So a buddy of mine and I decided to finally start ripping up my 01 Maxima SE. I had a fried ECU due to a bad IACV so I'm doing all the replacements myself since I don't have $2000 to spend at a stealership. These replacements include a junkyard ECU, a new OEM Idle Air Control Valve, and a new TPS. I removed the old ECU last week, but never got around to removing everything else until today.

So let's start by saying my friend and I have very little automotive experience, but it can't be all that hard right? We start by disconnecting the battery and removing screws to remove the air intake. Turns out all of the screws holding the air intake in were stripped, but luckily they had a head that could be removed with a socket. I didn't have an extender so we couldn't reach the one behind the battery. We removed the bars holding it down and took the battery out of the car. Now there's a plug/sensor/something in the front part of the air intake, don't know what it is but we can't get it off so we just move it out of the way. Cool, so everything else is going smoothly, we take off the intake and we get to the TB. We try removing TPS plugs and they don't budge. In fact we nearly broke the clips holding them in in the process. So we skip that, start unscrewing everything, got the IACV unplugged no problem, now we reach another problem. There are 2 coolant hoses underneath the TB, so those were a total ***** to get off with the clamps holding it on plus the absolute caking that held the hoses onto the valve. Anyway, after about 20 minutes the hoses are off, coolant is flooding everywhere, but now the TB is pretty much off. We seriously COULD NOT get the plugs off the TPS, they would NOT move. So we just unscrewed the whole damn thing from it and left the throttle sensor just chillin under the hood still plugged in.

Cool! Throttle Body is off! Now we see four screws holding the IACV on. 20 minutes later, the screws are stripped to nothing after several attempts to get them off. We tried WD-40, Liquid Wrench, everything and they were shot. We drive to Home Depot and by a Dremel tool, and like 50 replacement blades (along with a 12v converter for his car to power the damn thing, we have no garage or space to do all this work since I live in the projects). After about an hour, we dremel a head into the four screws holding the IACV on and eventually got them off! BUT the sonuva***** still won't budge. Wait, what's that? A screw in the oddest spot, but okay. We strip it (of course) and try dremelling a head in it. The screw decides to break in half. Great. During the next two hours, we completely cut the IACV in half and finally got it off. It was 9pm and we were hungry so we threw all the tools in my car, bought some Gojo, and went to Chili's.

Next step is to buy some replacement screws (not even sure what size screws I need) for the new IACV to screw it onto the throttle body, screw the f--ker on, change the TPS (that's gonna be fun) and put my car back together (OH and add some coolant too, that'd probably be helpful. Or maybe not so I won't have to worry about **** leaking and shorting **** out.). I have a feeling I'm just gonna end up back to square one after the new ECU is in and reprogrammed and ****. Something's gonna screw up and the new ECU is gonna fry. Whatever, f--k this car with a burning passion. I've had the car for two months and can honestly say I will never buy a Nissan again.

Anybody wanna give me tips on where I screwed up and what to do in the future? Maybe out of some miracle it will all work once everything is put together? :O Thanks in advance!

-Stru

 

Looks like you jumped the gun on the IACV, the sensor itself only has two screws holding it on. You shouldn't have to replace the housing itself.

 

If the electrical connectors are gray with a green locking tab, you have to push the green tab down into the connector and then pull the connector off while you are holding the tab down. Nissan didn't want people taking those connectors off.

I don't know what size those bolts are, but I would think that if you took one to a good hardware store, they would have some. I had to get some nuts and bolts Tuesday and Home Depot had them.

Hoping that you can get everything assembled correctly, the car probably will not start. Because you changed the ECU, your keys won't match what is stored in the ECU. If this happens, the red led in with the clock will be on solid while you are cranking the engine. You will need to get a locksmith to re-program all your keys. Once you get the car started, you will have to do an idle re-learn.

 

Okay, that makes a little more sense about the connectors. I'll remember that when changing the TPS. I'll just bring the screws to Home Depot and let somebody there find the same ones for me lol but yes I am aware about the ECU programming. I'm not even going to put the key in the ignition after I put the new ECU in because I hear you can destroy the immobilizer like that. I'm just gonna tow the thing to the dealership and let them do all the programming and relearning (if I make it that far with this job). Thanks for the help!

The OEM part I ordered came with the entire housing, so I might as well be safe than sorry.

 

Trying to start the car with what Nissan calls a "non-registered key" should not destroy the NATS immobilizer. When I read about situations like that, there have been lots of other "things" that also happened before the finding of a bad NATS.

Do it whatever way you want. But I would call local locksmiths first and see what they would charge to come to your place and program the keys. Probably cheaper than a tow plus dealer charges. This would also be a good time to get and extra key or two made.

 

The FSM is your friend in these types of situations. Helps greatly to look over what you want to work on before actually working on it.

 

You should definitely replace the whole IACV housing because it most likely failed due to coolant leaking from either the o-ring gasket or internally which shorted out the IACV.

