EVAP Purge Valve/Solenoid Help

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ash10hunt
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Car: 1999 Infiniti Q45

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I just finished putting my intake manifold after replacing my MAP/BARO solenoid and I got a P1492, but my car was running fine, so I said I'd order a new solenoid later. I drove around a bit and it ran just fine, then I parked for a bit and tried to start it back up but it wouldn't start. I finally got it going by pumping on the gas and it had a misfire and was running rough. I assumed this was because of the P1492, and ordered a new solenoid off Amazon. However, the part I ordered, and all the others I've seen only have two vacuum outputs, but the one in my car has 3. The part I'm referring to is in the back left of the engine bay, and from all the diagrams I've seen, should be the purge/evap solenoid. Am I looking in the wrong place or did I order the wrong part? I'm very confused and any help would be greatly appreciated. Thanks.


Ryantzer
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Did you diagnose the solenoid as being bad or are you just throwing random parts at it hoping to fix the problem?

Actually that's a rhetorical question because if you'd tested the solenoid to see if it was causing the problem, you'd already know where it was located and what it looked like.

Your best bet is to read through the factory service manual and follow the diagnostic procedures for that code - the trouble code doesn't tell you what part to replace, it tells you where you need to start looking for the cause. Throwing parts at it is rarely successful and something no real mechanic does.

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Q451990
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Good advice from Ryantzer, although I've met way too many "real mechanics" that throw parts at cars, so I'll disagree on that one point. :)

The service manual is available at www.infinitiservicemanual.com if you don't have a copy available.

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VStar650CL
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Q451990 wrote:
Fri May 28, 2021 9:29 am
I've met way too many "real mechanics" that throw parts at cars, so I'll disagree on that one point. :)
Then they only think they're real mechanics. We real mechanics have a term for them, it's "parts changer". The world needs those too, but they shouldn't be doing unsupervised diag.

Ryantzer
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Q451990 wrote:
Fri May 28, 2021 9:29 am
Good advice from Ryantzer, although I've met way too many "real mechanics" that throw parts at cars, so I'll disagree on that one point. :)
Lol, my point was that anyone who's just throwing parts at a car instead of diagnosing it ISN'T a real mechanic. I too have met plenty of "mechanics" who just changed parts without testing first, so I used the term "real mechanic" to differentiate between them and the ones who go through the repair process properly.

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VStar650CL
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I knew what y'all meant, that reply was intended as a "second that" from a professional, not a criticism. Sorry if I caused any misimpression.

98_Q45
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Not to get off topic but; sometimes throwing parts at things isn’t always the worst. Sometimes it can very much seem like something is the issue: but by buying parts you can eliminate the possibility without necessarily chasing the rabbit hole of diagnosing something lol. And sometimes, you can inadvertently fix one or several issues, by replacing a part for another issue.

In my case: it’s hard to find mechanics to diagnose my vehicles. For one: I live in a small town and most the mechanics work on Ford’s and Chevys. If an issue arises, I have to book 2 or even 3 weeks in advance. And then pay a fee. And it might not even be the right diagnostic.

Dealt with this recently on my Maxima. Went to 3 different shops including Nissan, diagnosing an issue where the engine would stall at random when at a stop. My go to shop cleared some charcoal from the canister in the evap lines. Didn’t fix. Another shop did some testing and changed spark plugs. Didn’t help. Dealer suggested coils. Didn’t help. I even changed idle air control valve and fuel pump. Didn’t help.

Finally after googling/YouTubing myself into oblivion, went and tried my luck at a $50 MAF sensor assembly on ebay. BINGO. Problem solved.

But what I don’t like: is when “store clerks” throw out suggestions about an issue without ever even opening the hood. For example: I recently kept having my battery drain overnight on the Q. Replaced the battery twice before I figured out it was my aftermarket radio (no diagnostic, just had to google similar issues). However, before that I was getting told “alternator”. I came close to replacing the alternator for good measure, but me being cheap and lazy... I’m thinking: if it was the alternator, all the old Nissans have the battery and brake light come on, and it would die while driving. Not parked overnight, and then be able to still drive for 600 miles after a jump.

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VStar650CL
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98_Q45 wrote:
Tue Jun 08, 2021 11:16 pm
For example: I recently kept having my battery drain overnight on the Q. Replaced the battery twice before I figured out it was my aftermarket radio (no diagnostic, just had to google similar issues). However, before that I was getting told “alternator”. I came close to replacing the alternator for good measure, but me being cheap and lazy... I’m thinking: if it was the alternator, all the old Nissans have the battery and brake light come on, and it would die while driving. Not parked overnight, and then be able to still drive for 600 miles after a jump.
Sadly, there just aren't a whole lot of good electrical techs in an increasingly-electrical world. That's why our dealership keeps me around, even though I'm too old to sling flat rate engines and trannies anymore. So electrical is sort of the exception that proves the rule. Guys guess, and if you happen to know enough to know which side of a voltmeter is which, then your guess may well be better than theirs. You have the advantage of knowing your personal car and its personal quirks better than anyone.

Ryantzer
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98_Q45 wrote:
Tue Jun 08, 2021 11:16 pm
Not to get off topic but; sometimes throwing parts at things isn’t always the worst.
Hate to disagree with you, but you spent time and money replacing a fuel pump and an IAC valve that weren't bad - that is exactly why you should diagnose the problem instead of throwing parts at it. There are only a handful of parts on most vehicles that can't be tested in some way, and neither of those parts fits that description.


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