Unusual exhaust smell

[rsmithdrift]

Hey, guys, I'm new to this forum and I tried searching for exhaust stuff but didn't find what I was looking for......

Anyways, I just bought this nice, clean '93 240sx fastback and it wont pass inspection. I found out that the previous owner hadn't given it a tune up since '95 so I just did a complete tune up on it (plugs, wires, cap, rotor, air filter, fuel filter, and put fuel injector cleaner with octane boost in it) and tried again and it faild again for the same damn reason.......too much carbon monoxide. Monday I'm taking it to get the pcv valve replaced (I'll leave that to those more apt to do it after seeing where it is) but I don't think that'll help much either.

Here's where the exhaust smell part comes in.......I have noticed that even with everything new it still seems to lack power, like something is holding it back for some reason, It runs smooth and idles fine, and has good throttle response, but it just doesn't pull very hard, and I get an occasional surge at 2,500 rpm. Also, I started to notice that the exhaust smell very strong and very bad, I cant even begin to explain what it smells like to you.....best I can do is say that it's like a mix of sulfur water and rotten eggs. You cant smell it inside because the car seals so well, but outside the car and you almost pass out from it. I took it to midas and they said that the catalytic converter was still good on it..........so now I'm just confused.

Why would it smell like that and lack power? I'm sure that's why it won't pass emissions. Whatever it is.

Any help is much apreciated, thanks.

[AZhitman]

I'd say bad cat (Midas = confused). That's a classic case of plugged catalytic converter. If you can't find a replacement, I have access to some for $155 shipped.

I'd also suspect a vacuum leak somewhere...

Check your MAF connection and clean the MAF with brake cleaner spray...

Get a couple cans of starting fluid and spray all around the intake manifold to locate / pinpoint any vacuum leaks.

Almost forgot to say, WELCOME aboard!!!

[AZhitman]

zerothread?id=155872

Grab this ASAP - Seller is a good guy!

[rsmithdrift]

Thanks for the tip. I guess the guys at midas are just retarded. Though the car does rev easily, but it does smell like a cat problem to me. They said the cat on my 300zx was fine, It got on my nerves so much I had them straight pipe it and yeah, that cat was not fine. lol. But that was before we had to do emissions.

They check for alterations to the cat at the emissions place, would that make them fail me irregardless??

btw, I tightened up the MAF connector and sprayed it and the throttle body with carb cleaner when I did that tune up. Also I just finished going over the entire car with a fine tooth comb for vac leaks and cleaned up the AIV valve, though it probably didn't need it, and hit up every electrical connection I could find with a can of electrical connector cleaner....... so besides the cat, idk what it's problem could be.

Could the O2 sensor cause that problem? I would think it'd have a more pronounced effect on the drivability than that though if it were bad, but all cars are different I guess. I know the z wouldn't drive at all when the O2 went out on it.

What do you think of this cat? seems fishy to me, but $30 is tempting me. cat on ebay

Modified by rsmithdrift at 10:50 PM 1/28/2006
Modified by rsmithdrift at 10:50 PM 1/28/2006

[AZhitman]

That ebay cat looks like a joke... Hell, the flanges alone would cost $30, so I wouldn't trust it.

O2 *could* be the culprit - sounds like you have a pretty good handle on doing some thorough diagnostics.

[tyrannix]

it definatly could be the O2 on my yukon, i just replaced 2 (of 4 :/) o2 sensorsthe truck was barely able to go on uphill roads.. it would slow down... and if you floored it, it would slip into a lower gear (automatic) then slow down and be rediculous

2 O2 sensors later, its not tripping any codes and feels brand new again (its a 96) ... it feels like i could pull a trailer again

being that universal O2 sensors are what $20? its definatly worth getting a new one

im assuming that you havnt tripped any codes or you would have posted it

[UK-SRi]

Bad egg smell is NOT a dead cat converter, its when the mixture is too rich that any sulphur is unable to be released until it breifly flips to stoichiometric. You know its running rich because the CO is high. Change the O2, reset the base idle and clean any egr you have, then tell me what your new numbers are.

Mike

[rsmithdrift]

I don't know if it's tripping codes or not. I don't have a FSM and none of the local auto parts stores carry a Haynes for it, so I don't know how to play with the ECU on this car. I check the codes on my 300 regularly, but then again I have that Haynes manual by my side when I do it also. That's the only way I know what the blink patterns mean. I've only had the car for 4 days now, so I don't want to go into the computer w/o knowing what I'm doing first.

[rsmithdrift]

Problem solved. It was the O2 sensor. The difference installing that new sensor made was night and day!!! Damn this car rocks now. So much faster and has so much more torque now, especially for a 4 cylinder it's unbelievable. Passed emissions with flying colors, guess I should've trusted my instincts and changed that out when I gave it the tune up like I wanted to.