Mastermike

I have a 2000 & 2001 Maxima both with the P0505 engine code. I have done some reading and researched this problem on the web and now I'm here. I will be working on the 2000 Max first. (info) 2000 max ,3.0 , automatic, AC, cloth seats, base model 210,000 miles. Going to replace the IACV and send computer out for repair. replacing the 2 at the same time seems to be the smart thing to do. What brand IACV? Where to buy? Where to send ECU? (Don"t want to reprogram keys or re-learn idle). anyone had there ECU done recently?

maxiiiboy

Re. the IACV, buy it here
https://www.rockauto.com/en/catalog/...ac)+valve,6072
and only buy the Hitachi part!

Re. the ECU (and other issues), read my document about ECU failures (link in my signature, below).

Mastermike

Rockauto and Hitachi only for the AICV (air idle control valve). Thanks maxiiiboy!! I read your preventing ECU failures. Very nice job there. I plan on doing all of your preventative measures to both the 2000 and 2001. Now about the ECU, I saw a couple of companies you recommended to do computer work, but was wondering if anyone here has used Circuit Board Medics?

Mastermike

Moving slow on the project due to illness. What is the trick to pulling the ECU? do you need to pull passenger seat out? or pull glove box to get to computer? Its tight in there! I cant see any bolts .

krismax

iTrader: (15)

Just put the seat back all the way. Pull glove box. 4 8 MM bolts (ratchet size) After that the wires are held on the ecu with cable ties ,snap them out with a door trim tool. Like a fellow orger says put something under the ecu ,and over the carpet otherwise you'll lose the bolts. I only put 3 back in. The top driver one is nasty to get to.

Mastermike

You have to unbolt the ECU from both passenger and driver side? OMG!!

krismax

iTrader: (15)

I weigh 250 lbs and have huge hands and arms. I have pulled MANY ECU's. In the junk yard i do it a different way. I go in through the back. I take the whole radio area out. And there are two 10 MM ,and you can leave the 4 bolts in. But i know these cars like butter on toast. And that will probably be harder on you.

Mastermike

Krismax, Im learning! I got the SOB out. It took about 2 hrs and almost did as you suggested instinctively before reading your post. I am 6ft 2in 280 lbs. Very tight for this fat boy to get in those tight spaces. LOL! Waiting on my Hitachi IACV and TPS from Rock auto. Gonna send ECU out today to Module Repair pros.com as suggested by Maxiiiboy. Next move is to unplug my electronic motor mounts and replace fuse #58 with a 7.5. Can I get some help on the location of the 2 motor mount plugs? Mike

krismax

iTrader: (15)

If you get under the car by the radiator. The electronic motor mounts are right on the mounts on the crossmember. Transmission mount and timing cover mount doesn't have them.

Find the wires with your hand and eyes that leads to the mount. I then cut the wire ( people like to hook it back up at oil changes ,inspections ect) then i go back on top and remove the wire and plug.

User1

Coolant bypass the IACV. Don't waste money on the ECU. Desolder the burnt FETs and throw it back in the car.

Mastermike

Already sent ECU out for repair User1. I really didnt see any damage or smell anything burt but gonna do it all the right way the first time. Its gonna be about $450 in parts and only want to do this 1 time and be rid of the PO505 forever!

krismax

iTrader: (15)

Like he said, bypass the coolant. Otherwise it will be back. I ordered on from a ebay where they change the chip.

And it must be loose the chip because the P0505 has been on and off for 4k miles. Gonna get electronic epoxy and set it in.

Mastermike

I trust you guys on the coolant bypass and I will bypass it IACV when it goes back together. Still waiting on the computer to come back. The guy Gino from the company {Computer Module Pros} in California called today and said the computer was damaged in 2 places. One was caused by the IACV failure and the other was caused by the electronic motor mounts. He told me to get New Hitachi IACV and disconnect the Electronic motor mounts. I told him I already disconnected the motor mounts and have the New Hitachi IACV . Im just waiting on computer to come back to finish the job. I told him I was going to bypass the new IACV and he said {NOT TO BYPASS NEW IACV } because it will cause a no idle or bad idle situation. Is this true? or is he looking for repeat business?

krismax

iTrader: (15)

It ABSOLUTELY causes no idle problems or anything at all.

