Renix Low Idle.

As of late, my 88 XJ has had some low idle issues. When its fully warmed up, idling in drive at a light, the rpms will sometimes drop down to between the first and second mark, the idle will be a little rough too, but it will sometimes catch itself, idle around 800, and then back down again. I seafoamed, didnt help and no smoke, TB and IAC were cleaned last fall, dont see how they can be THAT gummed up already, and if it comes down to it, ill check them again.

When I searched, all I came up with is High idle symptoms, and no help with low idle.

Any ideas?

Mine changed and I found that my TPS was out of adjustment so I readjusted it and my idle is where it should be again. Must be the electrical wiper inside that gets burned in or something like that.

My 90 is a low idler(chugs like a John Deere tractor). Everything is new under the hood includint the engine. I have adjusted the TPS, done all the other tricks and nothing helps. I just live with it, I get great gas mileage and have plenty of power. It runs as good as my 4 HO XJ's.

With the flowmaster 40, high flow cat, and 2.5" exhaust, it sounds good like that!

xjtrailrider said:

My 90 is a low idler(chugs like a John Deere tractor). Everything is new under the hood includint the engine. I have adjusted the TPS, done all the other tricks and nothing helps. I just live with it, I get great gas mileage and have plenty of power. It runs as good as my 4 HO XJ's.

With the flowmaster 40, high flow cat, and 2.5" exhaust, it sounds good like that!

Click to expand...

I would almost agree with this... only because my 90 RENIX had a low idle since day one. It would go down to the first line on the tach (approx 330 RPM's). Never hesistated ran poorly or stuttered etc. Just idled low. The only reason why i wanted to fix it is because at that low of RPM, the alternator is not rotating fast enough to put out enough current.

I dont think you searched very well cause there ARE threads about low idle...

Check this one out... its when i finally fixed mine:

http://www.naxja.org/forum/showthread.php?t=933682

Basically, i made sure the idle air bypass screw (on the drivers side of the TB sometimes covered with a cap) was tightened all the way (after tons and tons of reasearch i have determened that this "screw" should never be touched ie.. always all the way tightened).
I then adjusted the butterfly valve opening (via the idle stop screw) until there was just enough room to get two peices (stacked) of paper through the opening without binding. Re-adjust the TPS (duh!), and then give that a shot.

This procedure of course is only for the RENIX TB. If the idle gets "better" open the idle stop screw a little more until the desired idle is acheived. (Making sure to re-adjust the TPS EVERYTIME you mess with the idle stop screw)

I would also say its good practice to either check or plainly replace the +b latch relay that operates the IAC when the engine is turned off via the key.


I hope this was informative, and helps.