Rough running bird.... - TCCoA Forums
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post #1 of 6 (permalink) Old 08-09-2013, 09:59 PM Thread Starter
Join Date: Aug 2013
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Question Rough running bird....

My 96 T-bird recently started giving me fits by not wanting to idle or run at all.... I had to break down and take it to a local shop that supposedly builds hot rods for a number of local area motor heads. They diagnosed that my idle air control sensor or valve was bad, so I had them replace it. When I picked the car up, they advised me that I will need to replace the mass airflow sensor at the air filter intake, as well as both the upstream and downstream O2 sensors in the exhaust system (all of which they will be more than happy to do for a pretty penny). Even after paying them to replace the idle air control sensor, the car still would not idle or drive until we took the leads off and disconnected that mass airflow sensor. I was able to get it home so I could start researching some of this on my own....
And according to the shop that did the initial work, I only have two of the O2 sensors to replace, but according to several other sources I have since found, Ford installed two per cylinder bank for the 4.6L V8, which is a great engine, by the way.... But I can't confirm how many of the O2 sensors I may be needing to replace....
Today I replaced the mass airflow sensor, and if the mechanic did in fact change the idle air control sensor, I thought I would see an improvement in how the engine was running, but it is back to where it was before any work was done.... I am stumped...
I can keep it running if I put it in neutral and keep the revs up while at stop lights, but it will stall during braking and if I don't get the trans into neutral at stop lights. I am also getting a flashing O/D warning light from how rough it runs while driving.
How long or how far should I have to drive it before the onboard computer senses the new parts and resets itself??
Do any of you members out there have any ideas where I should go in my repair work to get my sweet Thunderbird purring again???
Fuel filter?? Fuel pump?? those pesky O2 sensors?? Like I said, I am pretty well stumped and have no idea where to go next with it....
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post #2 of 6 (permalink) Old 08-10-2013, 12:28 AM
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I think the mechanic got the diagnosis wrong. Or at least incomplete.

Is the Check Engine light on? Did you get a readout of any trouble codes from the mechanic?

The car shouldn't have to adjust to new parts. Something is definitely going on.

A test of fuel pressure and a test for vacuum leaks would be another good thing to check, but check for trouble codes first.



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post #3 of 6 (permalink) Old 08-10-2013, 12:33 AM
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Not enough details about maintenance, mileage, recently changed parts, how long the problem has been occuring, etc.

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post #4 of 6 (permalink) Old 08-10-2013, 06:47 AM
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well my 94 had a problem like this one time. rule of thumb if you unplug it and nothing change then its probably bad. my maf was unplug for about 6 months cause I was too lazy to replace it. but then I had a huge vac leak that would kill everytime. I bet that's whats wrong. check all the vac lines. I just come across this and I plan on doing it soon.
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post #5 of 6 (permalink) Old 08-10-2013, 09:42 AM
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and you have 4 O2's, the forward ones are the ones that really do work, and the ones out back behind the cats are just for a check engine light. change all 4 if you want, but i would clean that MAF first. and if all else fails go buy a MOTORCRAFT MAF sensor from the dealer. avoid all the remand A1 cardones, or even the 'new' A1's... an engine running fine with the MAF unplugged is a sure sign of a dirty or failed MAF. the ECM is falling back too stored factory running tables for fuel mixtures known to run the engine.

and you could also try spraying some of that sensor cleaner around your intake and vacuum lines. if your RPM changes, you have a leak in that spot, start changing all your 18 year old vacuum lines with the link above.

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post #6 of 6 (permalink) Old 08-10-2013, 07:29 PM
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$20 says you have a vacuum leak somewhere. That would cause the stalling, rough running, O2 sensor codes, MAF sensor codes, and someone who doesn't know how to diagnose it would just see all those codes and say you need all those parts. I don't know how mechanically inclined you are, but if you feel like trying to tackle it yourself, get a can of carb cleaner and start spraying the various vaccuum lines. When you spray near a vacuum leak, you will be able to hear the rpms rise. If you can't figure it out, time to find a shop that knows what they are doing.

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