Hi,

I've recently experienced with my Nissan Maxima 2001, idle issues where the car is stalling at low RPM and instantly stalling at startup, unless I give it some gas, which in return allows the car to idle. After I first started to notice this problem I began smelling a burning smell that I linked back to the ECU board. At first there was no code but the P0505 showed shortly after. After doing some research I think i determined that I've fallen into common problem where the bad IACV short circuits the ECU. It looks to be a very expensive job by a dealer so I am attempting the fix myself.

I just yesterday replaced the IAC valve. Initially the car ran at a high RPM and I attempted a manual relearn of the idle. Following that attempt I am again experiencing a low RPM and stalling at startup.

My question is, could it be possible that the ECU, although showing signs of a circuit short by a slight black mark on the chip and burning smell, could still be functional? Might a relearn by a Consult II be all that is required or do I most likely need to replace the ECU as well? (I would like not to venture down that road if possible).

I appreciate any insight or suggestions.
(Attachment: I've attached a pic of the ECU i pulled from the car.)

Nissan Maxima 2001 (3.0L)

Thanks
-Matt

 

The ECU cannot control the IACV with the blown chip. That means you can't do an idle relearn until you replace it. The entire ECU does not have to be replaced, just the chip.

The chip is a STA509A, not real common, but not impossible to find. Here is one place for $7.20: http://www.aliexpress.com/store/prod...361120235.html

here is a bunch of choices from E-bay: http://www.ebay.com/sch/i.html?_trks...at=0&_from=R40

There are television repair shops by me that will sell the chip. Try looking/searching for STA5009A.

 

If you have the patience but not the skill to do it yourself you can pay someone to fix it for you for about 100 bucks or less

 

Although I haven't before soldered a chip, I would be willing to learn. Do you know of any online resources? I have taken that approach with most of what I've been able to accomplish working on my cars at home in the last two years.

Also, I have read about people not having good results sending these boards out for repair. What are your thoughts on repair compare to say buying one off of eBay? With a new soldered chip, is a re-program of my keys required as well? Ultimately trying not to go to the dealership.

Thanks for the help!

 

If you live in Toronto or close to Toronto,my brother can replace the chip for $60,he has ST509A chip on hand so you wouldn't have to buy one.

 

I just finished the repair on my own maxima. Here is a link to a great thread on the topic

http://forums.maxima.org/5th-generat...d-seconds.html

Here is a great video on the topic:


I bought the new valve and chip from eBay for $49 and $7 respectively. You'll probably have to jumper a couple of burn traces as outlined in the above thread...

The only thing I disagree with in the video is the part where he doesn't recommend repairing the ECU... Many folks (including myself) have repaired it with good results.

Good luck

 

fried

 

Soldering isn't hard to do but you need to get a few items, a soldering iron and solder, and either solder wick or solder sucker, all can be had for about $25 total. If you want a crash course in soldering just type "how to solder" in Google, you'll find YouTube videos and other helpful websites.

You'll find a few posts here where those board repair places failed to do a proper repair, and afterwards ran away from their warranty guarantee, so using them is a risk, and will cost you much more than doing it yourself.

 

Thanks everyone for the input. I'll take some time to look through and see if I'll be able to solder the board myself, my concern there would be I attempt it myself, mess it up and then might not be repairable by someone else. I've seen repair shops on ebay for approx ~$80/repair.

Does anyone have any online recommendations that I may send my board to for repair? (if i decide not to tackle on my own)

So as i mentioned before, I've already replaced the IACV. But as I go through more threads I read more about needing to replace the TPS as well? I don't have any codes indicating this may be true, but I'd hate to replace/repair the ECU and then have the TPS re-fry the board. Any thoughts there?

Thanks again!
-M

 

It is possible to damage the board, for example if you heat up a pin to remove the chip and it gets too hot, it can cause the solder pad on the board to lift (delaminate) and possibly break off. Removing a 10 pin chip can be tricky if you aren't careful and rush it, or just don't know what you are doing.

You don't need to replace the TPS unless it is bad, when my IACV failed I read the same threads and bought a TPS, removed the old one and tested it and found it was good... so I wasted $80! The TPS itself cannot be damage by a bad IACV/ECU, and vice versa, however you might as well test the TPS just for your own assurance, you can follow the test procedure in the Nissan manual.

 

Thats good information. Thanks. I'll go ahead and test the TPS first.

Anyone have any recommendations for places you've used or heard of that have been reputable in repairing these ECU's?

 

wow i thought the entire ecu had to be changed!!

 

no, just replace the damaged mosfet is usually all it takes. in some cases a trace or two are fired, so you just jumper in a new wire. it's a total waste to replace an entire circuit board simply because one bad part is bad.

 

UPDATE: So I wanted to provide an update to this thread. I ordered a new IACV and replaced myself. Tested the TPS and determined that it was not damaged and functioning properly. I decided to sent out my ECU for replacement instead of fixing myself. For me that turned out to be the better decision. I was satisfied to know that a reprogramming of my keys would not be necessary.

Following those steps I attempted to do a manual IDLE relearn, and although I don't think I performed exactly as it was listed out, my idle levels and shifting are working. The rough idle, stalling problems are now gone.

I have noticed however that my IDLE may be a bit low than what is supposed to be normal. I am hoping here that someone could provide some insight. I have a manual transmission, and when in neutral say at a stop light, the idle is sitting just north of 500RPM. This is a slight problem when i lift off of the clutch, I get the car to move slighting forward without applying any gas but the rpm drops to a borderline stall. Prior to me replacing the IACV and fixing the ECU, the rpm did not idle as low and the car was able to get off the line easier without approaching a stall.

I've attached a picture to show current idle level. Do you think this is below normal levels? Would running another idle relearn fix the problem? Any suggestions?



Thanks
-Matt

 

Where did you buy the new IACV? You should buy an OEM part, preferably from Nissan. After-market parts have bad reputation. In either case, I would try another idle re-learn. If that does not work, check out your MAF.

 

Standard Motor Products AC278T

I don't think that the part is defective. Can someone tell me what a normal idle level is? 7500? Does mine appear to be low?

Since the repair the P0505 code cleared but I now have code P0135 (O2 heater circuit malfunction code). I haven't tested the circuit yet but could that have any effect of this issue?

 

Yes, it could be. It has affect on fuel richness. So, I would check the O2 heater function. See the FSM, procedure EC-205.

You'll need a copy of the Factory Service Manual. You can get it from here:
http://www.nicoclub.com/archives/nis...e-manuals.html