P0420, 0175, 0172 - cleaned MAF, running great, any ideas?

[drdd]

Well I'm getting codes for bad cat and bad o2 sensors (P0420, P0175, P0172). However, the truck is running great. No rattling cat, no rotten egg smell, no excess fuel smell.

I've cleaned the MAF twice. In the last 6 months: new plugs, wire, cap, rotor, pcv, checked MAP and IAT, cleaned TB.

I got a 97 Jimmy 4.3 with 117000 miles so warranty isn't an option on the cat.

I read a post about the PCM reading too narrow a range. Is this something that dealerships will reprogram for free? like a recall?

any ideas? I'm still reluctant to just go out and buy a new cat and 02 sensors with the vehicle running so well. Any harm in waiting?

[BlazerLT]

Just because it isn't rattling doesn't mean it is not bad.

Also, those codes are not for the O2 sensors, they are doing their jobs fine.

Seeing you have cleaned the MAF, how do you clean it?

Did the problems and codes come after you cleaned it?

[drdd]

Codes were there before cleaning MAF. I thought cleaning MAF would do the trick. First time I cleaned it, I just sprayed TB cleaner onto the sides and onto the filiment-type wires and just wiped the sides with a rag. Still got the codes a day-or-two later. The second time, I sprayed and rubbed fairly delicately with my finger in a rag.

I should mention that it never looked dirty or sooty in the first place.

maybe i'm just not wanting to believe its the cat ... ??

Originally Posted by BlazerLT

Just because it isn't rattling doesn't mean it is not bad.

Also, those codes are not for the O2 sensors, they are doing their jobs fine.

Seeing you have cleaned the MAF, how do you clean it?

Did the problems and codes come after you cleaned it?

[drdd]

oh yeah ... also, after cleaning the MAF, I always reset the computer by disconnecting the battery for 15 min or so ... codes still came back ...

I'm also hearing a faint "meow" sound ...

Originally Posted by BlazerLT

Just because it isn't rattling doesn't mean it is not bad.

Also, those codes are not for the O2 sensors, they are doing their jobs fine.

Seeing you have cleaned the MAF, how do you clean it?

Did the problems and codes come after you cleaned it?

[BlazerLT]

A bad MAF can cause the problems you are seeing.

Also could be the CAT causing the last O2 sensor to put the engine in limp home mode which would cause the rich condition.

I would first replace the MAF, it has been know to fix all your problems before with another guy I helped over the phone.

[drdd]

any way for a shade-tree mechanic to check the MAF ?

Originally Posted by BlazerLT

A bad MAF can cause the problems you are seeing.

Also could be the CAT causing the last O2 sensor to put the engine in limp home mode which would cause the rich condition.

I would first replace the MAF, it has been know to fix all your problems before with another guy I helped over the phone.

[BlazerLT]

No unless you have a Tech2 computer to monitor its readings.

[drdd]

Okay, my 97 Jimmy W is still getting the running rich codes in both banks.

I've done full tune-up, clean MAF, swapped with an Ebay 2001 MAF, replaced cat converter today. Still get codes.

The only thing I haven't done is replaced O2 sensors. I'm beginning to think I have a injector leak and that it is running rich and the 02 sensors are doing their job. That would explain the codes and the bad cat.

I don't smell gas inside the truck or under the hood. The truck seems to run great. Unfortunately I haven't kept great records of the gas mileage.

Other ideas ? Any ways to check for injector leaking? I think I have Central Sequential Electronic Fuel Injection ... will I need to replace all 6 injectors?

Originally Posted by BlazerLT

No unless you have a Tech2 computer to monitor its readings.

[drdd]

MAP sensor ?? anybody? ideas?


(what a loser ... replying to my own post !) haha !

Originally Posted by drdd

Okay, my 97 Jimmy W is still getting the running rich codes in both banks.

I've done full tune-up, clean MAF, swapped with an Ebay 2001 MAF, replaced cat converter today. Still get codes.

The only thing I haven't done is replaced O2 sensors. I'm beginning to think I have a injector leak and that it is running rich and the 02 sensors are doing their job. That would explain the codes and the bad cat.

I don't smell gas inside the truck or under the hood. The truck seems to run great. Unfortunately I haven't kept great records of the gas mileage.

Other ideas ? Any ways to check for injector leaking? I think I have Central Sequential Electronic Fuel Injection ... will I need to replace all 6 injectors?

[BlazerLT]

Are you resetting the computer each time you do this?

[drdd]

Yes everytime except ...

yesterday after I had the new cat put on. I asked the guy at Midas if they typically reset the computer after installing a cat. He said no. When I recieved the truck from Midas with my new cat, the SES light was off. It came back on in about 10 miles.

I'll try resetting ...

Originally Posted by BlazerLT

Are you resetting the computer each time you do this?

[drdd]

oh I forgot ... I had the codes read at Advance Auto after the new cat install and after the SES light came on.

Their code reader resets the computer after reading the codes. So ... the computer is already reset, I'll just keep an eye on it ...

Originally Posted by drdd

Yes everytime except ...

yesterday after I had the new cat put on. I asked the guy at Midas if they typically reset the computer after installing a cat. He said no. When I recieved the truck from Midas with my new cat, the SES light was off. It came back on in about 10 miles.

I'll try resetting ...

[BlazerLT]

I don't know if a 2000 MAF will work on a 1997.

I suggest getting a MAF from Advance AP and trying it out.

[blazee]

MAF is the same 96 - present. AC Delco part # 213352

The code scanner clears the code, it doesn't reset the computer.

[BlazerLT]

Originally Posted by blazee

MAF is the same 96 - present. AC Delco part # 213352

kew, just making sure.