Ok so the idle in my 01 2.4L has been running extremely rough for the last couple months. I finally decided to take it and get a look at it.
So far I've done the following to no avail
- Ran the OBD II to check for any misfires. (Scan came out good)
- Replaced the spark plugs with AC Delcos which were properly gapped.
- Checked all of the vacuum lines (replaced a small one to the left of the throttle body as there was a slight air constriction in the fold.
- Checked the timing chain (found out it was actually slightly stretched and I replaced it)
- Recent oil change with Mobil 1 5-30 and K&N filter
After all of this, the first start up was very smooth. It ran smooth in the garage for awhile, but then after taking it out on the road for a bit and letting the engine get hot, it started to sputter again in idle.
I'm running out of ideas and would really appreciate any input.
Thanks!
ShiftyCav wrote:thats probably the dumbest thing i have ever heard. you should take that serpentine belt and wrap it around your neck.
maybe some blowby?
I'm back from the dead.
Currently Driving: RSX Type-S.
My Cavalier Burnt up :-(
Check your coil packs, once they start to get hot they will go. It just happened to me, some part stores test them for free. Best of luck.
i dont know if the 2.4L have egr? but I would check that because if the solenoid is holding open it will cause a rough idle
I believe this is just a mystery to some Z24s. Mine has been doing this for 2 years and I have done everything possible plus just changed the coil pack. Yeah she starts up quick, but the rough idle is still there. I was told by a mechanic it's like a ghost he can't keep throwing parts at it because it will be pricing trying to find it. Something would have to happen with it before I'll be able to find out what it was.
my TPS was broken and no codes came up for that....pop that off and check to see if it's spring loaded like it should be.
how much spring is it suppose to have cause i took mine off, I have a 96 Z, and it moved a little bit but not a whole lot
"sometimes the respect is more important..."
well my old one moved 90* freely by sticking my pinky in there and turning it....
the new one I got I couldn't turn it at all using the same method....
I'm not that familiar with the valve setup in the 2.4, but is there any lash adjustment on it, or is it strictly hydraulic? Valve clearances tighten up when an engine gets hot, and if an intake valve is setup too tight, it can cause exactly what you're describing.
I experienced this with an older engine that had mechanical tappets - it only needed about 1/4 turn of the adjustment screw to make things smooooooth again. Prior to that, the hotter it got, the crappier it idled. It drove me nuts until I figured it out.
If they're hydraulic, is it possible that maybe a lifter is sticking internally, not allowing it to compress? Usually they get stuck compressed and make lots of noise, but nothing's impossible.
An exhaust valve may cause a similar problem, but slightly less noticeable. It would likely deteriorate quickly though, as the valve would burn from not seating and cooling properly.
If you don't believe it's anything in the valvetrain, then I would try to go after the injectors. I'm not usually in favor of flushes unless there's a real problem, but this may be the case. It would be handy to get your hands on an extra set to swap in, but I know that's not always easy. If you do pull them out, make sure you have a new o-ring set - sometimes they may tear or get damaged when removing the injector. Cheap insurance against vacuum or fuel leaks.
If I get time, I'll try to dig up my service manual to see what it has to say about the 2.4's valves. It just sounds all too familiar...
It sounds like you've covered the ignition end, and since it works fine when cold, I wouldn't bother looking there much more. With no misfire codes set, the problem's likely unrelated.
The Mobil 1 oil should help to clean up anything that's sticking in there. If it turns dark quickly, it may be worth another change a bit early. This is only if it's been somewhat neglected in the past. I believe that oil has a more aggressive detergent package than most conventional oils, so there's a possibility that it may darken quickly if you haven't used it before. I just had some Amsoil do that with my car. I thought the engine was already quite clean, but by the time I got to 7,000km with that stuff in there, I couldn't see the dipstick through it. If you've done regular oil changes for the life of the car, then this last paragraph probably doesn't mean anything.
Just some more ideas to try to help...
John
I found out my problem. It ended up being the fuel pressure regulator. Once I replaced that my idle issues were finally gone after almost 2 years
Better late than never....lol
