Idle Air Control Valve testing help needed. Surging getting worse!
Hi All~
Could you guys give me some insight on the proper way to check the voltage on my 92 5.0 Idle Air Control Valve?
Over the past year, I've had an increasing surging issue upon hot or cold start ups. It does finally settle down after feathering the throttle but it's been getting worse.
I already have my TPS set at .98 so I don't believe it's that and have reset the computer as well.
Thanks
~ Mark
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"HAPPINESS IS AN OFFCAMBER APEX"
92 LX 5spd Conv LE "Summer Special" Track Heat intake, TFS Track Heat Heads, 75mm TB, 95mm Anderson MAF w/ 4" Power Pipe, F303 cam, 30lb inj, Aero reg, HI6, 1 3/4 full length hdrs, Xpipe, pullies, custom strut tower brace, k brace, sub conn, Steeda CC plates, KYB adj struts and shocks, Steeda Full Comp Springs(front), Steeda Sport Springs(rear),upp/low control arms, subconnectors, Steeda front swaybar, Steeda Panhard Bar, and 3.73's
has it always produced this problem, or 4k ago when you replaced it, i had the same problem, turned out it was my coolant temp sensor, also makesure it clean in there, remove it inspect it, then squirt some throttle body cleaner in there for extra assurance, and how old is you TPS sensor that can cause idle problems as you described
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1993 LX 5.0 stock long block, 1.7 crane roller rockers, cobra valve springs, explorer intake upgrade, 65mm throttle body, 80mm maf ,Moroso CAI,Shorty BBK headers,BBK Adj fuel reg, BBK underdrive pulleys, electric fan, B303 cam, off-road Hpipe, 40series flowmasters, 3:73 gears, Alum drive shaft, King Cobra clutch, Pro 5.0 shifter, BBK gripp LCA,190lph fuelpump,Moates Burn2 Chip Programmer, with EEC-IV bank reader
It was starting to act up just before I replaced the IAC, thinking that might cure the problem. My coolant temp sensor is working fine if you're referring to the sensor that displays the water temp on the dash cluster. Is it possible that it's faulty anyways? The TPS is most likely original, but am still able to adjust it to .98volts.
__________________
"HAPPINESS IS AN OFFCAMBER APEX"
92 LX 5spd Conv LE "Summer Special" Track Heat intake, TFS Track Heat Heads, 75mm TB, 95mm Anderson MAF w/ 4" Power Pipe, F303 cam, 30lb inj, Aero reg, HI6, 1 3/4 full length hdrs, Xpipe, pullies, custom strut tower brace, k brace, sub conn, Steeda CC plates, KYB adj struts and shocks, Steeda Full Comp Springs(front), Steeda Sport Springs(rear),upp/low control arms, subconnectors, Steeda front swaybar, Steeda Panhard Bar, and 3.73's
im talking about the sensor on the coolant rail on the passenger side of the intake not the sender , even though you can get the TPS set .98volts dose not tell you if you have a dead spot within its travel, a realible check is hook up a digital volt meter like you were going to adjust it, slowly open the throttle plate, and observe the volt reading, your looking for abnormal volt flucuations, if it starts @ .98 and then jump around, thats your dead spot, the cheapest is the checks, and the cleaning, parts hunting with sensors gets expensive quick
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1993 LX 5.0 stock long block, 1.7 crane roller rockers, cobra valve springs, explorer intake upgrade, 65mm throttle body, 80mm maf ,Moroso CAI,Shorty BBK headers,BBK Adj fuel reg, BBK underdrive pulleys, electric fan, B303 cam, off-road Hpipe, 40series flowmasters, 3:73 gears, Alum drive shaft, King Cobra clutch, Pro 5.0 shifter, BBK gripp LCA,190lph fuelpump,Moates Burn2 Chip Programmer, with EEC-IV bank reader
no there should be two CTS (coolant temp sensor) one for the gauges one for the ECM, if the one for the ecm is not clean it will not get a correct reading and cause problems, if you want to chance it take it out and wire brush it clean because over the years it gets that brown crap on it from coolant, if you want to be extra sure put it in water and hook up a volt ohm meter and watch the resistance change as you heat the water also consider checking your entire air induction system, filter and cleaning MAF
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1989 Ford Mustang LX Notchback,5.0L 5 speed
331 Stroker wuth forged eagle rotater, Scorpion roller rockers, mahle forged pistons, AFR185s,Spec Stage 2+ Clutch,Steeda Sub Frame Connectors with Seat supports,Hurst Short Throw Shifter, Mr. Gasket Hi0-Flo 180* T-Stat,Lunati VooDoo Series cam,Trickflow upper and lower intake,BBK CAI,BBK Long Tube Headers,BBK Off-Road H-Pipe,Flowmaster 40 Series Mufflers,Aluminum Driveshaft,17" Cobra R's,10000K HID's One problem after the next !!