I had two cars with this problem . Bypassed both ,no problems at all.

A lot of people who do this stuff don't hook stuff back up ,or don't tighten everything then they have idle problems and hesitations.

My wifes I30 started having this IACV and ECU problem around 50-60 thousand miles. People will tell you not to bypass the IACV because it takes a long time to go bad. That is horse sh$t.

I live in up state NY and have cold weather.

Mastermike

Thanks for the peace of mind. I have a 2000 and 2001 Max and I will bypass on both cars. I should have figured he was full of sh*t looking for repeat business. Cant wait to get my computer back and get this 2000 fixed.

Mastermike

Coolant bypass! I"m installing the new IACV and doing the coolant bypass today before my computer shows up later in the week. Can someone explain the bypass to so I get it right the first time, and not cause any damage. I'm working on a 2000 Max. I see 1 coolant line that goes to the IAC motor. 1 coolant line that comes out of motor to bottom right of IACV. Then 1 more line that comes out of the top left of IACV and returns to the coolant stream. To properly do the bypass do I take the outlet hose from the IAC motor {the one that plugs into the bottom right of IACV } and connect it to the hose coming out of the top left of the IACV together? That would leave no hoses going to IACV at all
. It would also leave 2 ports of the IACV open to the elements. Thanks in advance for the clarification. Mike

maxiiiboy

Yes, no hoses on the IACV. And since your IACV is brand new, you don't have to worry about blowing out any remaining coolant.

Mastermike

10-4 !! Should I plug to 2 open ports on the IAC? Or will it be ok to leave them open?

krismax

iTrader: (15)

Just leave them,nothing going through them.

Mastermike

Computer came in today and I installed it. Disconnected the electronic motor mounts and bypassed the new Hitachi IACV . All went well but car still not running properly. NO CODES but car shifts irraticaly . Idle is around 600-650 a little low i think.. If car is in park idling and I give it gas the RPM will start to surge repeatedly from 1000 to 2000. Vroom, Vroom,Vroom,Vroom. RPM will bounce from 1000 to 2000 repeatedly untill I let foot off gas and it will go back to Idle 600-650 RPM. Also if I give it gas and go over 2000 RPM it doesnt surge or bounce. WTF? Thought I had done everything perfectly to the T and wasnt going to have anymore problems. Any ideas on what this problem is?

User1

maxiiiboy

Yes, I agree that this looks like a MAF problem.
However, I don't think the above part fits our cars; try this one instead: https://www.rockauto.com/en/moreinfo...59222&jsn=2198 .

User1

Been running it on my '03 intake feeding a 2014 motor for about 10k mi with no issues.

Mastermike

Guy's not sure this is a factor in your MAF decision but I failed to tell you of one thing. In addition to replacing the IACV, cutting motor mounts , sending computer out and doing coolant bypass, I replaced the TPS . I did the TPS because the guy that fixed my computer said it was a good idea. Im ordering the MAF today from rock auto. While Im waiting for the MAF to come in Ill pull the old one and clean it. That may help.

User1

Yours being an '00 or '01, I'm not sure about TPS or any relearn procedure. I replaced the engine in my '03 with a newer engine that has a TPS built into it's throttle body. I've pulled my ECU, replaced my accelerator pedal, DC'd my battery and TB multiple times and never did a relearn of any kind either manually or with NDSII and never had any issues, but I'm not sure about yours as the equipment really isn't the same.

You're on the right path with the MAF, though. I would pull it, spray it down and see if it had any effect. If so, then you found your culprit.

slvr2KSE5

idle relearn procedure for a 00/01.

It may take a few attempts for it to take. Even on my 02 it took me 8 tries to get it to take using a snap on modis.

Mastermike

I have both a 2000 and 2001 that have the PO505 code. Just working on the 2000 till it is completely fix then move on to the 2001. Thanks for the relearn procedure, I hope I dont need it! I would like to thank everyone who has contributed in this post, you guys have been a life saver! Ordered MAF today from Rock Auto it will be here next week. I took the old MAF out and cleaned it still not running properly. Ill wait on new MAF install and report my finding back here. The PO505 code in the 2000 Max is gone but still not running correctly. { NO CODES }

User1

Oh right, you have two cars. Swap MAF from other car to test.

krismax

iTrader: (15)

It needs to be set with a feeler gauge. You did this right?

