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1989 mustang running rough and loss of power

2033 Views 9 Replies 3 Participants Last post by  87frankenstang
ok so i have been working on this for a couple of days now and i think i need some help. so i found that when it is idling it runs fine but when i put it in gear it and give it a decent amount of gas(not full throttle) the car slows down but when i give it full throttle it gives it enough gas to accelerate but no where near as fast as this mustang normally accelerates. so i looked at plugs, wires, cap, and rooter and not knowing how long ago they have been changed out(i bought this car a year ago used) i replaced that and it help out a little bit but still ran really rough. changed the fuel filter and then it ran great again but only lasted for about 2 days before all the problems came back. replaced the fuel filter again to find the new one i just put in was clogged up again but unfortunately this did not fix the problem. tested the fuel pressure yesterday and found it idled at 35 psi and ran at 40 psi and i think the number are good.? i rechecked the firing order and all the parts i just replaced to make sure there was no where and everything check out good. ran the check engine codes yesterday and it told me that there is a problem with the mass air flow sensor, and the oxygen senors. don't really know what to do about the oxygen sensors yet but i did clean the mass air flow sensor and cleared the code but it just came right back. im up to any suggestions on what to do next i have ordered a new mass air flow sensor to hopefully fix it.
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ok thanks for the suggestions here is an update for what has gone on so far I have replaced the Mass Air Flow sensor with a new one with no change in state it still runs really rough. one thing I did notice is after I drove it is I went to check the oil just to make sure it still had some in it and noticed after I took out the dipstick out of the tube came white smoke. I am thinking next thing I will do is to change out the O2 sensors because I have an error code on that as well and hope that helps. also how hard is it to drop the tank to see its condition or is there something I can put in it to see what it looks like inside?
also one thing I forgot to mention while checking the check engine lights it did give me a code for the EGR valve being closed. im wondering which one might be a more promising fix the O2 sensors or the EGR valve or is the problem a combination of the 2.
looked at the EGR valve and all looked good then reset the computer and drove it around some and it still is just as bad. I did another check engine light test an got code 12 and 91. I also ran a cylinder balance test ran it 3 times with varying results. the first time it told me just cylinder 5 was bad. the second time it said cylinder 5 and 6 and the third time it said 8,6,5,3, and 2 where bad. this seems odd to me but am now going to look at the timing to see if that is still good.
got a timing light and found the timing was off redid the timing and now it runs great. looks like the timing was just off.
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