87 VIN9 307 High Idle

Status
Not open for further replies.

88hurstolds

Royal Smart Person
Jun 24, 2008
1,747
650
113
I have an 87 442 VIN9 motor running top notch on the computer in my 85 442. It's been rebuilt, as was the trans with a light shift kit (KCF from an 87 Salon) and has a 7.5" 3.73 posi from an '83 Hurst.

After 30 minutes of driving this morning I got on the gas really good at WOTand the idle bumped up from 850 in drive to 1100 rpm in drive and 1100 to 2400 rpm in park.
I checked the carb for sticking linkage, choke bits, secondaries etc. to see if anything was sticking and nothing was. I even turned down the idle screw all the way with no change.

Is it possible that the mixture solinoid is causing the high idle or the ignition module in the distributor after putting the motor through the ringer?
Would a stuck TPS plunger in the carb body do this?

It's not mechanical, no vacuum leaks either... more of a computer issue...
I suspect it will be back to normal come lunch time, just curious as to what may cause this.

BTW I managed to go 62 miles yesterday on 3.2 gallons of gas with extremely light driving, 19.3mpg is pretty good for 80's technology :D
 

pencero

Royal Smart Person
Feb 20, 2008
1,466
25
38
Ind.
Wow that is very good mileage! Where do you buy your gas if I may ask? When I come from Indiana I always try so hard not to buy gas there bc of the 'blend' bs is reallllllly bad in my cars who has the purest gas? Dont tell me you've been putting that 85/15 bs in your 442 now! I know youre an enthusiast so i doubt it
 

ERIC87442

G-Body Guru
Jul 18, 2009
615
0
16
Monroe, Wisconsin
Is it possible its going back to open loop? Possibly an o2 sensor problem dont hold me too that though. I dont know if the tps would have that effect on the idle?

Or maybe a bad coolant temp sensor?
 

69hurstolds

Geezer
Supporting Member
Jan 2, 2006
8,089
17,299
113
Another issue, albeit very unlikely, is the primary metering rods were hanging up. When my then-wife wanted a new Monte Carlo SS in 1986, we traded her car in for one and within the first week that thing would abruptly just idle up and stay that way, about 1100 or 1200 rpm. You could go 30 mph at idle down the road! The TSB said to remove the burrs off the primary metering rods to fix it. They simply replaced the whole carb.

Again, just throwing it out there.
 

88hurstolds

Royal Smart Person
Jun 24, 2008
1,747
650
113
I suspected it to be the primary metering rods being held up since the choke bits were not holding anything open however I still could not move the throttle down when I turned the idle screw all the way down, perhaps the primary butterflys are loose and hangin up.
The choke on this carb is junk and it's not the right carb for this motor anyways, time to rebuild and install the correct 009 carb.
 

KmK442

Apprentice
Aug 29, 2012
65
2
0
i currently have the same issue with my 85 442, but it has a reman champion carb, which im going to rebuild the quadrajet, and i beleive the temp sensor is shot, i already adjusted the fast idle, to no effect,it goes back to normal, sometimes, when i fiddle with the kickdown cable, but besides that, i will replace the temp sensor some time in the next couple of weeks after wedding and such,see if it is that , the gauge only works some times,, but i tested the gauge, its fine, ill also be adjusting the linkage and shift points then to.
 

Attachments

  • IMAG0046.jpg
    IMAG0046.jpg
    1 MB · Views: 906
  • IMAG0047.jpg
    IMAG0047.jpg
    1.4 MB · Views: 902

88hurstolds

Royal Smart Person
Jun 24, 2008
1,747
650
113
Dam idle was acting up again tonight, this time I just turned off the car and it would be fine until I reached 1100 RPM and it stuck like cruise control (which has been completely gutted).

I did this a few times before I had a eureka moment when I ever so slightly touched the A/C slider and moved it an 1/8" to the left out of the Defrost setting.

Found out the Idle Load Compensator Solinoid was kicking on at the oddest times, not sure why... I've never experienced this before.

It would kick on namely after heavy driving if the A/C control was in Defrost.

Does the defrost use the A/C compressor?

The same effect happens when the A/C Max setting is engaged, even though the system isn't charged, which is expected.
 

techg8

Master Mechanic
Feb 29, 2012
475
342
63
yes the ac compressor comes on for defrost sometimes. It can be used as a dryer for the defroster air. the evaporator core sucks the moisture out of the air prior to the heater core heating it.
 

88hurstolds

Royal Smart Person
Jun 24, 2008
1,747
650
113
That's what I thought, never noticed it on my 87 442 or 83 Hurst Olds before and they're bone stock, my other 85 442 has yet to see the road and I've never owned any other Gbodies that weren't molested in someway under the hood.
 
Status
Not open for further replies.

GBodyForum is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to amazon.com. Amazon, the Amazon logo, AmazonSupply, and the AmazonSupply logo are trademarks of Amazon.com, Inc. or its affiliates.

Please support GBodyForum Sponsors

Classic Truck Consoles Dixie Restoration Depot UMI Performance

Contact [email protected] for info on becoming a sponsor