Bad Gas!

[hfrez]

Gosh, I must have gotten a tankful of bad gas from a gas station on the Florida Turnpike (Shell). At least I hope that is what it is/was. Every time I stop at an intersection my RPM's will drop from 750 to 625 after about 15 to 20 seconds and the motor vibrates like it is starving for gas but never really stalls. I'm on my second tank since then with gas from a trusted gas station and this last time around I added some STP Fuel System cleaner for Ethanol gas. It seems to help some.

Has anyone else had this kind of experience or could it be something else that is causing the engine to shudder like that? Other things that I tried was taking it out of gear and putting into Neutral or Park but the engine vibration did not seize.

I have also purchased a VOLO V12 that I have not yet installed and I think it will change the fuel mapping to a higher idle which may help but I do not want to install it until I am sure that it will not just mask a problem that has a potential to get worse.

[bbermann]

This sounds familiar. I had essentially the same experience-I would come to a stop light and the car would shudder and the idle would drop to the point that if I did not gas it it would die.

Using my OBD scanner came up with code P0131 which is O2 sensor circuit low volts (Bank 1 sensor 1).

I looked for this in the service manuals ( there is a link on this web site). I was suprised that in following the procedure I did fix the problem by simply tightening the grounding points under the hood. There were three of them. No O2 sensors needed replacing.

Be careful to not overtighten the bolts/screws. I sheared one off. You might also want to actually remove the screws and clean up the contact areas before tightening them.

Good luck.

[hfrez]

You would not happen to know the link?

[bbermann]

http://www.thenissanpath.com/filelib/R5 ... ce/FWD.pdf

Above is the service manual link. I'm not sure about the exact pages. I do recall the wires were ground to the insides of the fenders and I needed to remove the battery and cold air intake to access them.

Actually, here are the actual points:

http://www.thenissanpath.com/filelib/R51/Service/PG.pdf

I don't remember where I found the original troubleshooting instructions.

[hfrez]

Thanks bbermann. I think my next step is to invest in a code reader or scanner. I saw one on amazon a Equus 3130 Innova Diagnostic Code Scanner with Live, Record and Playback Data Capability for OBDII Vehicles for $128. My truck is only been in my possession for the past 2 mos. Seems silly that it would be a problem like that but I want to know before I bring it into the dealer since I'm under warranty.

[bbermann]

DO get a code reader, they are cheap and universal.

Here is what I got and it works:
http://www.ebay.com/itm/U380-OBDII-OBD2 ... 48431a4e2e

Let us know what the dealer figures out...

[hfrez]

Well, got my new code reader today and it showes no DTC codes presently. Back to square one. She continues to idle in a bad way. If the RPM's are at 750 it feels fine but then after about 15 sec it will drop to 600 RPM's and the motor will vibrate and shake the whole truck but will not stall. It does not matter whether its in gear, Neutral or Park. I also turned off the A/C and other items that might affect the situation with no avail.