Iac Control
 

Hey Guys

I need to change my IAC valve, i have the new one here with me, but, have no idea how to change it (or even where its located)

If someone could send me a diagram, or better yet, instructions on how to change it, I would REALLY appreciate it!

Any/All input welcomed and appreciated!

Michael

[email protected]

Sorry guys, I forgot to mention, 1995 454EFI, Bravo 1 set up, Thanks!

Michael

I should be right behind the throttle body.Two screws usually torx and unplug a wire.Very simple

So, what, if anything? Do I have to do to get to it? THANKS!

Michael

You should be able to just remove the flame arrestor and throttle cable from the throttle body, slide the thottle body off, flip it over replace the IAC and reassemble. Should take 15 mins to complete.

http://www.mercruiserparts.com/Show_...sp?dnbr=824418 93&ivar=images/CRUISER/824418.93/18.png&inbr=1614&bnbr=180&bdesc=INTAKE+MANIFOLD+AN D+INTAKE+PLENUM

I think this is your engine,its #33


The link did not show up,Go into Bam marine go to lookup mercruser stern drive then find your engine.It will give you a picture.

Thanks guys! Will have a crack at doing it tommorow, Thanks!

Michael

Replacing the IAC would be best. But, I did see a show on speed channel that showed how you can clean them with carb cleaner and it will be good as new. The reason they usuallly stop working is that the plunger gets gummed up.

I had been told the same thing, the fella who did the top half of my motor a few years ago cleaned it out, he told me it would be "ok" for awhile, but, eventually it would need replacing. I was told the tell tale sign is a "surge" at idle (which I have)

I figure if I have to take the air cleaner and throttle body off to clean it, I might as well change it, APPRECIATE the info though! Once this IAC starts to act up, I will try cleaning it.

I had hoped to get to it today, but, I spent all day (in 90 degree heat) resetting and replacing the poles for my floating docks, water here is highestvI have seen it in years, but, NO complaints!!

Michael

Hey guys

I had a look at the motor, I removed the air cleaner and the throttle cable, but, the actual "throttle body" appears to be 1 piece attached to the upper plenum, I see NO way to get to the bottom of the throttle body other than removing all the torx bolts and lifting off the upper plenum? When I say upper plenum I mean the flat black piece on the top of the motor that says "Mercruiser Cross Ram Injection" or something similiar, am I missing something? Or do I actually have to remove the upper plenum to change the IAC?

I can take a pic with my iPhone if someone needs one?

Thanks guys!

Ps: I am changing plugs too (gluton for punishment!) i was told the factory recommended ACMR43T are interchangeable with the NGK "R" YR5's, when I got looking at them, the NGK's appear to have a slightly shorter tip (looking from where the plug seats in the head to the electrode) is this important? The difference is maybe 1/16 th of an inch


Appreciate all the help guys, sorry for the "lame" questions

Michael

If you removed the 4 bolts marked "36" in the pic, the throttle body will come off.

My set up uses "studs" that protrude through the "throttle body", the air cleaner slides over them and 4 nuts hold it in place, I cant see any way to remove the studs? Do the come out? I seem to remember trying before and not being able to move them

I believe that drawing is of a MPI set up, mine is the older "EFI"

Yeah, those studs are threaded on both ends. Use 2 nuts to lock against each other on the outer threads and back the stud out. (Or you can use vice grips but it may score it up some)

Ok, will give it a shot, Thanks!

Any thought on plugs?

No, I always used MR43s in mine.

Ps: I am changing plugs too (gluton for punishment!) i was told the factory recommended ACMR43T are interchangeable with the NGK "R" YR5's, when I got looking at them, the NGK's appear to have a slightly shorter tip (looking from where the plug seats in the head to the electrode) is this important? The difference is maybe 1/16 th of an inch

Why not stick with the original plugs? If the plugs cross reference they should be the same heat range but what you describe surprises me. Definitely how much of the plug sits in the head will affect it but is that how NGK designed it? Again check cross reference.

Most info I see on the net is NGK BR6FS and AC MR43T are a match

I only have my iPhone with me, So, if SOMEONE with access to a PC could check for me, I would greatly appreciate it

Thanks!
Michael

Use one of those. They are the correct plugs.

Ok, thanks, guess I will go out tommorow and rip out the YR5's I put in earlier! LOL!!

Better safe than sorry I guess!

Thanks guys!
Michael

I got an Email from NGK who claim that AC MR43T cross reference to NGK YR55, anyone use these?

Michael

WFT the two NGK plugs are different heat ranges...right from ngk.com

YR55

V-Power Plug, 14mm Thread Size, 11mm (7/16") Reach, 5/8" (16mm) Hex Size, Tapered Seat, Resistor, Solid Terminal Nut, V-Power (V-Grooved Center Electrode), .060" (1.52mm) Gap, Heat Range 5


BR6FS

Traditional Spark Plug, 14mm Thread Size, 11mm (7/16") Reach, 5/8" (16mm) Hex Size, Tapered Seat, Resistor, Solid Terminal Nut, .031" (0.8mm) Gap, Heat Range 6


Also attached a cross ref chart...MR43T = BR6FS
MR44T = YR5

I hear ya! It was a nitemare trying to get any help from NKG, THEY told me the YR5's and YR55's are identical except for the gap (40 thou for 1, 60 thou for the other) when I asked, I was told that the YR55's are DIRECT replacements for the AC MR43T, so......since they are supposed to be "identical" the YR5's should work as replacements too, right? NOPE!!! According to NGK, ONLY the YR55's are replacements for the AC MR43T??!!! LOL!!

I said "screw it" and just went into town and grabbed 8 new NGK BR6FS' plugs and spun them in, for what its worth they are EXACTLY the same size as the YR5's, but, are a little shorter than the AC's

IAC CON'T!

I pulled the air cleaner off and had another look, it appears the studs that protrude threw the throttle body and the air cleaner are not removeable? There is a heli coil on all 4 studs in the upper plenum, I did try spinning them out with the dbl nut technique, and tried vice grips and they didnt budge at all.

I took a pic of the throttle body and studs with the air cleaner off if someone wants to have a look, but, I dont know how to post "here" I can Email them if someone wants to post and/or have a look at it. I am out of options, to me, it APPEARS that I need to lift off the entire upper plenum to get to the IAC, but, I hope I am wrong!

ANY input welcomed and appreciated!

Michael

Any ideas????

Yeah, shoot me a pic at insptech at comcast.net , I am curious now. If you jave to lift the top it is pretty easy, I have done it like 4 times in an afternoon (don't ask). The only thing to be careful of is the seals between the 2 plenums, but if you break them they are like 3 bucks a piece.

Thanks! Will shoot a pic in the AM!

Pics sent, Thanks!

Michael

i would like to see too

[email protected]

Pics sent! If I need to pull the upper plenum, how do I go about it? Anything to watch for? (other than trying not to wreck the gaskets)

Thanks!
Michael

a couple of sensors to unplug and a vacuum line. lift straight up