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90 SC rotten
11-16-2005, 07:21 PM
92 5-speed
What should normal idle speed be? Chiltons says 550 for both automatic and manual cars. Thats where mine used to idle until I replaced snought seal, cleaned out throttle body and IAC, changed engine mounts, swapped in a better tansmission and my car now idles higher than I would like it to 750-800. I know alot of these things don't relate but why the difference in idle speed. I also have great vaccume 22hg compared to the 20hg I used to, I figure that is because of the high idle. Any ideas would help. Thanks in advance for any suggestions.

JimmyDean
11-16-2005, 07:27 PM
My car has always idled at ~750, except when the IAC broke. Vacuum is 18in/hg at idle, and about 20 with the ac. My car only pulled that much vacuum at idle when I had a vacuum leak at the collar nut.

90 SC rotten
11-16-2005, 07:32 PM
Is yours 5-speed

littleboylan
11-16-2005, 07:59 PM
Mine is a 92 5 speed, and it Idles at 750 with 19in/hg. To me it sounds like its normal, but Im sure a lot of cars it varies. Maybe cleaning out that IAC might have not been such a good idea?!.

trife86
11-16-2005, 08:02 PM
my idle And power when kickin it is great but my vac isnt normal dunno if its good or bad

at idle in Park it only gets about 15in on the vac side, in gear if im at say 2000rpm in 4th gear and let off the gas it will go to 20in but usually in gear about 14in vac idle in gear

90 SC rotten
11-16-2005, 09:15 PM
my idle And power when kickin it is great but my vac isnt normal dunno if its good or bad

at idle in Park it only gets about 15in on the vac side, in gear if im at say 2000rpm in 4th gear and let off the gas it will go to 20in but usually in gear about 14in vac idle in gear


You have a vacucume leakfor sure. You should have 20hg at idle in neutral.
Does anyone know what the ford service manual says about idle speed

90 SC rotten
11-16-2005, 09:16 PM
my idle And power when kickin it is great but my vac isnt normal dunno if its good or bad

at idle in Park it only gets about 15in on the vac side, in gear if im at say 2000rpm in 4th gear and let off the gas it will go to 20in but usually in gear about 14in vac idle in gear


You have a vaccume leak for sure. You should have at least 20hg at idle in neutral.
Does anyone know what the ford service manual says for normal idle speed on a 5-speed?

trife86
11-16-2005, 10:26 PM
saying i have a vac leak will that also mean i have a boost leak somewhere?

Blown 91 Bird
11-16-2005, 10:40 PM
my car makes 18-19" of vacuum at idle with it at 650-700rpm. After getting out of the throttle coasting it makes 22-23" of vacuum.


Wouldnt his motor be surging at idle if he had a vacuum leak? :confused:

gspacerant
11-17-2005, 11:00 AM
i believe idle speed is supposed to be 750 rpm, mine starts out at 1000-1100 rpm, then after it warms up for about 15-20 seconds it will drop down to 750.

At idle in neutral i pull just under 20" HG according to my gauge...

I know the stock boost gauges are known to be off quite often, at least on the boost side.... does this hold true for the vacuum side as well?

90 SC rotten
11-21-2005, 06:04 PM
Anyone know what the ford book actually states for the spec. I am just curious and do not have axcess to the book.