Sputtering, and smoke in engine after replacing alternator

I looked through and searched the site, but couldn't find anything that addressed my problem 100%.

First, I'd guess my problem is a boost or exhaust leak, but want to get some opinions.

Heres the story: I was driving my car, a 91 vr4, home, and it was running fine. When I got in my parking space it felt kind of weird, I turned it off and it wouldn't start. I left it for 20 min and it started, so I thought it was fine. I drove it, and it immediately started hesitating and sputtering badly and I had to drive it around the block. It wouldn't go much more than 10mph. I didn't know what was wrong, I figured fuel pump or something. The next day I get my friend to hook up some jumper cables and it starts up fine, and idles and works perfectly. I figure, somehow, it must be the battery or alternator. I go get my batter checked, it takes a charge, and is fine. Damn. So I go back home, put the new battery in and it runs perfectly. I go back to get my alternator tested, bad alternator. So I continue driving my car on that initial charge, and it's working fine. The next day I drive about 30 miles to a mechanic I know. He switches out the alternator, and when I leave it sputters really bad and dies. It'll idle, but roughly. When I apply gas, the revs will drop, and if I leave it running black smoke starts to come from the engine (not a lot, but noticeable). The oil also smells like gasoline.

I hate to come across like an ignoramus, but, really, I am. /ubbthreads/images/graemlins/smile.gif Thank you guys!

N

 

[BoostedAWD91]

well the alternator doesnt have anything to do with your car running badly. Does it run horrible when its cold and warm or just when its cold?

 

It doesn't make a difference really. It seems to do the same thing whether the engine is hot or cold. Usually when I initially start it up, it won't idle and will die, but the second or third time it'll stay, but roughly.

 

[prove_it]

Sounds like a boost leak. I'd start there anyway.

 

[sydrew]

that sound like one of my problem i had before see if this help unplug ur maf and started it up and see if it idle like normal again if it does then that the problem need a new maf if it still idle poor when u unplug the maf then it coming from somewere else

 

[Hertz]

I wouldn't make that determination... bad airflow sensor is a rather rare occurrence.

Actually unplugging the sensor and having the condition improve is often a sign of a massive intake leak. Removing the sensor puts the car into a "limp home" mode. If you lose driveability due to blowing off an IC pipe, driving it a short distance in limp home can save your butt.

If you're seeing smoke though, that's a whole 'nother problem and not a good thing at all.

 

[prove_it]

You have black smoke coming out the tail pipe or from the engine bay?

 

[1990ggsxnj]

What do the connections to the temp sensors look like on the T-Stat housing? I've heard of that causing problems. If it thinks you're running at 30 below Zero, it will compensate with WAY more fuel than you need. I've never had it happen to me so I can't comment on how things feel on startup. I would immediately get a logger on it to see what's going on with the sensors & ECU. It could have also told you if you're alternator voltage was spiking/dropping. If nothings shows up there, boost-leak test (good to do anyways) to see what's going on with your pipes.

 

[BoostedAWD91]

if u have a bad coolant temp sensor or harness it will see -degree temperature and add alot of fuel which will flood the car causing no start or very hard starting, but if it starts fine and just wont idle than its most likely not your connectors or CTS sensor

 

It seems to me like the mechanic must've messed something up in the process of changing the alternator. I drove it there no problem, he changes it, and then bam, the car is a nogo.

Once the car starts idling, black smoke will emanate from the engine bay after about a minute. It's not a lot of black smoke though -- and it will also come from the exhaust, but, again, not a whole lot.

I have to take a look at the sensors, the car is across town at a friends house right now. I'm trying to get as much info as possible before I go over there. You guys are great! Thanks so much for taking the time and answering my question.

What really gets me is that when I apply gas the revs drop. And it sounds like the engine is missing hard and it smells really, really rich. Its bizarre.

Thanks again guys!

N

 

[prove_it]

Quoting 1990ggsxnj:
What do the connections to the temp sensors look like on the T-Stat housing? I've heard of that causing problems. If it thinks you're running at 30 below Zero, it will compensate with WAY more fuel than you need. I've never had it happen to me so I can't comment on how things feel on startup. I would immediately get a logger on it to see what's going on with the sensors & ECU. It could have also told you if you're alternator voltage was spiking/dropping. If nothings shows up there, boost-leak test (good to do anyways) to see what's going on with your pipes.




I completely forgot about that, duh! Anyways check into the temp sensor. A bad sensor will read -40 and yes it will behave exactly like you describe yours to be.

It could be damaged or a coincendence when it all happened.

GVR-4 motto: two steps forward, one step back. Get used to this.

 

[TRBODSM]

I have had a similar problem in my DSM before. When i changed out the alternator I made the mistake of not unplugging the battery and blew the 90 amp alternator fuse. It would turn on when i jumped it but then it started to smoke and miss. Try checking that fuse and if it is still good i would go on and check the temp sensors as stated by other members on the board.

 

So I replaced the fuse, but it didn't do anything. It idled better at first, but seemed to go back to its rough ways -- I think it idled well because it had been sitting.

Just a few notes, it'll seem to idle fine if I leave it for awhile. It'll even rev well, but then will die out and sputter. On subsequent restarts after I rev it, it'll idle but as soon as I apply gas it'll die. The smoke I wrote about before is actually coming from the exhaust, high up on the pipe, under the engine basically. It still smells really rich, and there was even a bit of oil in one of my spark plug housings.

Thanks guys. BTW does anyone have link or tutorial for help with the sensors on T-stat housing?

N

 

[Hertz]

So it doesn't sound like you tried unplugging the MAS...

 

No, my bad, I totally forgot. If I do, and it goes to 'limp mode,' and runs better, that'll indicate a large intake leak right?

Thank you.

N

 

Unplugging the MAS made it idle better. After revving it up, it will die with MAS plugged in, with it unplugged, it won't die, and will idle well.

However, everytime I rev it to 4-5k it'll start to miss and sputter, eventually dropping the rpms down with the gas pressed in the same amount -- while smoking a bit and smelling really rich.

 

[prove_it]

Quoting Hertz:
I wouldn't make that determination... bad airflow sensor is a rather rare occurrence.

Actually unplugging the sensor and having the condition improve is often a sign of a massive intake leak. Removing the sensor puts the car into a "limp home" mode. If you lose driveability due to blowing off an IC pipe, driving it a short distance in limp home can save your butt.

If you're seeing smoke though, that's a whole 'nother problem and not a good thing at all.



^1. Your problem lies here. Intake leak. The smoke could be grease on the exhaust burning off. I would get it running right first, then figure out the smoke issue. I highly doubt they are related, but could be.

Your in limp home mode buddy, that's why you can't rev past 5k. It's limp home mode, not race home mode.
You have an intake leak. I would get the pipe that runs down by the alternator, since someone was around there then it got messed up, I would start where someone was working. All it takes is one loose hose clamp. On Vfaq.com there is a guide for building a boost leak detector and how to test your system. Read up and good luck!

 

Awesome, I'll try it today. Thank you guys!

N

 

It was an intake leak like you guys said. I built a boost leak detector, and found a massive leak. Fixed it, and it runs fine.

Thanks for all your help and patience guys! Its much appreciated.

N