[mechnut450]

So guys short and sweet. I need help again.


I have a 2007 Nissan Frontier (sv ) crew-cab with 226k miles on it.
I getting a 0171 code with check engine light on ( and seen fuel mileage drop ( almost in 1/2) Truck runs fine has get up and go no carbon build up. I stopped in to a Autozone and they did the code check( in truck) but mainly I am told it can be anything from a leaky vac line to injector issues.

The part that sucks is I was promised a place where I use to work in another store and found out it only 10 hours a week and it will take me 45 Minutes to get there(one way). So I need to make sure A: the truck not going to crap out on me . and B: hold up until I can either get a newer one or a closer to home job that if need be I can take a bus. Between what little I have in savings (holidays and faith in a corporation that lied to me, and repairs/maintenance I have had done in last few months) budget tight and shrinking daily. I need Ideas or someone IN Delaware area that got more skill and knowledge to take a peek for me. If i can find the problem I am willing to take the time to replace the parts myself if it not internal like pulling a head to work on it .( I can do starters,alternators, brakes and Wheel hubs, but anything with real strength and finesse I am no good. ( i break impact socket like they paper lol)

 

[finallygotatruck]

https://www.engine-codes.com/p0171_nissan.html

 

[mechnut450]

already read that all but, I not sure were the maf senor or pvc thing is or what it looks like.

I felt last night it idles a littler rougher than earlier in the day. I put some high test and fuel cleaner in the tank to see if that helps if an intake fouled. I think I have most the tools I need I just need to figure out where the issues from and i think I can replace it. I am going to check my air filter today once i get some light. My rotten luck it will be a some little 3.00 buck part that I cant reach or find lol..

 

[Zero Six LE]

Sounds like an O2 sensor most likely. With the mileage your truck has, it's very likely in need of replacement. Bank 1 sensor 1 is the sensor on the passenger side and visible through the fender well.

 

[KurtVH]

Best case is a vacuum leak. Rule that out first.

Next best case is a dirty MAF sensor. You can try to clean the MAF sensor to rule that out

O2 sensor could be the culprit, but absent any other O2 sensor code, probably not. If it is an O2 sensor, it may be because it is fouled with oil. You can inspect the O2 sensor for that. In that case, fInd and fix the source of the oil replacing the sensor. Only the upstream sensor can cause this. The after sensors just monitor the emissions only and do not feed the ECM.

 

[AutoBravado]

Some help with common lean issues.

Best case is a vacuum leak. Rule that out first.

Next best case is a dirty MAF sensor. You can try to clean the MAF sensor to rule that out

O2 sensor could be the culprit, but absent any other O2 sensor code, probably not. If it is an O2 sensor, it may be because it is fouled with oil. You can inspect the O2 sensor for that. In that case, fInd and fix the source of the oil replacing the sensor. Only the upstream sensor can cause this. The after sensors just monitor the emissions only and do not feed the ECM.

That's good advice. Let me add to it.

The easy way to usually rule out a vacuum leak:

Use live data. Watch short and long term fuel trims together. Their combined number are the actual fuel trim adjustment. At idle, increase your RPM slowly, if the fuel trims go from positive, to closer to zero, or even from zero to rich (usually not the case) then the data is confirming look for a vacuum leak.

This test is harder (easy with practice): (not a frowny face, lol)
When I check O2 sensors, I watch for a good stoichiometric pattern. At about .450 millivolts, your at about 14.7:1 fuel ratio. The O2 sensors can show sensor trace patterns up and down under normal behavior. Do a snap throttle test. They should go rich. Introduce a vacuum leak. They should go lean. If your upstream or bank 1 sensor 1 and bank 2 sensor 1 sensors pass this test, they should be fine.

Less common lean issues:
I like to use a basic laser guided, touchless thermometer. I shoot coolant temperature sensors (often ECT on a scantool) at cold and as an engine heats up during the above tests. Does my Harbor Freight tool help me catch a lot
of bad ECT's? Oh yeah. Very accurate. It's done the same for me for IAT or intake air temperature sensors.

