I have a p420 and p430 issue. Catalytic converter below efficiency bank 1 and 2 . I have long term fuel trim 1 at .8 and long term 2 at -.8 short term 1 at -5.5 and short 2 at -6.3 I just changed out the MAF sensor. I was wondering if this would indicate an 02 sensor problem??

 

Move to correct forum.

Use the full code: P0420 etc, then Search and read.

 

I've moved your question from General Tech Help to X-Type forum. This is the place to post technical questions about your model.

Graham

 

your cat could be toast after the missfire from a bad maf ,the cats are fairly cheap on ebay
but i cant be sure if its your cats,try clearing it and see if it comes back

 

First let's hope you haven't driven it a lot after the CEL came on. The codes are telling the ECU that the convertor is not burning off the fuel in the air flow. From the looks of your short term fuel trims you have a pretty good vacuum leak. Not severe enough for a misfire yet but enough that the ECU is adding fuel to the mixture.
Step one remove and clean the MAF sensor. It is bolted to the side of the intake tube between the air filter and throttle body. Make sure to only spray clean it and use MAF sensor cleaner only.
Step two get a can of spray carberateur cleaner and with the engine running spray the area where the tube enters the back of the intake manifold from the brake booster. Next spray the brake booster check valve. It is a odd shaped piece on the pipe between the brake booster and the intake manifold. Then spray the underside of the PCV hose that runs from the cam cover to the intake manifold.
These are common areas for vacuum leaks. When spraying if you note anything changing in the engine idle like speeding up or bogging then you have found your leak.
Continual driving will destroy your convertors, even though cheap they are an ordeal to replace.
Give it a go and get back to us with your results.

 

I replaced the MAF already. It is brand new. It cleared the misfires and hesitation. The car drives well enough but I read that a dead cat = dead engine. I suspected a leak originally (and with more codes 5 misfiring cylinders) but getting all that stuff off the intake manifold in New Jersey winter is painful at best. So I will do the tests with carb cleaner/brake booster tomorrow when it should be hospitable outside Thanks.

 

If it’s not a problem with one of your sensors then two easiest ways to either identify or solve the problem are to use cat cleaner solution or check for leaks in your exhaust system by attaching a vacuum cleaner with duct tape. More details here: http://topautotools.com/error-code-p0420-obd-ii/

 

I tried cataclean, wasted 20 dollars. I got a better scan tool and found my o2 sensors, evap catalytic converter, fuel, misfire monitors all check out, my ccm has a big red x and my secondary air, egr and heated catalyst monitors have a no sign in grey. I still suspect a vacuum leak so i will check the live data of my fuel trim and drive at 2500 rpm. If it drops I believe this will confirm the leak.

 

Update: Using the scan tool I got short term fuel trim 1 and 2 both at 25 (positive) at idle. Long term 7.0 for 1 and 2. I was mildly alarmed at the short term fuel trim being so high, but I took the car out on I 80, drove the car to 2500 rpm and the fuel trim dropped to 0. Long term 1/2 showed positive at 0.8 and neutral at 0. respectively at 2500 rpm. I looked at the MAP and it is about 11 hg at idle. I read that it should be between 16-20. I think the leak is in the intake manifold. Thoughts?

 

High short term at idle suggests you either cleared the trims recently (e.g. battery off) or engine cold or some such. It's learning (STFTs migrate to LTFTs, making the STFTs near zero).

Forget driving except to get engine hot. Then park. LTFTs at idle & about 2500. Make sure STFTs are fairly near 0 or it's learning and you're getting LTFTs that haven't learned fully.

(Even so, 7 is fairly high. That they drop does suggest an air leak.)

 

There are several places you can have vacuum leaks on the 2.5 and 3.0 litre units:

• IMT o-rings may be leaking and not sealing correctly
• Breather hose under the lower inlet manifold
• Leaks allowing unmetered air into the engine around brake booster seal and other hose unions

You can also have misfire(s) caused by oil-fouled coil units. If they are shorted due to oil contamination, they need to be replaced. The ones on Bank 1 against the engine bulkhead will require removal of the inlet manifold to replace the cam cover gaskets and spark plug boss seals.


Under no circumstances is the vehicle to be operated under conditions that cause the MIL to flash as catalyst damage is occurring.

Correct the vacuum leaks first and do not erase the DTCs until the engine has been run through at least two start cycles.

 

"High short term at idle suggests you either cleared the trims recently (e.g. battery off) or engine cold or some such. It's learning (STFTs migrate to LTFTs, making the STFTs near zero).

Forget driving except to get engine hot. Then park. LTFTs at idle & about 2500. Make sure STFTs are fairly near 0 or it's learning and you're getting LTFTs that haven't learned fully."

(Even so, 7 is fairly high. That they drop does suggest an air leak.)

So doing as you suggested, I get the following, high Negative fuel trim stft 1 at 11 and stft2 at 13 at idle after driving to warm car up, at 2500 rpm, fuel trim raises to high positives 13 or so ltft drops to 0 at ltft 1 and 0.8 at ltft 2. tried again and the numbers were different, but the trend was the same: Long term fuel trim drops, short term fuel trim raises (or rises)

 

What do you mean?
STFT1/2 at 11/13 are not high negative.

What are the LTFTs?

 

I just posted a new thread (Vacuum Leak) showing the symptoms of my vacuum leak and steps I am taking to correct them.

Ideally, you want the STFTs to stay between +/- 10% steady state. I believe that when you add the STFT and LTFT for a bank together, the ideal result is between +/- 5% with concern starting > +/- 10% and CELs when LTFTs exceed 20-25%. When you reset the DTCs in the ECU, this also resets the LTFT values and they will not be able to help control/dampen the STFTs until they (the LTFTs) relearn "normal" by getting data from what the STFTs are doing. If STFTs are consistently running high positive, the LTFTs will learn this and become increasingly negative to dampen and lower the STFTs from being high positive to closer to zero - (and vice-versa).

Wow - I just used more acronyms than I have since I left the Navy....

 

Generally clearing DTCs does not clear LTFTs.

Have you changed user name from jmackey5?

 

Ok so I redid this test with the STFT closer to the proper parameters i.e. finished learning. Attached are the fuel trims at idle and 2500 rpm respectively. Could this be being caused by an exhaust leak? I am 99.9 percent sure I have one. I run the heater and it smells like something burning.

 

Would be a very small one, but could be.

A smoke test might be best but bear in mind there are hoses that are not reached if they're behind valves that are closed.

 

So i was desperate and tried the carb cleaner test. I didnt notice a rise in rpm, but when i used the ac the drive immediately following spraying it, i noticed a smell like off bug spray. I sprayed some on a piece of paper and it smelled like a stronger version of my ac.