99 escort rough idle

[geers182]

My escort shakes a reasonable amount at idle, it seems to be worse in the morning (when it's a little cooler) then when i go home from work. It gets real bad when I put a load on the alternator (whether it be my fan or rear defrost, or anything). I replaced the IAC, alternator, checked for vacuum leaks, etc., and nothing has fixed this problem. Also, not sure if this is a related problem, but my fuel efficiency seems a little subpar, could this be a faulty MAF, if not, what could it be?

[Davescort97]

Have you ever changed the spark plugs or wires? The PCM sends a signal to the IAC to increase idle speed when under a load. It's expensive but you may have to put one in. But, first disconnect the negative battery terminal for 10 minutes to reset the computer. See if that helps. It could be the MAF. When it's not working the mixture goes to rich by default.

[tripletdaddy]

Definitely be sure you have good fire at each plug. So check plugs, wires and coil. Distributor cap and rotor if it has them. With a long screwdriver or mechanics stethescope, listen to each of the cylinders for one to sound different, most likely the one not firing. You will want to pull plugs to see if one looks different, most likely wet with gas. If you have a coil pack (no distributor), try switching wires on paired cylinders to see if vibration changes after trying other remedies first. Do you have any codes like for a misfire? If so, the switched wire from the coded bad cylinder will travel to the new cylinder if it is related to the wire or coil. Your coil itself my be bad to cause a misfire. That can be resistance tested, but you will need an ohms/resistance tester. Offhand, your primary will be very one or less ohms and the secondary around 6.5 to 11.5 k-ohms. I like to also make sure none of the wire contacts is not shorted to the body of the coil. Inspect it for hot, burn spots, cracks, anything that doesn't look homogenous.

[mightymoose_22]

Ditto. This engine will run on 3 cylinders.
A bad plug or wire, or even a bad connection, can cause these symptoms.
My first suggestion is to always check for a vacuum leak, which you have already done. If you are confident the vacuum is ok then move on to other possibilities. Leaks can be hard to find though, so if there is any douby hook up a vacuum gauge and see if you can locate something.

[Hungrycat7]

EGR? O2 sensors?

[wolfe]

Ive cured a ruff idle sometimes by cleaning the opening of the throttle plate with carb cleaner, an old tooth brush & a rag. Scrub the throttle plate & the opening until you dont get any dirt running out.Dont use a brass brush because the opening has some kind of coating on it. Also use the cleaner sparingly as to not to spray too much down the intake. If you do, let it dry for a while before starting the car. It takes some time to get all the dirt out but Ive seen it fix a bad idle. After your done with the brush, just sneak it back into the wifes holder for the morning!

[geers182]

thanks for the responses, i have no check engine lights on my car, and it seems to run fine when i'm driving, but then when i come to a stop it seems to idle lower and lower, until it really starts vibrating. When i disconnect my MAF, things get worse, so it is working, i'm just not sure if it can "slightly fail". what is the best way to check for vac leaks? I heard a hissing noise from my "brake booster check valve" but i replaced it and it makes the same noise, so i'm guessing that's just the noise it makes.
Also, when i step on it, it picks up fine for like a second, then it seems to have a little hold back, then it picks up fine again, not sure if that's related.

[tripletdaddy]

You sure the vac noise at the vac booster isn't a hose to it or the booster itself? Are the brakes getting harder to apply or the pedal harder to puch down? This would indicate a leaking vac booster.

[geers182]

The brakes feel fine. Today I did a bunch of things to my car which included: -Checked for vac leaks with soapy water (especially my brake booster check valve, and hoses attached to it) and there didn't seem to be any leaks any where.
- Cleaned my throttle with throttle cleaner
- disconnected my battery for about an hour
- checked my spark plugs visually and by disconnecting the cables one at a time, then starting the vehicle - each one makes things worse when i disconnected them - so they seemed to be operating fine

After i was all said and done, absolutely nothing changed, it still vibrates at idle in the exact same fasion. So what do i do next? Compression check? does a leaking head gasket fit the symptoms? Or could it be the MAP sensor, and how do I check it?

[mightymoose_22]

On these engines, it seems to me that vacuum leaks at the intake manifold are difficult to detect. If you have searched thoroughly and have not found it elsewhere, then I would feel confident that your intake manifold gasket is leaking. Maybe try again with the soapy water and try to get it on the manifold on the top and bottom side. It will be difficult to spray the water where you want it.

I still think that what you describe sounds typical of a vacuum problem.

[tripletdaddy]

Offhand, could this be egr related? Maybe clogged egr port or stuck open valve? When's the last time you've replaced your fuel filter? Is your fuel pressure ok? Your injectors may be not working right. Others recommend a fuel injector cleaner, Berryman's B-12 or Seafoam to clear that up. It may take more than one tank. You may need to clean and test your IAC as it may not be opening at idle like it should, which other than a vacuum leak, could easily be your problem. Hopefully Autozone.com has the test procedures for this as I don't for your specific car, though what I have may or may not be right for yours.

[geers182]

I am going to look into the fuel pressure, and testing the IAC, but i have a question. When i first start my car, if I unplug the MAF sensor, my car shuts off, which i'm guessing is normal. But after it warms up for a bit, if i unplug my MAF sensor, it keeps running like nothing happened, is this normal?

[tripletdaddy]

It doesn't to me, but I'm no expert, so I'm not 100% sure, but I would definitely look into it. Have you cleaned it? It can be tested if you have a voltage and ohms meter. A bad MAF is known for rough idle problems. Unfortunately, I don't have access to the test specs for your car. Maybe someone else does or you can check Autozone.com in their repair section for you specific car.

[geers182]

k, i checked my IAC and MAF through resistance checks and voltage tests, which were on Autozone. Both seem to be fine, (the IAC was supposed to read between 6 and 13 ohms at the vpwr and iac terminals - mine tested 14 ohms) but i think they are both fine. But, there is a little green vacuum hose on the top of my egr, when i disconnect it (when the car is running) the car runs the exact same, and there is no vacuum at either the hose or the egr. This can't be normal. Does anyone know what if this is still just a vac leak somewhere or is it my EGR solenoid?

[Arnoldtheskier]

Originally Posted by tripletdaddy

Offhand, could this be egr related? Maybe clogged egr port or stuck open valve? When's the last time you've replaced your fuel filter? Is your fuel pressure ok? Your injectors may be not working right. Others recommend a fuel injector cleaner, Berryman's B-12 or Seafoam to clear that up. It may take more than one tank. You may need to clean and test your IAC as it may not be opening at idle like it should, which other than a vacuum leak, could easily be your problem. Hopefully Autozone.com has the test procedures for this as I don't for your specific car, though what I have may or may not be right for yours.

Could be a clogged/dripping at idle injector. Sure..Seafoam..then maybe Seafoam in the rail/at the injector./power flush.
I would do a cylinder balance/rpm drop test for each cyl Some code readers will do this. Find the weak cyl then work back through plug,coil,wire and then a comp test.