Some help with understanding Secrets of Fuel trims and O2 sensors. I actually made this video. I rarely explain things so simply and clearly. I managed to even keep straight moving my hands back and forth like lean and rich fuel trims and added visuals to make it easier to understand.

 

[AutoBravado]

light misfires and an UNLIKELY HUZAH MOMENT!

Light misfires can cause fuel trims to go lean as well.

I define light or mild misfires as misfires which are too mild to show up as a misfire code.

Using your once again handy $20 on sale ($30 full price I believe and way less than other stores, while actually accurate) Harbor Freight Infrared thermometer, you can actually shoot the fuel injectors and see if if your engine is running even. A dealer level scan tools balance graph per cylinder is more accurate, but you can do a lot with some ingenuity.

They should be about the same temperature. If they aren't, the cooler ones aren't getting as much fuel, or their spark isn't as strong. I know you're on a tight budget otherwise my advice would be different at this point. If you identify this as an issue, you should probably replace your spark plugs, but if you can't afford it...partly thanks for buying your infrared thermometer, which you need to diagnose many of these issues, then you can just adjust the spark plug gap.

On my 2004 the spark plug gap is supposed to be .044" (I don't know if Nissan changed this on other years). If I had a cooler injector and wanted to raise it's temperature to better balance the engine, I'd increase it's gap to .046". Small changes like this can improve fuel trims. If misfires are actually the only cause for lean code, then it's less likely mild misfire, if this is your issue, would be your only issue.

If a fuel injector is a lot cooler, it may be the cause of the misfire - I usually don't hear of Nissans having any issues with fuel injectors, so it's more likely a spark issue or even a worn out engine with low compression (this also makes for lean fuel trims - all the unburnt fuel carries a lot of oxygen with it).

On to the unlikely huzah moment, lol.

My fuel trims with severe cold went very rich the other day, but not enough to set a code. Some customers came buy with lean codes during our severe cold snap and while they had P0171 or P0174 (bank 2) codes stored, they didn't actually have a lean condition when I checked live data.

You're getting terrible gas mileage, so while I think your fuel trim issues are ongoing...is it possible you're just experiencing cold weather gas mileage? What's your actual gas mileage now, versus before the code? (None of this, I spent $5 more often doing partial fill ups - actual full fill ups and trip meter reset, and hand calculated numbers, or the "data" is useless.)

 

[mechnut450]

autobravado I have one of the temps gun lol. but it only short run it seems to burn more fuel.still idles at 1k even warm. I did 3-5 short trips since i filled it up ( taking my wife to work and coming home over 4 days) about 40 miles total and I used a 1/4 tank. runs fine takes off like she wants to pull a wheelie , no carbon in exhaust. ( wipe my finger in pip test lol) but i feel she got a vac leak but I don't know where to look but I hearing a almost tapping hiss under the hood. I didn't here this summer.

 

[AutoBravado]

From the most expensive to the easiest test

autobravado I have one of the temps gun lol. but it only short run it seems to burn more fuel.still idles at 1k even warm. I did 3-5 short trips since i filled it up ( taking my wife to work and coming home over 4 days) about 40 miles total and I used a 1/4 tank. runs fine takes off like she wants to pull a wheelie , no carbon in exhaust. ( wipe my finger in pip test lol) but i feel she got a vac leak but I don't know where to look but I hearing a almost tapping hiss under the hood. I didn't here this summer.

Any of the below are easier while looking at live scan data, but if it's enough of a leak, you can hear engine changes, versus seeing fuel trim/RPM changes, which may be more subtle.

The safest way to look for the leak is probably propane, but it is the most expensive. (obviously don't light a torch)
Just open it up and spray it on any tube, intake, etc after the maf which could leak. When the engine changes it's sound, you've found the leak (assuming it's warmed up, a warming up engine will change it's sound as it settles in).

