Rough Idle

[pipeline010]

*********SOLVED!! JUMP TO THE END IF YOU WANT THE FIX THAT WORKED FOR ME ********


back at it again....

many of you may remember my stalling issues last month. well, it seemed that was caused by a faulty ig. module or diz (or wires) not detonating the cylinders well enough, flooding, then stalling with an inability to start for a while.

Put in the pertronix all in one (no external module), pushed it to 9/10 advanced with vac @12 and it ran absolutely beautifully again, like it was new....for 3 days.

ISSUES:
Now it's idling extremely rough, sputtering. It's got a ton of speed off the line, absolutely no noticeable hiccups at speed. Yet if I lay off the throttle and try to coast I will immediately hear sputtering (almost, not quite, backfiring). Coming to a stop it threatens stall, idles and shakes very rough, sputtering. The engine bay seems exceptionally warm just from road tests around the block as well.

Also, I could be crazy but small black flake(s) from exhaust? Only saw one and it crumbled in my hand immediately.

INFO:
302 v8 RV CAM / original RAT
pertronix ii coil +diz (new) electronic
carburetor - 2100 autolite/motorcraft - recently rebuilt by me.
new brake booster drumx4

TESTS:
-rolled back timing (ccw) by ear, no change to sputtering/idle. brought it back to where it was.
-vacuum gauge bouncing fast at 20-22.
-adjusted carb mix down and idle up.
-all plugs pulled to verify hiccup in engine all fine. checked spark against engine block all fine, spark YELLOW.
-fuel filter against carb removed and blown out, no debris.

IDEAS:
-in-line fuel filter crapping out? NOTE: entire fuel system is very new.
-power to new pertronix coil isn't high enough due to crappy old wiring (12v minimum?). no idea how to test this, I have no ammeter.
-bad coil?
-head gasket blown!?

thanks for help. 30 days ago this truck literally ran like it was brand freaking new and did again last week for 3 days. frustration level dangerous.

 

[blubuckaroo]

-vacuum gauge bouncing fast at 20-22.

At what RPM was this vacuum?

 

[pipeline010]

that was at the original idle setting (before i started troubleshooting).
RPM was at 800 according to timing light (no tach) but sounded to me to be higher. That may have been engine noise tho; from the rough idling.

 

[pipeline010]

Here's a post from summit racing regarding the coil i installed. This is a little bit of chinese to me, so does this seem like it would have caused my issue and, if so, what the heck is he talking about and how do i do it?

"The install needed for my 1968 Mustang took a not too well published turn.

After reading the install procedures it became apparent that some cars have a "Pink Resister Wire" that runs from the ignition switch to the firewall UNDER THE DASHBOARD that controls voltage to the positive pole on the coil. The voltage drops from 12V down to as low as 4.5V after the engine starts which of course the Pertronix system doesn't like at all.

What has always been a relatively simple Pertronix install became a task and a half. After hours of making futile attempts to get access to the PINK wire without dismantling my entire dashboard I surrendered and starting looking for an alternate answer. It took a few more hours of intensive web browsing but I finally hit on a reasonable answer to the problem:
A 12V SPST Relay wired to use the 12V supplied by ignition to trip the relay and use the relay to supply a clean 12V to the positive pole on the Coil.

Strategic placement of the Relay and extra wiring kept the engine compartment very stock looking."

 

[Joe473]

that was at the original idle setting (before i started troubleshooting).
RPM was at 800 according to timing light (no tach) but sounded to me to be higher. That may have been engine noise tho; from the rough idling.

Do a leakdown test and make sure the engine is healthy before replacing a bunch of parts.

On the coil and pertronix what coil does it have? Stock or pertronix? and where did you power the pertronix from? Check voltage running on pertronix. It should not go through resistor wire.

What carb are you running? Did you set float levels? Did you check to be sure power valve or power valve gasket isnt leaking at idle?

Good luck.

Sent from my SM-G960U using Tapatalk

 

[pipeline010]

Do a leakdown test and make sure the engine is healthy before replacing a bunch of parts.

On the coil and pertronix what coil does it have? Stock or pertronix? and where did you power the pertronix from? Check voltage running on pertronix. It should not go through resistor wire.

What carb are you running? Did you set float levels? Did you check to be sure power valve or power valve gasket isnt leaking at idle?

Good luck.

Sent from my SM-G960U using Tapatalk

-many tests conducted before replacement of ignition system. zeroed in an issue between module and distributor and I replaced both as the layout of the module wiring was rotten and unsafe.

