Running Rough

Epwillis

Epwillis

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Hi all I got the oil changed in my 95 mark a couple days ago and now it's running a little rough, mostly at idle(seems like it's being choked on fuel) and a tiny but while driving. I had the fuel lines on the passenger side below the passenger door replaced a few months back because the old ones got crushed. Going to put a new fuel filter in today and see if it's better. Anyone have any other ideas of what the problem could be?
 
Yes- all the ones that concern vacuum
If they've never been replaced, then they are at least 15 years old, go to Parts Store and buy a roll of vac tube and about 10 of the elbows, and then replace them 1 by 1 so you don't confused as to what goes where
 
Ok now I'm getting a check engine light at high way speeds, and the car kinda pops like it's choking still. Could I have an oxygen sensor dying on me? I hope it's not anything to do with the fuel pump, seems to be a lot about dying fuel pumps on here lately.
 
flashing CEL? didn't know a 95 could do that. but yeah, get the codes pulled.
but ruling out fuel pressure is easy, throw a gauge on it and roll around the block. if its always 30-40 psi, its not your problem.

fwiw, popping and choking on my brother's car was incorrectly routed plug wires, so double check them since that's easy.
 
Code came up as DTC: 538 Insufficient change in RPM/operator error in Dynamic Response Check

Also says it failed cylinder balance test

going to take a look at plug wires now.
 
Epwillis said:
Code came up as DTC: 538 Insufficient change in RPM/operator error in Dynamic Response Check

Also says it failed cylinder balance test

going to take a look at plug wires now.
Click to expand...

well there were a few wires in the wrong spots at the coil 6and 1 were swapped and 2and 8 were swapped, ill find out when I drive it long enough if the problem is gone.
 
Half of the cylinders misfiring...yeah I guess you'd call that a "rough idle" wow
 
did you ever check your fuel pressure?
put a gauge on it and drive around. you need to see what its reading at the same time the car is acting funny.
 
Well I thought I was in the clear then my CEL decided to pulse at me the other day. Here's the codes i pulled:
176 Lack of Heated Oxygen Sensor (HO2S-2) switches, indicates lean (Bank #2)
524 Low speed fuel pump circuit open—battery to PCM
542 Fuel pump secondary circuit failure

So I'm trying to figure if this is O2 Sensors dying or fuel pump Dying.Also read somewhere it could be the Vcrm although i put a new re-manufactured one in last year. Anyone know whats going on?
 
i see those fuel pump codes come up so often i just ignore them now.
i seem them on ford trucks, my lincoln, my brothers taurus, everywhere. ignore those.
focus on the lean bank 2 code.

since its only lean on one bank, it is either, O2 sensor, spark plug, spark plug wire, fuel injector, or fuel injector wiring. something affecting only the one bank.
if you have never put new O2s in, now is not a bad time. they are a 60k item, and your sig says 140k miles.

side note, if the plugs are not firing, you don't burn oxygen. the O2s see the oxygen that didn't burn, thinks the car is running lean because a proper burn will have no leftover oxygen. or very little. lean code is set.

i doubt vac leak cuz that would run both banks lean. unless it was leaking near an imrc as to only affect that cylinder? doubtful.

did you ever test the fuel pressure? does it miss at all? ever repeat the cylinder balance test?
 
chris2523 said:
i see those fuel pump codes come up so often i just ignore them now.
i seem them on ford trucks, my lincoln, my brothers taurus, everywhere. ignore those.
focus on the lean bank 2 code.

since its only lean on one bank, it is either, O2 sensor, spark plug, spark plug wire, fuel injector, or fuel injector wiring. something affecting only the one bank.
if you have never put new O2s in, now is not a bad time. they are a 60k item, and your sig says 140k miles.

side note, if the plugs are not firing, you don't burn oxygen. the O2s see the oxygen that didn't burn, thinks the car is running lean because a proper burn will have no leftover oxygen. or very little. lean code is set.

i doubt vac leak cuz that would run both banks lean. unless it was leaking near an imrc as to only affect that cylinder? doubtful.

did you ever test the fuel pressure? does it miss at all? ever repeat the cylinder balance test?
Click to expand...

It rumbles and pops(like it's missing horribly) when the CEL comes on and runs like sh** but if i restart the car its fine for a bit then it eventually comes back.

Haven't changed the o2s in my car that i know of, that was gonna be my first plan of attack to rule options out. Do the gen1's have more than 2?

Also redid the cylinder balance test and it passed.

Gonna have to see if i can get a hold of a fuel pressure gauge to check the pressure. What pressure should i be looking for?
 
93-95s have 2.

96-98 has 4.

you just need two.

you want 40 psi engine off. so cycle the key a few times, see what it says.
then start it. you should 30 psi at idle. it should jump to 40 psi when you floor it. then back down to 30 at idle.
 
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