The OEM Idle Air Control Valve (IACV) normally costs anywhere from $140 to $200. The part number is JLM12185

But I've been seeing a number of off-brand versions on Amazon and eBay for around $20

Now I'm definitely of the "you get what you pay for" philosophy, but then again I can change ten $20 IACVs for the price of a single OEM unit... that's a huge difference in cost. Of course there may be a huge difference in reliability too.... or maybe not.

So, here's the real question, has anyone had any experience with these inexpensive IACVs?

Two examples:

https://www.ebay.com/itm/New-Idle-Ai...R/371555978063


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Can't specifically address the X300 as I haven't worked on one, but before anyone declares an IACV to be broken, make sure you understand how to bench test it. Look for a youtube video or something. Many years ago, before the general population had Internet, I bought a $300 one new after following the test procedure in the factory service manual to the letter. But those books are written for the shop technician and assume he knows the basics of how things work and only needs to know the details like pinout order. I did what the book said and it did not appear to move so I thought it was dead. I didn't understand that I needed to repeat the procedure 126 times to fully extend or retract the plunger. The new part didn't fix the problem and of course I couldn't return electrical parts. I still have a 25 year old, $300 spare part. I guess at $20 though, its cheaper than what a technician would charge to test your old one.

 

Clean it first. They get grungy...

 

Hi Al,

Several years ago I installed a stepper motor for a Renault Megane in our '93 XJ40 based on a tip from a member of the Jag-Lovers forum. The part I purchased was made in Germany by LÖWE and cost about U.S.D. $33. The end of the plunger was shaped the same as on the original, and the mounting holes and electrical connector fit perfectly, and it's been working great. Our member katar83 installed a Renault Megane part on his X300.

A quick search of ebay turned up this one:

https://www.ebay.co.uk/itm/LOWE-auto...MAAOSwEUdahBRq

I agree with Ric that you may just need to clean your old one because they carbon up and won't close completely, but getting to yours on an XJR is enough of a job that you may as well install a nice clean new one and keep the old one as a spare. You can clean the port into which the stepper motor plunger fits with a battery terminal brush and some throttle body cleaner.

One thing to know is that the two screws that secure the stepper motor are installed with threadlocker, and there are many accounts of owners breaking one or both screws while trying to remove them. Carefully heating each screw with a soldering gun or small butane torch just prior to removing them may help.

At the link below are some photos comparing our original stepper motor and the one for a Renault Megane. Sorry the large images still aren't working, but you can see the thumbnails and descriptions.

Idle Air Control Valve Stepper Motor

One other thing to be aware of is that there are some similar stepper motors whose plunger tips are shaped differently. The ones used on Jags are conical with a gradual slope at the base and a sharper slope at the tip, as seen in the ebay photos at the link above.

Cheers,

Don

 

I was aware of the Renault part, but hadn't put much effort into researching it further, so thanks for the additional information. I went ahead and ordered one.

Agree on cleaning first, and I had the entire intake and TB off last winter for a thorough cleaning, including the IACV port, although I cleaned it from the inside of the TB without removing the IACV noting the infamous risky loctited bolts.

At this point I'm not planning to remove and replace the IACV, but with my "coast to idle stalling" problem that then clears if I "pump the accellerator" the IACV is suspect if nothing else cleans it up. Although otherwise the car idles perfectly.

So just doing some research to possibly avoid $150 for an IACV if possible

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Hi Al,

One issue that has been associated with stalling while slowing to stop or make a turn is low transmission fluid. Jaguar issued at least one TSB about it.

Cheers,

Don

 

Hrmm, that is the first time I've heard of that and is certainly an easy thing to check. So I'll add that to my list.

Of course, if I were to find that the fluid were low, then I'd be a bit concerned about where it went considering there are no transmission leaks AFAIK.

Thanks!

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As part of the ongoing, and now hopefully completed, repair of my stalling issue.... the problem does so far seem to indeed been the IACV.

However, after trying to install the cheaper Renault IACV, I can confirm that it will not fit on an XJR6. It may work fine on normally aspirated X300, but the clocking of the connector on the Renault IACV causes the connector and wiring to interfere with other hard parts and the throttle itself on the XJR6.

So I ended up getting an OEM equivalent from Jagbits, which fit perfectly. There were some other off-brand aftermarket alternatives that were between $50-200, but I didn't have the time or energy to risk testing those.

