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The car is a high mileage (about 215k miles) 1998 GXE automatic to which I have done some mild performance modifications. Let's just say the car doesn't owe me anything and I spent more on modifications then I probably should have given how little the car is worth now. But I love it and don't want to put it out to pasture if I don't have to.
I have had two codes, P 1440 and P 1493, for quite some time. The OBD reader I use indicated EVAP control system small leak (P 1440) and EVAP canister purge control valve/solenoid valve (P 1493). The FSM confirmed those code definitions. Because I heard a high pitched whine when I would get home, I replaced the gas cap with another Nissan cap and I replaced the vapor canister purge valve since those seemed to be most consistent with the noise. That didn't change anything. I bench tested the other three valves that are involved with these DTC codes and they were OK. The car has run really well so I decided not to upset the apple cart any further.
About three weeks ago, I began smelling a very mild gasoline vapor smell only for a couple minutes after starting the car but it would go away after driving a few blocks. I checked for any gasoline leaks again and found none. There was no evidence of dried fuel anywhere that fuel lines, hoses or other fuel holding systems reside. I was also still getting very good gas mileage (consistently 27-28 MPG city/hwy some of which with fairly vigorous driving) so I assumed that the problem was related to the codes; possibly one of the valves that handle fuel and vapor back to the tank was getting worse. One or more of them may be evacuating fumes to the atmosphere too as it continues to fail further.
When I filled up on Sunday the car showed signs of using much more gasoline (around 22 MPG with no change in driving pattern). Again, no evidence of fuel leaking anywhere from front to back. And the odor is not any different.
The FSM indicates about a dozen tests for the P 1440 code, many of which required the Nissan diagnostic machine. I'm not sure I'm up for that nor am I crazy about taking it to Nissan for a car that isn't worth much money. The P 1493 code looks more like straight forward parts replacement which isn't as big a deal. Besides, it doesn't look like any of this will help me find where the fuel is going.
I'm hoping that you guys will have some shortcuts to help me decide what to do next. Thanks.
I don't think anyone is offended I get like 22-25 mpg running premium in my 99. Fair number of stoplights where I live though... Not that this helps you at all
I don't think anyone is offended I get like 22-25 mpg running premium in my 99. Fair number of stoplights where I live though... Not that this helps you at all
Thanks for your reply. I think the fact that I have the vapor odor and having gotten such consistently good mileage for so long makes me think there's something new going on. An 18% drop in MPG in such a short time seems pretty extreme.
I didn't mention that most of the mods I've done over the last year shouldn't contribute to declining or bad gas mileage. Tune-up items like plugs, coils, injector cleaning and calibrating, cleaned and re-oiled K&N air cleaner, Warp-speed Y-pipe and high flow cat, big pipe exhaust with Magnaflow resonator and muffler, TransGo transmission kit, etc.) actually contributed to improved mileage. I haven't changed anything with them in a few months. I use mid-grade fuel which is 91 octane at most pumps in Colorado. Also higher altitude tends to decrease efficiency and fuel mileage.
Thanks for your reply. I think the fact that I have the vapor odor and having gotten such consistently good mileage for so long makes me think there's something new going on. An 18% drop in MPG in such a short time seems pretty extreme.
So then some other silly questions...
You said the car has been running smoothly? No odd idle?
Is the gas smell strongest in one place? In the cabin? Under the hood?
Does your exhaust smell unusual / rich?
I'm seeing a lot of "clogged EGR valve / bad catalytic converter" answers online, but they don't match up with the symptoms you've stated thus far.
Also just a thought, have you taken off the back bench seat to see if there's anything funky going on around / near / with the fuel pump?
Your symptoms are pretty vague which makes for difficult troubleshooting - always the worst kind of problem to have!
You said the car has been running smoothly? No odd idle?
Is the gas smell strongest in one place? In the cabin? Under the hood?
Does your exhaust smell unusual / rich?
I'm seeing a lot of "clogged EGR valve / bad catalytic converter" answers online, but they don't match up with the symptoms you've stated thus far.
Also just a thought, have you taken off the back bench seat to see if there's anything funky going on around / near / with the fuel pump?
Your symptoms are pretty vague which makes for difficult troubleshooting - always the worst kind of problem to have!
The car starts well except when it is started hot. Then it cranks a few more times before starting. It has been idling like a sewing machine.
