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Discussion Starter · #1 ·
Sorry if this topic has been addressed elsewhere here but, i have spent several hours searching for some definitive answers re: IAC valve issues and would appreciate some more direct info if anyone could help with this:
My car was idling rougher lately than it normally does so, about a week or so ago,I cleaned the MAF and throttle body with electric parts cleaner and, TB cleaner,respectively,thinking the rough idle was possibly due to carbon build up and whatnot.Also checked for possible vacuum leaks and found none.Now this week the high idle won`t kick down and RPM`s hang before dropping to around 500 at idle.All this and no trouble codes.Took off the IAC and soaked it in carb cleaner,being careful of the solenoid,and cleaned the inside as best I could.I watched a youtube video last night where a technician tested the solenoid functionality by connecting the valve to a 9v battery to see if the valve actually functioned.I got nothing but clicking sounds from the solenoid by doing this.After reinstall no lasting improvement.turn on the fan or turn the wheel hard and car nearly stalls.
Now,does the 9v test idea hold true or is that bogus?
Could the valve simply need more than an hour to soak before becoming unstuck?
Should I soak it with PB Blaster or something similar instead to try and lubricate it?
If the valve is shot and I can find one at the salvage yard,what years are interchangeable ,if any?I`m not entirely sure that the IAC is the cause here so, it seems that a used one may be a better choice,in case it`s not the problem.
I found a new one on Amazon for around $47 shipped but,I`m in the middle of doing a timing chain on my wife`s car and need to save the bucks for that job.
Any help here would be greatly appreciated!! Thanks.
 

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I dont know if a 9 volt batt would be a good 'test' signal (as I think it moves in response to pulses from the PCM), since I havent tried it.

I think cleaning them works in -some- cases. In other cases its just worn out, or the crud is baked hard inside. Soaking it for 15 minutes would be as much I would bother with. Any penetrating oil would for a a soaking.
I -think- the IACVs work the same for all of the 1.9L 2nd gen. Escorts, EXCEPT: - the 91's have the connector coming straight off the end of the stepper casing (instead of at right angles to it), and the 96's have a slightly different shape to the unit. If you go to www.rockauto.com, you can put in the different years, click the link for 'fual/air' parts, and see if the parts numbers change from 92-95. I replaced the IAC on my 91 with a used unit taken from my 94 1.9L engine - and it works fine.

I imagine your chances of getting a useable unit from a JY are probably decent; maybe 70%-90%.
 

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Discussion Starter · #3 ·
I should also note that my a/c clutch or pulley locked up at the same time.I installed a non-a/c belt to get around it for now but,I read on the Wells manufacturing site,that my IAC problem may have something to do with a short in the a/c circuit.?
Why did the a/c seem to come on whenever I turned on the fan for heat or defrost?Is it supposed to do that?`Cause that really bogs dowm the rpms and sucks gas big time!
Anyone have any thoughts on the possible interelatedness of all this?
My car is really sucking dowm the gas right now and running like crap and,I could use some insight on this as soon as possible if anyone has any experience with any of this.Thanks!
 

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With the engine shut off you should be able to turn the a.c. compressor 'insides' by grabbing the outer end in your hand. There would be some resistance, but it should turn smoothly. The pulley of course should spin freely with the a.c. clutch not being energized. I like to replace the tensioner and idler pulleys when I replace a serpentine belt by the way.

The a.c. will come on anytime you use the defrost position. This is so the seal on the compressor shaft gets some 'lube' over the course of a long winter. And in humid climates, having the a.c. running dramatically lowers the relative humidity of the 'defrost' air blowing onto the windshield. If the a.c. comes on anytime you turn on the heat - then the button in the middle of the fan control knob must be in the depressed position.

I dont know of any reason the IAC circuit would be involved with any problems with the a.c. circuitry. Not that I am an expert though.

If your car is using gas a lot - what color are the spark plugs? They should be a very light brown or beige or white.
 

