check engine light comes on after filling with regular

[mel]

My check engine light started to come on after filling with regular gas . It goes off after I refill the low tank with premium gas. Do I need my fuel filter chaged or fuel system cleaned?? I have a Pathfinder 2001

[Towncivilian]

The VQ35DE engine prefers 91 or higher octane, but will tolerate 87 without throwing engine codes. Have the codes pulled at an auto parts store (AutoZone pulls codes free) and post them here.

[mel]

Does the check engine llight have to be on to get the code?? It is off now but I just filled it with 87 octane so should I wait to see if it comes back on ?

[Towncivilian]

No, pull codes anyway, they should be stored for a while.

[bordin34]

I ran my Pathfinder for over 50,000 miles on 87 with no problems so I wouldnt think thats your problem unless you have heavily carboned chambers.

[mel]

Auto Zone tried to run the codes "passed" The fellow told me to come back when the check engine light is on. I will see if comes back on while running with the 87 octane. Thanks for the help I didn't know auto zone did it for free and I was recluctant to go to the dealer. I do need front tires will look into that this week.

[Towncivilian]

Try running some fuel system cleaner containing polyether amines, which is a chemical proven to clean deposits without leaving behind its own residue. Products which are known to contain PEA are Chevron Techron, Gumout Regane, and Redline SI-1.

[SBK03SE]

I run 87 80% of the time, and I've only had it for <10,000mi. No problems.

The few times I pay the extra 5-6$ for 91/93 I can't say I notice a real difference.
Side note: Today I got up to 332.8mi before the light came on. Usually comes on at 275mi. I kept it under 2500rpm 95% of the time, eeked out almost 60mi more. This was on 87, I'm gonna try 91 now.

[Alfredo24.pr]

I run 87 80% of the time, and I've only had it for <10,000mi. No problems.

The few times I pay the extra 5-6$ for 91/93 I can't say I notice a real difference.
Side note: Today I got up to 332.8mi before the light came on. Usually comes on at 275mi. I kept it under 2500rpm 95% of the time, eeked out almost 60mi more. This was on 87, I'm gonna try 91 now.

Last time I had to fill with regular because there was no 91 or 93 nearby, my gas went down noticeably quicker than when I use 93 octane, but now I have to settle for 91 since about a month ago, I don't know why, my country just stopped bringing 93 to gas stations.

[Densetsu]

I run 87 80% of the time, and I've only had it for <10,000mi. No problems.

The few times I pay the extra 5-6$ for 91/93 I can't say I notice a real difference.
Side note: Today I got up to 332.8mi before the light came on. Usually comes on at 275mi. I kept it under 2500rpm 95% of the time, eeked out almost 60mi more. This was on 87, I'm gonna try 91 now.

Last time I had to fill with regular because there was no 91 or 93 nearby, my gas went down noticeably quicker than when I use 93 octane, but now I have to settle for 91 since about a month ago, I don't know why, my country just stopped bringing 93 to gas stations.

The gas stations around here mix in ethanol with the lower-grade gas. 89 has 5% ethanol, 87 has 10% ethanol. Ethanol isn't as efficient as normal gas, so this should contribute to some of the decreased fuel efficiency I notice. In terms of stored energy, ethanol is 34% less efficient, so a 10% mix should be 3.4% less efficient. It also likely affects how our engines run, which could also lower fuel economy.

The differences I've noticed are larger than 3.4%... in the winter, 91 with no ethanol gives me over 15% more km than 89 with 10% ethanol. The difference in summer is less, but still more noticeable than 3.4%.

[Chuck Tribolet]

You'll get better mileage on 91 than 89, ethanol or not, because on 91 the knock sensor will allow more spark advance.


Chuck

[91Path]

My 2001 Path has a knock sensor code, I use 87 octane, the truck gets terrible gas mileage could this code be the cause of the terrible gas mileage?

[Towncivilian]

Not necessarily. Are there any other engine codes?

[91Path]

Yes, map sensor something. I will re-scan my truck and then post the codes on this thread. These are the codes P1105 and P0325 Thanks. My van 2005 Mazda MPV gets better gas mileage than this truck

[Towncivilian]

Yes, a MAF sensor code will kill your mileage since the engine can't go over 2,400 RPM and the air/fuel ratio is incorrect as a result of improper airflow input. It'll be P0100 and the P0325 knock sensor code is a side effect. Try cleaning it with some MAF cleaner spray (don't use anything else); instructions are at the bottom of this article. If cleaning doesn't help, inspect the MAF sensor wiring for damage and loosen and retighten ground screws:



Failing that, this $90 OEM Maxima MAF will be a direct replacement, and is much cheaper than the $442 Pathfinder OEM MAF.

[91Path]

Not to hijack the thread but the codes are P1105 and P0325. The CEL dont bother me except that the gas mileage is terrible.

[Towncivilian]

P1105 doesn't exist for 2001 Pathfinders. Please provide the manufacturing date of your Pathfinder, located on the driver door jamb sticker.

[91Path]

P1105 doesn't exist for 2001 Pathfinders. Please provide the manufacturing date of your Pathfinder, located on the driver door jamb sticker.

8/00

[Towncivilian]

P1105 doesn't exist for 2001 Pathfinders. Please provide the manufacturing date of your Pathfinder, located on the driver door jamb sticker.

8/00

Can you re-read the codes and ensure P1105 is popping up? Also provide your VIN so I can confirm whether you have a 2001.0 or 2001.5 model year Pathfinder - 08/00 is the switchover month and I can't be certain without a VIN in this case.

[91Path]

VIN JN8AR09X91W580166

I ran my scanner on the truck again and it gave me

P1105 Map/Baro Pressure Switch Solenoid Valve
P0325 Knock Sensor 1 Circuit

If this does not sound right I will borrow another scanner tomorrow.


Thanks,

[Chuck Tribolet]

2WD or 4WD? With that VIN, it's 2001.5 if 2WD, 2001.0 if 4WD. AH, I see from the FIN that you have 2WD.

The character string "P1105" does not occur anywhere in my 2001.0+2001.5 FSM. Neither does "Map/Baro" or "Pressure Switch Solenoid".

I can see the knock sensor getting involved after switching to regular gas. The FSM has a procedure for trouble shooting P0325.
I'd suggest stepping through that.

Chuck

[Towncivilian]

FAST pulls up a 2000 Pathfinder with VG33E engine, 2WD XE A/T. In this case, P1105 does exist. Very strange that it has a VG33E given that it was built so late.

Start by ensuring the MAP solenoid hoses are not clogged or damaged in some way.

[91Path]

Yes it is a 2wd, can you show me a picture of what the MAP/BARO pressure solenoid switch is found and how it looks?

Thanks for all the help, can I relocate the knock sensor? where can I buy the harness?

[Towncivilian]

Don't worry about the knock sensor yet, it's probably just showing up as a side effect of the P1105 code. See EC-20 for the MAP solenoid location.

[91Path]

Thanks I will try to replace the MAP/BARO Pressure solenoid valve

[Towncivilian]

Do you want an exact OEM part number?

[91Path]

That would help if you have a number, thanks again

[Towncivilian]

Sorry, I can't seem to find a part number. I'd give your local dealership's parts desk a call.

[91Path]

Thanks

[91Path]

SPO ONLY PN# 14956-38U01 $ 129.20

This is what I got from the dealer, SPO Part $129.00 is this reasonable? or is it highway robbery?