Idle Issues

sticking idle.

sounds like you could have a binding throttle body..fwiw it sounds like it cause you have already changed the parts around it.and cleaned it.my 03 cobra had the same symptoms ,i even tryied a stronger return spring,and when snapping throttle it still would hang high,,,with mine if i was to hold back throttle at tps with hand idle would drop back down to normal,,dude the car only had 40k on it so anything is posible..as LRICHKER said code 34 is egr solenoid and could be set because of the high idle,code 67 i see you did a trans swap..ive seen that other stangnetters have found a wire needs to be moved on harness if heat/ac switch is not the cause for 67.

sticking tb shaft

with mine if i used my thumb to push back throttle as would the spring,,i only pushed thier..my idle dropped to normal and only stayed untill i did something,(something meaning move tb shaft),,I would have never believed it untill i changed it,,I also tryied using the tb again 2 yrs later,for a diagnostic test and it did the same thing on a car that had a low idle problem,,,its stuck like chuck

with mine

on mine i replaced the whole throttlebody..i even move the idle screw back ,no change .the only change on mine was holding throttle back by hand and only by hand....MY only other suggesting.would be start back at the beginning,,good battery volts and set the timing and base idle,and what everyone else suggested,,you have most likely just overlooked something.

Best thing to do before buying parts is to take the EGR valve off and give it a really good cleaning and reinstall it. Unplug the battery to reset the codes. Run the car to operating temp then pull the codes and post them here. I spent over 3 weeks troubleshooting wiring problems with hotcobra03 and jrichker's help and all it cost me was time not money. I had a wiring problem not a part issue. Replacing parts without finding out why the code is present does not always solve the problem.

Remove the EGR valve and clean it with carbon remover. Prior to re-installing see if you can blow air through the flange side of the EGR by mouth. If it leaks, there is carbon stuck on the pintle valve seat, replace the EGR valve ($85-$95).

There is nothing to clean on the EGR sensor except the electrical contacts.

Late Model Restoration has the Ford Racing M-12071-N302 kit with the EGR valve & sensor along with the ACT & ECT sensors for $45. See * * * N/A * * * 86-93 SENSOR KIT, 5.0L EFI, INCLUDES EGR VALVE & SENSOR, COOLANT TEMP SENSOR, & AIR CHARGE TEMP SENSOR MUSTANG for more details

codes

ok shot me if im wrong,,,,your computer reads input/outputs that are hooked to voltage...an egr valve isnt controled with volts,,its controled by vaccum...the egr solenoid is controled by volts,,,than sends a vaccum signal to egr valve to open/close

Makdaddymac said:

ok but does a faulty egr realy cause a loopy idle?>

Click to expand...

It is just like a vacuum leak. Air or exhaust gas is sucked into the intake manifold without the computer managing how much and when it happens. This changes the air/fuel ratio and upsets the engine. Anything the computer cannot manage causes problems.

