Not Quite Overheating

[Hellraiser14]

I recently took my 96 xlt (V6, 119,000 miles) to the shop for a diagnostics test. My check engine light was on and the first place I took it failed to give me results. The second garage I took it to gave me a reading of P0420(Catalyst System Efficiency Below Threshhold (Bank 1) and P0332(Detonation "Knock" Sensor). Right now I can't afford to pay for an overhaul on my catalytic converter nor do I have the time to do it myself. I had to take the car home as is. Lately I have noticed that when I go up large hills my temperature gauge is almost maxed out by the time I reach the top of the hill. The engine doesn't overheat but it makes me nervous that it does that especially when I rely on my car to get to three jobs and school. Does anyone know why this might be? I recently replaced my serpentine belt because it fell off about 3 miles from my house and had to have it towed and repaired. After that my car hasn't been the same. I bought the car with about 96,000 miles on it and a majority of the miles I put on the car were highway miles. If anyone has had a similar problem or knows why my temp gauge is doing this I would really appreciate it. Thanks.

 

[NHale623]

Check your oil, see if there's any coolant in the oil. Pull your spark plugs and check their condition. Do a compression check.

You may have blown a head gasket, or cracked a head or the cylinder block if you drove it without a water pump.

 

[ma96782]

The second garage I took it to gave me a reading of P0420(Catalyst System Efficiency Below Threshhold (Bank 1) and P0332(Detonation "Knock" Sensor). Right now I can't afford to pay for an overhaul on my catalytic converter nor do I have the time to do it myself.

NOT AN EXPERT......I'D BE THINKING:

The A/F mixture is being affected.......getting hot temps as you climb up hills (lean mixtures)......and the pinging (lean mixture) starts as you put a load on while climbing hills.

So, perhaps......start w/ the P0420 code.......someone w/ more experience w/ this code, could be of help here..........perhaps-O2 sensor or cat or EGR (whatever). Once that is tracked down. Reset the computer.

Then, drive her around some more (up hills again)...........see if the PO332 code comes up again.

Aloha, Mark

PS........search:

http://www.explorerforum.com/forums/showthread.php?t=145300&highlight=PO420

 

[NHale623]

Well, the P0420 is Catalyst System Efficiency Below Threshhold (Bank 1), and P0332 is Knock Sensor 2 Circuit Low Input (Bank 2), so I don't know how they are related. If the converter were plugged, I would suspect a rich mixture, not a lean mixture due to the excessive backpressure. If the converter were plugged, I would suspect he would have complained about driveability problems. Something caused that converter to get plugged, if it is in fact plugged.

You could try to swap O2 sensors for bank 1 and see what happens.

He said that these codes were recently diagnosed. He also says the truck recently threw the serpentine belt. How recent is recent?

How long ago were these codes pulled? How long ago was the belt thrown? Did the truck exhibit the high temp symptoms before the belt was thrown? Did the truck exhibit the high temp symptoms when the codes were pulled after the CEL came on?

 

[ma96782]

Simple......"lean"......it pings (knock-knock sensor), when under load.

OK.......it it were "reading lean"........then, the computer would be throwing more gas at it........so running, "rich." Eitherway I try to explain..........IMHO, A/F mixture issue. I'm NOT SAYING to just replace the sensor and you'll be done.......or just change _______ and you'll be done, either.

OK.......perhaps, something else is amiss......why not.......anything can happen.

Anyway, IMHO.....fix the, "P0420 is Catalyst System Efficiency Below Threshhold (Bank 1)" first. Then, go on to the, "P0332 is Knock Sensor 2 Circuit Low Input (Bank 2).

Aloha, Mark

PS............somemore:

http://www.explorerforum.com/forums/showthread.php?t=162902&highlight=P0420

http://www.explorerforum.com/forums/showthread.php?t=157561&highlight=P0420

________________________________________________________________

Dogfriend said (read the whole thing here):

http://www.explorerforum.com/forums/showthread.php?t=154116&highlight=P0420


This is what my Powertrain manual says:


Quote:
The Federal Test Procedure Catalyst Efficiency Monitor is an on-board strategy designed to monitor and determine when a catalytic converter has deteriorated below the minimum level of effectiveness in its ability to control exhaust emissions. This monitor relies mainly on the front and rear Heated Oxygen Sensors (HO2S) to infer catalyst efficiency based upon oxygen storage capacity. The front and rear HO2S switches are counted under specified conditions for the purpose of calculating a rear-to-front HO2S switch ratio. After the switch ratio is calculated, it is compared against an emission threshold value. If the switch ratio is greater than the emission threshold, the catalyst has failed. The oxygen storage capacity of a high efficiency catalyst will have a low switch ratio and high HC efficiencies. As catalyst efficiency degrades, its ability to store oxygen declines and it will begin to have a higher switch ratio and low HC efficiencies. In general, as catalyst efficiency decreases, the switch ratio increases. Inputs from the ECT, IAT and TP sensors are required to enable the Federal Test Procedure Catalyst Efficiency Monitor.