-pertronix 2 billet plugnplay, pertronix ii coil. I was just reading about this as well, gonna make sure it wasn't installed with the resisted wire.

-carb listed above, autolite 2100. I set float levels, flushed and blew out system, and all gaskets were replaced.

 

[DirtDonk]

I may be remembering the wrong thread, but I thought you bypassed the resistor wire, or used an existing 12v wire?

If you are powering your ignition from the factory Green w/red stripe wire, you are using the resistor wire.
Unless you changed something under the dash to bypass the Pink section.

Paul

 

[pipeline010]

Can't be sure until I get a meter on it in the morning, but it appears as if I'm using the same stock wire that was running the duralast coil.

I mean, I AM running that same wire, the only question is if it had ever been made unresisted. I don't know much about the previous coil, but I think they weren't designed to handle a 12v constant.

Thanks folks, I think this was it. Now I gotta test then run a parallel line up to my ignition.

 

[DirtDonk]

Might be able to verify this theory by using a jumper wire straight from the battery to the coil's positive post (temporarily only), or to the distributor's Red wire to see if that helps.
If you are already running a separate 12v wire to the distributor, and the resistor wire is only for the coil, then the ignition should work fine I would think. But if Pertronix says this coil can handle full voltage, the advantage is to use it.

What's really the question here is whether the coil prefers lower voltage or not. The Ignitor in the distributor very likely requires the full 12v to be happy, but you'll need to verify which model it is as well.

In my experience the standard Ignitors don't like lower voltage. Not sure about the Ignitor II and III models, which may be able to get away with it.
Pertronix is sometimes confusing, but they do have their recommendations as to whether or not to run a resistor to the coil, even if you're running full 12v to the distributor module.

Paul

 

[pipeline010]

According to the install instructions they say to remove any resistor wires running to the coil. Seems the Mustang guys have lots of threads on the subject, altho some people have had issues with the old wiring and other people haven't had any issues at all.

https://www.wildhorses4x4.com/product/Pertronix_Billet_Distributor/Bronco_Performance_Ignition

The pertronix diz has two wires, each to the positive and negative on the coil. the positive on the coil also connects to that original resistor wire,

When you say a "jumper" wire you simply mean an unresisted (12/14 guage) wire direct from battery to coil? Nothing else right? I understand the need for this to be temporary, just want to be sure I shouldn't be adding any other items here for the test.

Thanks Paul.

 

[Skytrooper15]

It sounds like a carburetor problem as in a choke not adjusted right.One easy way to check this is to loosen all three screws on the choke spring housing and set the choke to wide open and then tighten them back up.Do this after the engine has been warmed up so it will start more easy.If this fixes the problem adjust the choke back to where it closes on a cold engine.It sounds like a fuel problem because of the black soot in the tailpipe and it is so consistent.You should be able to smell a strong gas odor at idle at the tailpipe if its a carb problem.

 

[DirtDonk]

According to the install instructions they say to remove any resistor wires running to the coil.

Yep, which it sounds like you did not. Correct?
Too bad they don't say what to do if you leave the resistor wire, like they do in the Ignitor conversion instructions.
However, maybe that's because whichever trigger mechanism is in your new distributor is not as finicky about it. They only say "for best results" to remove the resistor. So perhaps this particular unit can run on less. But I wonder just how much less is acceptable?
I should search that out so I know. There is usually a range specified, and if your particular resistor wire is lowering the voltage too much, it might be causing trouble.
Easy to check though, with the engine running for a few minutes, take a voltage reading at the positive side of the coil and report what it reads.

If the voltage is sufficient, it might come back to the other possible issues, such as the choke adjustment that Skytropper was talking about.

The pertronix diz has two wires, each to the positive and negative on the coil. the positive on the coil also connects to that original resistor wire.

That's the simple way of connecting and would work best if you always had full current capability, as would be the case if you remove/replace/bypass the resistor wire.

When you say a "jumper" wire you simply mean an unresisted (12/14 guage) wire direct from battery to coil? Nothing else right? I understand the need for this to be temporary, just want to be sure I shouldn't be adding any other items here for the test.

Correct. Just a temporary wire to supply a more than adequate current flow at full system voltage to the ignition. A 12ga wire is likely a little overkill, but would not harm anything temporarily so if that's what you have handy, use it. A 14ga wire should be more than sufficient.

