All day yesterday I was working on the car trying to figure out why it decided to idle extremely rough when in idle, just out of the blue!
It acts like there is a vacuum leak somewhere but I cannot find any. I've changed my plugs, no change. I reset all of the engine timing, no change. Inside of carb is fine.
I just don't know what else to do! I can't even idle the car at a low RPM anymore because after revving the engine then letting the pedal go, the engine slows down and nearly stalls, but it saves itself and raised the RPM back up. During this time the engine shakes violently. After it raises the RPM back up, it fluctuates between the high and low RPMs every few seconds.
Any ideas everyone?
take a can of starting fluid and spray around your vaccum lines this will make the rpms go up where there is a leak..check your disty and maybe your carb float is sticking.. happened to me once
I was thinking that the float might have been sticking which is why I took the top of the carb off. It's doing just fine. The distributor is fine as well unless it's the cap and rotor, which I can't replace until the 20th when I get paid.
Hello Dave1987,
Does your Pinto have A/C?
The doors that move on a A/C equipped Pinto are actuated by vacume.
Since the weather has been getting colder have U move the selector from "SAY?" defrost to heat?
Maybe the door is stuck and creating a leak.
From Pintony
Quote from: dave1957 on October 12, 2007, 11:08:48 AM
take a can of starting fluid and spray around your vaccum lines this will make the rpms go up where there is a leak..
NO!! - NO!! - NO!! - NO!! - NO!! - NO!! - NO!! - NO!! - NO!!
DO NOT USE STARTING FLUID FOR THAT.
ONLY use the junk non-flammable brake clean for that! (the ONLY thing that stuff IS good for)
All you need to do is temporally block the vac leak, NOT set the car on fire.
Bill
How does non-flammable brake cleaner detect or seal a leak temporarily?
From what I gathered, I was use to use starting fluid so the engine would speed up if the fluid were to get into the combustion chamber. That would only work when detecting a leak around the intake manifold though, correct?
Quote from: dave1987 on October 12, 2007, 11:51:24 AM
How does non-flammable brake cleaner detect or seal a leak temporarily?
From what I gathered, I was use to use starting fluid so the engine would speed up if the fluid were to get into the combustion chamber. That would only work when detecting a leak around the intake manifold though, correct?
Quote from: 77turbopinto on October 12, 2007, 11:47:31 AM
...All you need to do is temporally block the vac leak...
All you need to do is test for a leak. If it runs different when you spray, you have a leak.
Just by pluging the leak, for a second or two, will make an engine with a vac leak run differently.
It does not take a lot of vapors built up in the engine bay to ignite by a hot manifold or stray spark.
Bill
OK Bill,
My opinion on starting fluid is that it burns so fast that the chance of fire is slim at best.
You MAY get a HOT SHAVE... ;D
Using carb cleaner is more dangerous as it burns a bit slower and can saturate.
I'm not sure it is possible to make a "PUDDLE" of starting fluid.
I think either could be used in very short bursts. Taking the proper pre-CAUTIONS.
1. Like having an extinguisher handy.
2. Doing this outside so fumes do not build up.
3. Safety goggles.
From Pintony
maybe starting fluid isn't the best choice..but i have never seen a pinto catch on fire.lol non flammable brake clean works great for killing bees hornets and wasps
Tony:
#4: Have your phone out with '91' dialed.
Bill
have you looked at the control module. most part stores can test it for free!
I've always been told to take an UNLIT propane torch and run them around the vac lines and carb base to detect vacuum leaks. Or you could unhook all the lines and plug the ports on the intake and mark where they all go. The only ones you REALLY need anyway is the one to the automatic transmission, if quipped, and the distributor and to the power brakes also if equipped. Bad gas will make it idle bad too. Timing BELT might have jumped too.
If you use your hand and partially cover the air horn of your carb., and if you have a vacuum leak, it will cause the engine to smooth out and idle higher. If no leak is present, it will idle down or stall. My 78 has a bad power break booster and idles kinda rough until I push on brake pedal, then it idles a little smoother. As our Pintos age, these boosters will go bad eventually, and alot of people forget these are in fact operated by vacuum. Just a thought.
You should never use a flammable product to test for a vacume leak,its not necessary.All we ever used was a spray bottle filled with water.If you have a leak engine rs will drop letting you know you found it,it wont hurt the motor,wont burn,and it wont harm the motors finish.And because most bottles can be set to stream you can more accurately pinpoint your leak.An old mechanics trick I learned from an old mechanic.
Figured out my problem. The car just needed a real good tune up. :)
It has started again. slow then fast idle. I have to really crank up the fuel/air mixture and the curb idle to get the thing to continue running, and even then it still idles abnormally. I'm starting to think it is the distributer or the ignition control module. Pulling the boot on plug #1 doesn't change the performance, just as it did before. Anything else?
Check for a vacuum leak on the underside of the #1 runnerYou may have a gasget sucked in...If not this then put a vacuum gauge to it,that will tell you where to look,Ignition carburation etc.
Alrighty. partially covering the air horn with my hand helps the car tremendously, so I must have an air leak.
Could the carb just be worn out after so much time and just need replaced???
My 76 didnt have an idle problem really (tho i think the idle mixture adjustment was set to compensate) but it did have an intake leak around cylinder #3 a few years back. It was the factory intake gasket and all those years and all that engine heat just did that gasket in i guess. Id be looking for an intake leak on something that bad. The only other thing i can think of that would leak that bad would be a brake booster if it has power brakes, or a leak from one of the vacuum ports on the back of the engine near the firewall. Could be the modulator or the line running to it if its an automatic. I dont really think its that tho.
The car doesn't have power brakes, nor is it automatic, so I don't think it is either of those. Perhaps the intake manifold gasket itself? The engine was rebuilt two years ago and all the gaskets seals and plugs were replaced though, so I'm doubting that could be but you never know!
Tomorrow I am taking off the entire intake manifold to look it over.
I removed the EGR valve today and cut a block-off plate for it from some 1/4" thick aluminum sheet metal my dad had lying around. For now I have been driving the car with that damn EGR tube from the exhaust manifold open, and the car sounds like a tractor! :cheesy_n: Tomorrow I am taking that tube off, since I've sprayed some liquid wrench on the joint to loosen it up from all the rust.
Hopefully tomorrow I will have found the source of the leak, have it fixed and be driving a good running car again.
How about the carb- EGR spacer- manifold gasketes?
Steve
Could the vacuum advance be leaking? Try pulling the line off and plugging it at the intake/carburetor. Also check the carburetor screws, carburetor mounting nuts, and the carburetor adaptor plate under the carb. Check the PCV hose above and below the valve, and the valve itself. Make sure it rattles when you shake it. It could be a pcv thing easily because alot of vacuum goes thru that.
I initially suspected the mounting hardware and adapter plate, but it all checked out to be tight, even with new seals.
For now it is working fine again. I flipped my EGR block-off plate around and put a new gasket on so I believe that was my source of it, considering the orignal EGR valve base broke around one of the mounting holes, which could have been my cause all along.
I can't seem to get my choke adjusted so it will warm the car up when the gas pedal is pressed down, then the car started. Do i just need to turn the choke fast idle cam screw in more?