Misfire codes and wheel speed sensor questionsI am hoping that I can get some clarity here and I hope this is the right segment of this site to get some answers. Last July I took a trip to Tampa from Pittsburgh and when I arrived I got the dreaded check engine light. It was not flashing but steady. I had the codes read and I had the dreaded cylinder misfire codes. Long story short, I had one bad coil and replaced all four to include NGK plugs. The care ran perfect until three weeks ago. This is a 2001 with 65000 miles. On a trip to New York I started getting codes again of all misfire codes again but I also had a wheel speed sensor code that I did not write down as it only came up once. I cleared all codes with my OBD and the car ran fine for the remainder of the trip. Two weeks ago the engine light came back on with a wheel speed sensor code an the misfire codes also. When I stopped at a traffic light the car just shut down. No power whatso ever. I let it sit about 10 minutes and she fired back up and ran perfect. Once again I did not record the wheel speed sensor code; my bad. I am having all injectors replaced as I am writing this inquiry. My question is: what the heck is a wheel speed sensor and how many of them are there. I read the misfire code portion of this site in its entirety and did not see one mention of the wheel speed sensor code. A friend of mine told me that a wheel speed sensor could shut the car down. Is this correct and what part should I be requesting? I do store this car over the winter season for five months but we use fuel stabilizer so I am not thinking the fuel would be a cause. I also read in the misfire code thread that replacement of the injectors could possibly remove problems with these codes; fingers crossed. This car is completely stock and the previous two owners have kept a complete history of all maintenance performed as I have to this date. I am not a mechanic but do have basic knowledge. I also have a friend that has raced Alfa's for the past 40 years and is quite knowledgeable of foreign cars in general so anything that comes up I can usually have them resolved. I have been obtaining parts from Majestic in RI. I will thank all of you in advance.

I moved this from another portion of this site as I believe I was in the wrong place. Additional info is that the valve retainers were replaced also.

Ed
Miner2003 is online now Report Post

 

This is what I Googled. Check bottom entry, in the thread. Were the speed sensors or other related parts (like wheel diameter or tire size) ever changed on your car?

https://www.s2ki.com/forums/s2000-un...sensor-808116/

 

Have you checked the codes and trouble shooting against the Service Manual?

-- Chuck

 

No clue about wheel speed sensor. Misfires - to get ignition you need fuel (injectors) air (intake) spark (coils and plugs). Also, you need compression (valves and rings and headgasket maybe). So, something is missing on that list. Not sure what caused you to replace the injectors - but maybe that will work. Hope so.

If it were me I would like to pull the plugs and see how they look. That can tell you a lot. Its easy to rule out compression problems with a simple compression test, and then if need be a leak down test will narrow down the cause of low compression.

 

No. 1000 percent stock.

 

Having considered all the suggestions, Donny checked the valves and they were actually perfect. The one test he did not do was a leak down test and that revealed the culprit to all my problems. An intake valve on the No. 4 cyclinder is bad so off the car goes to the machine shop. I will let everyone know what that outcome renders.

 

Was a compression test done? Results?

Did the leak down show a leak at only one intake valve? You report misfires all over, not just in one cylinder.

Good luck.

Keep us posted.