Hi, im new to these forums. I have a 74 pinto thats pretty much stock except the header. It has a very rough idle and no matter how much I turn it down it will always stick around 1500 rpms for about 5 minutes before it goes down to about 900 rpms. I Think it might be a vacuum leak. Or people have told me that the choke needs to be adjusted. I would appreciate the help. This is my first car and i Really want it to run a lil better.
UPDATE: I would like to thank every body that helped me out. I finally figured every thing out and now my pinto purrs like a kitten. I found all the vacuum leaks, removed and blocked my EGR valve. Then I realized that there was a small vacuum booster on my vacumm advance line that hooks to my carb. turns out it was on backwards and was preventing my advance from working at all. I flipped it around and itr ran so smooth. Although I had to turn my idle screw down like 5 turns. It now runs like it is supposed to. The idle is at 850.
:welcome:
Two things I would check would be the decelleration valve (located at the back of the intake manifold, next to the coolant line), and the EGR valve. If the car has EVER backfired, the decelleration valve will be toast. You can just remove the valve and plug the hole without loosing any performance. The EGR valve's diaphragm may be rotted away and causing a leak (that was my problem a couple years ago).
I hope this is of some help.
Thank you for the quik reply, ill check in the morning and post back.
Whats the best way to test my EGR valve? I know what it is and what it does just how do I test it? Ive unhooked it while its running and it makes no difference. im also haveing a lil trouble finding my deceleration valve.
Ok. I looked at a pic of the 2 decel valves and there isn't one on my car. There is a thing with two outlets on it tho, but it does not look like a decel valve, it is directly below my choke on the manifold. Its not hooked up and I tested it for vacuum leaks and found none. Also where is my EGR valve supposed to hook up to? I think I might need a vacuum diagram, the vacuum hoses are all screwed up.
Ive looked around the forums, since I don't have an automatic tranny or power breaks, the only thing I really need hooked up is the vacuum advance? I don't have a decel valve and my EGR valve works. Would it be ok to unhook and block everything off except the vacuum advance?
The valve below the choke goes to the carb base and the charcoal canister under the fender. I don't know exactly how it works, though.
Since it doesn't sound like you have a decell valve, and your EGR valve is good, try this....
Warm your car up all the way, take your air cleaner lid off and the filter out. Now make sure your choke is fully open, and put your hand over the carb. If it smooths out, then you have a vacuum leak somewhere. For mine, I replaced all of my vacuum lines (since the tubing is cheap) before replacing any valves.
If that that makes no difference, then it MIGHT be your timing.
Have you checked the plugs, cap and rotor? How about wires? I have found the Borg Warner premium silcon wires seem to last a long time without any issues. It would be the NASCAR select series of their wires for the Pinto, however the Merkur wire set is longer and makes things easier to route.
As a side note, the only way I know how to check a EGR valve for a good diaphragm is by disassembling it. I would still check for vacuum leaks by covering the throttle before taking anything off the engine, first.
Ive done what you said. It smooths out and speeds up alot. Ive replaced the plugs, wires,cap and rotor. Theres only two outlets on my carb and ones hooked up to the vacuum advance and the other is hooked to the pcv valve. Ive checked for vacuum leaks and found none. I think Im going to go buy a carb rebuild kit. I think it needs a rebuild anyway.
Yeah. I looked by my header, the car came with one. The metal tube that goes to theold exhaust manifold to the egr was just hanging there. Plugged it up and every thing is smooth. It still stick around 1500 for about 5 to seconds tho.
Did you check your intake gasket? hoses? Double check all the connections?
Someone once told me to try spraying small amounts of starter fluid (not to much, or you may start a fire), and spray small amounts around the intake mating surface. It speeds up slightly, then you have a faulty gasket.
It could even be a hairline crack in the EGR valve like I had, in which case you won't know until you go to remove it, and it breaks into two pieces.
Im just gonna remove my egr since I have a header and make a plate to bolt on to it. Can you tell me were my pvc valve is located on my 74.
right below the intake manifold, towards the front of it. Between the distributor and the block. It should have two hoses coming off of it, and the one that goes into the crank case breather hose. One of the two goes to your fender, the other to the manifold I believe. It looks like an "F", you can't miss it. :)
The 74 will only have one tube coming off the top of the pcv valve.as for the sticky throttle make sure there is a small spring on the back of the carburetor. If not, the secondary throttle plate will not close all the way when you release the throttle.
Sweet thank you for all the help, my pcv valve is good. I also removed my egr valve and made a plate that bolts on to block the holes so it doesn't have a vacuum leak. I also put a non vented oil cap on and my idle is super smooth, it runs great for having 100000 miles on it.
So it's all running great now?
Its running great it has alot more power. It still has kind of a fluctuating idle though. When I let off the gas it will stop at 1500 for about 10 or 15 seconds then drop down to about 750, then comes up to about 900 were my idle is set currently. Oh and it really only does this when its hott after being driven for about 40 minutes.
That part may be a sticky choke or butterflies. Good to hear you got the main problem fixed though!
No it runs perfect no idle problems what so ever.
Sweet! Got any pictures of your little Pony?
I will take some tomorrow in the light and post them in the your pintos section lol.