Ruff idle

[TriktoutmarK]

I have a 1987 Mark VII and every once and a while it dies. I'll just be sitting at a stop and the engine will start to idle ruff. It'll almost die then it'll dump gas in and then it will rev up. Then it will do that over and over again and sometimes it doesn't just almost die, it does die. It hasn't been a big problem, but it's annoying. I haven't done anything to engine. It's not like I put a new cam on it or anything. Does anyone know what my problem might be?

[LSC-GT]

Clean out your idle air bypass. Take the sir tube off, look into the throttle body and on the right wall there is a hole. With the car running, get the TB cleaner and spray away into the little hole. There is a valve in there that lets enough air through to keep idle. Spray enough to keep the car from dying. And clean out the TB while you are at it.

[pro-five-oh]

You might also want to remove the idle air bypass (2 bolts) and clean it out with the same cleaner. Mine was caked up with junk after 110k and cleaning it did the trick!

[WILLIAM SHIREY]

My '85 Mark has the same symptons as TriktoutmarK. I looked in the factory book and all I see is what is called a fresh air tube to the EGR. It doesn't mention an idle air bypass, although it shows one for the mustang. I have replaced one on a Chevy Astrovan, but it's been a while. Pro-five-oh, can you describe where the idle air bypass is as best you can? How accessible is it? LSC-GT, are you talking about the same thing as Pro-five-oh? How do you remove the sir (what does that stand for?) tube? Is it in the throttle body itself?
Thanks.

[Charlie]

Willam, Doesn't your 85 have CFI (central fuel injection) These guys all have Secqunetial Fuel Injection. So there directions will not help you out because your system is so different from theres. I don't think the CFI has a IAB. If you are having problems when cold. I beleve it is probley because your enrichment thermostat for the CFI is getting weak. Remove your air cleaner pan and look on the pasanger side of the throttel body. You should see a round, black, plastic thing. It looks just like a choke thermostat on a carbed car. There are 3 screws holding it on. Lossen these screws and rotate the black pice clock wise (purty sure) just a liittle. there should be some marks on the top so that you can see how far you went. If not make some. Do not turn it more than a quarter inch. That is a lot just a little makes a big difference. This will make your car think its colder outside and should hold you idle speed up which will keep it from doing what you said. Good Luck, Charlie

[pro-five-oh]

William, I don't think the CFI cars have an IAB. There is a throttle actuator/sensor that does the same thing as the IAB...albeit very poorly.

I'll have to look it up and get back to ya.

[WILLIAM SHIREY]

I checked the wiring book for the Mark last night and the EEC controls a EGR control valve using a pressure and vent EGR solenoid valves. The valve body and its position sensor is located behind the throttle body near firewall. Haven't checked out what's actually there. If it's like the Astrovan, the valve must bolt on somehow. Once it's removed, then I can check for carbon deposits and see if the valve can move freely. I'm not sure how the valve operates with two solenoids, the Astro uses just one. Any help out there in Lincoln-land?

[pro-five-oh]

William and Charlie,

The CFI equivalent to the IAB is the "throttle kicker solenoid" (TKS) and its actuator (TKA). I know that EEC-II and EEC-III had it, so here's what you look for.

The TKA and TKS are controlled by the computer and control the idle speed of the motor with vacuum assist. The TKA is a round shaped thingie with a vacuum line on it. The TKA is real close to the throttle cable. Hopefully the CFI Marks have this thing too.

[Charlie]

Pro-Five -OH I know the thing you mean. It is in the driver side of the throttel body. It holds open the throttel slightly whenever the computer tell it to. It is respossible for your idle speed. It looks a lot like one of those things that carbed cars had on them to keep the idle speed up when the AC is on. Only this one has a vaccume hose going to it. When they go bad they usually either stick and make the car idle to high continusually or the just don't come on and the car idles to slow under load like when the AC is on.Willim if you think yours is sticky try to move it by hand and use a little WD 40 on the shaft. I have had to lube mine up, but,mine was just causing the car to idle to fast all the time. There is a adjustment on this part so that you can adjust your idle speed. Maybe you shuld try turning it a little the correct way to set you idle speed up a little. If you car was idleing to slow it would do what you decribe because the computer would sense this and allow this thing to push the throttel open more. Than the computer would return the car to it's normal idle speed which is to slow so it would allow this thing to the throttel open agin and so on.... You could also be on the right track by looking at ehe EGR if it was stuck open it would act like a vaccume leak. Try unhooking the hose to the throttrel kicker solinoid thing. Andcheck you idle speedwith it unhooked.If it is to slow turn it up a bit. Unhook your battery for 10 minutes. Plug the hose back in and see what happens. Sorry for the long rambeling post.

[WILLIAM SHIREY]

The '85 has an EGR control valve with a cooler? that mounts to the manifold. If the valve or intake manifold is dirty, would this not affect idle? Are new ones still available?
I'll also check the idle controls as well!
Thanks guys for your advice.

[Charlie]

Yes, it's strange but, I own 2 84 Mark VII. the LSC one has a little water hose going to it from the heter hose line. The standard model has this hose blocked off. I would say it is more of a warm up thing than a cooler. Whatever. yes if the EGR was acting up it could affect your idle. I am sorry I can not help you futher. I have never had this problem and I only know how to fix things I've had trouble with before and have learned by experance.