How To Fix "Running Rich"...

Hey everyone.
I am really at a loss here and was hoping some of you guys could point me in the right direction for some do-it-yourself fixes.

Not really sure how to best explain the hardship I'm having with my 4-Banger, so I'll share some processes and assume you guys could get the idea of my situation from that.

1. CEL turns on with P0420
2. Replaced front Cat.Conv. and reset CEL
3. CEL turns on with P0430
4. Replaced rear Cat.Conv. and reset CEL
5. CEL turns on with P0420
6. Replaced front O2 sensor and reset CEL (sensor replaced due to failing test read on OBD-II scanner)
7. CEL turns on with P0420
8. Replaced front Cat.Conv. and reset CEL (previous new front Cat.Conv. was fried after <500mi.)
9. CEL turns on with P0430
10. Replaced rear Cat.Conv. and reset CEL (previous new rear Cat.Conv. was fried after <300mi.)
11. Currently no CEL, but could foresee that it will come on sometime real soon since both the Cat.Converters are already showing signs of excessive overheating (purple-pink-blue color hue starting to show).

Now here is my dilema or area in which I need help in, how do I fix the assumption that my truck is "running rich"? I was told by the muffler shop guys that usually the reason a cat.conv. goes bad sooo quickly is due to having an engine run "rich". They told me that based on their minimal knowledge of overall engine mechanics, usually a bad O2 sensor is the culprit, but since it's been changed out already, it's probably something up in the engine area that's causing the truck to run rich.

So what, where, how should I go about identifying any and all of the possible areas or components of concern that could trigger this "rich" running status? I'm not too great on mechanics, but can do pretty good with swapping out parts here and there if needed, just dont know where to start so to keep the cost factor down as best as possible.

Any advice guys?

Thanks in advance for your help!

PS: Just realized I forgot to include info on my truck... sorry guys!

2000 - PreRunner Xtra-Cab - 2.7 - 2wd Automatic

 

I'm no wrench,but,if your getting extreme heat signatures from you cat(s)...isn't that a lean condition?.Does this year of vehicle have hydraulic valves...if not,have you adjusted them?.

 

Weird, the new 02 sensors should help to correct any rich/lean condition. If there's excess fuel in the exhaust, I'd think the cats would have to burn it all and that is why they are running super hot, not totally sure tho. Maybe disconnect the battery for an hour and let the ECM reset...? This might help, assuming the new exhaust hardware is not yet "fried." Good luck, and let us know if you figure it out.

 

Make sure the egr system is working correctly, also spec out the egr vsv under the intake plenum that can make the egr system not operate correctly causing a rich running vehicle.

 

How many miles on the truck?

Didn't have any codes about the EGR system?

How is the truck running overall? How is the idle on the truck?

I wanna say check your intake gasket for leaks.

 

what kind of O2 sensor did you put in? i understand the bosch ones are garbage

 

pull a spark plug if its black its too rich if its white and cooked looking its too lean if its tan or brown its running great. sometimes a shop will tell you things just to have you go to a recomended shop to gain buisness lol

 

Replace the Cat... If its over-heating, that could mean its clogged not letting enough exhaust gasses through...

 

A rich mix will make a cat run way hot like glowing red a lean mix will run the EGT up. O2 sensor will rarely make it rich enough to cook a cat check fuel pressure and coolant temp sensor. Seems like if it's rich enough to cook the cat it should run pretty poorly and use gas like crazy.

 

Rich is not caused by intake/vac leaks, Lean is. Check your air injection system for proper pressures. Check exhaust backpressure by removing the O2 sensor(probably not the cause, but rule it out anyway)
How's your air filter, Mass air flow sensor, Intake air temp sensor, engine coolant sensor? If those aren't working properly, it will screw up the mix.
After replacing multiple cats and o2 sensors, I can pretty much guess you have other problems

 

Bump for the FIX .......

 

Hey again everyone. Sorry for the delayed reply but I've been out on vacation and just got back.

First off, thanks everyone for your insight, opinions, and all around help.

After touching base again with the mechanic I was told that the reason my truck went through a total of 4 new cats in under a months time is because the wrong "aftermarket" cats were installed.

According to him, what is needed is something called a "Warm-up Catalytic Converter" specific ONLY to the 2.7l engine. His assistant, in a brief discussion with me, I believe also identified this type of cat as a "Thermonuclear Catalytic Converter". I could be wrong on the titling, but indeed it was "thermo"-something.

