1996 IAC replacement

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markviii96

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I just got a 1996 mark viii and it is running rough on idle. I already tried seafoam treatment in it. It runs great after being warm, but I have to let car warm up a couple mins. Has anyone ever replaced this part, and if so how hard is this to do? I haven't really found any good write up on how to do it. Thanks in advance
 
I have done about 4 or 5 of them and it is a bitch to do. I have flexible T handle that acts like a ratchet and is around 18" long, give or take. I put on the little 1/4" extension to get to both bolts. It requires a gasket also. If you have help, make it easier on yourself and take the hood off. Take the cowl off. Take the throttle body off and replace the TPS while you're in there. Disconnect the battery when plugging in new parts. My first IAC took me a couple of hours. Now I can do one within 30 to 45 min.
 
have you ever seen a tutorial on this? I know I need to do it, but I heard its a :q:q:q:q. Thanks for the help
 
I did mine a couple of years ago before I bought the car while it still belonged to the previous owner. I remember it was a real PITA, but I got it done and the lady was so happy to have her 95 Mark VIII LSC idle so nicely! :D
 
the1andonlygr81 said:
had no idea they were such a pain on gen 1. on mine its easily accessable and done in 10 min
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Yeah, Gen 2's are right there like laying out on a table for you to grab. Gen 1 is pretty much up against the firewall, down to the left of the TB and so is the TPS. It's at the back of the TB, very bottom. It can be done with the hood on but it really does make it easier on you "if" you have the help there to remove and replace the hood. It allows you to look straight down on what you're doing instead of rubbing the back of your head into hood insulation.
 
Woo...I am doing mine this weekend, Gen 1. First time at it, with the engine in. Ordered a standard motor products one, let's hope this one works! Hey VIII96, you in Mount Pleasant Texas?
 
Did mine today finally, took a bit of time, but it's done! Used a 8mm wrench, and a 1/4 ratchet, with a long extension, and a swivel adapter, with 8mm socket! Car idles way better, and starts right up with no problem. No more, trying to start her over and over in cold morning, and no more idling like it's going to die. Well worth it!
 
Hey again guys, just a quick question. When your idle air control is going (like shot, i think) is it just cold idle it effects or all the time? Mine wont drive when its cold i have to let it warm up before i can move and it when engine temp get up it runs a little better. still a very rough idle.
 
On mine, it was when it was cold. Rough Idle, would idle like at 600 or so and act like it wanted to die. After cold start up, and putting it into gear, without letting it warm up, it would bog down and want to die out. I am 100% sure it's your idle air.
 
markviii96 said:
Hey again guys, just a quick question. When your idle air control is going (like shot, i think) is it just cold idle it effects or all the time? Mine wont drive when its cold i have to let it warm up before i can move and it when engine temp get up it runs a little better. still a very rough idle.
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depends. mine was stuck, but in a position that let the car run ok. yours may not be. probably stuck too low. if your car doesn't rev to like 1500 rpm or something on a cold start, and then slowly come back down, its stuck.
 
The TPS could also play a part with cold start idles. Never hurts to go ahead and swap out the TPS whenever you do an IAC, especially on a Gen 1. I mean, you're all back in there anyway, so why not take out 4 8mm bolts and remove the TB, get old gasket off, remove two phillips head screws that hold the TPS on and replace it. Put on a new TB gasket and don't forget to plug your TPS in before bolting the TB back down. While the TB is out is the best time to swap out IAC's and gasket for that too.

Always a good idea to disconnect your battery when unplugging and plugging in the new TPS. It is a sensitive part and if it goes bad, strange things can happen that will puzzle the mind.
 
So I need 1) new IAC, 2) New TPS, and a gasket for the throttle body? Thanks for all the help guys.

Also would you go with motocraft for these parts?
 
I have yet to install these things on my car, but I do have a question. first of all my idle just plain sucks all the time now. It is a rough idle. Now the thing I seem to notice is when it shifts into like o/d at like 55-60 it seems to run rough (so like low rmps). Is all this related to my IAC, and TPS do you think?
 
I had a bad gen 1 IAC, the engine idled too slow but still smooth.

I had a bad gen 2 IAC, the engine idled too fast but still smooth. The idle speed would jump around a little when cold though.

How are your plugs and wires?
 
Plugs I am unsure of as I haven't changed them out yet. The wires looks fairly new. (I just got the car a little over a month ago, so only know what I have done)
 
Well I got the IAC, TPS, and gasket all put in today and man was it a bitch. I am taking a break right now, but I also have plugs to do and put it all back together.. Ill post some pics later on tonight
 
When I got my 96' it was because the IAC was bad and he didn't want to change it. Car would stall if you where at a light after it was all warmed up.

I did full tune up with plugs and wires but be warmed when doing the wires. The plastic corrugated covering that is on some of the wires is there for a reason. I left it off and later on down the road on rainy days I would get a misfire code. Wound up from the wires rubbing next to each other or on the engine and was letting it ground or jump to wire it was laying on :(
 
Heres what not to do!!!!!!!!

I finished up the iac job yesterday. Went to put the hood on today and as i was backing out i found that the iac gasket fell off when putting it on:mad:..... So I am back to stage one on this and have to redo the whole job AGAIN.:Bang :Bang :Bang
 
I finally got her running great. and no check engine light :D. I replaced that IAC, TPS, PCV, and did 2 seafoam treatments through the pcv hose.. Man did she every smoke.
 
IAC How to on Gen 1

Here is my write up on how to do an IAC on a gen 1.
unplug your negative (-) battery cable.
I removed my hood to make this job easier. (probably could do with hood on)
you need to remove the wiper cowling, and then your air intake should be able to come off. Now that you have this off if you look at the back of the engine you will see your throttle body. remove the four bolts that hold this on and disconnect your cables and your TPS sensor (only electrical plug). once you have done this put rags of some sort down there so that nothing can fall in. Now if you look to the left of where your throttle body was you should be able to see the Idle Air Control (IAC). There are 2 bolts. The one against the firewall is a bolt (8mm), and the other is a stud that will unscrew (8mm). I used an 8mm wrench to break the bolts lose and then on the firewall side I used a flexible socket extension (6 inches long) and a sold extension about 6 inches long. You can get at the bolt through the passenger side (ITS A TIGHT FIT). I had someone watch and guide the socket on with a screw driver. The stud one is a little more tricky. I got a piece of tubing the was a tight fit and slid that over the stud part. I was able to use the tube and back the bolt out also through the passenger side when had someone guide me. Now you should have an electrical connector on the top disconnect that and pull the IAC out. You want to get the old gasket off so just lightly use a razor blade and scrape off if needed.

Now you are ready to install the new one. put something sticky (i used formagasket) onto the new gasket to hold it in place on the IAC. once you get the valve in place start the bolts and use those same tools as above to thread in. I recommend replacing that electrical unit on the throttle body (thats the TPS), because its not that much money and your already right there. You need to scrape the old gasket off the throttle body and replace with a new one. Once this is done you can rebolt the throttle body back on and reconnect all the lines. Now you can reconnect everything.


I Hope this helps. Sorry its not the best its my 1st write up

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