You need to ID what the ECM (what controls the IAC duty cycle) is "reacting" to. Run a set of the DIY KOEO/KOER self tests, they're free, and will provide you with the info to ID the culprit(s) that could be causing the idle control problem. Also suggest to do a Base Idle Reset Procedure, setting the TPS to the mythical .98 -.999 vdc calibration will not solve anything. LUK
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ACRONYMS:
LUK=Let Us Know, GL=Good Luck, LMK=Let Me Know, JIC=Just In Case, BTSTDTRT=Been There Seen That Done That Repaired That, YCYDYP=Your Car Your Dough Your Prerogative and the classic... DILLIGAS=Do I Look Like I Give A S***
1986 GT-X303 cam, 289 heads, 1.72, Holley 700cfm DP, RG 4+1 Trans.
I've been fighting a similar battle with my car. Most recently I found that it would not even start if I unplugged the IAC. I adjusted the idle screw so it would start without the IAC and now it runs from startup without such bad surging and it doesn't die when cold like it used to. However, all is not completely well. Idle is a bit high and it still surges slightly. Also getting an intermittent CEL (31 and 63 KOEO, IIRC). I'm planning on cleaning the salt/pepper connectors next, plus testing the TPS and temp sensor as described above.
Wow you guys, this is all great info! I REALLY appreciate it!
The car has been sitting for 2 weeks and tonight when I started it up, it's really running rich more than normal.
Guess I better get at it huh.
Thanks again to everyone and will let you know what I hopefully find.
~ Mark
__________________
"HAPPINESS IS AN OFFCAMBER APEX"
92 LX 5spd Conv LE "Summer Special" Track Heat intake, TFS Track Heat Heads, 75mm TB, 95mm Anderson MAF w/ 4" Power Pipe, F303 cam, 30lb inj, Aero reg, HI6, 1 3/4 full length hdrs, Xpipe, pullies, custom strut tower brace, k brace, sub conn, Steeda CC plates, KYB adj struts and shocks, Steeda Full Comp Springs(front), Steeda Sport Springs(rear),upp/low control arms, subconnectors, Steeda front swaybar, Steeda Panhard Bar, and 3.73's
Well the Coolant Sensor is good. I warmed the car to about 180 and according to the Ford Ohm chart it's fine.
The O2 sensors were clean.
The IAC was clean and set at .98 with no obvious volt fluctuations when opening the butterfly.
I have vacuum to the EGR valve, but don't know if it's sufficient. How can I check the valve itself? Should I notice obvious valve movement to the naked eye?
The plugs are a bit rich but no signs of manifold leaks.
I haven't checked the MAF for cleanliness yet but I don't I'll find anything there.
I sprayed some starter fluid around the vacuum lines but found nothing.
Did the Base Idle reset... No change.
Have not done the whole self test though.
At this point I'm really starting to get frustrated.
Geesh
__________________
"HAPPINESS IS AN OFFCAMBER APEX"
92 LX 5spd Conv LE "Summer Special" Track Heat intake, TFS Track Heat Heads, 75mm TB, 95mm Anderson MAF w/ 4" Power Pipe, F303 cam, 30lb inj, Aero reg, HI6, 1 3/4 full length hdrs, Xpipe, pullies, custom strut tower brace, k brace, sub conn, Steeda CC plates, KYB adj struts and shocks, Steeda Full Comp Springs(front), Steeda Sport Springs(rear),upp/low control arms, subconnectors, Steeda front swaybar, Steeda Panhard Bar, and 3.73's
Idle Air Control Valve testing help needed. Surging getting worse! 
