i am about to give up on my engine... arg, i can't get it to run smooth. i think its timing / valve lash issues but don't know for sure. i am hoping somebody in the memphis area could help me get this stupid thing running.
a few quick suggestions. are you running the right firing order for the cam? do you have any vacuum leaks? have you done a compression test? have you done a leak down test? need as much detail about your motor and the problem to be able to help. ill see if there is another post that has this info.
ok looks like you have the fast ezefi system. i put one on a customers car and it had problems. some days it would run like a champ and others it wouldnt run well at all. he had an exhaust leak before the o2 sensor. i had him fix that before we did anything else. he had it fixed but the efi still ran poorly. i had told him that after the exhaust leak is fixed we can call fast tech line and get it figured out. the customer decided that he just wanted to go back to a carb. so i have no idea what was wrong. so if you have no exhaust leaks before the o2 sensor try calling fast. also the explorer motor should not have valve adjustment. it should use pedestal mount rocker arms. all you do is tighten them down till they seat in there pedestal then you torque them to i think 15ftlbs but look that part up.
i am running a rebuilt short block, with trick flow heads, and roller rockers. i have a summit distributer for a msd box. i don't have exhaust yet, just the headers and collectors installed. i have the explorer cam and the firing order should be 1-3-7-2-6-5-4-8
the o2 sensor is most likely seeing oxygen from the open exhaust. i think you need at lest 2 ft of pipe after the sensor. right now the computer will keep trying to add fuel to compensate for all the oxygen it senses.
What Bryant said sounds right. get some collector reducers from the parts store and a couple pieces of pipe and clamp it togethor. should be cheap and you can still use the collector reducers when you take the car to the exhaust shop. Also just to double check, did you get the correct length pushrods? Stock pushrods will not work with the TFS heads and roller rockers.
I am getting the exhaust installed tomorrow. then i can go from there. i have extra length push rods installed. the geometry is right for the rockers. cars finally on its original tires and wheels, off the jack stands, after almost 2 years.
Cool, report back after the exhaust is installed. Not sure with your EEC but maybe after the exhaust is done you could try resetting the EEC and and starting over incase it has learned something you want it to forget.
Does that system have closed loop vs open loop, might not be a exhaust o2 sensor problem... That shouldnt be an issue until the car is warmed up?
I posted a question a couple weeks ago about who is running those efi setups, and this is the kind of stuff I wanted to hear about. I agree, open exhaust is giving the efi sensor the wrong feedback. I bet it works after exhaust is installed.
it uses a wide band o2. im sure there is a short time period for the o2 to heat up. my wide band o2 gauge takes about 15 secs to start reading. the fast system uses a similar sensor so i figure its in closed loop and making adjustments in under 30 secs.