I do this with the TB off the car much easier. Get someone to help you. If you do not do this the car will never run right. 95-01 maxima's have do do this when TPS is changed.

Mastermike

User1 My 2001 Maxima is not here. It is broke down 300 miles away at Virginia Tech. New Hitachi MAF has been ordered from Rock auto and will be here Jan 2nd 2020. Krismax, { I DID NOT SET TPS WITH FEELER GAUGE } !! Thanks for the tip . I'm thinking about taking it to the dealership. Tell them to set the TPS

Mastermike

Took it to dealership to set the TPS. BIG mistake!! It left running worse than it did when I took it in. Mechanic said I should try the old TPS. I did ! another mistake. Gonna put new TPS back in the car. Ill try it the way Krismax said although I havent a clue how to do it. MAF should be in tomorrow, not adding any new parts till I get TPS set.

User1

Why would you leave the dealership in worse shape than you arrived?

You don't need the dealership. Plenty of people here that know what's up with the Maxima. Some that will steer you the wrong way, but you just weed them out.

Mastermike

These guys these days cant fix sh*t unless the computer tells them exactly whats wrong. I miss old school "mechanics". New age "Technicians" cant hold a mechanics wrench! LOL no offense to you Technicians out there I'm just venting "pissed off" . Im pulling throttle body off like Krismax said and putting it on the bench to try and fix the problem myself. The problem is I'm not very mechanically inclined.. Stick with me guys! Looks like all I have to do is pull it off get feeler gauge gap to between .012 and .016 . So I will shoot for a .014 gap between the TPS arm and the arm in the throttle body. I guess I should be fine after that. Mike

slvr2KSE5

Lol. Don't talk **** unless you can do it yourself without help.


Signing off from this one as an ase master with L1 certification and 20 years under the hood.

krismax

iTrader: (15)

It's very simple i am not surprised dealer could not do it . MOST are just a step up from Walmart service guys.

And NO that is not gonna work. How you were gonna do it.

What you do is put a gauge where the TB makes contact with the set screw. (if the set screw is moved in any way or touched the TB is no good) So leave that alone.

Put a .012" feeler gauge in where that set screw is,then hook a multimeter up to term 5 and 6.(use two people)
Screws on the TPS should be loose enough to move it but tight enough to stay where they are. Then turn the TPS until continuity shows on Multimeter.

Next put the .016" feeler gauge in that spot (take the .012" out) and no continuity should then show. These are slight adjustments to the TPS. Then tighten the two screws down.

Then check it over to make sure it's done right . Do the .012" and the .016" again.

Again this can be done in your house in comfortable atmosphere.

Mastermike

slvr2KSE5, You are correct, I shouldn't shoot my mouth off like a jacka**.. The fact is I am a dumb *** and can't figure this out. I was just venting. I didn't mean to offend you or anyone else. Krismax the set screw {not to ever touch} you are talking about is on the left side of throttle body, under where throttle cables go, and at opposite end of {underneath} the vacuum canister? And is that where I use my feeler gauges ? Between the flat spot and the bottom of vacuum canister?

krismax

iTrader: (15)

This is where you put the feeler gauges ,where red arrow is. Between throttle stop and set screw. (green arrow shows set screw, do not adjust !)

Once you take the TPS out or change to a new one it messes up the setting. many people change tps and have problems,that's because they can't just bolt things on and think it will work.

I wish you would have told me you were buying TPS ,i would have said don't bother.

Mastermike

I listened to the guy that sold me the computer and bought TPS. If I had listened to you and the good guys on here I would be rolling down the road P0505 free a week ago. Thanks for the picture. Got my feeler gauges and buying a multimeter tomorrow. If I do the .012 and .016 on the bench. will I have to do the TPS Idle position adjustment on the car?

krismax

iTrader: (15)

No you can do it in your house.

get someone that knows how to use a multimeter,to help you. The full procedure is explained also, in a Haynes manual, with diagrams.

Mastermike

Krismax, I had to get my neighbor on the multimeter . I don't know about continuity, but after about 25 tries we got a beep out of the meter with the .012 feeler gauge in and no sound out of the meter with the .016 feeler gauge in. I think I am where I need to be now. Gonna install it Friday morning and drive. Hope I dont knock it out of spec on the install. I will report my findings back after that.