rough idle in park or neutral...

[mlc5]

My wifes 2004 3.5L V6 AWD Vue has been battling problems the past several months... The idle has been rough.. and we had a few P030x codes in the past.. but I've addressed those.. (plugs, and one bad coil pack)....

The car is better , but it still has a rough idle, though not as severe... I noticed that the problem seems worse if the car is in Park or Neutral... When I put the automatic into DRIVE, it seems smoother/ok...... Not sure if this is revelant or not....

Additionally... I've replaced the tranny fluid several times over the past 6 months... using the recommended Mobil z1... Another note .. is we had the timing belt replace a year or so ago...

Any suggestions?

[far2grumpy]

There are several possibilities ... see attached ... repost if you'd like to see any of the other referenced documents.

You didn't mention number of miles on the truck.

[mlc5]

thanks far2 .. this is helpful......

The Vue has 142K miles on it thus far.....

I should have also have mentioned that I did replace the throttle body over the summer, along with the PCV valve.. As I mentioned, I just replaced the plugs, along with a single coil pack... and the EGR Valve was replaced earlier in the year......

Ironically, I did order a new coolant sensor this past week, based on the number of posts here, and elsewhere, about it being a common cause of a rough idle condition with these cars..and it was cheap enough.. so I thought why not? In any case, it just arrived in the mail this evening.. and I'll pop it in tomorrow evening, I'm hoping.... so we'll see..

[far2grumpy]

Does your water temp gage read as it has in the past? The water temp sensor typically sends voltage to PCM which provides data to fuel management circuits and also routes signal to water temp gage (via data bus).

How many RPM at idle?

Do you suspect the miss is caused by low idle? Or, do you hear a "spit" in the exhaust at regular intervals?

Moving into gear or turning A/C ON are two things which kicks the IAC up a notch.

Do you have a vacuum gage in your tool kit? These can be handy when troubleshooting idle problems.

[mlc5]

Not sure on the temp gauge reading.. I put the new coolant sensor in this evening, so we'll see what happens over the weekend...The temp gauge reads slightly less than the halfway mark .. at around the 11 oclock position

It idles at around 725rpm in Park or Neutral...

I didn't hear any type of sounds that you suggest ....

[mlc5]

here's the latest....
I had a chance to drive it extensively over the weekend ...

1) THe car makes some noises when cold.. that appear to be coming from the area where the timing belt is.. so I suspect the tensioner perhaps.. but they do seem to go away as the car warms up....

2) No engine light the entire weeked.. though it wasn't a perfectly smooth
idle.. but it felt fine on the highway and locally..

THis morning my wife noticed the CEL went on again. and I plugged in the OBD and it now shows a misfire on cylinder #2... Given that the plugs were just replaced... I'm wondering if it makes sense to just go ahead and replace the remaining coil packs..? Just not sure if the startup noise/vibration and the idle miss are related or 2 independent problems?

[far2grumpy]

Originally Posted by mlc5

THis morning my wife noticed the CEL went on again. and I plugged in the OBD and it now shows a misfire on cylinder #2... Given that the plugs were just replaced... I'm wondering if it makes sense to just go ahead and replace the remaining coil packs..? Just not sure if the startup noise/vibration and the idle miss are related or 2 independent problems?

I'd throw another coil pack at it ... I suppose you could pull the #2 plug to verify it was wet first.

The PCM (and TAC) will try to keep idle RPM on plan if one cylinder is missing but there will be vibration.

[mlc5]

yeah.. i'm inclined to think I should just replace the 4 packs that are original to the car with 140k plus miles..

I ordered the 4 additional packs, and will install over the weekend and let you know...

Thanks for all the suggestions... I'll keep you posted

Mike

[mlc5]

well . . i replaced the 4 remaining coil packs.. but the idle is still rough and somewhat noisy... SOunds like its coming from the timing belt area..
... the saga continues....

[saturn69]

when the timing belt was replace was the tensioner replace at the sometime?
If you are hearing nosie in the timing belt area the tensioner could be going bad and have allow the timing belt to jump a tooth.