Remember too, that aside from the "temporary" thing, you will only be able to turn the engine off by disconnecting the jumper wire. Just turning off the key won't do it, because there will still be power to both ignition components.

Paul

 

[pipeline010]

Checked coil line with meter, I've got a bit over 12volts continuous in the coil. Whoever did the previous ignition upgrade must have upgraded that wiring.

So the problem persists. It sounds like it's somewhat misfiring, but igniton, timing, all seemingly perfect. So that brings me to fuel.

The upgraded pertronix system may have a greater fuel request than the duralast I had been using. I checked the fuel pressure with a guage and, with just the "on" key I had zero pressure. This means I don't have an electric pump, right? So I crank it a couple and see pressure at 4-5 psi. OK. So I unplug the guage and no gas comes out at all. Hmm.

Checked the choke assembly. Wasn't QUITE straight up when choke was disengaged, but nothing crazy. I adjusted it.

The main reason I don't think it's fuel is because at high rpm the truck is extremely responsive. For example, slowing down for a red light the car is sputtering, spitting, and (seemingly) missing. But if the light turns green and I'm still at say 20mph and I hit the throttle the car is extremely responsive. Absolutely no hiccups or stutters. Maybe they're there, but I don't feel any.

So compression. Could I have some stickyness in the cylinder heads? Maybe sticking only when they don't have the force of higher rpms to move them? I dumped some of that marvel mystery stuff in the oil tank, have yet to see any difference.

Anything I'm missing? Anything obvious or not so?

 

[Joe473]

Checked coil line with meter, I've got a bit over 12volts continuous in the coil. Whoever did the previous ignition upgrade must have upgraded that wiring.

So the problem persists. It sounds like it's somewhat misfiring, but igniton, timing, all seemingly perfect. So that brings me to fuel.

The upgraded pertronix system may have a greater fuel request than the duralast I had been using. I checked the fuel pressure with a guage and, with just the "on" key I had zero pressure. This means I don't have an electric pump, right? So I crank it a couple and see pressure at 4-5 psi. OK. So I unplug the guage and no gas comes out at all. Hmm.

Checked the choke assembly. Wasn't QUITE straight up when choke was disengaged, but nothing crazy. I adjusted it.

The main reason I don't think it's fuel is because at high rpm the truck is extremely responsive. For example, slowing down for a red light the car is sputtering, spitting, and (seemingly) missing. But if the light turns green and I'm still at say 20mph and I hit the throttle the car is extremely responsive. Absolutely no hiccups or stutters. Maybe they're there, but I don't feel any.

So compression. Could I have some stickyness in the cylinder heads? Maybe sticking only when they don't have the force of higher rpms to move them? I dumped some of that marvel mystery stuff in the oil tank, have yet to see any difference.

Anything I'm missing? Anything obvious or not so?

When you rebuilt the card did you replace power valve and check existing size. Before you assembled cover did you check for leaks to make sure power valve was good and gasket sealed. If it seems rich and it's not ignition miss then it's possible power valve is leaking. Gaskets supplied with kits are thin on power valve and sometimes develop leak

Sent from my SM-G960U using Tapatalk

 

[pipeline010]

Thanks for the tip Joe. I did change power valve and, at the time, seemed seated properly. I'm not ruling that out as an issue at this point I'll check anything. I still have the previous PV as well, and it seems to be fine in case I need it.

Picture time, as I'm truly out of ideas. Here's the stuff I changed recently:
(explanation in no particular order)

1. Spark Plugs - they look fine.

2. I removed the rubber fuel connector from steel to carb filter and replaced it.

3. In attaching the new brake booster I removed a vacuum hose with splitter that was near, but not attached to, this thing. It seemed that they were meant to be connected at some point, but both were simply looped. What is this thing?

4. Look. A screw hole?

5. My PCV grommet has a lot of play. No leaks tho.

 

[DirtDonk]

Checked coil line with meter, I've got a bit over 12volts continuous in the coil. Whoever did the previous ignition upgrade must have upgraded that wiring.

Maybe. Or maybe the ignition just isn't putting much load on the wire, which does not bring up it's resistance value, which does not lower the voltage.
There is a slight loss obviously, since the engine is running and the alternator is letting the system run on roughly 14.4v at that time.
So at least a 2v loss, but not enough to be due to a full resistance wire.

Only way to know for sure is to measure resistance. But that's a pain and is not indicated at this point.

So the problem persists. It sounds like it's somewhat misfiring, but ignition, timing, all seemingly perfect. So that brings me to fuel.
The upgraded pertronix system may have a greater fuel request than the duralast I had been using.

