So I just replaced my IACV and cleaned my throttle body. I also just replaced all my coils. Now the engine will turn over very nicely however does not stay running it will just die within 30 secs even with some throttle being applied.

I was chasing a p0300 - multiple cylinder misfire

I also have a p1140 & p1145 camshaft and crankshaft position sensors. Do you think these could be causing this new issue of the engine not staying running?

I have tried putting back the old IACV and it repeated the same behavior nice turnover then die after 30 sec. Next attempt at turnover nothing happened. Just spins. I have pulled all the plugs to check for fouling they all look good gave a little cleaning to them checked all plugs on coils added straps to broken plugs to ensure connection. I pulled all camshaft and crankshaft position sensors cleaned them and re in stalled but still just spins. I have on order new cam/crank position sensors and a throttle position sensor. Anyone have any thoughts?

Was it running OK before you did the work?

Negative, it was throwing p0300 and behaving like misfires were present. Had to get towed because I couldn't leave the garage at work, uphill exit. This is when I began the work because I already had the coils and was planning on replacing them.

Was it burning oil before the misfires?

I do not believe so, I just purchased in September. Didn't pass smog. I will be doing an oil change as well with all the sensor replacement. Every time I have pulled the dipstick looked and smelled good.

The camshaft and crankshaft position sensors are absolutely critical to the engine timing. Fortunately, they are easy to replace and basically plug-n-play. The IACV and the TPS are easy to replace as well but they are not plug-n-play, so to speak. On my '02 Pathfinder the TPS is the only emission and engine control component that is adjustable and it requires a precise adjustment for it to work properly. The IACV on my '02 requires an idle air volume relearn procedure to be performed after it is installed. Do the camshaft and crank shaft position sensors first. All of your trouble code issues may go away after that.

Will update after the new sensors are in.

All new sensors have been installed and still just spinning not turning over...

Check your eccs1 and eccs2 fuses

Eccs 1 & 2= engine control fuse? 10a & 15a? I checked both and they are still good. Any other thoughts? Any methods on checking the ECM other than just visual inspection?

The fuse box should be in the engine compartment passenger side. I believe on is 10a and one is 7.5a.

Thank you for the location, I checked and found that someone had swapped a 15a from a headlight to the 10a for eccs. This 15a was blown so I just switched them back into their correct locations. It turned over with the good 10a in place however did not idle well. Off to work now more troubleshooting later. Does anyone know exactly what these 2 fuse's are protecting?

Just a guess on my part, but misfire and/or camshaft-crankshaft circuit codes can all be caused by a timing belt that has jumped a tooth or two. If there is an easy way to check camshaft timing, i would do so before the belt snaps and leaves you with possible bent valves! I have little experience in that area, on this engine, so i'll leave that to others, as to how to perform that check

nalz wrote: ↑

Thu Dec 19, 2019 10:27 am

Just a guess on my part, but misfire and/or camshaft-crankshaft circuit codes can all be caused by a timing belt that has jumped a tooth or two. If there is an easy way to check camshaft timing, i would do so before the belt snaps and leaves you with possible bent valves! I have little experience in that area, on this engine, so i'll leave that to others, as to how to perform that check

01 QX4 has a chain not belt

My bad, thanks for letting me know

If that fuse is blown then most likely the IACV had a short in it and pulled too much amperage through your ecm. You can remove your ecm, open it up and check for a blown transistor. If it did blow, then it'll be easy to spot.

It seems this a pretty common failure on early 2000 Nissan and infiniti's with the 3.5. if it's blown then you have three options.
1. Send out the ecm for repair, about $200
2. Buy the $10 part off Amazon and repair yourself, I did this but its real tricky.
3. Get a working ecm,bcm,key from another car. If you want to go this route, pm me because I have a spare set that I was going to use if replacing the transistor didn't work.

Link to correct $10 part off Amazon? I was planning on pulling the ECM to check it next anyways.

Another question, as I have also been coming to find from research that this is common.

I have swapped in and out the old and new IACV during my troubleshooting. I can do the ohm test on whichever I need. But if there is a blown transistor and I repair should I also have a new IACV with it or just ensure it passes the ohm test?

