Bad Idle, Bad Cold Running, Pulled codes, Need help

[Jason5.0]

ok my 5.0 has a new 306 (setup described in sig) and has a lousy idle that will continuosly search for an idle no matter what i do, and will refuse to stay running while cold unless i keep my foot on the gas pedal. so i pulled the codes today and got #'s 41, 56, 63
i looked them up and got this:
41 is Ego/ h02s oxygen sensor always below lean on bank 1 no ego sensor rich/ lean transitions detected
56 is MAF sensor voltage to high
63 TPS voltage to low
i checked my tps and that is junk, it is at 1.45 at idle (with the screws in the stock location (drilled sensors holes into slots for adjustablility) and no matter how big you drill the slots it wont drop below 1v but above .5v (it was set ot .5 volts before), so im gonna replace that which i hope should fix code 63, but what is wrong with my mass air and code 41? i heard #41 may be caused by a vacuum leak i checked everywhere i could see for leaks with carb cleaner and nothing, could it be my lower intake gaskets didnt seal well? at a 900 rpm idle the engine pulls 10-12 " vacuum and it sweeps around a bit at 600 rpm it pulls 5" and jumps around a LOT, any help or insight is great btw i already read all pages of the surging idle checklist and searched around quite a bit

 

[The Shape]

what your describing sounds very much like it could be a vaccum leak.

 

[jrichker]

Code 63 - Throttle Position Sensor (TPS) signal too low TPS. Vref missing (5 volt reference voltage supplied by the computer), bad connections or damaged wiring, TPS sensor failed, TPS sensor way out of adjustment. Use a DVM to check for 5 volts on the Orange wire. If it is missing, look for +5 volts at the Orange wire on the EGR or MAP sensor located on the firewall near the center of the car.
Try this... Currently there is some dispute about setting it at .99 volts being worth the effort, but anything less is probably OK. All you need is less than 1.0 volt at idle and more than 4.25 at Wide Open Throttle (WOT). You'll need a Digital Voltmeter (DVM) to do the job.

Here’s a TPS tip I got from NoGo50…

When you installed the sensor make sure you place it on the peg right and then tighten it down properly. Loosen the back screw a tiny bit so the sensor can pivot and loosen the front screw enough so you can move it just a little in very small increments. I wouldn’t try to adjust it using marks. Set it at .97v-.99v, the closer to .99v the better. Just don’t go over .99, or you upset the fuel calibration and idle quality will suffer.

(copied from MustangMax, Glendale AZ)

1. Always adjust the TPS and Idle with the engine at operating temp. Dive it around for a bit if you can and get it nice and warm.

2. When you probe the leads of the TPS, do not use an engine ground, put the ground probe into the lead of the TPS. You should be connecting both meter probes to the TPS and not one to the TPS and the other to ground.

3. Always reset the computer whenever you adjust the TPS or clean/change any sensors. I just pull the battery lead for 10 minutes.

4. Check the procedure for your year, on my 90 I have to turn the idle screw until it just touches the tab, then insert a .010 feeler gauge and give it about one more turn. Then you adjust the TPS voltage to .98v, reset the computer. Start it up, if the idle is to low then turn the screw in until it is just right, then readjust the TPS voltage to .98v and reset the computer and start it up. The key is to adjust the TPS voltage and reset the computer whenever the idle screw is changed.

 

[ebiggs1]

You have some things to check but the B303 is never going to idle like the stock cam so don't expect it to.

 

[Jason5.0]

ok, i replaced my tps and my iac today, it seems to idle way better and start a little bit better, havent had a chance to check the voltage yet, ill get back to you tomorrow on that one, as for the code 41 any idea what could cause that? or hows about the maf voltage to high? im lost on those ones, thanks for the help

 

[Marlboro_Man]

Code 41- check your o2 sensors and make sure the wiring is all in good shape and hasn't burned itself on headers or h/x pipe. If all the wiring is good either check the voltage or replace the o2 sensor.


When i installed my LT's i had an extra 02 sensor so i used it and the car ran a little funny. I pulled the codes and got a 41 and ended up putting the old o2 sensor back in. No more codes or problems after that.