No. If anything, a better ignition puts less demand on the fuel system, since it should be burning more efficiently and effectively.
Even if it was needing more fuel at lower rpm, your system could supply it from what it sounds like, because it runs fine at higher rpm/loads where it needs more fuel.

Did you pull all the plugs and clean them and check the gap? How old are the plugs? I would gap them at .040" at least. But likely no more than .045" with our old style combustion chambers.
But clean and/or new is the way to go with plugs.

Do you have a timing light? If so then clamp it to each plug wire to see if the flashing light is erratic on any of them.
Check the resistance on the plug wires.
Check and/or replace the plugs.
Check and/or replace the cap and rotor.

Granted, this is all about the ignition at this point, and not touching on the potential fueling issues. But unless you know the full history of each part, and can verify that each one is perfect (remember, we live in a Chinese-supplied parts world...) then this is one of those times when throwing a couple of new (inexpensive) parts at a problem can go a long way.

But don't ignore the power-valve and other carb issues that Joe just mentioned either.

I checked the fuel pressure with a guage and, with just the "on" key I had zero pressure. This means I don't have an electric pump, right?

Or one that's not working well. Where did you check the pressure? This is carbureted, correct? Did you unplug a fuel line and put a gauge in it?

So I crank it a couple and see pressure at 4-5 psi.

That's correct for a carbureted engine. Which carb again?

So I unplug the guage and no gas comes out at all. Hmm.

Yeah, hmm indeed. Not that it's always going to spit at you and depends on where you're connecting the gauge. But yes, most likely it should have had at least some wetness around the area, if not a full on squirt-mess-and-dab-with-rag session.

The main reason I don't think it's fuel is because at high rpm the truck is extremely responsive. For example, slowing down for a red light the car is sputtering, spitting, and (seemingly) missing. But if the light turns green and I'm still at say 20mph and I hit the throttle the car is extremely responsive. Absolutely no hiccups or stutters. Maybe they're there, but I don't feel any.

Maybe a vacuum leak. Have you checked (again) lately?
Bad PCV valve issue? And speaking of which, where exactly do you have your PCV plumbed?
And do you have power brakes? Where is the booster plumbed to?

So compression. Could I have some stickiness in the cylinder heads? Maybe sticking only when they don't have the force of higher rpms to move them? I dumped some of that marvel mystery stuff in the oil tank, have yet to see any difference.

Always a possibility with an older engine. And not always simple compression, but a valvetrain issue that just doesn't let it burn cleanly until higher rpm where it doesn't matter.
But it would have to be pretty bad to give you spitting and sputtering on deceleration I would think.
Is it more of a popping sound when you slow down? Maybe it's just too lean.
That would give you fits at idle too.
Which could lead us back to vacuum leaks. And have you tried re-adjusting the idle/air mixture screws lately? What about timing again?
Basically just giving it a full tune-up and check?

Sorry if you just covered them. I have not been back over the full thread.

Paul

 

[DirtDonk]

Well ask and ye shall receive....;D

Thanks

Paul

 

[pipeline010]

from the ford bard website:

"a bad power valve would cause a rough idle (too rich) and rich when cruising at steady throttle."

Joe may get the chicken dinner. Heading outside to pull the carb right now.

 

[Joe473]

from the ford bard website:

"a bad power valve would cause a rough idle (too rich) and rich when cruising at steady throttle."

Joe may get the chicken dinner. Heading outside to pull the carb right now.

Check not just the power valve but the power valve gasket. Requires pulling power valve cover filling bowl with gas and making sure no dripping

Sent from my SM-G960U using Tapatalk

 

[DirtDonk]

Wow, I'd forgotten just how short some of the reach is on some plugs for our engines.
Have you ever verified that you at least have the proper plugs for your heads? Ford had a nasty habit of changing that just to mess with our minds.

The Blue Meanie thingy in your third pic is part of the timing control mechanism for distributors with dual-diaphragm advance/retard mechanisms. Not used in your case.
So you need to find and cap any vacuum lines or fittings. The looped hose is fine, and doing just that, if there is any vacuum at that point. Which there may not be.
You'll have to follow all the hoses to know where they go and cap/plug/remove any that are not needed and that can cause a future vacuum leak.

And speaking of which (timing-wise that is), where is your vacuum advance connected?
Did you connect it to full vacuum or ported vacuum? Did you re-check your timing again?

Paul