Google "STA509A - Sanken N Channel MOSFET" and it will show you a couple options.

I didn't have any issues with using a bad ecm with a new iacv. I'd say check the ohms, then connect the iacv to the harness with the new ecu installed. When you turn the car on, you should see the plunger on the iacv extend. Once confirmed, you can finish buttoning her back up.

born2lse wrote: ↑

Thu Dec 19, 2019 11:41 am

If that fuse is blown then most likely the IACV had a short in it and pulled too much amperage through your ecm. You can remove your ecm, open it up and check for a blown transistor. If it did blow, then it'll be easy to spot.

It seems this a pretty common failure on early 2000 Nissan and infiniti's with the 3.5. if it's blown then you have three options.
1. Send out the ecm for repair, about $200
2. Buy the $10 part off Amazon and repair yourself, I did this but its real tricky.
3. Get a working ecm,bcm,key from another car. If you want to go this route, pm me because I have a spare set that I was going to use if replacing the transistor didn't work.

There are several places on ebay that will do the repair for around $100

Yea, I didn't want to recommend eBay since it's hard to gauge the work quality of those vendors.

Honestly, try looking up tv repair shops in your area. You might be able to find an old school shop with a guy willing to solder the new chip on for cheap.

Confirmed the sta509a is burned. I have one on order as well. Will update after I repair the board and am able to continue troubleshooting

Did you replace the coolant gasket on the bottom of the throttle body? A common reason the iacv goes out is due to the gasket failing and leaking coolant into the iacv. Might be a good idea to replace the gasket as well if you haven't already.

I not long ago had the IACV issue that did burn up my ECM, I did find a place in CA that did repair the ECM, AFTER i had sent the ECM to a ebay/electronics ECM repair gig, deemed it un repairable, as I was unable to find the exact ECM replacement to swap one with as I have a 2001.5 mind year Pathfinder 3.5 SE Manual 4x4, I still have the brochure in the HAynes book as I"m in the middle of pulling the motor for a bad head gasket..let me know what you do/find..the outcas eof my bad ecm was visibly smoked and burned, once opening up the toasted resister is obvious, can DIY job for sure IF you have the right soldering equipment.

OH..my bad ECM symptoms were that at idle, and it would normally start etc, but idling it would loop, having a constant up and down VROOM idle between say 1,500rpm to 2,500 rpm..nothing fixed it, it did this AFTER it warmed up etc,..I did the "idle relearn procedure" several different ways, AND AFTER putting on an OEM IACV..AND AFTER searching the posts on this site checked the ECM for a burned resister..the vehicle was graciously passed on the me as the previous owner gave up on it not realizing the IACV has failed and thus wiped out the ECM...now Im tacking the head gasket job via pulling the motor, just removed the front diff yesterday

The board is burned as well as the transistor. I still attempted to clean up and re-solder a new transistor, it wasn't until I removed the old one I was able to see the damage to the board. I sent a PM to born2lse as they said they have a ECM BCM key set. Is this the case, need to replace all with a matched set otherwise need to take to dealer/someone to reprogram? Additionally if anyone else has a working set please PM me.

Actually I sent my computer out to an Auto Electronics Repair company AFTER SPEAKING WITH THEM AND GIVING THEM MY PRODUCTION YR AND MONTH ON THE PHONE then I sent it out, due to the multiple functions inter-related that connect thru the ECM/computer I had to FIND A PLACE THAT ALSO HAD THE EXACT SAME YR AND MONTH RANGE PRODUCTION of the car (mine being a mid year 2001.5) so the correct resistor could be found, ie came out of a matching used ECM/computer) , this way i didnt have to buy a new NOR used ECM and hope for the best and FYI--those online parts locator svc's can be a RACKET..ie one place found a used matching ECM and wanted $600 BONEs, it was simply located at a Junkyard in Texas..The cost for repair was $100 etc, plus S/H fedex, they were an Ebay listing yet I called them first to verify my 19yr old ECM dilemma w/ the IACV failure which is so common ebay has listing for the ECM's etc.

I used ModuleRepairPro.com for the ECM repair

In Van nuys? I'm thinking of going over there with my ECM since they are down the road and around the corner