The smell seems to be strongest in the cabin. I will see if I can confirm that the odor isn't as strong under the hood. My wife has a very sensitive sniffer so she will turn off the blower when she drives it which works for her. I told her that I don't notice it after a couple minutes so she's going to see what happens when she leaves the blower on.
The exhaust doesn't seem rich at the exhaust pipe but I will see about that this afternoon.
I tried smelling around the rear seat yesterday (tank sending unit is what I'm after, I assume) but not with the seat out. I'll try that.
Let me get home from work and dig up my Evap thread.
Recently I examined six 4th gen Maximas (with good bodies and decent interiors) in a local salvage yard and found that 4 out of 6 vehicles had charcoal granules in the evap line that feeds into the solenoid valve on the Upper Intake Manifold (UIM). That told me the vehicle's evap canister had ruptured and started leaking charcoal into the system for a period of time before the car was sent to the salvage yard. Though I cannot determine why these cars were sold for salvage instead of being repaired. I suspect a persistent evap code problem caused the owner to just give up on the vehicle and sell it or trade it for cheap.
Let me get home from work and dig up my Evap thread.
Recently I examined six 4th gen Maximas (with good bodies and decent interiors) in a local salvage yard and found that 4 out of 6 vehicles had charcoal granules in the evap line that feeds into the solenoid valve on the Upper Intake Manifold (UIM). That told me the vehicle's evap canister had ruptured and started leaking charcoal into the system for a period of time before the car was sent to the salvage yard. Though I cannot determine why these cars were sold for salvage instead of being repaired. I suspect a persistent evap code problem caused the owner to just give up on the vehicle and sell it or trade it for cheap.
Just out of curiosity, do you flip these? I see your profile says you do IT but you certainly seem well versed in this. Plus every engine bay picture I've ever seen from you was clean enough to eat off of.
The smell in the cabin is also about the same under the hood. I start the car and it has the gasoline odor for about two minutes then stops.
The exhaust looks and smells normal, no richness.
I forgot to mention that I also replaced the IAC (Idle Air Control Valve) probably ten months ago. It threw a code and replacing it fixed the code immediately.
The access cover to the fuel pump/sending unit was bone dry when I took it off. I had it out when I was first trying to determine the source of the codes a few months ago so I was pretty sure it was OK but it was a good idea to check.
The car still has the high pitched whine around the tank filler when it builds up pressure. Releasing the gas cap makes it stop. Is that a hint regarding the charcoal canister issue you mentioned, CS_AR? BTW, the canister doesn't seem to be damaged and when I replaced the vapor canister purge valve nothing seemed amiss.
I looked, smelled and listened again and I'm not seeing any indications of a fuel leak anywhere.
When the car is first started, there's a rattling sound in the same area as the IAC valve that goes away in a couple minutes too. I touched all the various parts in the area to see if there were any vibrations and nothing was happening.
I also thought of one other development. I don't think it's related but the radiator let go about three months ago which spewed coolant around the engine compartment. I've cleaned it the best I could but the codes started showing before then anyway.
Do you think it would be wise to replace the canister as a precaution given your junk yard visit? Also is it difficult to clean all those granules out if that's the problem?
The car still has the high pitched whine around the tank filler when it builds up pressure. Releasing the gas cap makes it stop. Is that a hint regarding the charcoal canister issue you mentioned, CS_AR? BTW, the canister doesn't seem to be damaged and when I replaced the vapor canister purge valve nothing seemed amiss.
Novice guess after reading CS_AR's evap code thread, but your gas cap is probably bad. Or something in its vicinity isn't properly sealing, thereby releasing fumes and causing that noise.
CS_AR, I've dealt with the charcoal canister issue on friends 96 Pathfinder. Tracking down all the granules takes time and money. Last time I checked, the canister for our 5 speed cars costs about 400 bucks.
I have read about a work-around. One installs a clear plastic gas filter into a certain vaccum line.
Doing this prevents charcoal from entering the vaccuum system in the first place. Basicly the gas filter would act as a charcoal filter. Vaccuum air passes right through the filter. Since the filter is transparent, we would know when a canister starts to fail.
Key question for you.....
WHICH of the vaccuum lines could/should we intall install a fuel filter.
Last edited by JvG; 11-08-2017 at 06:03 PM.
Reason: Additional comment added.
