sascuderi

Can someone who has done the bypass post a pic of where these hoses are on the IVAC?

nelledge

iTrader: (6)

It's pretty obvious if you go out and look at your car. I don't have any pics, but I can give you the link to NWPs spacer install for the VQ30DE which will give you an idea.

Darkrock

Start here: search...... Coolant Bypass

Pilm

I know this is an old thread, however from what I can see it's one of the best threads for repair of a P0505 code, so rather than start a new thread it seems like it would be better to keep questions on this in one place. Anyway, as noted in the quote above, ECU rebuilders recommend (in fact, they say it is required) that both the IACV and TPS be replaced before installing one of their repaired ECU's. I think I understand their rationale, a stuck open throttle could (I guess) cause the ECU mosfet to rail and pop just as much as a shorted IACV, so to be safe, they want you to do both. But my question is, if you really have a throttle sensor problem, wouldn't you get a code for that (e.g., P0120, or maybe P0510)? That is, can you really have a defective TPS/maladjusted throttle and no code? Or would a defective TPS also throw a P0505 code because it results in a fried ECU, which in turn might damage the IACV? I hope someone might be able to clear this up for those of us who aren't sure if replacing both are really necessary, thanks!

EDIT: my own answer to this would be to test the TPS to see if it is good or not, you can remove it from the throttle body easily (at least in an 01 Maxima), and check the closed throttle switch path and open throttle switch path for proper on/off continuity, then test the sensor side to make sure closed resistance is correct, then watch the resistance change as you open it up, make sure it changes and is linear as you rotate it. I found that mine was good so I ended up not replacing it.

Pilm

Anyone know how critical the TPS adjustment procedure is? The procedure says you should have continuity with a 2 mil feeler gauge, and no continuity at 6 mils. I'm finding it difficult to hit these numbers exactly because just a very slight rotation of the TPS easily changes the point between continuity and no continuity by 10 mils. Of course it moves slightly after tightening the bolts too! So the best I've gotten so far is continuity at 5 mils and no continuity at 9 mils. I know if I rotate it again and retighten I'll be off by more, so I'm wondering what would happen if I left it at this point, would I just get a slightly higher idle RPM?

EDIT: I went ahead and kept settings at 5/9 mils, started up car after replacing damaged IACV and replacing blown mosfet STA509A in ECU, and P0505 code is gone and car runs great so far. This thread has been instrumental in helping me fix this problem myself, particularly the posts by Kaane and nakis, they did some really awesome work, Chapeau gents!

dozu

question on the STA509A - does the 'SK' number on the chip mean anything? e.g. 'SK 1129'.

looking at the *bay now and there are lots of them for sale, but some says (B2) and some says (A80)....

are they all the same?

dozu

bot the IACV and the STA509A chip off the flea bay... both arrived today so I got right into it.

already took the bad chip out yesterday, so today just a matter of soldering the new chip on, tested the connections on pins 2 thru 9, everything looks good, so I put the ECU back in.

took a while to take the airbox assembly off, then unbolted the throttle body. I then gave the 4 screws between the IACV and the TB a good soak of WD40, but missed the 5th screw in the middle! duh!

next step was to cut out the coolant hoses... then had to run to autozone and sears to get a replacement screw, and 2 feet of hoses.

then did the coolant bypass by running 1 hose between the 2 nipples on the coolant passage, and running another hose between the 2 nipples on the IACV to cap them off.

then reconnected the TPS and the IACV, bolted on the throttle body...

Fired the car up and it idles like a champ now. the error code was gone instantly. I didn't need to do a idle air relearn.

Kudos to the folks on this thread who gave such detailed info.

by the way, car is 5th gen MT.

camsauce

Just started my adventure with this problem as well. I went from a very low idle 300-500 (car would stall until warm). Replaced IACV and TPS, now idle goes from 1700-2300 and bounces back and forth. Pulled ECU and low and behold, the STA509A took a digger. Ordered replacements from eBay and will solder on when they arrive. Wish me luck.

camsauce

Got the new STA chip and soldered it in. Tested all the circuits and found that the trace for pin 3 had burned completely and repaired it from the back side with some wire (same thing Nakis did). Unfortunately I still have the idle problem even after running the TPS sensor reset and the Idle Air Volume Relearn. Any suggestions from the hive mind?

dozu

time for a new computer I guess

EuroDriver

iTrader: (21)

Check your idle adjustment via the idle screw on the TB, and your TPS adjustment. On mine, I had to crank down the TPS in order for it to accept the relearn procedure. Once it did, readjusted TPS, did idle relearn again and that's all it took.

4th gen maxi

iTrader: (1)

I HAVE THE SAME PROB. LET ME KNOW HOW YOU COME OUT LOL....all i see is DEEP ****!!

