How to clean your IAC (Idle Air Controller) valve
- Thread starter Chris
- Start date
I guess mine was idling a little rough but it ever since I bought it it just seemed that way, so I never really thought about it. Took it all apart and saw that it was in need of much cleaning! Maybe acceleration will be a little a little better now after it's all cleaned up....MTF. 05' 4.0L with 110k.
So, this hasn't gone well for me haha. Ever since I installed the IAC and TB back together the jeep wants to stall after turning over....unless I give it gas for a while and even after that it wants to idle rough until I drive it around for a while. I chipped the slightest little piece on the IAC thinking it was a plunger or something that came apart. It apparently does NOT come apart! Probably need to grab another one now. '05 4.0L
^ Update: I read somewhere that only IACs with a plunger can be cleaned. This doesn’t suit the 05-06 models if that’s true. Replaced the old one with a cheap version on rock auto and it fired right up with no issues. Anyone heard of this “only plunger type IACs can be cleaned and reinstalled?” Either way, glad to be back on the road without air/fuel ratio problems now
antonio
Member
for the IAC it was only 2 screws. The throttle body had 4 and I probably should’ve replaced the seal but it seemed fine
antonio
Member
antonio
Member
antonio
Member
No the square with the z in the middle gasket do you need it because I broke mine
Last edited:
John Wolf
TJ Enthusiast
If you have idle issues, check your vacuum lines too. I had a missing cap on the fitting beside the TB. Also chasing the line down to HVAC. Leaks around the T's check valves and fittings can cause rough idle and issues with A/C and cruise control too. I just ordered a new replacement vac line kit.
antonio
Member
OP
antonio
Member
I'm guessing this will likely be the same for the '96 XJ 4.0...? The wife's Cherokee has been sitting a lot lately, and lately has been idling rough on first start-up. And second start-up. And thi...well, you get the idea. It isn't until after it's been fully warmed up and had the engine revved a few times that it settles down to a decent idle. All new tune-up parts (low mileage, anyway). Fairly fresh gas, too. That's why I'm thing perhaps a dirty IAC. Thanks for the great write-up, Chief!
OP
I can't say for sure, but I think it should be, yes.
Let me know what you find out, this is at least where I would start.
Lowcountryearl
TJ Enthusiast
Worked great on 98 with 172k on the speedo, didn't look like it had ever been done before. Idles so much better
MrMark52
TJ Enthusiast
@172k you might also want to check if your cats and O2 sensors are original or not.
See @Chris ‘s O2 sensor thread for more info.
And I just did a full rebuild of my exhaust from manifold to back bumper, including O2 sensors. I’ve only run a little over 2 tanks of gas since the rebuild, but so far an increase of about 1-1/2 mpg and more importantly, much improved performance and idle. Oreo’s an ‘03 with 119k on the clock and she had OEM cats, pipes, and muffler. I had cleaned the throttle body when I got her at around 103k.
See @Chris ‘s O2 sensor thread for more info.
And I just did a full rebuild of my exhaust from manifold to back bumper, including O2 sensors. I’ve only run a little over 2 tanks of gas since the rebuild, but so far an increase of about 1-1/2 mpg and more importantly, much improved performance and idle. Oreo’s an ‘03 with 119k on the clock and she had OEM cats, pipes, and muffler. I had cleaned the throttle body when I got her at around 103k.
johny_knoxville
New Member
I can't thank you enough for this. Jeep been dying and rough idling for months, while saving up for a fuel pump, found this gem! Many MANY thanks!
OP