I just went through all of this and found my ECU didn't fry (I was lucky) so I just replaced the IACV and TB gaskets. It is really important to replace both the O-ring type TB gasket and the one on the black plate to insure no air leaks.

You may be interested in getting Nissan Data Scan II program as well (about $70 bucks plus $12 for a generic adapter). This will give you easy control of idle air volume reset as well as can reprogram keys (!) and of course gives you real-time read out of RPM, coolant temp, and more.

I went through all of this and found that someone jacked with the idle screw. After all of the IACV replacement etc it was a simple couple small turns of idle screw which got my idle down to normal.

While you are at it you should replace the TPS (throttle pos sensor) bolts and the ECM bolts with some hex heads and the appropriate washers (home depot, lowes etc). This will make your life a lot easier when adjusting TPS and reinstalling ECU.

 

Those plugs are a bit awkward to get to, so what I did for practice was unplug one of the connectors in front of the engine near the cover plate for cylinders 2,4,6. You'll see like 3 or 4 connectors and 1 or 2 of them are similar design. Push tab with screwdriver and wiggle it out. Once you see how it works, it'll help removing the TPS connectors.


I know you've already done it but I put an old towel under the IACV to catch coolant, however despite it looking like a lot of coolant got out, it really isn't, I didn't need to top off after doing mine, but check it to be sure when you get to that point. And yeah, those hoses, after 12 years, are a PIA, probably took me an hour cause my big hands could hardly even fit to reach them! On the good side, they go back on easier!


LOL, I didn't see the 5th one either till after I removed the four screws and it still wouldn't come apart.


Those never work for me either especially on tough jobs, best thing I've found is PB Blaster, it has yet to fail me! The thing to remember with these loosening compounds is the tougher the job, the longer you need to leave the stuff on to be effective (like 2-3 hours, if not overnight).


Damn!


Remember that you must remount the TPS in exactly the right location on the TB such that the requirements of FSM page EC-444 step 7 are met (switch ON with 2 mil shim, switch OFF with 6 mil shim).


It's a PIA, but remember it's a 12 year old car, and after that many years some things are going to fail, though I agree Nissan's engineers were incredibly lame to have a design where one failure (IACV) causes a secondary failure (ECU), that just shows incompetence, though I suspect the engineers responsible have been long ago "retired", unless they did the "honorable thing" instead!

 

Hey, I didn't see that you were in Branford. I live in East Lyme and maybe can reset the idle for you and even program your new ecu to your keys if you get hung up so you don't get raped by the stealership.

Get everything back together and let me know. Maybe we can work something out with some dough for gas money and/or decent beer.

 

lol thanks my dude but I just got off the phone with Barberino Nissan in Wallingford. Once I get the junkyard ECM, I'm gonna have them do everything and it's gonna only run me about $400 for labor (a lot better than $2000 since I'm not purchasing a new ECM, IACV, or TPS through them). After looking further into the IACV harness and running further diagnostics, the wires are fried and I'm almost positive that will just fry the new ECM I put in so I'm not even gonna bother touching anything anymore. I don't think there's a way to install all new wires to the ECM without replacing the whole entire ECM harness. Just gotta save a few hundred dollars, that's all. Maybe I can even get them down a little bit depending on how much more work I can get done plus how much work I have them do. Maybe I can get a flat rate at what it'd take to just replace the wiring harness and TPS (since I CAN NOT get that son of a ***** off, I have tried everything).

 

Ok man well if you get jacked up give me a shout. Just went through this on my max. Only had it for like a month too. Let us know how it turns out!

 

Well I know I kind of jumped to conclusions about the wiring harness and connections to the ECM, but I highly doubt the IACV harness is supposed to look melted like this



Aaaand there's the TPS hanging in the background, still haven't gotten it off...

 

How much are the parts costing you at the scrapyard?

 

The only junkyard part I'm getting was the ECM for $245. Throttle Position Sensor I got off of RockAuto and my IACV was an OEM part I ordered off of Ebay that another user on this forum recommended to me. All together I probably paid about $450 in parts, then if I bring it to the dealership it's gonna be about $500 worth of labor. $950 total, really beats $2000 when you don't order new parts through them.

 

Hate to point out this but the FSM will show the different electrical harness connectors and how to remove them.

 

Even if I was to replace them myself, where does one acquire an entire new harness?

 

A new wire harness? You can always visit the salvage yard and cut the wiring harness off then splice it into the wire harness in your vehicle. But it has to be done right for the splice to last. Otherwise you are looking at pulling the engine to replace the entire engine wire harness.

 

If you ever need a connector for the IACV that burn up I located one at a specialty connector company. I had them make me 11 of them. I used one at my shop on a repair job (it was worse than this one).
Search ' Nissan Six Pin Pigtail ' on eBay. Thought this may help you or someone else.