4th gen maxi

iTrader: (1)

i have this same issue for months now. does your idle stick at 2-3k and sometimes bit lower ? i have tested iacv and tps along with egr since my last replacement was injectors not a clue how ima deal with this junk if mine fries when i get one.

Amave

i was so afraid of this issue i did the coolant bypass before anything tragic happened ..


sorry guys about your problems, do the coolant bypass asasp

nestorlugo

iTrader: (11)

Hi fellow max head...how did the ecm turned out?i got the same problem have the mosfet thing and was going to try your method...

avritch

I just had this problem on my 2001 Maxima with 185K miles on it.

I removed the IACV and it has a shorted coil. I removed ECU and it has the fried mosfet array. I've got the new chip on order, but and perplexed with the cost of the IACV.

I see eBay prices for new non-OEM starting at $49 all the way up to new Nissan OEM at about $240. That's a really big spread. Autozone and Advanced Auto are over $200?.

Has anyone gone with the less expensive non-OEM ebay version?

Please let me know what you've used.

Thx
Steve

97maximachief

iTrader: (1)

I've used the $65 one off eBay for a buddies car. Been 2 years with no issues.

avritch

I ordered the eBay version for $50... (includes gasket and hardware)

http://www.ebay.com/itm/261162458207...S:3160&vxp=mtr


Mosfets also ordered from ebay (2 for $15)

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=151071095926&ssPageName=ADME:L:OC:US:3160

Took the MOSFET off of the ECU today. Found 2 burned traces. One on Pin 5 and the other on Pin 9 of the STA509A

We'll see how it goes when the new parts arrive....

avritch

OK... chips arrived and installed into the ECU with 2 burned up traces jumpered....

Now just need the new IACV to arrive.

Pilm

Pretty good work. I didn't have a solder sucker so my repair turned rather ugly, but I got the new mosfet deadbugged in there and it's been almost 2 years now and it's still running good!

clive

@nakis: true engineer, props to you, man.

Donkeypunch

Is this 100% what happens?
Some seal breaks and coolant shorts out the ICV???
Only way?

avritch

OK... the $49 IACV from eBay arrived today... installed it and every worked great. The idle settled right down to ~700rpm once the engine warmed up so I didn't even do the idle relearn procedure.

The hardest part of the whole repair was those stupid little 8mm screws holding the ECU in place... there's just not a lot of room to get your fingers in there. A ratcheting box wrench really helps.

One little oops... I had tested everything prior to re-installing the ECU and all checked out good. I had to disconnect the big electrical connector to re-install the screws... well, when I reconnected big connector a pin got bent. RPM gauge didn't work and a couple of idiot lights were on... Thankfully I was able to locate and straighten the bent pin and then everything worked great.

If you haven't seen the video on youtube... you can find it here

To sum it up... not a hard repair and turned a $1000+ dealer charge into a $65 home repair
I didn't do the coolant bypass. I may do that as well as pull the engine mount connectors to protect the ECU from future damage.

TravisCadello

Wow, I just read every bit of this. Weird thing is i never had the issue until i removed my Throttle Body to clean it all up then never idled right again and got code p0505. Its a 2000 MAXIMA 5speed. been 3weeks same issue.


My timing is at 7BTDC used to be at 17....it idles at 1100RPM constantly, ive adjusted both small screws as low as they would go, it was idling at 1400. I replaced my IAC the old one OHMed at 27.1 on all 4 test which means should still be good. Tried relearn over 50 times. Guess ill removed ECM and see if i see anything burnt.

Any other advice?

00Lightsout

vq35 swap

TravisCadello

yesss!!!

car5car

Продай мне свою Максиму и не мучайся.

00Lightsout

Clean/replace MAF.
Clean intake temp sensor with MAF cleaner, maybe it'll help a rad.

If u reinstalled the throttle body with the old gasket, you prob have a vacuum leak behind the throttle body.

list what you did to it in order on your next post

maxiiiboy

I have bought the $58 IACV from eBay/AIP Electronics but have not installed it (yet). The part looks good, and its DC resistance is "per spec" (21.95 ohms), with no shorts.

My problem is: I am trying to understand whether most IACVs fail because of leaking coolant, or because of the insulation failing due to heat or poor material. The answer to this question will determine whether I do coolant bypass, or IACV replacement.

There are reports on this forum of failed IACVs that on inspection show no coolant leak whatsoever.

Avritch & all, what is your experience, and what do you think is the best solution for the IACV/ECU problem?

isrb710

Maybe this link will help.


http://www.avproecm.com/nissan.htm


Avpro will now repair your ECU (ECM in their lingo) back to its original not-so-good design for $190 including shipping back to you. And they promise to fix yours within 6 hours of receipt and ship it back quickly.


