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Do thgrottle bodies go bad? Nissan trying to tell me it is. 01 Maxima

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Old Feb 25, 2012 | 09:08 AM
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A bad throttle body? Nissan says so -01 Maxima **RESOLVED**

01 GXE automatic.

Car began stalling out of nowhere yesterday at low rpm or when coming to a stop or trying to accelerate slowly. I wasnt with it but mom described the symptoms. I couldnt get there to check it so she had it towed to a garage she uses. They said "the computer needs upgrading and reprogramming... Hmmmm... Its an 11 yo car...and NOW it needs a computer flash? He tried to compare it to upgrading software in your home computer. Ooooooo kayyyyy. Yeah...I know what a computer flash is....but 11 years later?!! The Nissan service advisor I spoke to afterwards was laughing at that one. Now I DID find on another thread in this forum that there WAS a recall for 01 Maximas to upgrade the emissions software but I imagine it was a loonnnnnnng time ago and wouldn't suddenly cause the thing to stall at idle and stumble on acceleration. That's a sudden component failure IMO....and that private garage shudv found the same thing Nissan did. IACV code! Maybe they did but didnt want to change the part since they couldn't do the re-program. Either way the guy didn't get into details about a component failure. He just said the ecu needed re-programming...which initself wasnt the entire story it turns out.

Had it towed to Nissan who gets $110 to diagnose the problem and at first they said MAF looked like a possibility. Now the word is MAF is ok but it needs a new throttle body. Short of a crack maybe due to age... how can a throttle body go bad? Its a hunk of metal with a TPS and IAC valve screwed on it and thats about it! Needs cleaning now and then but otherwise theres nothing to it!! They want $940 for a new one (which of course isnt even in stock). Sooo....do these things go bad or what? Short of an age crack...Ive never heard of it happening.

I mean ...if its really bad...I can prolly get a performance TB for that price or less and pick up a few ponies...and still have money left over to get one of those electric superchargers, a tornado air velocity improver and a magnet on my gas line to increase mileage...! LOL!!! My BS buzzer is goin off....

He's awaiting my answer. Car is at the dealership now. I'm not sure about the bad throttle body story. Any thoughts?

Thx.
Dave

Last edited by Dave448; May 24, 2012 at 02:45 PM.
Old Feb 25, 2012 | 09:13 AM
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Originally Posted by Dave448
... Its a hunk of metal with a TPS and IAC valve screwed on it and thats about it!...
Several threads on bad IACs. I wouldn't doubt it. Be careful, though. It's not a big deal for some dealerships to 'guess' a part is bad, replace it, and find it's actually something else. Like, they'll end up telling you the ECU needs to be replaced too(common story on the 5th gens.). Ask them to have the diagnosing tech(not the service writer) explain to you specifically what is wrong with it. You are the customer. You will have to ask specific questions or you may get broadsided. Take notes while speaking to him and report back with his explanation.
Old Feb 25, 2012 | 09:41 AM
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$1000 for a TB......LOL

$15 at a junkyard and maybe 30 minutes to change
Old Feb 25, 2012 | 10:52 AM
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Actually having a IACV (Idle air control valve) go bad is a common occurance on 5th Gens. It is the escape valve that lets air through even when the TB is closed at idle. When it gets clogged up it goes bad and generally people replace them istead of going through the trouble of trying to clean them out. You are probably better off buying a IACV new from a online dealer and installing it yourself. That is what I did when mine went bad. Still pretty expensive but not $940 expensive.
Old Feb 25, 2012 | 04:23 PM
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Thanks for the replies. IAC motor (valve) was my first thought as well.

I wasnt buying that bad throttle body assy (tho to be honest the possibility of corrosion didnt occur to me - which has YET to be proven). I talked to another Nissan dealership and the parts guy checked his computer. U know how many throttle bodies their parts dept has sold for that car? NONE! EVER!