[mlc5]

That's my guess as well.. I'm not sure if they replaced the tensioner or not.. but I have been receiving the random misfire codes .. and now I'm pretty certain the noise is from that area..

The belt was done by an indie.. so who knows?

Is this something I can check myself? Is it as simple as pulling off the timing belt cover.. and inspecting the tensioner visually?

[saturn69]

you can check yourself and also verified that the timing marks line up

[vue04]

Try cleaning the throttle body if you haven't already. Mine was rough idling since the butterfly valve was sticking....

[Taipans]

I have the same issue, along with it sounding like a diesel at idle. I notice it most when up against a building that can direct the sound back. I am broke though so I am going to have to do all the things myself. What would you guys suggest I start at first as in cheapest and easiest?

Don't mean to Hijack I am waiting to see if you can find the fix and wanted to add my situation.

[mlc5]

well.. I finally broke down .. and took the car to a Honda dealer to take a look at the engine woes... Here's what he told my wife....

1) timing belt tensioner was bad
2) valves were burnt
3) cylinder heads needed to be replaced
4) 2 bad engine mounts....
5) and some other front end component...

basically he said it's probably $5K or so of repair work.. !!!

I hope to talk to him in person tomorrow.. but that's the low down.....

[far2grumpy]

Originally Posted by mlc5

well.. I finally broke down .. and took the car to a Honda dealer to take a look at the engine woes... Here's what he told my wife....

1) timing belt tensioner was bad
2) valves were burnt
3) cylinder heads needed to be replaced
4) 2 bad engine mounts....
5) and some other front end component...

basically he said it's probably $5K or so of repair work.. !!!

I hope to talk to him in person tomorrow.. but that's the low down.....

I'm a cynical old coot and a few questions come to mind ...

Did your wife stay with the Vue? If so, how long was she there?

The only way I know to check a timing belt tensioner is to gain access to determine how much pressure is being applied to timing belt. This means removing drive belt and timing belt cover at a minimum.

The accessory drive belt also has a tensioner ... I've had two of these fail (rattle and squeal at idle) in the last four or five years on Dodge 3.8L and Chevy 4.3L.

Burned valves would normally be determined with a compression test of each cylinder. If you changed your own spark plugs you could definitely do a compression test. If you try this test - see if you can use a bright light to check top of one or more pistons ... you're looking for evidence of carbon build-up (black as opposed to shiny metal). Upper engine carbon can normally be removed using a top-end cleaner.

The valves are in the cylinder head so 2 and 3 of your list are inclusive.

A guide to test engine mounts has been previously posted ... say the word and I can send a link.

A bad "front end component" is a blank check.

I believe you're on the right track by talking to these folks person-to-person. I'm not saying a Honda dealer is out to cheat you but it doesn't hurt to let them know you understand the basics.

[mlc5]

thanks for the guidance and advise....My wife said they had the car and were looking at it for 2 hrs...

1) Honda said they were unable to communicate with the PCM/ECM to read the full diagnostic data.. as he said even though its a honda engine.. Saturn has a different computer system that interfaces with it....
2) on the receipt for the diagnostic work it shows the following:
- broken motor mounts, causing vibration and bang in reverse
- valves need to be adjusted, but may not help. May have burnt valve (misfire). May end up needed cyl head or motor.
- timing and belt ok...
- no repairs recommended.

The comment on the timing belt made it seem like he felt that was ok.. though she told me he mentioned the tensionser as a problem. so not sure what the discrepancy is there.. need to follow up....

I have no doubt they were honest, in the sense that they told her not to put any money into it.. and if she did, they would recommend some place if needed, but their dealership typically wouldn't work on the Saturn.. despite the engine being a honda... He told my wife that the tensioner is the least of the problems..

My inclination is to investigate what it would cost to get the valve job done and replace a burnt valve or 2 ? As that along with the mounts seem to be the biggest pain point..