1989 XJ 4.0 135,000 miles 4x4 auto.

Does anybody know what size the IAC O-Ring is for these? I had a problem that went away when I cleaned my IAC and throttle body. Then it came back. I cleaned it again and it went away. The last time I cleaned it I noticed the O-Ring was a bit chewed up but didn't replace it right at the moment.

Anyway the problem has returned and I want to clean it and the throttle again plus replace that O-Ring and see what happens. For anybody curious what the intermittent problem is, in case it can help you help me or in case someone else has the same issue. When I crank it up sometimes it will almost cut off. It will do this when coming to stops too or sitting still and shifting between gears. The idle will drop and stall as does the battery hand , but then it will pick back up and run perfect. I can sort of feel it while driving down the road sometimes but it's way less noticeable. None of this is constant when it's even doing this. And as stated it has even went completely away and returned for - at this point I am not sure. A year or more. It makes it hard to track down because of this. But it has improved with throttle body and IAC cleanings. Which sort of makes sense why it goes away and comes back until it gets dirty again. I am not even sure if the IAC bad O-Ring is letting air pass but I want to rule it out.

I went by an advanced auto and all they had was an expensive box of 4 or 5 O-Rings and I'm not even sure which size they are and if the box has the one I need. I believe NAPA has them in singles so I would like to know if anybody knows the size. I realize I can try to match my old one but as I said it was chewed up so if I can know the exact size ahead of time it would help me. If not, I'm sure I'll figure it out by matching. Thank you.

 

My parts guide doesn't list the o-ring as a separate part.

When IAC "acted up" I removed it to clean it and noticed the o-ring was quite "distressed". I had a bunch of different size o-rings already and fpund one that fit. I didn't compare it against the old one. I found one that fit around the IAC and seemed thick enough to seal once tightened down. It resolved my funky idle issue.

 

It doing it as well while driving suggests not your IAC involved only. Especially the battery gauge dropping.
How is battery?batt connections and grounds clean and snug? Id check the TPS sweep as well.

 

As far as I know the battery is ok but I can load test it. It's strange how it can go completely away for months and then return for who knows how long.

The weird feeling at driving also leads me to believe that maybe it's more the throttle body getting dirty or a leak in the gasket, but who knows. Maybe I am imagining while driving because when stopping it's obvious. While driving if it is even doing anything it is subtle to thr extreme so perhaps I am so hyper-aware I'm making it up.

 

Your TB should be good for while after cleaning. That's what makes me curious about the TPS