So..... I went to the Nissan dealership and spoke to the mechanic whos working on it. He said the coolant passages on that TB are right near the IAC valve seat and hes seen many corrode thru the aluminum and affect the IAC valve to where it damages the computer. Of course it usually only affects 00/01 models and not the rest for some reason! Unless im mistaken....he said something to the extend of coolant/water can lead to corrosion in the TB coolant passage and rot thru the aluminum then short the IAC valve out and sometimes damage the IAC driver in the ECM. I cant imagine water getting in the IAC valve coils since theyre sealed in resin. My guess if there is corrosion present wud be corrosion maybe causing the IAC valve to STICK and not spiral in n out anymore or just get stuck in the TB bore and the excess current draw from trying to open and close it might cause the ECM output to be overloaded and damage the driver transistor. Either way.... IAC valve was the code that came up and without even taking the TB off the car to inspect and verify that its ONLY a bad IAC valve thats the problem... they ASSUME its a corrosion problem and want to order the TB ASSY which includes TB and IAC valve for $651. I can understand why. It means less chance of a come back in the event the TB is still good but then does corrode later and also gives them an instant markup on more parts by selling the TB and IAC valve together. HOWEVER it wud be nice if they at least TRIED to save a customer some money... AND TIME...especially since Pep Boys, Advance Auto and Autozone all have a NEW IAC valve on the shelf for $200-210 each - (Nissan wants 316 for the IAC valve alone...which they dont have either).

The mechanic is guessing the TB might be corroded based on past experience. Its quite possible the Throttle Body is fine and just the IAC valve went bad on its own. I called an ECM rebuilder I found online and he said the 00/01 Maximas use an IAC valve that after time...the resin can break down and cause the valve to short internally and sometimes damage the output of the ECM. Its the most common ECM damage he sees in Nissan ECMs of that era. Sooooo it CUD just be a bad IAC valve and have nothing to do with corrosion!! Guess I'll find out after the fact bcus rather than take the car back and let me give it a shot...the folks just want it done....so they left the car there while they rent a car and wait for a TB/ IAC assy to arrive in a few days. $900 + rent a car... CA-CHING!!

I'm requesting the old parts back and will inspect them myself.

For anyone who wants to attempt replacing the IAC themselves... I have to add that a dealership master computer or scan / set tool MAY be required to set the valve position (so mayber $100 for an hours dealership labor). The mechanic said most of the key on/off voltmeter set procedures dont work and it usually requires a scan tool that has the ability to tune the ECM or a master computer to set the IAC valve idle speed properly.

Soooo....$651 TB assy + $222 labor and another $22 for shop consumables (which are paid for 100x over every day by every customer who comes thru). Thats a LOT of RTV....and some expensive shop towels! I hope theyre embroidered. Guess thats how they stay in business....

Well....folks made the decision to and its their car soo.....

"Thank you sir may I have another?!!"

And thanks again for the responses. I'll post a follow up if this fixes it once we get the car back and it has a week or so of proven reliability.

Enjoy your weekends
Dave

Last edited by Dave448; Feb 26, 2012 at 11:36 AM.
Old Feb 25, 2012 | 04:32 PM
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dave - you are an example of a GOOD n00b. hats off to you.
Old Feb 25, 2012 | 04:34 PM
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Clean your TB, IACV and MAF before buying anything.
Old Feb 25, 2012 | 04:47 PM
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had the same problem with my dads max.. and Chrisman287 is right clean all those before even dropping a dime at the dealership, and if it does in fact turn out to be that problem do wat we did and just adjust the idle a lil higher so atleast you can use the car for the meantime until you get it fixed the rite way.
Old Feb 25, 2012 | 07:17 PM
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Originally Posted by Amerikaner83
dave - you are an example of a GOOD n00b. hats off to you.


best n00b I've encountered
Old Feb 25, 2012 | 08:56 PM
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Wow, it only cost $500 to replace my gf throttle body.
Old Feb 25, 2012 | 09:55 PM
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Wire control FTW. I replaced the valve cover seals on my dads 02 today and i didnt even want to touch that TB lol I just left it attached to the IM. Didnt want to have to deal with a reset. The 35 engine is great in alot of ways but its bad in alot of ways too.
Old Feb 26, 2012 | 02:54 AM
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so if i replaced my IACV i would need a Nissan CONSULT to set my idle?

thinking of buying a new valve as preventative maintenance
Old Feb 26, 2012 | 06:12 AM
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Originally Posted by ShocknAwe
Wire control FTW. I replaced the valve cover seals on my dads 02 today and i didnt even want to touch that TB lol I just left it attached to the IM. Didnt want to have to deal with a reset. The 35 engine is great in alot of ways but its bad in alot of ways too.
The 2001 has a VQ30DE-K w/cable operated TB. The 2002 has a VQ35DE w/drive by wire TB. Totally different setups.
Old Feb 26, 2012 | 07:27 AM
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Looks like one more thing I need to be on the lookout for. Had to clean out the TB and IACV on my wife's P5 when it started throwing codes and idling like crap. Took some time and effort, but it only cost me a can of CRC parts cleaner. Maybe I should think about doing this just as a preventative, although you guys say I would need to have the ECM hooked up to relearn the IACV position afterwards?
Old Feb 26, 2012 | 01:29 PM
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Appreciate the advice to clean IACV MAF TPS etc guys...but I wasnt with the car when mom had it towed to garage 1 where it was diagnosed as "ecm needs re-program upgrade" but he can't do it...and no mention of bad components. - Then car was towed to Nissan where they said bad throttle body without ever mentioning IACV till I met the mechanic when we picked up the rental car and grilled him to find out the code was IACV. If it had been towed back to the house...I would've cleaned everything and gotten hold of an obdII scanner b4 takin it anywhere but...that wasnt the case.