 

You'd need to post a pic of both as I can't see how Renault part would not fit in there, I've replaced mine few years ago with Renault part and they looked exactly the same, apart from a slightly different puncher cap. That said, that was on a normally aspirated engine so maybe we're talking about two entirely different IACVs?

 

Unfortunately I don’t have the Renault IACV anymore, but from my experience removing IACVs from a normally aspirated versus supercharged AJ16, the location and clearances are much different.

So the Renault IACV may install just fine on a normally aspirated AJ16.

But on the supercharged AJ16 my mechanic was unable to get the Renault IACV installed in any orientation such that the electrical connector and wiring didn’t interfere with the throttle and surrounding parts. The factory OEM IACV however fit perfectly.

 

Just checked and JLM12185 is used on both N/A and S/C cars and Renault D95174 is exactly the same shape. I suspect you might have received either a wrong Renault part OR the socket on the Renault IACV maybe points in a slightly different way by a few degrees hence your issue with the wiring and plug. Its difficult to see this from google pics though and I don't have an SC car to confirm this for sure but glad you got it all sorted, time to finally enjoy driving it!

 

A very interesting conversation. I used the same Renault Clio/Megane stepper motor on our '93 XJ40.

Al, I think you may be right about the connector orientation. I just looked up the photos below and it may be my imagination, but it does appear that the electrical connectors are clocked differently depending on application.

Here is Jaguar JLM12185. Note that the connector is not quite at 90 degrees to the mounting screw ears, and if you rolled the motor over 180 degrees and viewed it from the pintle end, the connector would aim at perhaps 10:00 if the ears were at 3:00 and 6:00.


Photo courtesy of SNG Barratt

Here is Renault D95174 for the Clio & Megane. The connector appears to be clocked at about 12:00.


Photo courtesy of spectroparts/eBay

Here's the stepper motor for the Chevrolet Aveo and Daewoo Kalos/Lanos. The connector appears to be clocked at about 2:00.


Photo couresty of Trofom.

Perhaps the difference in clocking is not an issue on the N/A cars but is an issue on the S/C cars.

katar83 mentioned a stepper motor with a "different puncher cap." There are very similar Renault stepper motors that have differently shaped pintle tips. Here are two examples. Since I do not know if these pintles would seal properly in our Jaguars, so I was careful to choose a stepper motor with the same double-bevel shape as the original one.



Photo courtesy of sinyoauto2011/eBay


Photo courtesy of amfindustrial/eBay

Cheers,

Don

 

I was a bit worried about the cap myself but that didn't seem to make any difference at all when fitted(counter intuitive I know but assume mainly the top bit seals) plus its possible to swap it entirely from your old original IACV. As Don mentioned its still best to go for the most similar pintle cap when buying a replacement.
From what I noticed when operating it by having someone moving the key in ignition while I was holding it in my hand is that the old Jag IACV coil was simply lazy and was slower to operate than the new IACV.
I did manage to operate it once until the pintle shoot out of the IACV but carefully inserting it back and moving the key ignition got it back in again without too much trouble.
In regards to socket orientation, I don't have an IACV in hand but I suspect all that it keeps it in its orientation are these two small metal bits sticking out through the case, I'm guessing that they can be pushed in and entire IACV taken out and reoriented as needed by simply drilling a pair of extra small holes in another location. I'll make sure to give this a try next time I'll have a chance. Its difficult to see the socket orientation from all the google pics but they do seem to differ slightly.
What I find most important though when changing IACV is to replace the screws that hold it to TB with ones that can be taken out later without removing the entire TB, this makes it later much easier to replace/inspect it and I can swap mine now in couple of minutes.

 

Agreed on all points, but one caveat is that with the SC IACV, the only way to get it out includes loosening and lifting the intake manifold & intercooler to get to the back bolt (according to my mechanic) which based upon my prior intake track cleaning I believe. Given that difficulty, we didn't want to roll the dice on modifying another IACV or finding one that might fit and be reliable. So we spent the extra $ on the OEM.

I'm sure with some additional research and time one could find another version of IACV that is much less expensive and would work on the SC application though. The various IACVs of this design seem to essentially all be identical except for minor variations in pintle tip and aforementioned connector clocking.

 

The Workshop Manual cautions against powering the stepper motor while it is not installed in the valve body for this very reason. But I do wish you would have captured that on video!


Great point and a good reminder for us all to think ahead to next time, because there will probably be a next time!

Cheers,

Don