Here's a picture of one of the junk yard cars where I cut the line and found charcoal. From what you can see of the engine picture, this was not a horribly neglected car -- on the outside. I just think the evap system is misunderstood.
A new Intermotor evap canister for a 98 model can be purchased from RockAuto for $31.79. So for roughly 2x the cost of an air filter, you can avoid a messy charcoal headache.
Note that when I replaced the evap canister on the 98 model, I did not notice any charcoal. I found mud, but no charcoal. It was sometime and many $$$ parts later that I found the vacuum line was clogged with charcoal. The clogged line was the root cause of the returning evap code.
Novice guess after reading CS_AR's evap code thread, but your gas cap is probably bad. Or something in its vicinity isn't properly sealing, thereby releasing fumes and causing that noise.
It's kind of buried in the text but I have replaced the gas cap.
I believe I've had that hose apart but I don't recall for sure. It sounds like the new canister as a precaution is a no-brainer. Using the fuel filter in the EVAP line also sounds like a no-brainer if you can answer JvG's question.
I will start working on this and get back to you.
Also, does any of this seem like it could be related to the fuel mileage issue? And what is your opinion on how hard it is to get the granules out of the line and the methodology if I have that problem?
The line in the picture is the one that was full of charcoal and clogged up on the 98 model. So I removed the clamp and line from the service port connection and used 125 lbs of compressed air to clear the line. The other side of the line should be open before attempting to clear a clogged line. I guess if you want to add another filter, it would be for that line connects to the service port connection. Since the cost a new canister is so low for a 98 model, I would just replace it and keep the line setup stock.
In my case, the line was completely clogged. It must have been clogged for years. It took multiple tries with compressed air to eventually clear the line. It looked like about 1/2 a cup of charcoal granules sprayed from the line at the back of the car once I was able to break the clog loose. So charcoal had filled a large portion of the vacuum line.
The lesson learned from my evap code adventure below is:
Make sure the vacuum line from the service port (picture below) to the canister area is clear of a charcoal clog before replacing/servicing any other parts or installing a new canister.
I didn't see a mileage issue with my evap problem, so I can't give any advice in that area.
Rats! I couldn't find any granules at least at the end where you found them. It looked very clean and normal. Do you think it would be worth trying to blow it out anyway? I would loosen the line at the rear of the car.
I bought a new canister and I expect it to arrive on Tuesday. I can't be sure if it's been replaced before since I haven't worked on the car myself that long (a couple years). It's possible it was replaced by a repair shop although I'm pretty sure it never threw a code like this in the past.
Rats! I couldn't find any granules at least at the end where you found them. It looked very clean and normal. Do you think it would be worth trying to blow it out anyway? I would loosen the line at the rear of the car.
It certainly will not hurt to blow out the line. If the line is not clogged and there is no charcoal, you are in luck with that part.
Gas mileage problem appears to have been an anamoly
The most recent tank was back up to over 27 MPG, still with some vigorous driving. Fuel odor still present but no worse. No time to work on the car until this weekend.
The most recent tank was back up to over 27 MPG, still with some vigorous driving. Fuel odor still present but no worse. No time to work on the car until this weekend.
Life got very busy since my last post and I just endured it. The gasoline odor kept getting worse and I finally found the cause. It was a leak at the fuel hose between the two rails at the front of the engine. I checked that spot dozens of time and nothing. New hose and it's gone.
Now for an update on the codes:
I bought a smoke machine and ran it on Sunday. There were no leaks. I also bought the EVAP Canister Purge Control Valve/Solenoid Valve that is what a P1493 is supposed to show has failed. I bought the Nissan part at $180. When I put the reader back on it the P1493 was gone. I cleared the codes and it didn't throw any codes UNTIL Today!
It's a P1493 again. At least it didn't throw the P1440 EVAP Control System Small Leak this time. Any ideas? Here is what the Freeze screen looked like:
Did you blow out the line as CS_AR advised? When my EVAP canister began leaking, I did not have the heavy concentration of granules as shown in the photos. The vacuum would suck the granules through the pipe and into the engine, but some would interfere with the valve operation. After many times clearing the code and seeing it come back, the granule leakage from the EVAP canister became worse and I finally saw them. But it was nothing like that photo in post 14.
The charcoal canister was partially disintigrated.
The lines were filled charcoal all the way from the canister to the valve you just replaced.