My guess is its exactly as that ECM rebuilder I found in ft meyers described. Prolly resin breakdown internally in the IACV...and HOPEFULLY it didnt damage the ECM.

I told the folks to call Nissan back and have em order a seperate IACV in addition to the TB/IACV assembly. That way if they find no corrosion...they only change the bad valve...and with any luck ECM IACV transistor isnt smoked. Its no skin off their nose to keep a TB assy in stock for the next "sucker" or send it back to the parts warehouse.

BTW.... Heres a 2006 post I found on this forum re: stalling, hesitation etc. Cleaning or replacing MAF IACV TPS TB.... Some solved their problems...temporarily...a couple permanently...most didnt...and some just got rid of their cars in frustration

http://forums.maxima.org/4th-generat...-randomly.html


And Galactica...changing the IACV as a preventive...*** NOTE: I originally posted here if it aint broke dont fix it....HOWEVER....FOODMANRY below put it in terms of spark plugs oil filter etc....and He's RIGHT!! Thats maintenance....and in this case.... the IAC valve is a KNOWN trouble spot that could short and cause ECM damage ending up with further expense and possibly even stranding you. If you've got a few bills layin around I WOULD replace the IACV if its original as in spend some now to save some later. It MIGHT be possible to set the valve yourself by adjusting TPS afterwards and idle screw but more than likely it will require Nissan to recalibrate the computer for the new valve. IACV prolly around 200 at autozone or advance auto and Nissan labor best guess $100 to correctly set the idle.


Will check back when I know something guys. Gotta go lay under my Eclipse now and pull an alternator. nothings workin right around here! Maybe rain will clear up so Daytona can run.

Noob signing off...Later...


(I'm not an ASE Certified Mechanic...but I play one on TV)

Last edited by Dave448; May 24, 2012 at 04:13 PM.
Old Mar 18, 2012 | 09:53 PM
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dude, any updates?
Old Mar 18, 2012 | 11:59 PM
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$940 to replace throttle body..
Old Mar 19, 2012 | 05:59 AM
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Originally Posted by nelledge
Several threads on bad IACs. I wouldn't doubt it. Be careful, though. It's not a big deal for some dealerships to 'guess' a part is bad, replace it, and find it's actually something else. Like, they'll end up telling you the ECU needs to be replaced too(common story on the 5th gens.). Ask them to have the diagnosing tech(not the service writer) explain to you specifically what is wrong with it. You are the customer. You will have to ask specific questions or you may get broadsided. Take notes while speaking to him and report back with his explanation.
Lol that's how I got my AE for $1400... dealer told him he needs a new ECU and a ton of crap and come to find out all he had was a bad MAF
Old Mar 19, 2012 | 06:00 AM
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Originally Posted by infinimax96
$940 to replace throttle body..
At that point id buy a PFTB and EU lol...
Old Mar 19, 2012 | 08:27 AM
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Originally Posted by Dave448
And Galactica...changing the IACV as a preventive..."If it aint broke...Dont fix it!" Why spend even $200 for one from the parts store it its still running fine?
I guess you never change your oil, coolant, ATF fluid, spark plugs, fuel filter, etc...

Personally, I'd rather pay the $200 to replace the IAC valve and have dealer reprogram idle for another $80 than end up frying my ECU and dealing with that mess.

Yes, in fact, I did do this a year ago on my 2k as part of preventative maintenance. Too many issues I saw online with the problem so I didn't want to risk it.

Good job experienced newb...you may want to reconsider playing "ASE mechanic" on TV.
Old May 21, 2012 | 10:34 PM
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Resolved

Sorry for the late update guys. Its fixed. Folks just wanted it done and not delay by ordering more parts so they went with Nissans advice and replaced the entire TB assy. It included the IAC valve and TPS sensor for just over $600. With labor the bill came to over $900! The code they had at the shop was ONLY IAC valve so they SHOULD have tried that first but I suppose for reasons of expediency and to avoid possible come backs or find out the TB is corroded after the fact they just order it as an assembly. Guess it was too tough for them to remove the valve from the throttle body and inspect it FIRST! So I got the old TB back and took the IAC valve off and as I suspected...TB was in perfect condition. Very clean inside and out for an 11yo part. NOT A SPOT of corrosion outside or in the coolant port either. Oh well...I offered the folks to get an IAC valve and try to change it. Cud have fixed it for 2-3bills total but whats done is done.

