Did you unlpug the MAF while the car was running? I think it could be normal for it to stall if unplugged while already running. My understanding is that the car should run in some sort of limp/fail mode if the car is started with a dead/unplugged maf. I could be wrong about all of this, but if your car can't ever run without maf, it might be a clue to narrow things down to something beyond my knowledge.
Something else that came to mind is the throttle position sensor. I remember a friend who would have unpredictable throttle response due to this, especially when stabbing the pedal. However, that was on an M20 and I don't know if it's directly relevant to S50s as well.
As for a head gasket leak, I don't think it would cause those symptoms. You'd notice other things before performance issues that severe, like some real obvious oil and coolant mixing and a much cloudier exhaust than what you're seeing. I don't have any guesses for the clogged cat, but at least that's something you can disconnect and test without spending money if you do it yourself. Don't failed cats result in a sulfur/rotten egg like smell? Maybe that's not always the case.
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A bad fuel pump connector could cause an issue with these symptoms. I'd wiggle the connector around to see if the pitch of the pump changes at all.Leave a comment:
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I had an issue on my M20 that was similar. Turned out one of the maf connectors wasn't seated all the way. Engine would get too much fuel or not enough fuel and sputter. Sounds like you've you've already checked your MAF though.Leave a comment:
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It might be a flaky fuel pump connector. I had to do the "Fonz" for a while. It turned out the fuel pump connector on the pump got damaged. The ground side started to melt and the pin got half-covered in melted plastic. The car would never die during times of higher engine load, but would die at idle.
So, I removed the melted plastic so that the pin was clean and fully unshrouded, and spliced on a new fuel pump connector.
I would open the fuel pump access hatch, and turn the car on and try wiggling the connector. If the pump buzzes on and off, you have intermittent electrical contact.Leave a comment:
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If I unplug the maf, the car dies. I have a check engine light but only at high rpms when the engine is cold. It throws maf code at those upper rpms.
Also, when the pulled the plugs they were pitch black. I don't remember if I mentioned that or not.Last edited by Danny; 01-11-2013, 08:08 AM.Leave a comment:
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I've had odd vacuum like issues be caused by a bad mass airflow sensor. Although to be honest, nothing as severe as your symptoms. I'd still say it's something worth looking into, especially if you can borrow one from a friend just for testing. I think you can also try disconnecting it to see if things change at all. Also, is your check engine light hooked up, and giving any codes?Last edited by e30user; 01-10-2013, 11:52 PM.Leave a comment:
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S50 running issues
Alright so, I have an S50B30 in my car, OBD1 of course. I'm having some issues with it. It started with an intermittent dying problem that would occur from time to time. This problem was solved by whacking the top of the fuel pump until the car kicked back to life. Eventually this Fonz style trick stopped working.
I then replaced the fuel pump and the three relays on the engine harness, the issue was fixed for about a week. Then I smoke tested the intake and found I had a huge vacuum leak where I repaired the brake booster nipple. I then replaced the intake manifold and every single vacuum fitting and hose. I also replaced the CPS. At the same time I installed my OBD2 pink top 21.5 lb rebuilt injectors. This was done after numerous techs told me it was fine and the car would still run fine. After that the issue persisted. I can start it and drive it but the car would die when letting the clutch out unless I slipped it quite a bit. Once I got out of the lower RPMs (<2500) the car ran fine, had good power, etc. If the car died I could crank it and it would come back to life but only after around 20 seconds of cranking. It would then idle very low for a minute or so until it seemingly "cleared itself up" and the idle picked up.
Then I replaced the spark plugs, the plugs that I pulled out of the car were pitch black and a tad bit oily on the threads, nothing on the electrode however. With the replaced spark plugs it ran a bit better but still had the same issue when I touched the throttle. I have uploaded a few videos for you to look at.
Ignore the high idle, I adjusted the throttle cable to have a high idle. Ignore the brake booster hose, that is temporary to ensure there is no vacuum leaks (or at least obvious ones)
My theory is the O2 sensor may be old and too lazy to properly adjust the fuel mixture for the larger injectors without a tune. I am going to order the proper tune from Turner tomorrow. My other idea is that my shitty aftermarket magnaflow cat that is rattling around may have finally clogged my exhaust. Lastly, could this be indicative of a headgasket leak? The only thing out of the exhaust is a fuel smell and steam due to the cold weather.
Cliff notes version: replaced all vacuum related items and intake due to massive vacuum leak, replaced fuel injectors with OBD2 injectors, see above videos.
Any help is appreciated, thanks.
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