Erratic Idle - My Problem Solved

ChrisKMN

Registered User
To anyone with an erratic idle issue,

Writing this to give a hand to other SC/XR7 owners that might be experiencing a "difficult to diagnose" erratic idle issue.

I have a '91 SC 5-Speed with 130k on the motor/car. Early August she finally blew the factory head gasket, passenger side rear breach, which wasn't so bad as it needed some other work done as well. Motor mounts, exhaust manifold gaskets, cats, plugs, ect. I also had the occasional CEL coming on, so I figured there might be a sensor or two that needed to be replaced. So I did the top-end rebuild replacing the following.

-All gaskets from the heads up
-Motor Mounts
-Catalytic Converters
-O2 Sensors
-Upper Control Arms
-IAC Valve
-Injector rebuild/reseal(seals and hat)
-180 Thermostat
-Plugs/Wires
-Belts

Prior to when the gasket blew, it did have a slightly low idle, and would especially drop low when I would initially turn on the A/C, but in no way idled erratic. Occasionally I would notice a quick on/off CEL, but would never stay on longer than a 45 seconds.

After the rebuild, I started it up and she purred. Everything seemed normal for about the first half hour of running time. So I took it out for the first drive and about 5 mins into it, I noticed the CEL come on. Shortly after, the motor started to idle low a couple times almost to a stall at a stop sign, or low speed turn. So I brought it back to take a look and it only got worse. Erratic idle started. It would lope from about 1100 rpm to an almost stall back to 1100. Looking under the hood, I would jump the throttle a little and it would even out for 15sec or so, than start to lope again, several time almost coming to a stall. When I would turn on the A/C, it would help, but not completely take it away. Also the drag on the motor from the power steering being turned would drag it down quit a bit, and if it was in the low of a lope, stall it. Keep in mind that when driving or giving throttle, it seemed to run well but not 100%. During this I also noticed it seemed to be running a little hot considering the 180 stat, would kick the fan on at the end of "M". As the evening progressed the lope only seemed to get worse. The last time I drove it to get some gas(about 5min from home), its stalled at almost every stop. I would have to double foot the clutch and gas to keep it going. That night I ran the codes and the first one up was 565(Canister Purge Circuit Failure). I really didn't think much of it as several more came up, but it was getting late and I was finished for the night, pretty frustrated.

The next day after work, it was time to go at it again. During the day, I read the SCCOA forums when I could looking up all terms of low, poor, erratic idle I could. Most all focused on vacuum leaks and the TPS/IAC system, which makes total sense. But I was sure that I did not have any vacuum leaks from hoses or poor assembly. The IAC was new and I was going to check the TPS that eve. None that I read mentioned the canister purge valve being the culprit of the erratic idle. Only one or two out of the many I read even mentioned it as a code they needed check into, and one mentioned replacing it but that it did nothing solve the problem. So I go to work that night and just out of the side of my head, remembering that it was the first code coming up, think I should at least take a look at Canister Purge Valve. To my surprise the first thing I see is the rubber line off the valve going to the canister is twisted. I start to think there might be something with this. So I go to pull the line and valve(best way I found was to pull the lower air box housing, remove the air silencer(which meet the "land of the misfit parts"), and stick my hand through the air box inlet hole). I get it unplugged noticing it's somewhat corroded. Take a look at the line, its twisted and collapsed. So I proceed to pull the valve off the line going to the engine. To my total surprise, this tar black oil/fuel mixture starts pouring out. I would say 4-7 tablespoons. It was nasty stuff, made my hands COMPLETELY black. After it stops draining, I decided to see what else was in the line by sucking on it. I don't necessarily recommend this, but it's what I did. BTW, tasted like S%@T. I must have gotten another 2-3 tablespoons of this liquid out of the line. Once it clears I realize this line goes right to the PCV line in the back of the motor. After clearing the line, I turn my attention to the purge valve itself. The "to engine(small arrow pointing)" side is plugged with this tar. I proceed to clean the valve though both tubes(carb cleaner). At first it's plugged, but after several soaks of the cleaner, I can start to suck air through it. So I let is soak for bit more, clean the terminals and plug, then re-attach the unit with new vacuum lines on both ends. I also replace the rubber portion of line from the tank to canister to be on the safe side. Lastly, I go get a new PCV valve to ensure that it's not causing this issue. Re-assemble the air box and go to start it up. Problem Solved!!!! Not one lope, idled perfectly smooth! I go take it for a drive, its running cooler(mid O), has much better responsiveness, and more power. CEL has not come on since. I really couldn't believe it, but am a believer now.

I apologize this post is so long, but I feel more details the better when it comes to giving this type of information. If anyone is having erratic idle issues and can't seem to find the problem, it might be worth taking a look at the canister purge valve/lines. If this helps just one other SC/XR7 owner, than it's done it's job. Any questions, let me know.
Good Luck!
Chris
 
When I've seen issues, it was usually related to a car that had been wrecked in the front/pass side and the eval components there were ignored during repairs.

The good news is that in most cases a code will throw a hint.
 
