I tossed my HO TB and installed a 97 explorer TB after making the little mods. Here's my scenario:
I start the engine cold, everything works perfectly -- IAC does it's job to warm up and leaves me with perfect idle. I take car out for spin for about 10 miles to get it up to temp and when I'm coasting down a hill I notice that it is surging a little with a frequency of about 2 small surges per sec. When I get home, put the car in park and the surging continues 2 per sec continuously. I kill the engine, start it right back up and the idle is absolutely stable and perfect. Any idea what is going on? Have I screwed up my ECU?
This doesn't sound like a hunting idle, it's quickly pulsing continuously.
Thanks in advance
What codes pop up?
Dumb question: are codes only presented when the service light is on? The service light is not on.
Yes codes can be present without the "Check Engine" light being illuminated. My Thunderbird always throws KOER codes of 44 and 94 but the "Check Engine" light is never illuminated (it throws these codes because I removed the Thermactor system).
The fact it only does it warmed up means the computer is using a sensor after it goes into open loop. that means more likely then not a sensor is sort of off and might be making it run funny. run codes and see what pops up.
Ok. I had some time so I pulled the codes.
The Key on Engine off, I get 41.
Engine on, I get 4 12 94 43
looking at these definitions 41 is oxygen sensor circuit indicates system always lean
4 ?
12 = idle control fault -- not too descriptive.
94 = torque converter clutch solenoid circuit failure -- what the heck is this? Sounds serious.
43 = oxygen sensor out of self-test range
My guess is o2 sensor. if you got a lot if free time you can switch sides to see if it follows.
KOEO
Memory code 41. O2 sensor not switching, lean indication. Could mean you have no voltage from the sensor or a break in the wire from the sensor to the ECU.
KOER
code 4. ECU is for an 8 cylinder engine.
code 12 Idle too fast.
code 94 Smog pump thermactor system not functioning.
code 43 Right O2 sensor not reading, check for switching. ECU pin 29.
Make sure the wires to the O2's are not reversed.
Right side should be the Dark Green/Pink wire.
Left side Dark Blue/Light Green.
Did you set the voltage on the TPS when you changed the sensor for the new TB? Also, did you re-use your HO idle air or the exploder idle air? The explorer's may function on a different voltage range than the HO IAC motor.
No. I just adapted the Explorer TPS to connect to my harness connector and plugged it in. Good idea on the IAC -- I didn't know that. , I'm going to have to buy another IAC?
If you used the h.o. intake egr spacer, your old one should bolt on.
The IAC bolts on the TB but I used the original IAC from my SO TB. Why would that be an issue -- it receiving the same voltage it always did even though the TB is from the Explorer. I'm going to change out my SO IAC with the HO IAC and see if that make any difference.
Thanks everyone for the great input.
Check for vac leaks. Either s.o. or h.o. iac should work fine. see why your idle is too high. try turning down the idle.screw, if you can't slow it down, iac is bad or you have vac leakswhere you changed intakes, id lean to vac leaks.
I know that the trucks use a different IAC than do the cars, even though the plug-ins are the same. I found this out trying to use a fox body IAC off a 70mm TB on my F250 when I put the car-style typhoon fuel injection intake on my truck. I had a problem with the truck idling.
ALSO with the TPS you are supposed to set the initial voltage to .98 volts, according to legend, but so long as the ECM reads a change of something like 2.7 volts from starting point to Wide Open Throttle the ECM will be happy. You just need to make sure you get that much change from closed throttle to WOT.
And without a tps code, non of that should have anything to do with his problem.
You have to adapt a Fox Mustang 5.0 HO tps sensor to make the 65mm explorer throttle body work.You will not be giving the pcm the correct signal if you use the explorer tps as the voltage range is different on both types of tps sensors.
here is the link you need. I do not know your car but I have to assume that you are running HO stang electronics if you are bolting on a 65mm tb.
http://www.veryuseful.com/mustang/tech/engine/ConvertingExplorer65mmTB.pdf (http://"http://www.veryuseful.com/mustang/tech/engine/ConvertingExplorer65mmTB.pdf")
this is the same write up i got when I bought the Explorer 65mm from ebay. Weird thing though, the TPS that came with it had a different connector but the screw spacing was identical. The thing I'm noticing now is that the surging has pretty much stopped. the only thing it does now is occasionally get 'caught' idling too high when I start it warm -- and it will continue too high until I turn off the engine and restart. then it is perfect for the rest of the drive.
Have you done a base idle reset?
nope but I'll look that up now.
Here ya go: http://sbftech.com/index.php/topic,1031.0.html