The most dangerous way that's easier and cheap to get your hands on is a can of brake clean and spray around. (Don't use starter fluid, way more dangerous, as is other more powerful cleaners). Also listen for changes.

Lastly is water. If you have a spray bottle you can use, this is a cheap solution, which is safe, and won't start a fire, but it can be more dangerous than propane in that you could damage sensitive electrical items. Spray it, poor it slowly from a water bottle. Lots of options.

 

[mechnut450]

so i went to my mechanic and he spent 3 hours looking at the truck. he heard a intake leak and took entire intake off the truck looking at everything. I asked if the seal rings could of gone bad cause where it been off a couple times he said it possible and replaced them put it all back together and reset the codes and ran the truck ona back road stomping on it hard a couple times I then drove it to my grandmothers and back home ( about 120 miles ) and i not had a issue since. and my mileage has gone back to where it should be. I was worried if the entire intake was bad and possible cracked since it got 226k on the motor. I not priced one for it yet but it mainly plastic from the feel of it.

 

[AutoBravado]

so i went to my mechanic and he spent 3 hours looking at the truck. he heard a intake leak and took entire intake off the truck looking at everything. I asked if the seal rings could of gone bad cause where it been off a couple times he said it possible and replaced them put it all back together and reset the codes and ran the truck ona back road stomping on it hard a couple times I then drove it to my grandmothers and back home ( about 120 miles ) and i not had a issue since. and my mileage has gone back to where it should be. I was worried if the entire intake was bad and possible cracked since it got 226k on the motor. I not priced one for it yet but it mainly plastic from the feel of it.

Maybe the communicty can correct me if I'm wrong, but I haven't known about these intakes cracking. The only plastic intakes I can think of for cracking a lot is some mid 3 liter sized Chevy plastic intakes, not Nissans.

 

[mechnut450]

Well it was what my mechanic was thinking if the new seals didn't fix it cause he could hear the vac leak but all the hoses are still good.

 

[AutoBravado]

Vacuum leak detection

Well it was what my mechanic was thinking if the new seals didn't fix it cause he could hear the vac leak but all the hoses are still good.

Take a spray bottle with water and spray around the intake. If the engine chugs you've found the vacuum leak. Something you couldn't spray would be a brake booster internal leak (rare) but spraying around you could just find out for sure instead of guessing at an expensive part.

A lot of people use brake cleaner. I've welded a while after using brake cleaner - a WHILE - and there was still spots of cement on the ground which poof went up into flame. So...yeah, there are safer things to check for vacuum leaks with like water or propane.

If that doesn't work maybe your mechanic has a smoke testing machine.

 

[mechnut450]

no it fixed once replaced the seals. lol one of the gaskets was totally crushed. we think that maybe when he did a valve cover gasket it crushed wrong and finally broke under recent cold weather. so far it been great I gotten almost 90 miles on a quarter tank.

 

[AutoBravado]

Glad your fixed - great gas mileage!

no it fixed once replaced the seals. lol one of the gaskets was totally crushed. we think that maybe when he did a valve cover gasket it crushed wrong and finally broke under recent cold weather. so far it been great I gotten almost 90 miles on a quarter tank.

Good fix!

Yeah. It doesn't happen often, but I've seen a gasket not quite made right. I figured it'd fail. Showed it to the customer..."I gotta get outta here. Make it work." Installed it anyway...and a few days later a worse leak than before and I was doing the work again. Usually they're made right...usually, lol.

 

[KurtVH]

Maybe the communicty can correct me if I'm wrong, but I haven't known about these intakes cracking. The only plastic intakes I can think of for cracking a lot is some mid 3 liter sized Chevy plastic intakes, not Nissans.

I’m at ~200K miles and it looks and feels as good as new. Have not heard of or seen any others having that problem.

