RPM loss and sputter at idle when warmed up

[mika]

It's been a couple of days now and I am scaching my head, everything was fine upto a couple of days ago. I thought at first something was wrong with the tranni, when I was leaving stops of lights I'd get a sputter. Last night I was stuck in traffic and I could the truck sputter and the RPM drop to about 400 then back, When I got home I didn't turn off the engine and just left it in park, opened the hood, you can accually see theengine shake. Do you think all I need is somenew plugs, TB cleaning, may be even a fuel filter change and a Sea Foam, I did all this about a 1 1/2 years ago or am I missing something elese?? I've done may be 25 000kms (10 000 miles).



Thanks for the help.

 

[mika]

Dose no replys mean that all it takes is a minor tune up?

 

[The_Roadie]

Does the erratic RPM smooth out when you turn off the AC? If so, it's probably the throttle body or CPAS. If it's a 10 Hz engine shake and the RPM stays steady, it's motor mounts. Or you have oil or water in the plug wells and you're about to get a misfire code (P030x).

I assume or else you'd mention it, that you do not have any codes.

 

[mika]

Nope no codes, ac dosen't work, and it's only when I am not driving only when I am stopped, in park or drive makes no differance. I even opened the hood to watch the engine, it gives a little shake then stops. It's also not consistant. Don't get me wrong, I am not ruleing out the mounts.

 

[MacMan]

Either throttle body needs a good cleaning, or you have a coil pack or 2 on the way out.

When you accelerate, the engine smoothes out?

Try the easy solution....remove & clean the throttle body (w/ battery disconnected 35-40 min.).

 

[mika]

As Roadie said if any water or oil in any well I would get a code, got home and had a code.. P0304.. cylinder #4 missfire, so pop off the coil pack and found moisture around the metal brass colored like ring if you want to call it that, so I air hosed it and got more wet stuff off of it. It was still hot so I left it out to coll down by air while I grabed a bit to eat., Just to rule out a coil pack problem I swapped it ou with coil from cyclinder #5. Fired he up, still rough idle, with a hollowish sounding like noise, I let it run until I could get another code, light came back on, put the scanner to it, Po304 agian. I pooped now after being up since 3:45 this morning, tomorrow I'll run out and get a new set of plugs and a can of TB cleaner.

Can someone just confirm that cylinder #4 in the one closest to the fire wall correct???? the fireing ordeer is 1,5,3,6,2,4 starting at the front bumper.

 

[McGMT]

As Roadie said if any water or oil in any well I would get a code, got home and had a code.. P0304.. cylinder #4 missfire, so pop off the coil pack and found moisture around the metal brass colored like ring if you want to call it that, so I air hosed it and got more wet stuff off of it. It was still hot so I left it out to coll down by air while I grabed a bit to eat., Just to rule out a coil pack problem I swapped it ou with coil from cyclinder #5. Fired he up, still rough idle, with a hollowish sounding like noise, I let it run until I could get another code, light came back on, put the scanner to it, Po304 agian. I pooped now after being up since 3:45 this morning, tomorrow I'll run out and get a new set of plugs and a can of TB cleaner.

Can someone just confirm that cylinder #4 in the one closest to the fire wall correct???? the fireing ordeer is 1,5,3,6,2,4 starting at the front bumper.

Nope, number 4 is the fourth one back... from front to back it is 1,2,3,4,5,6.... The firing order is just which one goes off when, so you checked the wrong coil... But that's what were here for, to help...

 

[mika]

When you accelerate, the engine smoothes out?

QUOTE]

No not really, a bit better but like I said cylinder #4 is the problem. But another question, has anyone ever seen just one plug give out like this??

 

[mika]

Nope, number 4 is the fourth one back... from front to back it is 1,2,3,4,5,6.... The firing order is just which one goes off when, so you checked the wrong coil... But that's what were here for, to help...

Thanks, I'll take a look tomorrow.

 

[McGMT]

When you accelerate, the engine smoothes out?

QUOTE]

No not really, a bit better but like I said cylinder #4 is the problem. But another question, has anyone ever seen just one plug give out like this??

No problem, but yes it happens... Could be the water/oil issue, a plug fouled up n gone bad, or the coil pack giving out.... All those do happen, and alot of times you get a miss it is just on one cylinder.

 

[The_Roadie]

Plug 4 is the classic one to accumulate water, due to runoff from the hood getting past the weakly-designed gasket. There was a TSB about putting shims in or behind the gasket to reduce the problem. We seem to get a rash of these after every rainy spring.

 

[McGMT]

Plug 4 is the classic one to accumulate water, due to runoff from the hood getting past the weakly-designed gasket. There was a TSB about putting shims in or behind the gasket to reduce the problem. We seem to get a rash of these after every rainy spring.

On mine I went ahead and sealed the gasket to the cowl all the way across. It sealed underneath the gasket and made it fit more firmly against the hood.

 

[mika]

Good morning everyone, now that I've been placed back on track on which cylinder is #4, I took it off and yup..... it was full of water... But why? I'm no stranger to engines and backyard mecanics but Ive never seen water not just moisture but water, a good ounce or so. What would cause this? I know the rubber seals on the bottom of the coil packs are pritty dry and cracked, would this be the cause? If so, can you buy just these rubber seals? I am also takeing advantage of haveing all the plastic of the top of the engine and gave the TB a good cleaning. Yes the battery is disconnected. For know I just wait. In about 30 to 45 min. I'll go see if my problem is gone.

But this water, wow and why?

 

[mika]

Plug 4 is the classic one to accumulate water, due to runoff from the hood getting past the weakly-designed gasket. There was a TSB about putting shims in or behind the gasket to reduce the problem. We seem to get a rash of these after every rainy spring.

I guess I should red before I ask certain questions.... Thanks Roadie. So dry cracked rubber seals are not totally to blame?

 

[mika]

Well all is good, purs like a kitten. Fells good when it don't cost much more than labor, my own labor that is.

Thanks guys

 

[The_Roadie]

Well, then, our job is done......

View attachment 21635

 

[MacMan]

.....#4, I took it off and yup..... it was full of water... But why?......

But this water, wow and why?

Water from rain, car wash, etc, runs off the cowl and directly onto # 4 plug coil. Factory fix is to put some 1/4-3/8" thick foam weatherstripping under rubber cowl seal right next to the edge. Stops water from dripping.