Hey Guys,

I've read through a few threads about rough idles and none really seem to match the same symptoms I seem to have so hopefully someone can enlighten me to what I may be facing here...

Got my car back from the shop last Friday after it being off the road for 4 weeks while the transfer case was pulled out and sent to Shep for a stage 2 rebuild. Had new clutch put in all nice nice. When I got it back and took it home I noticed that the car was producing a bit more vibrations than normally, it just didn't seem the same. When I got out of the car I immediately notice that the exhaust note was also very different. It now sounds like my car is cammed and I'm definitely still on stock cams. It's not a consistent lobe sound like you'd get from cams but more on a random scale. I spoke to a few people and they suggested a few things like car misfiring, timing could be off, EGR valve, IAC valve, or possible vacuum/boost leak.

I don't have a CEL. I scanned the car with a tool to make sure there were no errors and it came up clean. I had the timing belt, spark plugs, and wires (not coil packs) replaced 3k ago for the 60k maintenance and everything was fine right up to when I had the tcase removed.

The runs great other than idle. Hits boost no problem and pulls hard and doesn't seem to hesitate like you'd expect if there was a boost leak. Another kinda strange thing which I don't know is related or is solely because my boost gauge might be F'ing up is sometimes I get in the car, start it, and the needle remains at 0 for like 25 seconds or so before going down to -17ish. Once the car warms up a bit, it goes to -10 and sits there until I drive the car around. Riding around under vacuum it sits at -20 but at idle at stop, it's about -13 or so.

Sorry for the long post. I'm taking the car to another shop to get it all checked out on Monday but I figured I'd see if anyone else had this problem before. Any help would be great. Thanks guys, much appreciated!

 

I would grab a manual or look at the online manual and test the iacv. Does the rpms drop any?

 

Sorry... forgot to mention that the RPM does not drop at all. Stay at just under 1k the whole time except for when it's cold of course.

 

Does it do this strange idle only when idling warm? Or is it off when idling cold too?

 

It idles like this the entire time...cold or warm. I mean, the thing sounds pretty mean right now lol but I know something is wrong. It kinda sounds like a carbureted mustang lol.

 

Hey Guys... found this thread while searching around on the forums. Seems like the same exact symptoms I am experiencing right now... increased vibration (engine movement) and the strange exhaust lobe. Turned out it was caused by the timing belt slipping two teeth on the intake side. I'm taking the car back to the shop that did my 60k maintenance tomorrow afternoon to inspect the belt. I'm praying I didn't do any damage to my valves! :-(

https://www.evolutionm.net/forums/ev...ough-idle.html

 

I am having a similar issue after installing my cams. I think the timing may have skipped a tooth even though I zip tied the belt to the gears during the install. How is this corrected? Do I use the tensioner tool to collapse the tensioner then move the exhaust cam? I guess I need to know how to move the timing a few teeth? Any Input?

 

Well everyone, figured out the problem. After inspecting the timing belt we found that the exhaust cam had slipped 1 tooth. Thankfully there wasn't any major damage so once we reset everything idle went back to normal and vibrations are no longer present. Vacuum looks a lot better at idle as well. Was pulling 10 in/Hg before and now I'm about @ 15 in/Hg. So glad that we figured it out in time...

whew!

 

Well... I think i got happy too fast. Now all of a sudden my boost gauge is not reading anything higher than 15psi. it used to hit 22psi and 20 in 5th gear and now all my gears are showing nothing but 15psi. I have a manual boost controller and it's strange that now all of a sudden this is happening.

Any ideas?

 

I went ahead and disconnected and reconnected all of my boost and vacuum lines and also reset my ECU and BOOM... problem fixed. Not really sure what fixed it though, the lines or the reset. Either case I'm hitting 22psi now like a champ. Car feels great.