Rough idle and misfire on accel

95ssn95 · Nov 4, 2008

Friday I left work and with out cause my car started running like crap. It misfired and the check engine light came on. The check engine light will come on (only after a misfire under acceleration) and go off after a bit. AutoZone couldn't figure it out because an error displayed when checking for codes. My neighbor is a ford tech and he also couldn’t figure it out even after checking for vacuum leaks and the computer and once again error is all we got. Is there something wrong with my computer, fuel filter, injectors??? I don't know maybe tp sensor?? I know its not the plugs I changed those Saturday and no change... also checked the timing and its 12 degrees. I don't want to spend 100 bucks just for someone to tell me that they can't find the problem either so that’s why I'm here with my first post. Thanks in advance I'm sure this is something simple but I'm overlooking it.

BlackVert · Nov 4, 2008

i had a similar symptom, turned out to be a bad spark plug wire

good luck and welcome

95ssn95 · Nov 4, 2008

Also when idling it surges and it will bog down when i give it a little gas. I will check the wires and appreciate any other suggestions. Anyone also know why the computer would read ERROR????

divit250r · Nov 4, 2008

Make sure that they're pulling codes from the connectors behind the passenger side strut tower, you can't use the connector under the dash. Other than that, just look for basic things like vacuum leaks, plug wires arcing, fuel pressure, etc... Good luck!

Scott

mo_dingo · Nov 4, 2008

Start with a cylinder balance test, and clean your MAF. Simple, free, and a good start.

Also pop off your dizzy cover and make sure the contacts are not fubar'ed.

Next pull each spark plug and note which cylinder it came from. If one is black, white, or out of the ordinary, note that cylinder, as it may lead you to your problem.

I am guessing they are reading the codes from the plug under the dash, which is connected to a whole lot of nothing. The one by the pass side strut tower is the one you want. A paper clip will suffice if you don't have a reader.

HISSIN50 · Nov 4, 2008

Agreed with the above thoughts to get your codes to read. The EECs seldom fail - it's often user-error and wiring issues that are at fault.

What kind of device was being used to get codes? The test-light method is solid if you cant get codes to spit (it removes some error with code readers and scanners). Otherwise, we'd have to run your VIP wiring pathways to figure out where the open in the circuit is.

RoushTbird · Nov 5, 2008

Sounds crazy, but do you have a K&N filter? have you cleaned it recently. I had this problem, and there was filter oil on my mas air sensor. Try cleaning it with MAF cleaner. About 2 bucks at the parts store.

RoushTbird · Nov 5, 2008

The 95s are ODB I but have the ODB II connecter under the dash. I agree with the cat above, make sure they check it under the hood, not the dash.

95ssn95 · Nov 5, 2008

Ok I know that it's ODB I and I had it checked. It threw a MAF sensor code and i cleaned it yesterday but still no better than before. I dont have a K&N its all stock. Plugs were changed Saturday so they are fine. No arcing in plug wires i checked that last night. Is there a way i can check my MAF sensor to see if its bad???

RoushTbird · Nov 5, 2008

Im not super good, but i know you can use a volt meter to check the voltage range. Someone smarter than me, could probably explain which of the three wires to touch.

HISSIN50 · Nov 5, 2008

What MAF code did it throw?

95ssn95 · Nov 5, 2008

157 i believe

HISSIN50 · Nov 5, 2008

157C would be if it baselined under .40 volts at idle within the last myriad starts. If you had the MAF's E-connector disconnected with the key on, this could generate the code.

Otherwise, you should see about 1.0 volt at idle (give or take, each car with different mods and idle setting is different).

The sig wire is either LB/R or T/lt blue. I just cant remember which (I've had to use both of them so I forgot which was which).

I would check the source feed to the MAF and the ground (ohm out the ground itself). If either is compromised, it will affect the output signal.

Now that you have the codes, I would clear the KAM and let it start over. That way if you're in FMEM, it will give you a fresh start.

To clear the codes, disconnect the battery and turn on the headlight switch for a minute. Turn the hdlt switch off and reconnect the battery.

95ssn95 · Nov 5, 2008

OK guys I figured it out and it wasn't as painful as i thought! It was the mass air flow sensor. After i cleaned it and it still didnt work i cleared the codes and took it back to autozone and they hooked it back up. apperently this time someone who knew what the f**k they were doing was there. it gave us a 157 mass air flow low voltage and a 158 mass air flow high voltage code. so i bought a new one and whalla! thanks for all the help and hope this helps someone in the future.

mo_dingo · Nov 5, 2008

darn MAF

Glad you got it fixed!!!

Rough idle and misfire on accel

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