[DavidH]

Hello Everyone! I have been having this problem every since I got this car. The check engine light will stay on until I push the gas, and then it will go away, but the second I let go of the gas the light comes back on. I checked the codes, and I am getting a code 91, which has to do with the O2 sensors. Both are new O2 sensors. The wiring to the sensors look a little shabby, but I have checked both the power and ground to the sensors, and they are both working. I have checked the fuel pressure, which is right on, and I have changed the fuel injectors. Any suggestions?? I am totally out of ideas now. The person who had the car before took out the cats, and disconnected the air pump lines. Can this cause this code.

By the way, the car seems to backfire through the intake under mild acceleration, (I'm not sure if that is what it is doing, I just hear a popping sound from the engine). Under hard acceleration it is fine. I don't know if these two problems are connected. Any help would be greatly appreciated...Thanks

[Fordgazm]

Sounds like your base timing is too retarded . In other words it is firing too early . If this is the case then you may not be getting a complete combustion and so you are sending un-burnt fuel out the exhaust . Your oxygen sensors are seeing it as running rich and sending a fault . Set your timing to about 13 degrees btdc . And it should fix your problem . By the way what is your timing set at now ?

[DavidH]

that sounds like great advice, right now it is set to 10. I am going to change it to 13. I will post how it works out. thanks!

[Fordgazm]

How many miles are on the car also ?

[DavidH]

Ouch! I know where that question is leading. The odometer say 140,000. I don't know if the engine has ever been rebuilt or not, and I am not sure if those are the correct miles. ( I hope that it isn't)

[Fordgazm]

Not really a big ouch . I was just thinking that at 140,000 your timing chain probably has some slack in it and that may be the reason your timing was off. No need for a rebuild till you get it running as best you can and then do a leakdown test . That would be a good Idea .Have you re - adjusted the timing yet ?

[DavidH]

Yeah I just readjusted the timing to 13 btdc. It is still getting the check engine code though. I am going to reset the computer again, and I am going to drive it around tomorrow to see if anything has changed. I'm pretty sure that the engine is in good shape, for the most part it drives good and has a clean idle. It just seems to be running either rich or lean at times. I definitely want to change the timing chain, but I need a good day to take things apart.