Alternatively, they will upgrade the ECU with 1 (or 2 depending on which ECU) of their chip/Integrated Circuit designs that prevent frying the ECU for $250!


Here's what they say:

The years 2000, 2001, 2002 and 2003 saw some problems with the Nissan Maxima and Infinity with regard to the idle speed control motor. It seems the urethane coating used on the magnet wire that was used to wind the coil pack starts to break down at the temperatures used to mold the coil. This leaves the possibility for the windings to short circuit after the cars have been in service for a few years. In addition to the IASC (idle air speed control) going bad, the excess current during the motor failure damages the ecm, sometimes severely.
Avproecm has studied the various damage modes and is expert at repairing burned fiberglass FR-4 circuit boards and have the replacement parts in stock.
The cost for the Maximas, Infinitys, Pathfinders and Sentras is $190. This includes return priority mail.


Avpro designed and manufactured replacement modules now available.

NO re-flash programming necessary. Plug and play. Simply indestructible!

These Avpro modules sense any overload on the outputs to the idle speed valve within 10 micro-seconds and shut down all outputs to the valve for 2 seconds. The Avpro modules then retest the valve for faults. The same P505 code will show and a check engine lamp will come on until a new idle valve is installed. The part is transparent to the normal operation and recovery, as well as the relearn process. No damage to the engine controller will result.

brando7

your pictures wont load ((. wouldnt it be easier to just add a fuse off the lead for the iacv then in the ecu? where do you add the fuse on the board and size of fuse??? my email is b_m_electronics@yahoo.com

Quickywd01

iTrader: (16)

I can see them.

SrgScott

iTrader: (2)

I can't see them just like brando7....

djbit

avritch (or anyone), would you happen to have high resolution pics of the back side of the ECU board? In trying to desolder the chip I screwed up the paths. Any help much appreciated!

I did find a way to solder the chip without disoldering it. I just wiggled the chip back and forth until it broke off. I then just soldered the new chip to the broken legs at the base (very easy!). If only I had of thought of this BEFORE attempting to desolder the old chip!!! Live and learn.

I guess this is my first post. Hi all!

djbit

Attached is a better pic. Thanks again!

The_Fixer

iTrader: (1)

Wth are you doing? You need atleast 500* F to desolder and some flux and or desolder braid you can NOT just solder the new sta chip to the remnants of the old leads it will not work.i have done over 70 of these repairs in the last 3 months and never had a issue.

djbit

To solder the chip to the "old leds" I used at he following soldering station:

http://www.xytronic.com/pi/379.htm

Soldering was not a problem.

To desolder I tried using a Radioshack desolder tool with the red bubble suction thing...this was a fail as you may have seen from the pic.

Why do you say the new chip will not work soldered to the old leds? Connectivity tested out fine on both sides of the leds (top/bottom).

Do you have a close up the paths? I can make a calculated guess on a few of the screwed up points but this ain't no guessing game. Anything helps.

Thanks!

avritch

Sorry, I looked through my files and I cant find the nice photos that Nakis had posted. Hopefully someone can get ahold of Nakis and have him repost his original photos.

djbit

avritch, thanks for checking!

Here is one of my guesses....if any one can verify....just shooting blindly. I may hit the yard this weekend and see if I can find one to snap pics only.

maxiiiboy

Djbit & all,
this is a noble effort and if you succeed, it may keep you going for a while.

However, the only permanent solution is to protect the critical driver transistors in our ECUs from failures of any actuator/sensor (IACV, Motor Mount, TPs, ... etc.). I know of two solutions:

1. Send your ECU to AVPRO. They will repair it within a day. For an additional cost, they will add their OVERLOAD protection to your ECU board. I believe they charge $140-190 for the simple repair, and $240 for the latter. The $240 solution is what you want: should your IACV fail, it will isolate the IACV from the ECU, and a P0505 will pop up. All you have to do is to replace your IACV and you are back in business. No need to replace any fuses, ever (at least that's what they say).
   
2. Implement a FUSE protection for your ECU yourself. The best bet is to install the FUSES at the ECU bulk connector side of the wiring harness on pins 6,7, 8 and 17; this means splitting the associated wires, finding the proper fast-acting fuse (6Amp has been suggested), finding a place in the fuse box for the new fuses, and adding & routing the fusing wires (ECU bulk connector <--> Fuse Box). And yes, test it to make sure your stuff actually works and that the fuse you selected blows before your ECU does.

I would love to have the AVPRO solution but I can't be without my car for 3-5 days - that's what it would take with shipping/handling. However, I have implemented both (Coolant Bypass + Motor Mount Disconnect), so I feel I am 75% protected.

To all ORG members: Has anybody implemented any kind of "fuse protection"? If so, can you share your experience? Any other alternatives or comments?

BTW, NISSAN engineers should get an "F" for how they designed this whole subsystem .....