The Merecedes, on the other hand, cracked at not much over 100K

 

[mechnut450]

Well my luck just cant go right. The code came back this past week. It all the same signs. It killing me cause I only worked 2 hours this week. and this coming week looks like crap too, but then hours will start to pick up. I almost wish I had a older simpler truck with a carb I know there a lot less hoses and cap to fiddle with to find the right one. My current mechanic so over his head he said it bee at least 3-4 weeks until he can even think to look at it. I would just take it to a dealer if I actually worked enough to afford bill cause i need the truck. I might look into a replacement vehicle with less miles but i love this truck.



On side note can you order a replacement for the little top cover/scoop piece that say ( in my case ) 4.0 v6 the plastic piece got busted after i took it off to check for a loose bolt( i fell on it and it split)

 

[mechnut450]

Umm this truck starting to irk me. I drove today out to put a new power supply in a friend computer and the service engine light stayed on. but as I left my friends house it went out and never came back on( today) knowing my lucky it be on in morning) Still runs fine the only thing i done was about 4 miles from his house I pulled over to take a leak ( don't drive 2 hours after drinking 64 oz lol) well I got back in truck and figure heck with it and stomped the acc to floor and took off got to about 110 and left off and coasted ( got to love flat straight back roads down home.) so after i left start ed up and drove home with no issues. I beginning to think that maybe my o2 sensor had some build up on it and when I stomped on her it all blew off. ( I do know that it rained all day so another possible issue could be there a break in o2sensor wiring and causing a false reading and being soaked all day as I drove allowed it to seal up some? OI will know in next 2 days as it going to be dry and I only taking my wife to work so if it comes back on I have t test if it build up or see if I can take a long ride on a wet day and it goes back out if it comes on.

 

[AutoBravado]

Another technique that I forgot about since I always look for vacuum leaks otherwise, is that you can use pliers to close off one tube at a time and see if the fuel trims go less lean. Sorry, but unless it's tremendous, I don't see how you'd hear the difference. I think you need live data.

Some leaks I've found with brake cleaner even wouldn't have been possible without live data as the leak was slight enough...yet bad enough to set a code.

Umm this truck starting to irk me. I drove today out to put a new power supply in a friend computer and the service engine light stayed on. but as I left my friends house it went out and never came back on( today) knowing my lucky it be on in morning) Still runs fine the only thing i done was about 4 miles from his house I pulled over to take a leak ( don't drive 2 hours after drinking 64 oz lol) well I got back in truck and figure heck with it and stomped the acc to floor and took off got to about 110 and left off and coasted ( got to love flat straight back roads down home.) so after i left start ed up and drove home with no issues. I beginning to think that maybe my o2 sensor had some build up on it and when I stomped on her it all blew off. ( I do know that it rained all day so another possible issue could be there a break in o2sensor wiring and causing a false reading and being soaked all day as I drove allowed it to seal up some? OI will know in next 2 days as it going to be dry and I only taking my wife to work so if it comes back on I have t test if it build up or see if I can take a long ride on a wet day and it goes back out if it comes on.

You could be right that yo have a dirty O2 sensor. I've cleaned them up before without using chemicals (they're very sensitive). The car ran great! But then the O2 sensor completely failed, even worse, within a week. Seeing as how you're short on work, I don't recommend this temporary fix. My rule of thumb is if I ever do it again, order the O2 sensor that day.

Sorry bro, in winter shops are slow, but this winter has been extra slow so I understand less work.

 

[mechnut450]

well not a issue any more wife looked at me and said trade it in, we don't want to be on the side of the road when we travel this summer to Kentucky. So I stopped in a local dealer and end up driving home 9 hours later a 2015 frontier sv. I can't believe how tight the drive train feels and steering handles and it dark grey. I have to go back this morning and remove the last of my stuff from the truck and drop off the title. Now I need to start saving funds and put the finishing touches on it like bug deflector and window vents and ( dare I dream to be able to afford a set of the runner boards/steps).