High heat (99 F) and humidity rolled into Louisville and my engine started stumbling. Happens from idle to all speeds, almost like I'm missing on one cylinder or have bad gas. Initially no codes and never any temp change on my 20 minute drive to work, so I put STP gas treatment in my gas and filled it up from half a tank to 3/4. Engine has 42 K miles and had been purring like a kitten since replacing the original (yes I replaced the tensioners and water pump). I did have one episode where the air cleaner got wet after I lost the headlight access panel, but I replaced the air cleaner and cleaned the MAF Sensor and all has been well. On the way home still stumbled and I got a 5 second Restricted Performance light and then the Check Engine came on. I did a precautionary oil change (3000 miles) air filter dry and like new and the engine is running smoother but still misfiring. There is 80K on the rest of the car, and the plugs and wires were replaced about 10 K miles ago.

I know you need the codes, which I will try and run out and get, but I am new to Louisville and wondering whether there is anything obvious to check before rolling the dice with an unfamiliar mechanic.

Really Appreciate the Help!

 

OK the Autozone guy said i had a "360" code -according to him Engine Misfire - and then he said that I was missing on my #8 cylinder. He messed with the reader and then said it was spitting out some other codes that he thought were caused by the base problem - P1000, P1314, and P1316. He said I should pull the plug and check it out and that It may be a plugged fuel injector or faulty ignition coil assembly ($108).

This engine was out of a XJ8 - how about a quick tip on which cylinder is #8.

Appreciate any thoughts and recommendations!

 

OK I pulled the #8 plug it was totally white with half of the electrode eaten away. I was expecting black and fouled? There was a very small amount of oil residue under the rocker cover lid and maybe a teaspoon of oil down in the plug well. The body of the plug had a little oil on it and the rubber coil sleeve was wet with oil on the bottom inch. I wrapped a socket extension with paper towel a few times and pushed it down around the plug until it came out clean before removing the plug, and then carefully did it a couple more times to remove all traces of the oil. I installed a new plug and new coil assembly and she purrs like a kitten. For now... When I had the engine swap done the mechanic noticed oil in the plugwells and replaced the rocker cover gasket. It has only been 3000 miles but the intense heat may have aggravated any mismatch between the plastic rocker cover and aluminum head. I guess I am going to have to drive her for a while and check for oil accumuilation around the plugs. Although I didnt pull the other plugs (99 F ...) I did note that their was a slight amount of oil residue visable near the #8 coil and virtually none near 5,6, and 7. I couldnt see any evidence of arcing or any tearing of the rubber boot. I suppose I might have a slightly oily spare coil and it was just a bad plug?

 

I wonder if the mechanic changed the gasket AND the plug hole seals, which are separate. When the weather is more amenable, it might be advisable to replace them all, as well as all the plugs.

 

way to dig in naz, now you know exactly what to look for on a misfire, and I'm glad you took care of it quickly instead of waiting around. I bet the plug well gaskets didn't get changed with the new engine, but very common to have #8 develop that problem...you're not alone. Keep an eye on it, if it pops up again before it cools down, may be time to buckle down and do it early morning or really late when its cooler. Better you sweat now, then sweating later over a damaged catalytic converter.