Rough Idle

[supkev]

My m20 has a rough idle after not driving it for 3 days the battery died and a fuse blew. I replaced the fuse my radio and everything is back to normal its just I have a weird idle that bounces from 900-1300 rpms. I took it for a drive and shifted through 3 gears short shifting around 2.5k after it's been warmed up and it felt sluggish when I push the clutch pedal in, it wants to stall after the rpm's jump up and when it doesn't stall I press the gas pedal and there is no response :/. anyone know why?

[nebulous123]

1000 - 1100 is warm up idle, does it go away when it gets down to 750? or does it still bounce?

i have the same issue with both my cars and still havent fully gotten it figured out. I would say start with ICV, then vacuum leaks, then injectors (in case they are dripping), then AFM?

it could possibly be a vacuum leak of some sort in the intake or the exhaust. i am currently in the process of replacing those to see if that takes care of it.

hopefully the experts chime in, but what you are referring to does not sound uncommon for the M20 as I see lots of threads with the same issue as yourself.

good luck

[supkev]

hmm my idle is at 1000 but its bouncing up and down even when the car is fully warmed up. Anyone else got any ideas?

Thanks alot I will see if theres a leak I drove it out to black friday at cabazon and hit some big rocks I'll check it out.

[mkcman17]

How much have you driven it since? My dme typically takes several starts and runs before it gets settled after losing power.

[supkev]

I drove 140 miles on black friday night and havent driven it since then

[mkcman17]

Will it rev up and/or pull under load?

[supkev]

so I pulled the negative battery terminal and connect it back and it works great now back to my original problem, battery drain -__-

[JrCamacho]

as told by your front plate : "NIIICE"

[supkev]

lol

[ROLLingKING]

so disconnecting the the battery just fixed it.lol
about the drain...maybe u need an alternator?

[supkev]

I pulled the negative battery terminal and it works so its not the alternator, either battery or there is a serious drain.

[paperplane94]

you need a multimeter set to amps mode in order to test the batt draw/drain.

Simply set the MM to DC AMPS and put one end of the probe on the neg. batt cable and the other probe touching the batt terminal. see if there is any voltage drawn above .2 volts. Then go to your fusebox and pull fuses one by until the voltage drops below .2 or at least around it. Then look at the circuit for the fuse you pulled and find the short. EASY!

[E30_fiend]

You need to test the entire charging system. The old "pull off the negative battery wire and see if it dies" trick isn't the best method. Your alternator could be weak enough to die over time but not immediatly. Your car would likely not even start if your alternator was so bad that the car died when you pulled the battery cable.

Get your entire system checked. That's the only true way to figure out what the problem is.

Another thing to consider is your main battery fuse. It's located on your positive cable in the trunk about a foot from the battery. It's a 50amp fuse iirc.

Good luck.


Taylor

[supkev]

I appreciate it e30_fiend I will look into it and paperplane94 I will try that method also.