maketo

Sorry for the title, but I am starting to get sick of the damn car. It is a 1996 T-bird 3.8L and bought the thing with 48K miles. It now has 115K miles and has cost me a lot of money to keep going. Twice it left me stranded driving between Missouri and Florida (effectively ruining my vacation). I know nothing about cars so I am easy to rip off and take for a ride. On my first vacation the car starting losing power, the check-engine light came on and it became difficult to start at a stop light. I would press on the gas pedal and it would putter for 5-10 seconds and then take off like one would expect. The local shops in Florida said it was anything from a catalytic converter (turned out not to be true), MAF sensor (not true), O2 sensors (not true), broken crankshaft (not true). Finally someone said it was the harmonic balancer. They apparently replaced it and lo and behold - the car worked. Fast forward next vacation, same story, same symptoms, same resolution. Now this was in 2008. No problems since. Now a few weeks back the check engine light comes on.

Shop says all 4 O2 sensors must be replaced (a $600 job). I take it to another shop, they say the same thing. I pay the monies, the O2 sensors get replaced but the shop mechanic tells me that there is a "pending code" in the computer indicating that the catalytic converter is failing. Well, I take the car home and it is puttering again when driven! The symptoms are as follows: when cold the car runs fine, starts fine, I press on the gas pedal and it goes. As soon as it gets warm, it starts stumbling when the gas pedal is pressed. It "bogs down" for 5-10 seconds, struggles and then it feels as if "something opened up" and it takes off as expected.

I went to the shop that replaced the sensors and told them that my car ran fine with the check-engine light on before they replaced all 4 O2 sensors and described the symptoms. The guy there said to take it to a muffler shop and see if they can "chop up the catalytic converter and weld pieces back" which would be cheaper than buying a $600 part and paying about $200 in labor to replace it. He also said something else might be the problem.

Now, I don't grow money on trees. This car is worth about $1000 and I like it (it is actually my wife's car and she likes it even more) but I am sick and tired of f***ing around with it. Any advice on what it could be before it turns into a pile of metal at a junkyard?

Thanks,
Pissed off in Florida

Bert

O2 sensors rarely need replacing.

Try it with the MAF unplugged but first go to an Autozone and they'll pull codes for free.

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Bert

maketo

OK - went out and bought a code reader. 8 codes - 4 thrown and 4 pending:

P0135, P0141, P0155, P0161 (same 4 pending).

From what research I did online, all these codes are O2 codes but I just had all 4 sensors replaced. Now, I also read that the codes get thrown based off of the coolant temperature sensor reading. Could this sensor be malfunctioning? If so, how come all of a sudden?

If I disconnect the MAF, what am I expecting to happen?

Thanks!

R.S.LOGAN

A sensor can fail at any time . Briefly ,the engine coolant temperature sensor lets the ECU know how much or little fuel the engine needs i.e more fuel on cold start up and then leans out as engine warms up etc . See if any difference on engine running when you disconnect MAF .

Bert

Those are the codes for the heater circuit in the O2 sensors. There's a problem in that area. I'd bet there was nothing wrong with the original sensors. If they give a problem, they usually have one and not all of them. I'd talk to the shop about that. Read this on just the one code about the cats. OBD-II Trouble Code: P0141 Oxygen O2 Sensor Heater Circuit Malfunction (Bank1, Sensor2)

With the MAF unplugged and the car runs better, that would mean the MAF isn't working right. They can be cleaned with MAF cleaner and help sometimes.

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Bert

maketo

Yes but with my limited understanding of cars and emissions systems, don't all of the above codes (P0135, 141, 155, 161) refer to wiring issues? I really know nothing about cars but it would seem that either whoever changed my sensors screwed up something with the wiring or since the ECM bases the timing of the measurements on these sensors off the temperature coolant sensor, the temp coolant sensors itself could be faulty? I fail to see how a dirty or faulty MAF could trigger O2 sensor wiring harness problems?

Thanks!

Bert

The MAF normally won't set any codes, just make it run poor. As you mentioed, it's in the circuit where the O2 code problem is.

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Bert

R.S.LOGAN

Not the first time an o2 sensor has been wrongly replaced as fault was in wiring .

maketo

How time consuming would it be to diagnose a wiring problem like this for a competent mechanic? I called the shop that replaced my O2 sensors and they said it is very time consuming. I am getting the feeling they are prepping me up for charging me for hours of work even though I don't feel I should pay for them since it was them that said I need $600 worth of O2 sensor replacements.

Any opinions?

Thanks!

Bert

It's hard to say how much time it would take without knowing what the problem is. They should give you some help due to replacing parts that weren't needed.

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Bert