1. In the Federal Test Procedure Catalyst Efficiency Monitor test, only switches during steady state cruise conditions of a drive cycle are counted. Switches at idle or other drive modes are not counted. The counting of front and rear HO2S switches continues until a drive cycle is completed. At that time, the ratio of total rear switches to total front HO2S switches is calculated. If the switch ratio is greater than the emission threshold, the catalyst has failed and a Diagnostic Trouble Code (DTC) is stored.

The DTC associated with this test is DTC P0420.

DTC P1408 is similar to P0401 but performed during KOER Self-Test conditions.

2. The MIL is activated after a fault is detected for up to six consecutive drive cycles.

Attached Images


And, there is more............search.........

Change whatever part you want.......or nothing at all.......it's your car.

 

[Hellraiser14]

I changed the O2 sensor back in June. The serpentine belt blew 2 months ago and the diagnostic test was done last week. I didn't notice anything different about how it drove after the serpentine belt was fixed. I am going to replace the thermostat this weekend and the knock sensor. If that doesnt' solve my problem I am not going to bother replacing the cat since all that would cost me 1/4 of what I payed for the truck since I don't have the tools or time to do that. Not many people are looking for a very broken in SUV with the way gas prices are so my other option is to trade the vehicle in for something else. I love my car and I got a ton of use out of it. I just wish I could keep it for another 2 years to get through school. If the thermostat and knock sensor do the trick I will invest in a new catalytic converter. Right now I basically work to drive and go to school. I really wanted to be able to lift the explorer and throw some offroad tires on it but that all got scrapped after I started running into problems. I'm going to see what I can do with her this saturday an let yall know what happens incase anyone else runs into this problem. Thanks for all your help. I rather like this forum.

 

[ma96782]

Say it was running rich and clogged the cat.......the computer would try to compensate and lean out the mix......thus, and you would as a result get a, "lean condition."

Now, I'm confused.....which came first the chicken or the egg?

It's still an A/F mixture problem as a result of an incorrectly or non-functioning part.

Lean-ping (knock), when under load.

Aloha,Mark

PS.........Which begs the question: "When is the computer doing anything right?"

Answer: "When there aren't any codes"......Ha, ha, ha.

 

[ma96782]

BTW.....you DO REMEMBER reading this right?

Ford has had a TSB out on the P0420 code. It seems that the PCM is too sensitive to changes between the before and after cat O2 sensors, and therefore triggers the cat efficiency code. Ford's cure is to reprogram the PCM. Be careful if you take it into a dealer though; many will want to replace the cat and O2s, (which will also fix it).

Aloha, Mark

 

[NHale623]

Say it was running rich and clogged the cat.......the computer would try to compensate and lean out the mix......thus, and you would as a result get a, "lean condition."

Now, I'm confused.....which came first the chicken or the egg?

Exactly. In addition, if the PCM (for whatever unknown reason) was making the truck run rich and clogged the cat, why wasn't a code (P0172, P0175)thrown by the upstream O2 sensor for the rich mixture? Also, since it appears too lean now, why isn't their a code (P0171, P0174) being thrown for the lean mixture?

That's why I suggested he swap the two O2 sensors on that bank. Not replace with new, just swap the two.

Which O2 sensor was replaced in June, and why?

 

[ma96782]

My hat is off to you...............

Exactly. In addition, if the PCM (for whatever unknown reason) was making the truck run rich and clogged the cat, why wasn't a code (P0172, P0175)thrown by the upstream O2 sensor for the rich mixture? Also, since it appears too lean now, why isn't their a code (P0171, P0174) being thrown for the lean mixture?

What do I know............I'm "old school" (before there were computers in cars monitoring functions telling you what to look for). Example: Lean-ping (knock), when under load.

Then again.........do I (or you) always trust a computer?

Ford's cure is to reprogram the PCM.

Garbage in garbage out.

I'm not saying that computers are bad. Hey, if the computer gurus were so smart......why not just have a single code to replace the cat when it's clogged? Then again....maybe it has already been done?

Aloha, Mark

PS...............as you said:

That's why I suggested he swap the two O2 sensors on that bank. Not replace with new, just swap the two.

Good deal..........I'm always up for saving money, too.

 

[NHale623]

You're old school? Crikey, I must be ancient.

My weekend driver is a '31 Model A. Bone stock. The only computer in that car is the one god gave me between my ears. Manual spark advance, manual gas adjustment, manual brakes, no heat, no radio, wooden floorboards ... There is a clock in the rear view mirror, but you have to wind it up. Four cylinders and forty horses. The kids think it's neat, but they don't care for the crank to roll their windows up and down.

Anyway, have a good weekend.