CA SMOG FAIL: High HC @ Idle Only

[threewagons]

Okay, all clamps tight, no leaks I can find.

Seems fine if i drive like an NA car. Decent if i don't push it. Under load, it starts to buck around at 4k rpm.

That definitely sounds like a bad catalytic converter. I actually still have the one off my 940, if you're looking for a used OE replacement.

 

[Mylesofsmyles]

That definitely sounds like a bad catalytic converter. I actually still have the one off my 940, if you're looking for a used OE replacement.

Hmm, haven't felt a clogged cat in a turbo car before...is that what you're suspecting?

Here's the suspiceous part. When I drove home from failed test, car still ran great. Now i've done all this work and i can't get back to where I was.

 

[threewagons]

Hmm, haven't felt a clogged cat in a turbo car before...is that what you're suspecting?

To be honest, I haven't either, but I threw all kinds of parts at my NA S60 before I figured out the cat was clogged. Any sort of load and the engine would start bucking, I could barely make it up some hills without inducing the bucking.

 

[Mylesofsmyles]

To be honest, I haven't either, but I threw all kinds of parts at my NA S60 before I figured out the cat was clogged. Any sort of load and the engine would start bucking, I could barely make it up some hills without inducing the bucking.

its just bizarre that this symptom has suddenly appeared, as I've worked to right everything else.

 

[threewagons]

Easiest way to check is to pull the exhaust and go for a drive

 

[Mylesofsmyles]

Easiest way to check is to pull the exhaust and go for a drive

I respect my neighbors, lol.

May see about taking it to the exhaust shop this week. Still feels like a fuel cut/vacuum dealio.

swapped in a cheapo new FPR from amazon today, and that didn't do anything. The old one wasn't leaking, nor smelled of gas, but can they fail in other ways?

Where do I test fuel pressure? Before FPR? Suppose I'll need some sort of fitting for my gauge to work

 

[James M]

Taking off 3 downpipe nuts is free and let's you know within 5 minutes if you can stop loading the parts cannon and replace a known bad part or not.

 

[Mylesofsmyles]

HC is unburnt fuel. You three way cat cleans up the three pollutants: HC, CO, and NoX.

Losing power at 4K doesn't sound like a learning issue. LH2.4 adjusts idle mixture and speed. One you are in boost and throttle, the ECM leaves closed loop and ignores the O2 sensor.

Have you confirmed the MAF female terminals and the terminal crimps are corrosion free? Maybe drag test the terminals with the correct male probe (from and old MaF) to confirm proper terminal tension.

I can take a closer look at maf terminals. I remembered to when you mentioned last, and didn't find any corrosion.

 

[Mylesofsmyles]

Throwing this riddle out there. I installed a 87-degree thermostat. Is that correct, or was I supposed to use the 92-degree?

 

[Mylesofsmyles]

Just drove it a few more miles, to get a pizza and bring home.

If I drive like normal, it feels like a normal car. I suppose the turbo sounds a bit more like a garbage truck....so maybe the cat is clogged? Didn't really boost it...just drove it around...felt fine.

 

[threewagons]

I would put my money on a clogged cat. Maybe have the exhaust shop weld you up a test pipe?

 

[Mylesofsmyles]

I would put my money on a clogged cat. Maybe have the exhaust shop weld you up a test pipe?

They open at 9

 

[Dvroofer]

They open at 9

I have a magnaflow cat that only was used for smog purposes for a 91 240 not sure the fit but would get rid of it cheap. I’m in Long Beach . home all day, also have welder if you need help

 

[Mylesofsmyles]

I have a magnaflow cat that only was used for smog purposes for a 91 240 not sure the fit but would get rid of it cheap. I’m in Long Beach . home all day, also have welder if you need help

Great offer, thanks...I can not weld, so I'd need help. Let me get through the diagnostics and I'll be in touch if I need ya.

 

[ZVOLV]

I doubt it's a clogged cat. You cam do some diag with a vacuum/boost gauge. I assume you already have one installed?

You can also do backpressure readings.

Or simply loosen up the exhaust or take the test plug out and go for a drive.

 

[Mylesofsmyles]

So, I did have a melty boi...

Car drives MUCH better now....most of my symptoms are gone. Still seems to buck like a fuel cut in the upper rev range at load, though nowhere near as bad.

 

[philski o'flood]

progress

 

[ZVOLV]

The cat got destroyed likely from whatever misfires you are chasing down

 

[James M]

The cat got destroyed likely from whatever misfires you are chasing down

+1 they don't die like that for no reason

 

[Mylesofsmyles]

Definite miss in boost with loads. Otherwise car feels good.

Maybe a puncture in intercooler? Maybe I didn’t tighten one of the spark plugs all the way when I checked them at smog shop?