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Misfiring but no CEL

1K views 5 replies 3 participants last post by  CRSHNB12 
#1 ·
Lately my gas mileage has started to tank. I used to be able to get between 280 and 300 miles out of a tank with mainly city driving. Lately I get at best 230 miles. So I bought the Bluetooth adapter for the OBD2 and starting using Torque Pro. On a 30 min drive to work it will show I have between 8-12 misfires, but again no CEL is going on. I ran a can of Sea Foam through the gas tank and that helped bring down the MF's to 4-6, but without I am back to the 8-12. The car has 137k miles on it, I have changed plugs, wires and fuel filter within the last 2 years. I cleaned the MAF about 6 months ago I have gotten 2-3 coil packs from junk yards on newer model cars (latest is from a 2000 car) but still getting the misfires and bad gas mileage. If I have to buy a new coil pack I will but would prefer to avoid the cost. The car might have original CATs and O2 sensors, but no CEL for those, in fact no CEL at all. Any help is where else to look to solve this mystery would be helpful. Here is a pic of my misfires from Torque Pro.

https://www.dropbox.com/s/3nwcqf8obg9vg3q/OBD%201.png
 
#5 ·
Throughout the driving range...

I feel it miss when sitting at a light, I take my foot off the brake and just as I give it gas it misses. Other times when it misses it is when I am driving and I can not feel it, but see it in the Torque app. On Friday I drove for 15 min in stop and go traffic before the 1st miss, yesterday within a few min of starting the car it happened, it is very erratic on when it happens
 
#6 ·
You could be lean, due to a small vacuum leak. The additive you tried would actually enrichen the mixture and reduce the miss. Try spraying brake-clean on the intake gasket areas, around the egr valve, or any other vacuum operated device. If the miss stops while the spray is present, you found the leak. Also, the way you should "clean" a MAF is by removing the sensor from it's housing and spraying brake-clean on the two sensor wires. Do not scrape the sensors, be carefull not to break the wires. Just spray until clean. Then reinstall.Good Luck.
 
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