misfires at startup only for a short time

[cheers007]

Hi all. I have a 93 Maxima SOHC 3.0 with a minor problem. When I first start it up (hot or cold), it misfires at idle and engine load, both parked or while driving. AFter a few minutes, the problem all of a sudden goes away and everything runs perfectly.

However, even when it is running smoothly, I notice an egg smell comming from the bottom of the car, but I don't hear any exhaust leaks.

I have done a full tune up (changed plugs, wires, cap, rotor, cleaned throttle body along with idle air valve, new air filter, and new fuel filter). I also had a problem with a dead injector and had that replaced, which fixed the problem for a month, then the misfiring came back.

Any ideas? Can this be related to the EGR valve? BTW, there is no check engine light at anytime (I mean the light works but I don't have any error codes from the PCM).

[Biggs]

i can't say anything about that misfire, but...that egg scent you smell is front your cat. It's probably a bad cat or it's at the end of it's life.

[Ovaltine Jenkins]

it's either the coils or a fuel injector...

[cheers007]

thanks for the replies. I will take the car to a muffler shop to have them check out the cat/egg smell.

As for the misfire, see once the car has warmed up for 4 mins or so, the misfire goes away and drives fine until I shut it off, let it cool a bit, then go to restart it. My gut feeling tells me it is an EGR problem but I'm not too familiar with Nissan woes, so would the EGR malfunctioning be an accurate assessment?

[Ovaltine Jenkins]

this was just discussed a few days ago. Apparently it's kinda common with 3rd gens...
http://chicagomaximaclub.net/showthread.php?t=2308

[cheers007]

thanks for the link Dave, but it doesn't seem to state any facts, only beliefs that it is the injectors.

My question is, that from my understanding of other fuel injected cars (93 Dodge Intrepid and 98 Honda Civic) temperature doesn't matter when it comes to performance. What I mean is if it is messed up (either clogged or just dead) it shouldn't matter if it is cold or hot. Besides, I've ran a few bottles of B12 in the tank over 2 month period and I replaced an actual dead injector too.

Shouldn't the computer record an error code for a dead injector, or is the OBD 1 on Nissan too "dumb" to know that?

Or could a bad cat cause this problem? I still feel like it is either a cat problem or EGR problem.

[walec05]

it wouldnt be a cat problem because a cat would cause emmissions failure, and not cause your car to die from time to time.

[cheers007]

Walec, my car never dies, it just misfires for the first 5 min of starting it.

[walec05]

thats definately not cat related. its more than likely an emmissions issue. get it checked out at some small shop and see what they say.

[DasTeknoViking]

Alright lemme clear things up a bit.

Injectors are the problem here, they are dumping too much or too little gasoline into the engine causing the engine to misfire, durring a misfire the temperature of an engine increases, fuel that was injected goes into the cat where the other HOT cylinders (engine has to work harder on 5 or 4 cylinders vs 6) ignite the air fuel mixture and cause the sulfuric smell of the cat.

Basically your cat is fine, and you need to repleace all 6 fuel injectors. Dont nickle and dime yourself and have to repleace one after another every few months, just do it all at once. They will all fail eventually. I used to have a 3rd gen Maxima, I know.

[Brian]

it's either the coils or a fuel injector...
he only has 1 coil

Alright lemme clear things up a bit.

Injectors are the problem here, they are dumping too much or too little gasoline into the engine causing the engine to misfire, durring a misfire the temperature of an engine increases, fuel that was injected goes into the cat where the other HOT cylinders (engine has to work harder on 5 or 4 cylinders vs 6) ignite the air fuel mixture and cause the sulfuric smell of the cat.

Basically your cat is fine, and you need to repleace all 6 fuel injectors. Dont nickle and dime yourself and have to repleace one after another every few months, just do it all at once. They will all fail eventually. I used to have a 3rd gen Maxima, I know.

to add to what mike has said. If you let the car continually run rich, you WILL ruin the cat (plug it) which will then cause running issues by stangling the engine.


Check your coolant temperature sensor, they corrode and cause running problems. not as common as injectors but fairly common.

[cheers007]

Wow, thank you all for all the information. So let me ask you, internetautomart, should I change the coolant sensor even if the temp gauge is working correctly?

And, I have already changed 1 injector a few months ago, but where can I buy 5 new injectors for cheap? Do you give a good deal or someone else sell parts on this forum?

[Brian]

Wow, thank you all for all the information. So let me ask you, internetautomart, should I change the coolant sensor even if the temp gauge is working correctly?
2 seperate sensors. you don't neccesarily need to change it, sometimes a good cleaning will work wonders

And, I have already changed 1 injector a few months ago, but where can I buy 5 new injectors for cheap? Do you give a good deal or someone else sell parts on this forum?
I can do the brand new for about $90 each if you have a little patience for me to get them from my non-local source.