Runs like a champ, idles like crap

[DUB]

Idles low and rough! Before you tell me to clean the IAC, I have done just that, including replaced every single sensor, T-body, coil, the "correct" plugs, nothing left.. No vac leaks, no intake leak.. Nothing has changed it. I'm to the point where it has to be ECU or engine itself. Suggestions?

 

[Steel City 06]

Plugged catalytic converter? The excess back pressure can cause a number of issues.

Low fuel pressure can also cause issues at idle, as could a clogged or failing fuel injector.

 

[DUB]

3rd cat removed, I have had the front ones off and looked good. Fuel pressure checks out, all new injectors too.

 

[macleanflood]

How's it run with the O2s out?

-Mac

 

[DUB]

How's it run with the O2s out?

-Mac

So I haven't tried that trick yet. These are all new as well which yielded no change when I replaced. Do you just unplug certain ones to test this?

 

[SouthernTJ2000]

Have you checked for codes, even if there isn't a CEL.

 

[macleanflood]

So I haven't tried that trick yet. These are all new as well which yielded no change when I replaced. Do you just unplug certain ones to test this?

Just pull all of them...it creates an exhaust leak. Ignore the O2 codes for now...it'll run fine on base map.

What we want to know is if it runs better then the cats are plugged... because the engine can finally breathe.

-Mac

 

[DUB]

Just pull all of them...it creates an exhaust leak. Ignore the O2 codes for now...it'll run fine on base map.

What we want to know is if it runs better then the cats are plugged... because the engine can finally breathe.

-Mac

Mac,

I will do this on Friday! thanks for the info!

 

[DUB]

Have you checked for codes, even if there isn't a CEL.

I did a few months ago and nothing. I will do it again. I have also reset PCM a few times.

 

[DUB]

Just pull all of them...it creates an exhaust leak. Ignore the O2 codes for now...it'll run fine on base map.

What we want to know is if it runs better then the cats are plugged... because the engine can finally breathe.

-Mac

Thinking about this, do you think the 6" glass pack I put in place of the 3rd could have caused an issue? I wouldn't think it would?

 

[macleanflood]

Thinking about this, do you think the 6" glass pack I put in place of the 3rd could have caused an issue? I wouldn't think it would?

I doubt it but with the way parts are made these days it's possible the fiberglass batting collapsed.

Got an endoscope?

-Mac

 

[DUB]

I doubt it but with the way parts are made these days it's possible the fiberglass batting collapsed.

Got an endoscope?

-Mac

I do, I'll check that too. thx!

 

[DUB]

Going to test by removing the 02 sensors on Friday but.. The front cats are literally the only thing I haven't changed, could be all 150K miles on them for all I know? Do you think this is a bad bet?

https://www.ebay.com/itm/2633282397...pid=5337789113&customid=&toolid=10001&mkevt=1

 

[DUB]

Code reader is pretty jenky but I tested all 4, 02 sensors and on one of them I get a fail for two different tests, the only tests available. I added one that was good for reference, as were the other 3 that I checked. It doesn't tell me which sensor this is though?

 

[AndyG]

Don’t forget to check the rubber “L”
vacuum fittings above the exhaust on the side of the intake manifold- they fail.

 

[DUB]

Don’t forget to check the rubber “L”
vacuum fittings above the exhaust on the side of the intake manifold- they fail.

They are all good! Really looking for advice on the 02 sensor situation above..

 

[AndyG]

They are all good! Really looking for advice on the 02 sensor situation above..

Hey just offering my experience- I’ve had 7 of these and 3 currently- any harm in that ?

The id of 1/1 appears to be saying bank 1 sensor one, that is the upstream sensor on the front bank, closest to the radiator. Unless that is the code count, the id indicates bank 1 ....you can also remove them and see loose media or scope it. I’d look close at the lower bank 1 sensor because the failing media hammers it.

Good luck on it.

Andy

 

[macleanflood]

I'd like to know what "fail" means ala the ODB tester.

To me fail means consistently running above .9v.

-Mac

 

[DUB]

Like I said this code reader is weird. When I go into a spot to check them, there are 4 "02" sensors in a row, nothing distinguishing what they are. I click on the first and it is a "FAIL", the other 3 are "OK". The 01 shows up in each of the 4 test lines. there is also another test down the list, again 4 different 02 sensors and the first is a fail and the next 3 are OK?

Assuming they are in order of location, Andy G, you would be correct that it's #1 I think? I'm going to test it the best I can and run down the wires and connection. Think is it never throws a code, just runs like it's really fat at idle!

 

[fourpointzero]

Following this thread, as I sometimes have funny idle and everything (almost) is new in terms of wear and tear parts / sensors. But I have never changed my upper cats. Though, I do have a new one I purchased 5 years ago, never installed. So Im ready when the time comes.