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I had a problem with the purge solenoid (which was locked up) and the lines (which were rotted to nothing). But it never really had much of an idle problem. It idled a little better after fixing it, I think, but not much. The computer did eventually throw a code for that system. I was able to replace everything from the top and underneath without removing the bumper or air silencer.

By the way, the air silencer also helps to protect your engine against hydrolocking if you go in a deep puddle.
 
Hi! Why must I have all the problems concentrated into my car? Sounds exactly like mine...I know where to look now, thanks!:)
 
Hi, me again, I am sorry I can't find what is a canister, asked to english friends here but I guess they are not mecanic entousiasts...So I am under the bonnet and try to find...I guess you are talking about all the pipes connected to pcv valves...I just want to cry when I see this engine now...can you tell me where is the purge? There is a valve like tire valve near the coil but I guess it is not that...I can't believe how little space there is around the engine.:(
 
Hi, me again, I am sorry I can't find what is a canister, asked to english friends here but I guess they are not mecanic entousiasts...So I am under the bonnet and try to find...I guess you are talking about all the pipes connected to pcv valves...I just want to cry when I see this engine now...can you tell me where is the purge? There is a valve like tire valve near the coil but I guess it is not that...I can't believe how little space there is around the engine.:(

Might be better instead of saying canister to say container? It looks very similar to a coffee can and it sits behind and below the passenger side headlight. If the fog lamp is removed it can be seen from there, but it cannot be reached from there. To get to the container you must get to it from the engine bay.

As mentioned above where the engine air filter box sits it is below that. Remove the air box and the plastic below it and canister is there.

Once I get home tonight I will try to take some pictures if none have been posted by then.

French was over 20 years ago, but I believe Canister is boyte en fer
 
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You don't even need to remove anything to see it. Just peek under the car and behind the bumper cover, but in front of the air filter housing. You can see a black plastic rectangular box.
 
Hi, me again, I am sorry I can't find what is a canister, asked to english friends here but I guess they are not mecanic entousiasts- can you tell me where is the purge? There is a valve like tire valve near the coil but I guess it is not that...I can't believe how little space there is around the engine.:(

As noted, if you get under the front of the car you can see it from below. You can also remove the black plastic inner fender liner for the passenger side front wheel. It sits between the frame rail and the white plastic intake silencer.

I believe 'vapor canister' is the correct reference.

It looks like this, out of the car:
2


The purge valve looks like this:
2


Attached photo is from underneath a 1990 SC showing it installed. The white air silencer is on the left, the canister is indicated by the red arrow, and the power steering cooler is on the lower right.
 

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Good pics, KMT.

One thing that is hard to see in the purge valve picture is that there is a white plastic barbed fitting on the top. There are hoses on each end. Those hoses were totally crumbled on my car. Fuel vapor is very hard on rubber.
 
:)

Two decades in use makes it that much more of a problem as well. I'd wonder if the fuel today takes a larger toll.

Ken

Yes, you might say everyone got their money's worth from those hoses. 20 years' service for $0.50 or so is not too bad. :)
 
Thank you sooooo much! I will try tomorrow, I don't know if french cars even have that kind of boxes, I never saw a pcv valve before either, just a rubber hose going to the airfilter box usually...
It might be why I could not find a translation, canister works for beers too? ;)
I was looking totally in the wrong place, at least it is reachable!
Good because my car stall all the time now, hope it will help!I
 
Hello America! So I Finally found my vapor canister, the hoses looks all right? But it was disconnected!!!
At the same time, I changed my coil, I had a brand new motorcraft one but made in china, and since I changed it sometimes the engine start and stop directly, so I put my old one back!
Seems better but did not try the car yet.
:)
Thanks to you all!

Guillaume
 
Well, I tryed the car, seemed to work well, did stall once...On my way back I WOT it...
Now it seems to run on 3 cylinders with greassy smoke...
I will see tomorrow but it might be the end of a dream...
:(
 
Greasy smoke ?? What color is it ?
Black = Fuel
Blue = Oil ( valve stem seals, bad piston rings )
White = Coolant ( head gasket / early morning condensation )

Ive never seen a Motorcraft part made in China ... weird. :eek:

Misfire .. you sure you hooked the plug wires in the correct order on the Coil ?

Dies .. check for vacuum leaks, check the Idle air control valve.


- Dan
 
Hi, thanks Dan, greassy smoke under the bonnet and during the night, it smells like burnt oil... Today I tryed to start it, perfect! Crazy car! I will drive it later and see...

Thank you

Guillaume
 
Greasy smoke ?? What color is it ?
Black = Fuel
Blue = Oil ( valve stem seals, bad piston rings )
White = Coolant ( head gasket / early morning condensation )

Ive never seen a Motorcraft part made in China ... weird. :eek:

Misfire .. you sure you hooked the plug wires in the correct order on the Coil ?

Dies .. check for vacuum leaks, check the Idle air control valve.


- Dan

And yes the motorcraft coil definitively had a made in china sticker on:(
I took it away else I would have sent a picture...
Motorcraft is also a simple sticker...must have come from Rockauto but not sure...
 
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