M42 failed emissions, high nox, help please

[z6ne]

What is the next step?

[IMG] image hosting 15mb[/IMG]

[jlevie]

The numbers shown could be indicative of the engine running lean, which would raise combustion temperatures and thus NOX. A fuel delivery problem or intake leaks could cause that. The first things I'd do would be to smoke test the intake and check rail pressure.

[jalopi]

Does your car run good? If so, then it's probably not running lean. A bad cat can also cause this.

[jlevie]

Does your car run good? If so, then it's probably not running lean. A bad cat can also cause this.

In other cases I'd have suggested that, but the HC numbers are remarkably low for bad catalytic converters. If they were bad I'd expect the HC numbers to be high.

[Gerta]

I had the same issue and it turned out to be the O2 sensor.

[jalopi]

Oh, the woes of pre-OBD... is there no such thing as historic or hot rod tags in Georgia? In MD if your car is at least 20 years old, you can get those and not worry about emissions.

[z6ne]

Oh, the woes of pre-OBD... is there no such thing as historic or hot rod tags in Georgia? In MD if your car is at least 20 years old, you can get those and not worry about emissions.

tell me about it. I've been to 6 shops, none of them can read pre 95 or pre 92 cars. I'm going to the dealership to get the code read tomorrow.

But the car runs well, too low of an idle at start up and alot of vibrations then, but once it warm the idle is fine. I read that this is a common problem for m42s, and that to test for vacuum leaks, pull the dipstick out, if RPMs drop, no leaks, if they remain steady, leaks. I did it, and they didnt change, so I'm gonna hunt for leaks.

Also, the PO installed a full magnaflow exhaust system in it, pipes, brand new cat ( so he says, but it does look new ), and muffler. BUT I finally got in contact with him recently and he said the O2 sensor is not installed. That's probably why the CE light is on. Does anyone know where I can source one? I checked pelican but they're all like 190 dollars, and I know I can find cheaper. thanks for the info guys, I have about 9 days to get this car ready for ~100 mile/week commute coming up when school starts, it's almost there!

[z6ne]

Also, GA requires the car to be 25 years old, sucks.

[Dj Buttchug]

why do you need a code reader when 5 depressions of the gas pedal will flash codes?
PO did not state cel status...?

There are no OBD "woes" The engines not running right. thats all.

This is probably not a cat problem. It seems to me you need try a few things first.
1.Run some seafoam through the intake.
2. Add seafoam to 1/2 tank of fuel
3. Drive it and burn up all that fuel
4. Then change the oil and put in some good new plugs(NGK)
5. Go retest and see where you stand.

[z6ne]

why do you need a code reader when 5 depressions of the gas pedal will flash codes?
PO did not state cel status...?

There are no OBD "woes" The engines not running right. thats all.

This is probably not a cat problem. It seems to me you need try a few things first.
1.Run some seafoam through the intake.
2. Add seafoam to 1/2 tank of fuel
3. Drive it and burn up all that fuel
4. Then change the oil and put in some good new plugs(NGK)
5. Go retest and see where you stand.

I've only ever had an m20, this is my 2nd e30, so I don't know a lot of specifics about m42. Plus I'm working with my dad on it so he wants to be very thorough.


"PO did not state cel status...?" what?

[Dj Buttchug]

I've only ever had an m20, this is my 2nd e30, so I don't know a lot of specifics about m42. Plus I'm working with my dad on it so he wants to be very thorough.


"PO did not state cel status...?" what?

The rules are kind of the same for all engines. What I meant was you never stated you had a check engine light or not. Do you? my bad on the typo.

[Danny]

Sell it.

[z6ne]

Sell it.

:finger: fuck off

[Danny]

Press the gas pedal to the floor with the key on engine off give times in quick secession. Count the times the check engine light blinks and post here.

[z6ne]

The rules are kind of the same for all engines. What I meant was you never stated you had a check engine light or not. Do you? my bad on the typo.

Oh. Yes, I do, and it wasn't there when I bought the car, just recently came on.

Would the light be on because of a lack of o2 sensor? I feel like that might be it, but in that case the light would've been on since I purchased it.
How much do these things go for used?