 

[jrichker]

Fix the Code 56 before you try to fix the code 41.

Code 56 MAF - output voltage too high. Failed MAF sensor, short between
MAF sensor and heater or short in wiring between pin A (12 volts) and pins C or D.

There are three parts in a MAF: the heater, the sensor element and the amplifier.
The heater heats the MAF sensor element causing the resistance to increase.
The amplifier buffers the MAF output signal and has a resistor that is laser
trimmed to provide an output range compatible with the computer's load tables.

The MAF output varies with RPM which causes the airflow to increase or
decease. The increase of air across the MAF sensor element causes it to cool,
allowing more voltage to pass and telling the computer to increase the fuel flow.
A decrease in airflow causes the MAF sensor element to get warmer, decreasing
the voltage and reducing the fuel flow. Measure the MAF output at pins C & D
on the MAF connector (dark blue/orange and tan/light blue) or at pins 50 & 9
on the computer.

At idle = approximately .6 volt
20 MPH = approximately 1.10 volt
40 MPH = approximately 1.70 volt
60 MPH = approximately 2.10 volt

Disconnect the MAF sensor, battery negative post and computer connector.
The computer connector is located under the passenger side kick panel & is
secured by a single 10 MM bolt. Do not make any resistance checks
without disconnecting the connectors. You will get incorrect readings.
Check the resistance between the MAF signal wiring and power.
Pin D on the MAF (dark blue/orange wire) and Pin A (red wire) should be
1 megohm or higher (meter shows infinite resistance or open circuit.).
Pin C on the MAF (tan/light blue wire) and Pin A (red wire) should be
1 megohm or higher (meter shows infinite resistance or open circuit.).

See the following website for some help from Tmoss (diagram designer) &
Stang&2Birds (website host)

http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif

Code 41 or 91 - O2 indicates system lean. Look for a vacuum leak or failing O2
sensor.

The computer sees a lean mixture signal coming from the O2 sensors and
tries to compensate by adding more fuel. Many times the end result is an
engine that runs pig rich and stinks of unburned fuel.

The following is a Quote from Charles O. Probst, Ford fuel Injection &
Electronic Engine control:
"When the mixture is lean, the exhaust gas has oxygen, about the same
amount as the ambient air. So the sensor will generate less than 400
Millivolts. Remember lean = less voltage.

When the mixture is rich, there's less oxygen in the exhaust than in the
ambient air , so voltage is generated between the two sides of the tip. The
voltage is greater than 600 millivolts. Remember rich = more voltage.

Here's a tip: the newer the sensor, the more the voltage changes, swinging
from as low as 0.1 volt to as much as 0.9 volt. As an oxygen sensor ages,
the voltage changes get smaller and slower - the voltage change lags behind
the change in exhaust gas oxygen.

Because the oxygen sensor generates its own voltage, never apply voltage
and never measure resistance of the sensor circuit. To measure voltage
signals, use an analog voltmeter with a high input impedance, at least 10
megohms. Remember, a digital voltmeter will average a changing voltage." End Quote

Measuring the O2 sensor voltage at the computer will give you a good idea of
how well they are working. You'll have to pull the passenger side kick panel
off to gain access to the computer connector. Remove the plastic wiring
cover to get to the back side of the wiring. Use a safety pin or paper clip to
probe the connections from the rear. The computer pins are 29 (LH O2 with a
dark green/pink wire) and 43 (RH O2 with a dark blue/pink wire). Use the
ground next to the computer to ground the voltmeter.

Most of the common multimeters have a resistance scale. Be sure the O2
sensors are disconnected and measure the resistance from the O2 sensor
body harness to the pins on the computer.

Note that all resistance tests must be done with power off. Measuring
resistance with a circuit powered on will give false readings and possibly
damage the meter. Do not attempt to measure the resistance of the O2
sensors, it may damage them.

The O2 sensor ground (orange wire with a ring terminal on it) is in the wiring
harness for the fuel injection wiring. I grounded mine to one of the intake
manifold bolts