carwilef7 Posted August 26, 2009 Share Posted August 26, 2009 (edited) Hot start flooding problem - I don't want to jinx it, but I think I found the problem: It had been intermittent for weeks, but the last couple of days it was happening on every start attempt made after a few minutes. Googled for a while and kept running across people saying a bad coolant temperature sensor could cause this - not just Nissans, either, but lots of others too. This is the sensor the ECM uses to figure out engine temp so it can adjust timing, fuel, etc, not the sending unit for the temp gauge. According to the FSM (found at www.pdftown.com), the resistance is supposed to be about 2K ohms at 68F and go lower as the coolant temp increases, for about 200 ohms at 194F. I checked mine cold (80F outside, middle of the day) and got 1.4K - reasonable. Checked it after running to operating temp, shutting off, and waiting 30 minutes, and I got 550 ohms - also reasonable, and the truck started fine. Then, I ran about ten miles and checked the resistance after shutting it off for about 5 minutes. I was INSANELY higher than it should have been - 12 megs! Truck flooded right away on attempted start when it was that high. Waited another 30 minutes or so, leaving the meter hooked up to eliminate any probe contact issues, and it was back down to 500 ohms and the truck started perfectly. Replaced the sensor - $23.99 at Autozone - and have had no issues at all since. That was this afternoon, so only a few hot starts, but I'm hoping that was the fix and will re-post if it turns out to be something else. BTW, the FSM has lots more tech info than Haynes, but it contains few replacement steps - so ya kinda need 'em both. Also, I have a meter that will go into the Meg ohm range - $30 from Sears. I doubt the average $10 meter from Wallyworld would show anything other than an error or overload - or it might give wildly changing values. It pays to invest in good diagnostic tools. Edited August 26, 2009 by carwilef7 Link to comment Share on other sites More sharing options...
k9sar Posted August 26, 2009 Share Posted August 26, 2009 awesome. thanks for posting the solution. It now makes sense since the truck ECU adjusts the mixture and spark based on sensor readings (temp being one of them). Link to comment Share on other sites More sharing options...
carwilef7 Posted August 26, 2009 Author Share Posted August 26, 2009 awesome. thanks for posting the solution. It now makes sense since the truck ECU adjusts the mixture and spark based on sensor readings (temp being one of them). Thanks for the reply. I knew it had to be something stupid causing it to dump fuel all at once, but if it had not gone to consistent failure, I'd probably still be stumped. Hopefully, I can save some other people from spending days on end running in circles and pulling their hair out. No worries here, though, since I'm already bald. Link to comment Share on other sites More sharing options...
Tungsten Posted August 26, 2009 Share Posted August 26, 2009 So is it like a plug in sensor? Or does it require taking the cooling system apart? Link to comment Share on other sites More sharing options...
k9sar Posted August 26, 2009 Share Posted August 26, 2009 chasing intermittent problems is a royal PITA. I love when things fail completely. it makes it soooo much easier to track down. Link to comment Share on other sites More sharing options...
Precise1 Posted August 26, 2009 Share Posted August 26, 2009 ^x2!! Thanks for the update/solution, I'm sure you will have helped quite a few people with this information!! B Link to comment Share on other sites More sharing options...
carwilef7 Posted August 26, 2009 Author Share Posted August 26, 2009 So is it like a plug in sensor? Or does it require taking the cooling system apart? It just screws into the upper radiator hose outlet on the engine. Takes a 19mm wrench. Put thread tape on the new one and have it ready to go in before you remove the old one and you'll only lose a tiny bit of coolant. Link to comment Share on other sites More sharing options...
carwilef7 Posted August 27, 2009 Author Share Posted August 27, 2009 ^x2!! Thanks for the update/solution, I'm sure you will have helped quite a few people with this information!! B I say pay it forward. Drives me crazy when ppl post and post about a problem and never post the fix. Hey, does your XE have the black plastic hub center caps? I'm missing a front one with the hole in the middle and can't find it anywhere. Nissan wants 50 bucks for it! Link to comment Share on other sites More sharing options...
Precise1 Posted August 27, 2009 Share Posted August 27, 2009 Yes, it does. $50?? That's insane!! I'll sell you one for $40+shipping... JK The ones I have do look used (weathered) but I'd bet it would just match your other one. I need to update the part out thread tonight, so make me an offer? Need anything else to throw in the box?? B Link to comment Share on other sites More sharing options...
adamzan Posted August 27, 2009 Share Posted August 27, 2009 That tire shine stuff does wonders for faded black plastics. Link to comment Share on other sites More sharing options...
87pathy Posted August 27, 2009 Share Posted August 27, 2009 good tech info. thanks! Link to comment Share on other sites More sharing options...
Tungsten Posted July 1, 2010 Share Posted July 1, 2010 great now i'm getting this same nonsense it started a while back when at first it would just flood slightly on a cold start when putting the pedal down and its progressively been getting worse now i'm flooding almost every time i step on the gas when the engine is warm its going to be until monday when i should get it changed and i got about 20 miles to drive tomorrow hopefully this stupid bib doesn't cook my catalytic converter Link to comment Share on other sites More sharing options...
Tungsten Posted July 7, 2010 Share Posted July 7, 2010 OK I just got the part from the dealership, it looks like this: Can someone verify that this is the correct part? Link to comment Share on other sites More sharing options...
amo1dun Posted July 8, 2010 Share Posted July 8, 2010 (edited) OK I just got the part from the dealership, it looks like this: Can someone verify that this is the correct part? That is a cylinder head temp sensor or an engine coolant temperature sensor(same thing)...Its definetely not the one for the gauge (That has 1 male end) Edited July 8, 2010 by amo1dun Link to comment Share on other sites More sharing options...
Tungsten Posted July 8, 2010 Share Posted July 8, 2010 alright cool, mine is yellow for some reason but this one is blue, i'm trying to figure out wtf was done there Link to comment Share on other sites More sharing options...
amo1dun Posted July 8, 2010 Share Posted July 8, 2010 alright cool, mine is yellow for some reason but this one is blue, i'm trying to figure out wtf was done there I just did mine recently and it was yellow Link to comment Share on other sites More sharing options...
Tungsten Posted July 8, 2010 Share Posted July 8, 2010 (edited) That part fits fine but unfortunately did nothing for me. It runs just like it used to... Maybe ECU? MAF? On second thought, it did kind of help, sometimes the truck would surge for no reason but it isn't doing that anymore after I replaced this sensor. Edited July 9, 2010 by Tungsten Link to comment Share on other sites More sharing options...
Tungsten Posted July 9, 2010 Share Posted July 9, 2010 (edited) I just did mine recently and it was yellow It probably looked like that, which is the 89 part number. I think those sensors were updated. That is what the old one looks like. This is the later year part number but I think it can also be used with the VG30I. Note that it is equipped with a copper washer to provide a tight seal unlike the other two which require the use of thread sealant to prevent leaks. Edited July 9, 2010 by Tungsten Link to comment Share on other sites More sharing options...
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