97 3.8 V-6 Prob - Trans, or Engine?

[Ol'Jim]

Car is fine when cold. After thoroughly warm/hot, especially in hot weather, acts up when pulling away from a stop. Sluggish, doggy, almost like it is in high gear. Once up to about 20-30 mph, runs good. It shudders a bit while it is dogging-out. Sometimes it doesn't do this at all. Trans fluid/filter was changed about 3-4K ago. Fluid level good. Check Engine light came on around same time problem popped up. Two different mechanics said the code indicated 4 fuel system sensors were faulty. Another said bad O2 sensor. Code was cleared, but light still comes on sometimes, then goes off. Could the apparent trans symptoms actually be due to a failed TPS, MAF, MAP, or O2 sensor? Or possibly multiple probs? Also, is there any way to tell which sensor is bad, vs replacing all 4, or one at a time? Thanks in advance for any advice. Not my car, and just relaying what I was told, as the car is 500 miles away, and owned by a retired lady friend who needs some help. I will be at the car in a few weeks, just trying to get some advance info. Mech told her ECM was bad.

[97Bird]

Hi Ol'Jim, Could you ask her to go to Autozone or some other parts store that will read the codes for free and then come back and post what they are?

[Ol'Jim]

97Bird, got the trouble codes for you. 9 of them!
Do these cars really have four 02 sensors? It appears that way, and the lady went ahead and had all 4 of them replaced BEFORE
she made the trip to Autozone to get the following codes printed out. (Note: No change in the car's driveability after her pricey sensor change-outs).
I am almost guessing (and hoping) for a vacuum leak, but please take a look and
share your educated input, as I am not very familiar with this vehicle or engine. Anyway, here you go:

P0135 - H02S11 Heater condition (Heated 02 sensor Bank 1 Sensor 1)
Explanation: PCM monitors 02 sensor heater. Computer has recognized a failure in this circuit.
Probable cause: 1. 02 sensor defective; 2. Poor connection at 02 sensor; 3. Check circuit fuse.

P0136 - H02S12 Circuit condition (Heated 02 sensor Bank 1 Sensor 2)
Explanation: PCM monitors 02 sensor to calculate Air/Fuel Ratio in the exhaust.
Probable cause: 1. 02 sensor defective; 2. Fuel system running very rich or lean-check other codes first; 3. Engine misfire condition-repair;
4. Fuel pressure very high or low-fuel pump or pressure regulator.

P0141 - H02S12 Heater condition (Heated 02 sensor Bank 1 Sensor 2)
Explanation: PCM monitors 02 sensor heater. Computer has recognized a failure in this circuit.
Probable cause: 1. 02 sensor defective; 2. Poor connection at 02 sensor; 3. Check circuit fuse.

P0155- H02S21 Heater condition (Heated 02 sensor Bank 2 Sensor 1)
Explanation: PCM monitors 02 sensor heater. Computer has recognized a failure in this circuit.
Probable cause: 1. 02 sensor defective; 2. Poor connection at 02 sensor; 3. Check circuit fuse.

P0156 - H02S22 Circuit condition (Heated 02 sensor Bank 2 Sensor 2)
Explanation: PCM monitors 02 sensor to calculate Air/Fuel Ratio in the exhaust.
Probable cause: 1. 02 sensor defective; 2. Fuel system running very rich or lean-check other codes first; 3. Engine misfire condition-repair;
4. Fuel pressure very high or low-fuel pump or pressure regulator.

P0161 - H02S22 Heater condition (Heated 02 sensor Bank 2 Sensor 2)
Explanation: PCM monitors 02 sensor heater. Computer has recognized a failure in this circuit.
Probable cause: 1. 02 sensor defective; 2. Poor connection at 02 sensor; 3. Check circuit fuse.

P1131 – Lack of Bank 1 02 transitions – Lean
Explanation: ECM detected Bank 1 02 at its lean limit.
Probable cause: 1. Misfire on Bank 1; 2. Vacuum leak affecting Bank 1 only; 3. Fuel injector problem Bank 1;
4. Engine mechanical condition.

P1132 – Lack of Bank 1 02 transitions – Rich
Explanation: ECM detected Bank 1 02 at its rich limit.
Probable cause: 1. Leaking fuel injector Bank 1; 2. EGR stuck open; 3. Engine mechanical condition.

P1151 – Lack of 02 switches - Bank 2 Sensor 1
Explanation: ECM could not adjust fuel trim because of a lean or rich condition.
Probable cause: 1. Fuel pressure high or low; 2. MAF Sensor dirty/defective; 3. Vacuum leak on engine;
4. Leaking fuel injector or fuel pressure regulator.

Fuel filter and spark plugs have been recently replaced also, with no improvement.

Thanks in advance for any advice you can share, it truly will be appreciated!

[97Bird]

That's quite a list you've got there Ol'Jim! Did they clear the codes after replacing all of the O2 sensors? Yes, there are four of them. If not then you don't know if changing them all did anything- it doesn't sound like it from your response. If they weren't cleared then have it done. Be sure all connections on the O2 sensors are clean and tight. There should be 12V at all four sensor's red wire. This red wire is the 12V supply to the sensor heater. If the sensor heater isn't working then you will get the heater condition codes.
After thinkiing about it some more, I would take it back to the place that replaced the O2 sensors and tell them there is no change in the way the car runs. This will give them a chance to redeem themselves or give you more information to use against them. If they won't do anything then consult your state's Attorney General's office and explain that quite a bit of money was spent but the problem still exists. You might find this place has more complaints against them. I'd go so far as looking under the cat to see if there are four new sensors installed.

[Ol'Jim]

Thanks, 97Bird. Man, I hate to ask more questions...
Can you tell me how to clear the codes? Does it have to be done with a code scanner? If so, can AutoZone do that?
Also are all 4 of the 02 sensors readily visible from underneath? (Are they in the usual locations - head pipes before the cat? On both sides, I am guessing)? Or are there 2 before & 2 after the cat converter? And could it actually be 1 or more blown fuses? Thanks again, -Jim.

[97Bird]

Autozone isn't allowed to clear codes. You can try disconnecting the negative battery cable for at least 5 minutes to see if that works. I was told it will but I have never tried it. I've used a scan tool to clear codes. The O2 sensors are before and after the cats. You'll see the wires going to them. The sensor heaters are supplied 12V through fuse 15 (a 20A). It also supplies power to the MAF, EVAP, transmission controls and injectors so I don't see how the fuse can be blown- sorry. You can check the red wire on the MAF sensor (on top of the air cleaner box) to see if it has 12V.