TheSamba.com :: View topic - Short sputter w.... *UPDATE* new problem. Smells too rich.

Tue Feb 02, 2010 9:10 pm

For the last few days i've noticed something strange and i can now reproduce all the time.
I noticed a sputter/misfire for about half a second long when turning on my signal light or headlights.
Only happens when at high rpms (usually when about to change gears).
Any idea what this might mean?
At first i thought it was my fuel pump. I checked the pressure and the readings were at 33psi idle.

1977 FI 2.0

0_o
please ask questions. im more than glad to respond. i would like to fix this rather quickly.

Tue Feb 02, 2010 9:13 pm

Hook up a volt meter to your fuse box (a VOM meter will do fine), mount it where you can safely see it and see what your driving voltages are, lights on and off.

Tue Feb 02, 2010 9:16 pm

First guess (although I could be way off) is temp II sensor. They cause sputtering at higher rpms. Could be affected by electrical changes. But so are most of the FI parts :D

How is your charging system?

Tue Feb 02, 2010 9:34 pm

Rebuilt alternator, new battery. Also got the starter rebuilt. Replaced them about a month ago.
Temp II sensor is fairly new. About 5 months old.

Tue Feb 02, 2010 9:36 pm

busdaddy wrote: Hook up a volt meter to your fuse box (a VOM meter will do fine), mount it where you can safely see it and see what your driving voltages are, lights on and off.
Alright.
Tomorrow will do.
What should my readings be?

Tue Feb 02, 2010 10:19 pm

jalex wrote: busdaddy wrote: Hook up a volt meter to your fuse box (a VOM meter will do fine), mount it where you can safely see it and see what your driving voltages are, lights on and off.
Alright.
Tomorrow will do.
What should my readings be?

Within a decimal or two either way of 14V, FI is voltage sensitive and just because the alternator is rebuilt doesn't mean it, something that connects to it, or another part of the electrical system is playing along nicely.

Tue Feb 02, 2010 10:23 pm

busdaddy wrote: jalex wrote: busdaddy wrote: Hook up a volt meter to your fuse box (a VOM meter will do fine), mount it where you can safely see it and see what your driving voltages are, lights on and off.
Alright.
Tomorrow will do.
What should my readings be?

Within a decimal or two either way of 14V, FI is voltage sensitive and just because the alternator is rebuilt doesn't mean it, something that connects to it, or another part of the electrical system is playing along nicely.

Ohhh ok.
Always learning something new :)

Wed Feb 03, 2010 8:52 am

Also, this might be related or might not.
My bus does not idle for very long. I'd say about one minute at idle it dies. It slowly drops lil by lil.

Wed Feb 03, 2010 7:36 pm

ok.
well i didnt know how to connect a volt meter to a fuse box and i also didnt have much time to figure it out.
so I connected a digital battery meter and hooked it up to the battery so i can check my charging system.
At first i had 13.02 volts with engine idling.
Then i disconnected it and reconnected the meter (with engine still running) it showed 12.81.
I asked a co-worker to turn on the headlights while i watched the meter and it dropped to 12.76.
Then he turned on the turn signal (headlights off) and the meter would change every time the turn signal flashed from 12.81 to 12.77.

Is this any help? or is this typical?

Wed Feb 03, 2010 7:42 pm

Did you try revving the motor to see if it was charging (higher voltage) as the RPMs increased?

Wed Feb 03, 2010 7:49 pm

calebmelvin wrote: Did you try revving the motor to see if it was charging (higher voltage) as the RPMs increased?

yes i tried it.
it did not raise much. went up to like 13.06

Wed Feb 03, 2010 7:49 pm

Try replacing the condenser on the distributor. Mine had a weak spark and symptoms like hard to start, misfiring, rough idle, etc. Replaced the condenser and runs like a champ. (2.0 fuel injection)

Wed Feb 03, 2010 7:51 pm

seventyfo wrote: Try replacing the condenser on the distributor. Mine had a weak spark and symptoms like hard to start, misfiring, rough idle, etc. Replaced the condenser and runs like a champ. (2.0 fuel injection)

I have electronic points.

Wed Feb 03, 2010 9:23 pm

jalex wrote: ok.
well i didnt know how to connect a volt meter to a fuse box and i also didnt have much time to figure it out.
so I connected a digital battery meter and hooked it up to the battery so i can check my charging system.
At first i had 13.02 volts with engine idling.
Then i disconnected it and reconnected the meter (with engine still running) it showed 12.81.
I asked a co-worker to turn on the headlights while i watched the meter and it dropped to 12.76.
Then he turned on the turn signal (headlights off) and the meter would change every time the turn signal flashed from 12.81 to 12.77.

Is this any help? or is this typical?

Sounds weak, try it with the engine revved and clean all the terminals and grounds.

Wed Feb 03, 2010 9:27 pm

busdaddy wrote:
Sounds weak, try it with the engine revved and clean all the terminals and grounds.

even it this weak, do you think this would be the cause of the sputter?

Wed Feb 03, 2010 9:28 pm

checked the belt tension?

Wed Feb 03, 2010 9:30 pm

Not impossible, lame voltage can mean lame running with FI, watch the volts as it idles for a while too to see if it drops off.

With all the switches and key off probe the fuse box for voltage with the - lead attached to a ground, when you get a reading you know where to clip it to.

Wed Feb 03, 2010 9:32 pm

pkrboo wrote: checked the belt tension?

that is something i noticed earlier today and told myself that i'll tighten it later.
As i was walking to my car after work i was thinking to myself..."what was i suppose to do???"
thanks for reminding me.
it felt somewhat tight tho. I can press down on the belt and it would move about 3/4 of an inch. Should it be tighter?

Wed Feb 03, 2010 9:38 pm

15mm or 5/8in deflection

Wed Feb 03, 2010 9:44 pm

busdaddy wrote: Not impossible, lame voltage can mean lame running with FI, watch the volts as it idles for a while too to see if it drops off.

With all the switches and key off probe the fuse box for voltage with the - lead attached to a ground, when you get a reading you know where to clip it to.

i did watch it for a while.
I had the headlights off and turn signal off and it slowly dropped to 12.76

I'll test the fuse box tomorrow when im back at the shop