A new problem, without warning. Very rough idle upon start today (Monday with no usage on weekend). After warming-up and 20 miles still rough, Can feel the car shake on highway. Less power on acceleration onto highway.

I'm thinking:
1. Bad gas but car worked fine for 100 mile trip last Friday -- so not likely.
2. Clog injector -- Add xylene and some Mystery oil to gas.
3. Bad oxygen sensor -- how to test?
4. Clogged catalytic converter -- how to test without disassembling exhaust?
5. Fouled plug?

Any other likely problem and how to test.

OnTheRoad
93 Maxima G with 120,000 miles.

 

does the rough-ness lessen if trans is placed in neutral?


i'm gonna go with #2 as i have similar symptoms and have narrowed it down to that or an exhaust leak - but i think it is #2

 

Check all your Vaccum line first, maker sure they are not cracked before you going crazy replacing parts.

 

Bad Spark plug wire? You have the GXE correct?
Go in dark. Open hood, DON'T GET FINGERS OR CLOTHING CAUGHT IN SPINNING BELTS, Look for blue sparks jumping from plug or coil wires. If necessary, mist wires with water spray bottle to enhance the effect.

 

+1

Always try that before replacing injectors. If you see a spark jumping or even hear a ticking sound from your spark plugs. Wrap the end of the wire in electrical tape and put it back (Sealing any cracks/holes sparks can get out from) then see if it still misfiries/ runs rough...
________
AMATEUR TUBE VIDEOS
________
Uhwh

 

Thanks for the replies and advise.

In the afternoon I ran the car again. Lot less rough.
In the early evening - smooth.

Test for vacumn leaks by starting fluid (opps dangerous, should of used brake cleaner). No leaks detected.

I put some gas dry (isopropanol), Cheveron injector cleaner, Mystery Oil and Laq Thinner (acetone plus others). Car is running very smoothly now.

With the warmer temperature and it working fine now, I think it was likely little water in the gas (separated with the lower temp and car sitting over the weekend) or some gremlin with the computer or sensors.

If I get the time or it acts up again, checking for the error codes will be useful. A friend said that some computer can be reset by disconnecting the battery for a day to reset the errant sensor.

OnTheRoad
93 Maxima GXE

 

well that was anticlimactic....i was about to suggest using some seafoam - but the concotions you used seemed to have had like effects...