I disassembled every item from front to back.
Then I blew out the lines with compressed air.
The amounts of charcoal in the lines was considerable.
Bits of charcoal were also clogging solinoid valves in the system.
it is possible and likely that the valve you just replaced has inhaled charcoal. Internal solinoid valves inside it can't function because they are jammed open or closed. This in turn will set a code.
Did you blow out the line as CS_AR advised? When my EVAP canister began leaking, I did not have the heavy concentration of granules as shown in the photos. The vacuum would suck the granules through the pipe and into the engine, but some would interfere with the valve operation. After many times clearing the code and seeing it come back, the granule leakage from the EVAP canister became worse and I finally saw them. But it was nothing like that photo in post 14.
In Post #21 I said that I had checked at the EVAP port and found no granules like CR_AS showed in his post but I hadn't blown it out yet. I did blow it out around two days later and checked the canister and both checked out fine. I also tried taking out the canister and tapping it see if granules would come out and nothing did. There was absolutely no indication of charcoal granules anywhere. I forget to add that update after I had blown it out back in November. Sorry. There was also no indication of granules when I took out or replaced the valve.
As I mentioned I tried a smoke machine and the smoke would only come out of the intake leading to the air cleaner and the relief port out of the charcoal canister at the very back of the car. No indication of a leak from the canister itself or anywhere in the system.
I have now driven several hundred more miles and the code has not appeared again. It seems a lot better which makes me think the EVAP Canister Purge Control Valve/Solenoid Valve was big part of the problem. From other sources I've seen (YouTube, etc.), that valve is such a common problem that it's a good place to start. It checked out when I bench tested it but I thought I would put the new on in anyway. When the code self cleared while leaving the stored codes, I thought I had it whipped.
There must be something else going on. I take it that no one so far sees anything strange with the freeze frame from the latest code.
This seems strange, how can smoke in EVAP purge line make way into the intake?
Originally Posted by rbuswell
I bought a smoke machine and ran it on Sunday. There were no leaks.
Originally Posted by rbuswell
As I mentioned I tried a smoke machine and the smoke would only come out of the intake leading to the air cleaner and the relief port out of the charcoal canister at the very back of the car. No indication of a leak from the canister itself or anywhere in the system.
The image of the valve - a vacuum-activated switch, normally closed (NC), until vacuum signal is present.
For testing for leak, would you have to close both ends of purge line while pumping in smoke? BTW the EVAP canister vent control valve is normally open (NO) until energized.
I probably bit off more than I can chew with this project but I intend to see it through. My experience with repair shops is that they just throw parts at the problem until the CEL goes out. I figure I can do that and not pay for the labor. I struggle with the imprecise, multi word names, the lack of uniformity for the various valve names between manufacturers, generic shop manuals, the FSM and the diagnostic equipment while still being so similar in name. Further the plumbing doesn't seem to follow logic. Of course, I'm a guy who loves cars but I am definitely not an automotive engineer. I’m sure everything makes perfect sense to an engineer.
According to the online Nissan dealer parts catalogs I viewed, the valve I replaced is the EVAP Canister Purge Control Valve/Solenoid Valve (the big valve that is bolted to the top of the intake manifold) and the receipt from the dealer I bought it from confirmed the name. It is not the valve you have pictured, saig. I'm not sure what the name of that valve is in Nissan vernacular. I have bench tested the valve you pictured and it checked out based on the electronics. The EVAP Canister Purge Control Valve/Solenoid Valve I replaced tested as open when not energized by the ECU. The old one did too. But replacing it has gotten me the closest to proper function of any of the things I've done trying to solve this problem. My theory for the smoke coming out of the intake was that the EVAP Canister Purge Control Valve/Solenoid Valve stays open when the engine is not running so smoke can back up through the intake. My smoke machine had all kinds of warnings about not running smoke with the ignition key on which meant the valve I replaced was going to stay open, old or new. In fact the smoke machine wanted me to disable the car battery and use inert gases rather than air from my compressor, which I didn't do.
You may have replaced the evap canister purge volume control valve.
But 98FSM page EC-416 lists the cause of P1493 as: evap canister purge control valve device stuck open. That device was mentioned in earlier post by CS_AR
Originally Posted by CS_AR
Here is a section of evap purge line when ECM performs pressure and vacuum tests .
That device should be in close state when there is no vacuum signal, ie. engine not running.