On a side note, I know some of you guys were suggesting or asking about the EGR, coolant temp sensor, and/or other components. I did make mention of it to the mechanic, but he stated that if there was to be an error with either of these electrical components per say, a CEL code would have been triggered already. Currently the only codes that keep coming up over and over are the P0420 and P0430... no other's. The truck for the most part seems to be running good with no issues of overheating, lack of power (if any power could be said to be present on a 4cyl-automatic...LOL), extreme foul exhaust smell, or rough idle. Not sure on MPG but I do average 20mpg at the moment and honestly don't know if that's in the ball park range.

So what do you guys think on that whole "Warm-Up Cat" notion? Is that such a part/piece that is needed with these engines?

Thanks again guys for all your help and advice.

PS: Quaker, truck current has 201,400 miles on it.

 

hmmm iv never heard of such a thing...

 

I'm thinking the shop is full of shit,

Google thermo anything catalytic converter and you'll just get a brand name and nothing about function, cats are cats. If the cats are getting hot, it means they're not rich. the EGR is not an electrical component, its exhaust gas recirculation.

How old are the O2s that were replaced? What brand were they? Were all O2s even replaced?
How old are the plugs and are they in good condition?
Have you checked for exhaust leaks?

Have you considered a different mechanic?

 

yeah man... check the color of the plugs... do a cylinder compression check. exhaust leak? maybe intake leak? a cat wont burn up because it is rich... it will be cooler with the extra fuel on it... so it has to be lean... check all the plugs too.. be able to tell if one of the cylinders is lean or all of them witch would be a bad valve, head gasket, intake leak, vacuum leak, exhaust leak, so on and so fourth letting more air into the motor after the MAF sensor. so check it out before you buy some cat that some asshole wants to charge you for that might just be hi flow less likely to melt down... and how did you know the cat was bad? what about the o2 sensors? or clean the MAF with electronics cleaner. and replace the TPS.

 

Hmmmm.... I think you guys might be on to something here.

Last night I developed a new CEL code, P0302. Right before that, the truck started sputtering while driving down the freeway, later hesitated pretty serverly on the road, till the point where it would not go any higher than 10-15mph and with severe engine sputtering. At times, the CEL would even flash and so I promptly would stop and turn off the truck for about a minute or two, then restart to a steady lit CEL and proceed from there.

Ugh... back to the drawing board and brainstorm some more.

Hey thanks again guys for all your help and input. Really appreciate it!!!

 

302 is a mis fire in cyl 2, check wiring and plugs or just replace them see if that helps

 

really?

 

Really really. Fuel actually cools cylinders, when you run lean or more air than fuel, you actually run hotter

 

Damn... spent most of the day toying around with the truck trying to problem solve here and there and nothing.

Currently I'm showing the following CEL codes:
P0100
P0110
P0300
P0302
P0420

The P0100 & P0110 are related to the MAF sensor and I think I may have caused that one yesterday when spraying it down to clean it. I did use appropriate chemical for MAF sensor cleaner, but I believe I faulted by spraying with the nozzle too close to the resistors found within and therefore maybe putting too much "fluid" pressure per say onto the resistor wires?

Ok... so here is what I did today. Since CEL code pointed at cyl.#2 as a direct culprit in the issue, I swapped out coil pack #2 with coil pack #1. Afterwhich, now P0302 still continues to come up as when before the swap. This I assume indicating coil pack #2 was NOT faulty or else CEL code would have changed from identifying cyl.#2 to cyl.#1 as faulty correct? So I'm wondering if from where ever these coil packs get their juice from could be faulty. I apologize for not knowing the name of that piece, but what I'm talking about is an assumed component/part that distributes the signal to the wires which connect to the individual coil packs. If I had standard boot plugs, I would best identify this component/part comparable in function to what I'm talking about as the cap and rotor. So could this said component be a possiblity being that despite the coil pack swap, the faulty CEL code still pointed at cyl.#2 before and after the swap?

*NOTE: Should I have reset ECU or driven a certain number of miles for the code to change or would it do it identify the appropriate CEL immediately while engine idles roughly for 3 to 5 minutes?

Finally P0420 is still ongoing issue I've had for weeks now, but never showed any performance issues per say while engine idles or runs. Also I think this would be the last of the issues addressed since without the truck running "normally" or at least being somewhat driveable, I can't go out to get cats swapped and such.

Guys, here is a new symptom per say that did develop overnight and now I kind of got a bit of a scare factor going on. I got what seems to be droplets of coolant or oil or some liquid dripping from underneath. I could not really track it back to where it might be coming from, but I fear that this is a symptom of blown head gaskets (or so I was told by my neighbor). Is this a possibility when factoring everything else going on with my truck, or can I rule this out?

Sorry for the rambling and/or not making much sense. Never was too speedy in typing and therefore lost my thoughts and what I wanted to say unto text quite frequently.

Thanks again in advance guys for all your help and input.