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Discussion Starter · #5 ·
Thanks for the reply Denis.It kinda makes sense in a way that the IAC would be affected by the a/c,as the IAC compensates for load during accessory operation and would increase the idle,leading me to think that a possible short in the a/c circuit is telling the IAC that the a/c is running when it`s really not.That would make it seem as though the Iac was faulty when the problem is with a/c ciircuit.
Does this sound possible?
I stopped by the salvage yard this morning and they want $20 for the IAC! Screw that! I found that one on Amazon for $47 and Advance Auto is willing to price match so,I think that`s my best bet for the part.
The problem is, I`m just not convinced that the Iac is really the culprit here.I`m really wondering about that possible short in the a/c circuit.
Any thoughts anyone?
By the way I snapped the damn housing on my tensioner when trying to get the new belt on so,I will be replacing that too.Didn`t realize my own strenght.LOL.
 

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I just dont know about any fault in the a.c. system that would affect the IAC. Except they are both controlled by the same PCM. But the a.c. control is a separate function from 'engine control', so I think a correlation is unlikely.
It would sure be nice if we could get a comprehensible block diagram of the PCM for our cars, along with some decision tree diagrams, and typical tuning tables for the EPROMs. Oh Well....I cant even understand all of the items on our cell phone bills.

Even if the IAC is not the culprit this time - its a part that will eventually misbehave. So its not like you had to buy a part you wont ever need. If the car has more than 100,000 miles on it, I would think of putting on a new IAC as Preventive Maintenance.
 

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I think you can move the IAC plunger by hand to confirm it's not stuck.

But I'd have to say, most of the time when some one has a idle problem, it's because of a vacuum leak, and not a bad IAC valve.
Check the hose on the PCV valve, and intake manifold gasket for leaks.
 

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the idle on these r supposed to be at 450 to 750 rpm's so i think ur idle is fine. unless the idle is bouncing then i would be concerned. check if the egr is clogged cuz i read this too can cause a low idle.
 

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What? 450 RPM is way too low for idle speed. 750-900 RPM is a good range. Mine idles around 800 RPM.
 

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that's what's listed in chiltons but it might be wrong. they even listed the 2nd gen automatics with fluid capacity of 12.3 pints. that's a little over 3 quarts. i put 4 in mine when i changed the fluid and found out that was too much. i even drained it from below the torque converter before dropping the pan.
 

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I think..... at the bottom end of its scale, you are lucky if the tachometer is pointing to within 150 rpm of what the engine might really be turning.

I also think the water temp gauges in our Escorts are only slightly more accurate than a fortune cookie. Just being consistent from day to day on your own car is all I expect of it.
 

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Discussion Starter · #12 ·
Well,I bought a new IAC at advance auto. this afternoon for $44 (they price matched the one I found on Amazon).The idle still hangs a little but,nowhere near as much as before.The car still runs like it has a vacuum leak though,albeit a small one.It idles between 750 and 500 rpms when it settles and,although the tach shows no movement,It has a slightly rough idle all the same.
I`m thinking that my EGR may be carboned-up because I`ve checked nearly every vacuum hose under the hood and they`re fine as far as I can tell.I also made sure my intake bolts are tight just for good measure.I already cleaned the MAF a few weeks ago and, if after I replace the fuel filter tomorrow it still runs rough,I`m gonna have to wrestle off the EGR and clean that too.The pipes on those things never come off easy.Oh well,thanks to everyone for your replies and advice.Any further insight is always appreciated.
FEOA rocks!
 

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I had an easier time disconnecting EGR at the exhaust manifold for my '94.

That's not just a rough idle, that's a *very* low idle. Only time I idled that low is when the alternator wasn't poot'n out 'nuff juice. (simple worn brushes +5 min to replace) Could be electrical or ignition system related? Check alternator/battery voltage levels, clean your posts and check your grounds. Spark plug regap .054", CHEAP spark wires (expensive ones have higher resistances than my ignition coil seemed to like - cheap=noproblem=better for me) has also helped smooth me out in the past.


Re Vacuum lines, there is a very tiny one that runs from the bottom of the throttle body to the fuel tank evaporator cannister which is beneath the air cleaner housing on the '94. Kind of buried and very easy to miss. Best to remove the air cleaner ducting, at least, for access.

You'll have to ask someone else (or/and Google) for the details on the testing procedure, but you can use a vacuum gauge connected to one of the unused ports on top of the intake to help verify whether there is a vacuum leak present. It is possible for a vacuum leak to be isolated to a component that is connected to the engine. Don't recall whether it was a 'scort, don't think it was, but for instance read a case where one individual isolated the leak as internal to his brake booster a.k.a. master cylinder. If the vacuum gauge test confirm that a leak may be present, using some line plugs to selectively cap-off accessories may help pin-point the location in such a case.