There are no uniform names for parts that have a very specific purpose. There should be universal name for this part just like a U-joint or brake rotor. The top picture you displayed appears to be this part:
They are very similar except yours doesn't appear to have a mounting bracket nor is it black. It is in fact the part I replaced. It has a Nissan part no. of 14930-3M201. It was referred to with about a half-dozen names when I first searched for it. Page FSM EC-368 also shows it as one possible source for the P1440. My parts invoice called it a purge control valve. The word Volume isn't included. It was also shown on several You.Tube videos on many different vehicles as the most likely source for my P1440 EVAP small vacuum leak code. Of course it also had numerous different names in the videos. I finally just took the leap and replaced it. When I did the P1440 small leak code went away as did the P1493. But the P1493 returned. Just as an aside, I have now driven the car another 400 miles approximately and the P1493 has not returned again. The P1440 never returned.
At this point, it appears you are telling me that I should also replace the pictured 14956-35U10: It did pass the bench test recommended in the FSM. I'm beginning to doubt if any of the bench testing suggestions in the FSM are worth a damn.
Given how things have played out, it appears I had/have two problems. The small air leak P1440 was solved by replacing the first part and the P1493 will be solved by replacing the second. It threw me a loop when replacing the first part cleared both codes and they didn't come back for awhile. That combined with the similar names has made this enormously frustrating.
I cleared it and it hasn't since. Do you think it coming back that time was an anomaly and I should wait one more time before replacing the part? By the way, the part was called a Valve Assembly-Solenoid on the Genuine part website that appeared to have the best price. The saga of dozens of names continues.
I cleared it and it hasn't since. Do you think it coming back that time was an anomaly and I should wait one more time before replacing the part? By the way, the part was called a Valve Assembly-Solenoid on the Genuine part website that appeared to have the best price. The saga of dozens of names continues.
You mentioned it has been 400 mile and no code, so I think you have fixed it. Just wait if it comes back. Don't be a part canon.
Regarding to the names, I agree, it has the worst naming ever.
part A,
part A part B, why do they have to mention part A in naming part B?
part A part B part C.
part A part B purge control part C
part A part B vent control part D valve
part A part B vent control part D valve solenoid
It makes you read the whole words, what ever comes last is the part. It's nuts!
For me, I try to understand the role of a part. Let not forget a primary (simple) goal is purge vapor. The majority of the system is for diagnostic purposes.
Since vapor of unknown air/fuel ratio is fed directly to intake manifold it can screw up the ignition. Therefore ECM and all ignition sensors are involved, front heated o2, engine coolant temp, .... to assure a stable running engine.
The volume solenoid you replaced is to feed intake manifold (chamber with metered air) with gas vapor. This device has settings so that it can feed different vapor volume depending on engine running conditions, accel/decel/standing...
And the function of the solenoid, which you found good price, is to send vacuum signal to a valve to block or open the purge line.
just an FYI. anybody replacing the evap canister purge volume control valve
should note that earlier 95 California and possibly 96 California models had this version of the valve. some Feds had it as well I think.
.
.
Nissan replaced the part with
14930-3M201
shown here installed with the adapter bracket for earlier models.
bracket PN 14921-2L900
.
.
comparo
old vs new
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this was the part I had to change with a 1008 code
Add to your analysis of the names is the fact that the manufacturers can't even stay consistent. It's tantamount to one company calling it an axle and another calling it a big stick.
I really like your term "part canon". That is what I wanted to avoid when I started down this road. It's one thing when it's a $20 part but when you start bumping up on $200 you want to be careful. I love my Maxima but one reason for driving an old car is to have low cost transportation. Mine is now around 220k miles and it runs great (thanks in large part to you really smart guys on Maxima.org). My hope is that it keeps running without costing an arm and a leg.
As far as the price and availability of factory parts, there are now many dealers who sell parts on the Internet. There are quite a few places that that part is available for around $80 shipped. A trick they use is post a good price but clip you on the shipping which, for many parts, is just an addition to the price. It doesn't cost $10 to put that part into a USPS box and pop it in the mail. Google is your friend on finding them though. Just type in the factory part number and a whole page of dealers will pop up.
11-07-2017, 03:27 PM
I get like 22-25 mpg running premium in my 99. Fair number of stoplights where I live though... Not that this helps you at all 
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