I recently had my car tuned and now I will get a code for cyl 1 misfire every time I take the car out and on a occasion cyl 1, cyl 4, misfire with a random misfire code as well. The weird thing is the car seems to run fine. Did a couple wide open pulls all the way to redline with no pops, loss of power, or anything that would indicate a misfire. It will also code a misfire with no cel light and put itself into open loop so that it will not adjust for short term fuel trim as it has done this to me twice now. The car is NGK9 with .17 gap on E85. Here is the link to what else is done. https://www.s2ki.com/s2000/topic/995...f22-645-23psi/. Any input would be helpful.

 

It's due to the changes in temp (assuming you had a recent change i temp)I had he same issue with my car. Have your tuner adjust the fuel trim based on coolant temp and it should go away. E85 is affected by temperature more than I would have thought.

 

The car was just tuned with no changes in outside temp. If that is what you mean.

 

I'm also using E85 and having misfire codes on cylinder 1,3, and 4. Do you think this may be because of the change on the ethanol content from the E85?

 

I am on the same tank of gas from when it was tuned so I am not sure about that. How often do you get the misfire code.

 

When i clear it, it pops back up about three weeks. Car runs perfect though but just seeing the CEL worries me sometime

 

Still having misfire code. Here is what my tuner did so far. Compression test got 260 a crossed the board, detuned knock sensor, disabled knock sensor, and now the kicker even unplugged knock sensor from block. And the damn thing still will pull timing out and throw a misfire code with it disconnected from the block. It mainly throws the code on the second key cycle after some stop and go traffic. As stated before runs fine with no signs of any kind of misfires.

 

Since cylinder 1 is the 1st code to appear, move the coil from cylinder 1 to another cylinder and see if the misfire moves with it. When you pull it out make sure that its free from signs of oil. If there is oil present, fix the leak. If you move the coil and the misfire is now in the cylinder you placed the coil, the coil needs to be replaced. Don't worry about the random misfire code or the other cylinders misfire codes as they are probably the result of the main misfire issue. In your case cylinder 1 was the first code to appear so it's the most likely cause. Usually, a misfire in 1 cylinder will cause another too and will throw a code for this cylinder as well as throw a random misfire code.

If the coil is free from oil and the misfire doesn't move to the new cylinder you placed it in, your next step is to move the injector and test again. If the misfire now moved then you need to replace the injector.

If you move the coil and injector and the misfire is still in cylinder 1, you need to do a compression test. Since you already have done that and compression is good, I would do a leak down test to see if there is an issue possibly in the cylinder head. Improperly adjusted valves can also cause a misfire.

Also and bare with me cause this will sound really stupid but I will explain myself...make sure you are using the proper weight oil. Yea, I said it would sound stupid but I had a 2012 Odyssey come into the shop with a misfire on cylinders 2 & 5 and did all the normal checks. After running all the tests I could and everything coming back normal, I was frustrated to say the least and left the car idling in the corner of the shop after about 20 minutes I went back to it and heard a very faint knocking sound coming from the valvetrain I hadn't heard before but it appeared after the car had warmed. So before ripping off the valve covers and looking inside, I went looking around the car for anything look abnormal. The only thing I could see is the oil was changed by one of those "quick lube" places and on a whim, I changed the oil. Put a filter on it filled it with 0w-20 started it up and sure as shit, misfire was gone. The guy at the "quick lube" place probably didn't have the right weight oil near him and instead of going to get it, he threw in anything he had near him which was too heavy of weight causing the valvetrain to be starved of oil causing the knock which the knock sensor picked up as misfire.

OK sorry for the long post...anyways, start there and see what happens. If you still can't find it let me know I will help you try and diagnose it further...GoodLuck !

 

^^ Good info...just had multiple and cylinder 1,2 and 4 misfire codes. Checked the plugs and number 4 was fouled. Also had a bigger gap than the cylinder 3 plug. Replaced all 4 spark plugs. Keeping an eye on the coil pack and injector in that cylinder incase it comes back. Spark plug was fouled within 5k mile of being blown and tuned.

 

Almighty-Si thanks for your input. The only things I have not tried is leak down test and switching injectors but the injectors are new and were tested before I got them. What is really confusing is when we unplugged the knock sensor from the block it was showing that it was still getting voltage and detecting misfires. Not shore if anyone else have had this problem with their 06+ with Flashpro.