Seems like any and everything can give 'scorts rough idle, but other things that have smoothed me out are: New Timing Belt (old one stretched, lost a tooth), ...and of course, the dusty MAF which you've tried cleaning. My fuel pressure always tested ~40PSI.

Fresh Castrol 5w-30 oil change, STP Complete Fuel System Cleaner (for injectors) + tank of PLUS or Premium fuel at Marathon or Speedway and some HARD runn'n has been good stuff for me.
 

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Oh... though I've never replaced it, do know that my IAC should probably be replaced. Just a number of days ago, I cold-cranked it and got a *really* low idle for a short second, then it shot wwwaaayyy up, then back down, then back up higher than normal again and just sat there. I let it idle for like 10 minutes just to see if it would ever change or come down. It didn't. So I shut it off for one second and cranked it back up and it proceeded to act normal, idling down to 800RPM. I think the computer got erratic feedback from the IAC and just gave up on it, until I reset it by shutting down and restarting. Carefully cleaned and lubed it (with ATF trans oil) a number of years ago. Never really showed any noticeable amounts of dirt though. (EGR was *completely* jam-packed clogged so that's probably where it all ended up) It also normally idles up relatively slowly when I cold-crank it for the day... like it's gradually taking longer and longer for the IAC to open up.
 

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denisond3 said:
Even if the IAC is not the culprit this time - its a part that will eventually misbehave. So its not like you had to buy a part you wont ever need. If the car has more than 100,000 miles on it, I would think of putting on a new IAC as Preventive Maintenance.
I agree, I replaced mine at 165K, but I wish I had done it much earlier.
 

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juggalo said:
they even listed the 2nd gen automatics with fluid capacity of 12.3 pints. that's a little over 3 quarts. i put 4 in mine when i changed the fluid and found out that was too much. i even drained it from below the torque converter before dropping the pan.
12.3 pints is over 6 quarts, over 1 1/2 gallons. 2 pints equals 1 quart.
 

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yeah ur right
 

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Discussion Starter · #18 ·
The car still idles at 500 rpms.The idle hang has improved quite a bit but,not entirely.My gas mileage has come back up but still is less than the 400 miles I normally get from a tankful.
So far i have cleaned the throttle body,MAF and pcv valve.I`ve replaced the fuel filter, IAC and the EGR (and of course cleaned the EGR tube and intake port).I tightened all the intake bolts and throttle body.I`ve checked every vacuum hose I could get my hands on and a few I couldn`t.I jusy got through trying to use a fog machine to check for vacuum leaks but,I`m not real confident that it`s any real substitute for an actual smoke test.
The only thing I can think of is that there is a vacuum leak somewhere that isn`t obvious.Although,I was wondering if the TPS or MAF could be faulty?I have a digital multimeter but, I haven`t really learned how to use it well enough to test sensors with any degree of certainty yet.Or could my catalytic converter be clogged and be causing this?
I`ve been unable to work for almost two $%#& years now and as with many others,have to figure out how to fix this problem myself or as cheaply as possible.
Any further thoughts or experience fixing this sort of problem will be most appreciated!!
Oh,the only thing I haven`t done yet are plugs and wires but,they aren`t very old since last change.Will check and change them next couple of days but,I can`t imagine that they would cause such a crappy low idle?!
 

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Discussion Starter · #20 ·
I just don`t have money for or,access to a Mityvac.Having read through some of the other threads on this site and the web,I found that some people had some success finding vacuum leaks using a fog machine to do a "smoke test".I didn`t find any leaks that way yesterday.I`m not sure if i indeed,do have a leak and couldn`t find it with this method or, if it didn`t show a leak because the idle problem is being caused by a faulty sensor or a clogged catalytic converter maybe.I`m gonna see if anyone I know has a mityvac or maybe just a vacuum gauge and test line by line as someone posted earlier.
I found the plugs to be fine and, although the wires look as though they could be replaced,I just don`t think they would cause the symptoms of a vacuum leak.Gonna have to wait a few weeks `till I get some cash for new wires.
As always, any help from my fellow escort enthusiasts,is greatly appreciated.
Thanks to all of you who have posted on this already!
I have owned many cars thus far in my life and have found that escort owners are die hard loyalists to their cars and fellow owners like no others.Rock on FEOA!
 
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