Lately the weathers been near 100 in St Louis,and I noticed my idle drops so low after running for a while,that the oil pressure drops to nearly 20 psi.And it starts to die. Where should I start,the pcv valve comes out of the hose it plugs into sometimes. Maybe the egr? Or the distributor or hoses to it?
Is the choke opening all the way after its warm?
An this missouri weather sucks right now. LOL
It sure does ill check the choke tommorow its going to be super hot again :(
Are you running the A/C?
Do you know if the engine is running too hot?
Does yours have an idle speed solenoid or compensator? (Used with A/C)
Is the timing okay?
I seem to have a variable idle on my 78 also. Sometimes high sometimes low. There is a cryptic confusing procedure in my manual for 'correctly' setting the idle speed but have not followed it yet.
I finally adjusted mine to have minimum of 900, as the valve guides are worn.
No the ac hasnt worked since I bought it 24 years ago :(. I think the guides are a little worn on mine too the vacuum is sort of shaky until it revs a little so I usually keep mine idled a little bit higher,maybe I have it set too low I did lower it some.
In a little while Im going to go somewhere then I can check if t he choke is opening right,sometimes that little rod does fall out of the choke,it hasnt happened for a while but I better take a look. I remember reading one time there should be a ported vacuum for hot idle I think it was. A pvs nd maybe it went to the distributor? So much is just disconnected in my engine. It doesnt have a choke pull off anymore the diaphragm went bad I found one for a chevette that fit but it was too thin and stretched.
Just remove the air cleaner lid and make sure the choke is wide open and held open securely (not floppy).
Make sure all your vac ports are sealed (no leaks), especially the big tree at the back of the intake.
The choke pulloff diaphragm come with the carb kit. I remember changing mine before when i did the carb.
If your choke rod falls out, it might be missing one of the plastic retainers.
My 78 gets manifold vac, as hooked up fromthe factory. Actually, the way all the vac lines are hooked up seems to contradict my haynes manual.
All of my vac hoses are original and never moved about.
I think the idea with the vacuum pvs was to advance the timing when it got real hot. The distributor has two diaphragms I think one for advance and one for retard. I always remember the vacuum came from the intake to one side on the distributor at least but I thought it should get venturi vacuum. Not like I know which side on the distriubutor was advance and which side was retard though anyway :)
Im really feeling like its just when the engine gets really hot,it doesnt happen so much when the weather isnt like this.
What year and engine do you have?
I have heard of the dual diaphragm distys but my 78 has a single.
For this reason, mine is hooked up all differently. However, a TVS for hot advance makes sense. My Olds had a switch that would switch from ported vac to manifold vac to the disty when 210 was hit (too hot for me!)
I disabled that and ran straight manifold vac to the disty.
Check to make sure your engine is keeping its cool with a infrared thermometer or accurate temp gauge.
From what I remember when I was in Houston in June or July of 2000 it can be just a little worse for heat and humidity than St Louis and thats saying a lot lol. So I suppose you know about driving cars in that type of weather.
Mines a 1978 2.3 I cant really see well enough to tell if the dist has 2 vacuum hoses or one.Maybe I didnt try hard enough,it could be just one though. Maybe the dual diaphragm one was cali ?
My little car has seem more than its fair share driving in 100*+ temps...
My mom has driven it in temps up to 116* in 1980. :nocool:
It is possible your car could have cali emissions or that DD disty was added mid year down the line. It is part of emission control. Get a flashlight and take a look down there for an extra hose to the disty.
I wonder if there is any ID on the door jamb sticker that would confirm as being a cali car??
If I can see in there good to tell if its a dual diaphragm or not I will