: Poor Throttle Response - PWSC '02 Zetec
06-19-2007, 09:06 PM
I am having some issues with my 2002 ZX3 (Zetec with Powerworks SC). Maybe one of you can help:
A few minutes after starting my car (it happens at the same intersection on my way home from work every day), I experience poor throttle response, sometimes resulting in a stall. I can prevent the stall by letting off the gas pedal and then revving it a few times, but it still does not respond for a few seconds. It is almost like the throttle is not opening when it should.
I bought this car used and with the supercharger already installed so I do not know if something was improperly hooked up during the install. When this lapse happens, I do not experience any electrical failure- my gauges stay normal, my radio stays on, my wipers and headlights stay on.
I also have a Check Engine light; I ran a code reader on it and it read errors P0113 (IAT Sensor 1 Circuit High Input) and P1506 (Idle Air Control Overspeed Error). I am still trying to figure out exactly what these errors mean and how to fix them. I am assuming that they have something to do with the problem.
06-19-2007, 09:09 PM
Sounds from the code like you may have a bad idle air controller. On the 4.0L Jeeps this is actually on the throttle body and it has a small movable needle that moves in and out to control the ammoutn of air gets though the throttle body with the throttle plate closed at idle.
They can get gummed up sometimes from intake gunk. I've had luck on some jeeps around here by spraying throttle body cleaner over the little needle hole.
06-19-2007, 09:19 PM
Have you ever heard of it happening with that strange, reliable timing though? Literally every day, the exact same spot, and it will only happen the one time.
I'll check out the throttle body cleaner; thanks.
06-19-2007, 09:29 PM
> Have you ever heard of it happening with that strange, reliable timing though?
When the engine is cold, before the O2 sensors have warned up, I beleive the engine runs "open loop," which means it does not tirm or adjust based on sensor readings. Once the engine reaches a certain temeprature, it swithces to "closed loop," where it adjusts factors such as fuel, based on the feedback from the sensors. This would explain the regular timing.
Now, this does not mean that the sensors, such as the O2 sensor, are defective. It simply means that the engine parameters when running under open loop conditions may help cover for the real problem, e.g., it likely is running richer under open loop conditions at the start.
As for the P0113 code, a google got this:
"P0113 Intake Air Temperature (IAT) Sensor Circuit High Input" indicates that the PCM has detected a signal from the IAT that is higher than 128°C, indicating that the IAT has an internal short.
And for the P1506:
"DTC P1506 is set when the PCM detects the engine idle speed is greater than the desired rpm. This is most commonly caused by a dirty or bad IAC valve. Cleaning the throttle body will, most likely, cure this problem."
A dirty or bad IAC would certainly give the stalling behavior you have described.
06-19-2007, 09:36 PM
Thanks a lot, I'll check it out tomorrow and see if it works.
06-19-2007, 09:38 PM
yeah the IAC is a very common prob in fords, especially the explorers. i have heard of lots of probs with foci having the prob too, it kinda causes phantom problems as well, like one day it will do it and the next it wont
06-29-2007, 05:08 PM
I bought a new Idle Air Control Valve from Advance Auto Parts and installed it. Now the car is making a crazy "humming" noise when it idles. I finished the install 20 minutes ago.
I turn the key and it seems to have a lot of difficulty starting. Sometimes it just dies, sometimes it stays running at a solid idle (at least that part is fixed) and makes that horrendous humming sound. If I give it any gas, the humming noise goes away and then comes back when the RPMs return to idle.
The code reader is now only reading the P0113 error- the P1506 is gone. I am not sure what my next step is here.
The humming noise is definitely coming from the IAC valve. It sounds muffled with the filter is on, and when the filter is removed it gets much louder and is coming from where the IAC is.
Can anyone help me out here? Did I miss something?
06-29-2007, 06:26 PM
I took it off and put it back on, and now the humming noise starts at 2500 RPM. The code reader is still reading P0113, and now P1504 as well.
It is drivable now.
06-30-2007, 10:37 AM
Check and make sure your IAC valve is oriented in the right direction. It's a common mistake to install it upside down. Check the PW installation manual for proper orientation. Also, it sounds like your IAT sensor is bad, also not uncommon with the PWSC. Hope this helps.
06-30-2007, 04:59 PM
Advance Auto sold me the wrong IAC valve.
The valve they sold me was for the SPI, not the Zetec. Despite the fact that I told them repeatedly it was the Zetec. It looks different but not different enough that I would assume it was the wrong part. I figured it was just the difference between OEM and aftermarket.
Correct valve is currently unavailable from the manufacturer for some reason. This is getting way too complicated.
I'll look into the IAT too.
07-05-2007, 08:13 PM
You will need a replacement IAT from a Lightning.