Oh and FoodManry...I see your point about pre-emptively changing the IAC valve on a 10+ YO car esp when its a known trouble spot and may lead to a damaged ECU down the road. Most ppl wouldn't just lay out 200 or 300 to change a running part but I do see your point about penny wise and dollar foolish in this instance. I occassionally overlook the obvious and am not too proud to change my line of thinking when something logical is pointed out. Editing my original post on that bcus a pre-emptive replacement of this part is callled for given the chance it might end up stranding someone or causing more expensive damage.

Last edited by Dave448; May 24, 2012 at 04:04 PM.
Old May 22, 2012 | 10:22 AM
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What's the name of the ECM rebuilder you contacted?

I'd love to get an internal diagnosis done on the 2002 Maxima's throttle valve. I pulled mine off and it failed the 'shake' test so I dropped in the used part I picked up ages ago. Car feels better but I really want to teardown the electronics and find out why it failed.
Old May 24, 2012 | 03:27 PM
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RR5 - WHY the IACV failed is ez? Poor design and age. After speaking to the rebuilder its that internal insulating resin that breaks down shorting the IACV coil to ground and ruining the valve ....and sometimes takes the IACV Mosfet driver transistor in the ECM with it.

Sounds like you replaced the valve and the car is running so chances are your ECM is ok. Im guessing the computer wasn't re-calibrated to set the position of the used valve after you installed it so your idle might not be spot on. My guess is idle rpm is prolly a bit low or high....or you could've gotten lucky.

** Keep in mind that used IACV you installed might be a time bomb if you took it off a car of the same vintage 00-03 meaning you risk the valve shorting out possibly leading to ECM damage**

With what I've found out about those 00-03 valves and given the alternative of a possible failure leading to a tow to Nissan, having them try to replace an entire throttle body and possibly an ECM replace or rebuild.... FOODMANRY is right! If you have an original valve that hasnt yet failed ...since its a known problem...AND you've got a few C notes looking for a good home and plan to keep the car....its not a bad idea to change the IACV and have the idle set at Nissan. Basically spend some money to save some money.

IF you ...or anyone ends up with an ECM issue.... the ECM rebuilder I found is AV PRO in Ft Meyers Fl and the guy I talked to is Nick. They also offer their own IACV driver module upgrade for the Nissan ECMs which is designed to prevent ECM damage if an IACV valve shorts out. Im not sure if this replaces the original Mosfet driver transistor or plugs externally of the ECM to prevent the original transistor from smoking. Sounds like it replaces the original transistor to me tho.

My ECM didn't require repair (FORTUNATELY It was just a bad IACV valve) so I didn't actually have any work done by them...but Nick sure sounded like he knows whats up and their pricing seems right! Note...He told me they usually DONT have rebuilds on the shelf ready to go but repair your computer after you send it to them. Never hurts to ask tho.

Heres the site in case anyone needs an ECM repair - The NISSAN button in dark blue explains the common IACV issue with the 00-02 Maximas and what they do to fix the ECM.

http://www.avproecm.com/

Last edited by Dave448; May 24, 2012 at 04:01 PM.
Old Jun 27, 2012 | 09:22 PM
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IAC Valve went bad, ECM, too

2001 GLE 3.0
The P0505 code came. I replaced the IACV and the idle wouldn't sit down afterward. Thought I smelled burning plastic but it went away and I shrugged it off.

The idle reset (no CONSULT-II) wouldn't procedure didn't work.

I asked the stealership to reset the idle and for $165 I got to hear them tell me I needed a new throttle body: $1,300!

I read more about this problem and decided to check the ECM. It smelled burnt. I called AVPro Corp (http://www.avproecm.com/). They warned me to check the resistance on the new IACV, since I had driven with it and a bad ECM. It was still at 22 ohms (correct). They repaired my ECM, and I got it back less 5 days after I sent it from Seattle to their place in Florida, $220 including shipping both ways.

I popped the ECM back in and it works GREAT! No codes! I didn't even need to reset the idle!

THANK YOU for helping me avoid giving the stealership the first and SECOND $1,300 bill. The second one would have been for a new ECM, once they had sold me an unnecessary throttle body.

This forum is the best!
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