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Bad distributor = not so smooth idle?
Topic Started: Apr 25 2015, 01:27 AM (1,229 Views)
freegeo
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If a distributor is not up to par or out of adjustment would it effect the idle but run smooth at 1000 rpm's and above?
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freegeo
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I swapped out the distributor today and it didn't effect the idle any. I think the timing belt is off a tooth.
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GeoStalker
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"Chicks dig me and guys think I'm cool."

I'm having the same issues. My gas mileage in a 1990 3/5 has only been 35mpg in mixed driving....maybe 40 highway if I'm lucky. I've replaced the MAP sensor, TPS, and intake, exhaust, distributor, and throttle body gaskets in case there was excess air sucking in from somewhere. No noticeable change yet. I just threw another vacuum advanced distributor on there from a parts car that I picked up today, but it could be compromised as well. I may get one rebuilt and try that out.

To answer your question, yes, a bad distributor could affect idle but smooth out at higher rpms.
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freegeo
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GeoStalker
Apr 25 2015, 08:10 PM
I'm having the same issues. My gas mileage in a 1990 3/5 has only been 35mpg in mixed driving....maybe 40 highway if I'm lucky. I've replaced the MAP sensor, TPS, and intake, exhaust, distributor, and throttle body gaskets in case there was excess air sucking in from somewhere. No noticeable change yet. I just threw another vacuum advanced distributor on there from a parts car that I picked up today, but it could be compromised as well. I may get one rebuilt and try that out.

To answer your question, yes, a bad distributor could affect idle but smooth out at higher rpms.
My gas mileage has been low to mid 40's if that on an engine that was rebuilt and has almost 3000 mile on it now. It has always had a not so smooth idle since I put it in. Like you, I have replaced all the vacuum lines, made sure they were routed correctly. Checked intake gaskets and throttle body gaskets replaced. Swapped out the distributor today and no real change. Maybe a slight one if any.

I had expected the engine to run smoothly since I had balanced the rods and pistons during the rebuild.
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Hanuman
"The Almighty Grounds Cleaner"

GeoStalker
Apr 25 2015, 08:10 PM
I'm having the same issues. My gas mileage in a 1990 3/5 has only been 35mpg in mixed driving....maybe 40 highway if I'm lucky. I've replaced the MAP sensor, TPS, and intake, exhaust, distributor, and throttle body gaskets in case there was excess air sucking in from somewhere. No noticeable change yet. I just threw another vacuum advanced distributor on there from a parts car that I picked up today, but it could be compromised as well. I may get one rebuilt and try that out.

To answer your question, yes, a bad distributor could affect idle but smooth out at higher rpms.
you replaced the map.........now replace the twin sister "O2 sensor"

and the one common point most of the sensors, fuel pump, and ECM have in common.......clean your grounds.

tire psi, bearings, dragging breaks?

cleaning grounds : http://geometroforum.com/topic/5720306/1/
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Hanuman
"The Almighty Grounds Cleaner"

freegeo
Apr 25 2015, 08:49 PM
GeoStalker
Apr 25 2015, 08:10 PM
I'm having the same issues. My gas mileage in a 1990 3/5 has only been 35mpg in mixed driving....maybe 40 highway if I'm lucky. I've replaced the MAP sensor, TPS, and intake, exhaust, distributor, and throttle body gaskets in case there was excess air sucking in from somewhere. No noticeable change yet. I just threw another vacuum advanced distributor on there from a parts car that I picked up today, but it could be compromised as well. I may get one rebuilt and try that out.

To answer your question, yes, a bad distributor could affect idle but smooth out at higher rpms.
My gas mileage has been low to mid 40's if that on an engine that was rebuilt and has almost 3000 mile on it now. It has always had a not so smooth idle since I put it in. Like you, I have replaced all the vacuum lines, made sure they were routed correctly. Checked intake gaskets and throttle body gaskets replaced. Swapped out the distributor today and no real change. Maybe a slight one if any.

I had expected the engine to run smoothly since I had balanced the rods and pistons during the rebuild.
low 40's is about right for a stock 95+ in good shape mixed driving. 45 mpg highway.
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Hanuman
"The Almighty Grounds Cleaner"

and remember...........below 850 rpm + or -.......idle will be less than smooth. gets more shaky as idle drops.

the lower the idle, the more "time" between the pistons firing on oppiset sides of the engine, so the engine has more time to move side to side between corrective piston pumps.
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GeoStalker
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"Chicks dig me and guys think I'm cool."

Should I get a check engine light code for a bad O2 sensor? I have no codes as it stands right now.
Edited by GeoStalker, Apr 25 2015, 09:50 PM.
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freegeo
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I haven't done the o2 sensors yet but the tire pressure, bearings, no dragging brakes, ground are already clean and extra ground ran.
My 96 that has 212,000 miles on it idles smoother than this one and it gets better gas mileage.
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Hanuman
"The Almighty Grounds Cleaner"

GeoStalker
Apr 25 2015, 09:50 PM
Should I get a check engine light code for a bad O2 sensor? I have no codes as it stands right now.
usualy you wont.

a o2 sensor or a map sensor can be under or over reporting.
you will only set a code if its reporting to far out of the limits.
and you will only set a code if certain conditions are met.....for example coolant and air intake temps must be in a certain range for most codes to set.........a iat sensor tricker will prevent most codes from setting.

the o2 sensor will set a code if its not switching.......but if its off by 10% so will your mpg, but its not far enough to set a code.

i can look up what it takes to set a 02 code if you want.....im in the middle of cooking kids dinner....or i would have looked everything up all ready
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GeoStalker
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"Chicks dig me and guys think I'm cool."

Hanuman
Apr 25 2015, 11:37 PM
GeoStalker
Apr 25 2015, 09:50 PM
Should I get a check engine light code for a bad O2 sensor? I have no codes as it stands right now.
usualy you wont.

a o2 sensor or a map sensor can be under or over reporting.
you will only set a code if its reporting to far out of the limits.
and you will only set a code if certain conditions are met.....for example coolant and air intake temps must be in a certain range for most codes to set.........a iat sensor tricker will prevent most codes from setting.

the o2 sensor will set a code if its not switching.......but if its off by 10% so will your mpg, but its not far enough to set a code.

i can look up what it takes to set a 02 code if you want.....im in the middle of cooking kids dinner....or i would have looked everything up all ready
It's probably worth replacing anyway. Thanks!
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sheananigans


One thing you may try... and I know it sounds weird. These engines idle like crap with expensive spark plugs. If you have iridiums or platinums I would change them out to coppers. I had a crappy idle and I changed out my spark plugs for Autolite Coppers and it fixed the issue. Also these engines will idle poorly if the oil viscosity is too high.
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t3ragtop
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Turbo3 and Twincam Tweaker

10w30 oil. i'm an ngk copper or power groove guy. ;)
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myredvert
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myredvert

Quote:
 
i'm an ngk copper or power groove guy. ;)
Don't you mean power groovy? :D
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Car Nut
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I'm with t3. I run 10w30 synthetic & NGK coppers.
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