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Discussion Starter · #1 ·
2007 Xterra SE - Anyone dealt with and solved the infamous wont start in cold temps issue. Still having it despite new battery, new fusible link, new pos and neg battery cables, freshly buffed clean ground points, and over the last couple years redesigned IPDM, valve cam and flywheel sensors (which did fail and a was separate issue), plugs, and is perfectly maintained? Many people think it is a bad ECU but obviously hesitant to go buy a new $1000 one. Anyone send an ECU to one of the test / repair services? Anyone heard of an ECU reprogramming to address this issue? I did see at one of the test services they list Maximas as having a no ECU communication in cold temps issue.
 

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Have you tried locally warming the ecm? Use a heat mat or gun or even hair dryer to see if the failure is related to it being cold?
I’d try that for sure.


Also, a quick Google search found this company:


I’ve no idea about them, so caveat emptor.
 

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Discussion Starter · #3 ·
Have you tried locally warming the ecm? Use a heat mat or gun or even hair dryer to see if the failure is related to it being cold?
I’d try that for sure.


Also, a quick Google search found this company:


I’ve no idea about them, so caveat emptor.
I have seen that company and almost sent my ecm to them last year for testing, but instead tried the new cables and fusible link and cleaned ground points. Success until this recent cold snap here in Texas. I have not tried heating the ecm when it wont start as a booster battery usually gets it going, however even that did not work this time. Should have tried heat during this last episode, but we were without power for much of it. Should have also connected my diagnostic tool to the obd port to see if it could communicate with the ecm. Will have to wait till next time to further test if I don't send the ecm off for diagnostics.
 

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So it starts fine at all other times except for colder temperatures?

Using a scan tool, I'd check the functioning of the temperature-related sensors such as the MAF (Mass Air Flow sensor), which also apparently functions as the IAT (Inlet Air Temperature sensor) and the ECT (Engine Coolant Temperature) sensor. These sensors send their data as inputs to the ECM (Engine Control Module), which then determines how much fuel to inject during a cold start.

For example, if it's actually 20F outside and the IAT is reading 40F, then the ECM won't inject enough fuel for the actual ambient conditions. Use a similar for method for the ECT reading. If the IAT reading is off, then give the MAF a good cleaning with a thorough spray down and check the reading again. If the sensor readings check out OK, then....???.
 

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Discussion Starter · #5 ·
So it starts fine at all other times except for colder temperatures?

Using a scan tool, I'd check the functioning of the temperature-related sensors such as the MAF (Mass Air Flow sensor), which also apparently functions as the IAT (Inlet Air Temperature sensor) and the ECT (Engine Coolant Temperature) sensor. These sensors send their data as inputs to the ECM (Engine Control Module), which then determines how much fuel to inject during a cold start.

For example, if it's actually 20F outside and the IAT is reading 40F, then the ECM won't inject enough fuel for the actual ambient conditions. Use a similar for method for the ECT reading. If the IAT reading is off, then give the MAF a good cleaning with a thorough spray down and check the reading again. If the sensor readings check out OK, then....???.
Thanks for the suggestions, I will monitor those those readings at several different ambient temps. The MAF is clean, actually spray cleaned it not long ago with electrical circuit safe stuff to not leave any residue.

As long as not cold / cool it fires right up. Often in past on cold days a booster or jump will fire it up. This is widely reported pattern from others. I don't know if that absolutely implies something going on electrical, as opposed to fuel issue, possibly in ecm with high resistance circuit or minimum required amperage level for ecm to activate ignition circuits, as some have suggested?

Hot temps down to about 45F it fires immediately, 45 to 32F takes a few cranks, a half second of weak firing then full running. Below 25 or 20F can't get it started even with extended cranking. This particularly cold time in Texas, 15F would not start even with booster attached to battery. Later when it warmed, immediate fire up. This is all with new battery, cables. When batteries get three years old, lucky to get it started at 45F. These are obviously all cold starts I am referring to.
 

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So on cold days a booster pack or jump will actually start it? That sounds like high resistance somewhere rather than misreading IAT or ECT sensors. A warm battery may be able to overcome that extra resistance, but a cold one can't. You stated new battery cables/terminals, so maybe the cable from the battery to the starter has high resistance somewhere? As in the starter connection is corroded, loose or just not making as good of a connection it should be.
 

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Discussion Starter · #7 ·
So on cold days a booster pack or jump will actually start it? That sounds like high resistance somewhere rather than misreading IAT or ECT sensors. A warm battery may be able to overcome that extra resistance, but a cold one can't. You stated new battery cables/terminals, so maybe the cable from the battery to the starter has high resistance somewhere? As in the starter connection is corroded, loose or just not making as good of a connection it should be.
Thanks, I'll take a close look at the starter cable and connection. However, at all temps the starter cranks the engine fast.
Whether high resistance in the cable to the starter or in the starter itself can put a big enough load on the battery to keep amperage flow to the ecm below some minimum hurdle required to activate ignition control circuits or flipping on solenoids to turn on power to the plug coils and fuel pump, I do not know. I have not done a lack of fuel or spark test. I did get a spark indicator light but have not adequately tested for that. I can only test on those cold days it wont start.
 

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2007 Xterra SE - Anyone dealt with and solved the infamous wont start in cold temps issue. Still having it despite new battery, new fusible link, new pos and neg battery cables, freshly buffed clean ground points, and over the last couple years redesigned IPDM, valve cam and flywheel sensors (which did fail and a was separate issue), plugs, and is perfectly maintained? Many people think it is a bad ECU but obviously hesitant to go buy a new $1000 one. Anyone send an ECU to one of the test / repair services? Anyone heard of an ECU reprogramming to address this issue? I did see at one of the test services they list Maximas as having a no ECU communication in cold temps issue.
I was actually just looking at this: 2007 Nissan Xterra 4.0L - ECM ECU PCM Programmed Plug&Play | Flagship One
As I have an issue very similar to what you're describing. They quoted me $562 dollars for a pre programmed ECM with my VIN already input so I don't have to go to the dealer. If you don't mind doing the install I know theres a thread on here somewhere that goes into how to replace the ECM/ECU.

Much like you my cables are completely clean and corrosion free, the battery is brand new, and even up to 50° weather I can't get mine to start without a jump pack now. Once its started, its fine.
 

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Discussion Starter · #9 ·
I was actually just looking at this: 2007 Nissan Xterra 4.0L - ECM ECU PCM Programmed Plug&Play | Flagship One
As I have an issue very similar to what you're describing. They quoted me $562 dollars for a pre programmed ECM with my VIN already input so I don't have to go to the dealer. If you don't mind doing the install I know theres a thread on here somewhere that goes into how to replace the ECM/ECU.

Much like you my cables are completely clean and corrosion free, the battery is brand new, and even up to 50° weather I can't get mine to start without a jump pack now. Once its started, its fine.
Thanks for the link. Will take a look. Now that spring is around the corner here, dont know if there will be another chance for cold weather testing. In any event, next steps for me likely to be inspect any cable ground points hidden under ecm box. Might send ecm off to one of the test/repair outfits that specifically test for cold temp operation.
 
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