is supposed to be. you will get the power back. you might have to change the plugs though. hit me back man.

I have been running for over 4 years with no cats. O2 sensor is ty-wrapped to the frame. No codes, no rough running, runs great!!

Tom

machine351
02-13-2008, 11:50 PM
I like to try and keep my stuff the way it should be.

tcuillier
02-14-2008, 12:19 AM
You absolutely have the right to keep it stock. But you're gonna miss out on a whole lotta horsepower!

Tom

machine351
02-14-2008, 10:33 AM
my truck is pretty much stock all I got is headers, mopar pcm and mopar intake and a k&N open air filter. its pretty dang quick. never sprung a check engine yet. runs really solid.