pcm/idle

i have been learning to read more before speaking,,thanks to JRICHKER and HISSION50,,,,your grounds must be good,,, i dont recall reading this or maybe its in other words,,this is from frpp ...EFI SYSTEM TIPS
Always remember to disconnect the battery before doing any wiring on your vehicle!
ELECTRICAL GROUNDS
The single leading cause of most electrical problems is poor grounds.
Ideally, the ground for the fuel injection system should connect directly to the battery at the negative post. Using the steel chassis or engine block as a
ground can create excessive resistance causing the Powertrain Control Module (PCM) to function improperly.
An example of how a high ground or connection resistance can have very serious effects is as follows. This particular case applies to a 2005 Mustang GT,
but can easily be extended to any electronically controlled Ford vehicle: consider the case where a PCM is reading a MAF sensor signal of 4.1 V (due to a
high ground or connection resistance) when it should really be reading 4.3 V. This equates to a difference in measured air mass of 13%. That is, the MAF
will be telling the PCM that there is 13% less air entering the engine than there really is. Let’s say this happens at WOT, where air/fuel ratio is critical not
only to performance, but also to engine durability. The result is that the actual air/fuel ratio can go from a safe 12.5:1 to a potentially damaging 14.1:1, just
from a 0.2 V change in the MAF return signal!
All PCM sensors, not just the MAF, are affected in a similar fashion, so it is absolutely critical that all electrical connections are solid and that the grounds are
reliable. The potential penalty for a bad ground can range from strange drivability issues that are difficult to diagnose all the way to a damaged engine, as in
the above example.
All resistance tests should be done with the ignition key in the off position. Having voltage going through the system can return a false reading of excessive
resistance. Additionally, it is possible to have a ground that tests OK when the engine is cold, but not when the engine is hot. Heat increases resistance, so
these tests should be performed on a warm engine when possible.
To test for an adequate ground circuit in the EFI system for a 1986 to 1993 5.0L Mustang, use a Volt/Ohm meter to check the resistance of the
following circuits:
• To verify a proper ground to the PCM, check the resistance from pin 40 and pin 60 DIRECTLY to the negative side of the battery. Resistance should be
no greater than 0.2 ohms.
• To verify a proper ground to the main PCM harness, check the resistance from the MAF sensor at pin ‘B’ DIRECTLY to the negative side of the battery.
Resistance should be no greater than 0.2 ohms.
• To verify a proper ground to the engine harness, check the resistance from the black wire at the Throttle Position Sensor (TPS) DIRECTLY to the
negative side of the battery. Resistance should be no greater than 0.3 ohms.
Note that while 0.2 ohms or less is desirable, a resistance as high as 0.5 ohms is considered acceptable. Greater than 0.5 ohms is excessive and could
result in drivability concerns.
A weak ground connection can also cause the PCM’s internal reference voltage regulator to function incorrectly. This can be checked at the Throttle Position
Sensor (TPS) by checking voltage between the black ground wire and the orange reference voltage wire. With the key on, this voltage signal should be
somewhere between 4.7 V and 5.3 V.
general tips
• Whenever possible, the PCM should be mounted inside the vehicle to protect it from water damage. The PCM should also be mounted with the electrical
connectors at the bottom to avoid trapping water. Some PCM’s on newer model cars are mounted under the hood, but they are sealed against moisture
and designed to operate in such an environment. When in doubt, mount the PCM inside the vehicle.
EFI SYSTEM TIPS
Always remember to always disconnect the battery before doing any wiring on your vehicle!
ELECTRICAL GROUNDS
The single leading cause of most electrical problems is poor grounds.
Ideally, the ground for the fuel injection system should
connect directly to the battery at the negative post. Using
the steel chassis or engine block as a ground can create
excessive resistance causing the Powertrain Control
Module (PCM) to function improperly.
An example of how a high ground or connection resistance can have very serious effects is as This particular case applies to a 2005 Mustang GT, but can easily be extended to any electronically
controlled Ford vehicle: Consider the case where a PCM is reading a MAF sensor signal of 4.1 a high ground or connection resistance) when it should really be reading 4.3 V. This equates difference in measured air mass of 13%. i.e.: The MAF will be telling the PCM that there is 13% entering the engine than there really is. Lets say this happens at WOT, where air/fuel ratio is only to performance, but also to engine durability. The result is that the actual air/fuel ratio can safe 12.5:1 to a potentially damaging 14.1:1, just from a 0.2 V change in the MAF return signal!
All PCM sensors, not just the MAF, are affected in a similar fashion, so it is absolutely critical electrical connections are solid and that the grounds are reliable. The potential penalty for a bad can range from strange drivability issues that are difficult to diagnose all the way to a damaged in the above example.
All resistance tests should be done with the ignition key in the off position. Having voltage going the system can return a false reading of excessive resistance. Additionally, it is possible to have ground that tests OK when the engine is cold, but not when the engine is hot. Heat increases so these tests should be performed on a warm engine when possible.
To test for an adequate ground circuit in the EFI system for a 1986 to 1993 5.0L Mustang, use Ohm meter to check the resistance of the following circuits:
• To verify a proper ground to the PCM, check the resistance from pin 40 and pin 60 to the negative side of the battery. Resistance should be no greater than 0.2 ohms.
• To verify a proper ground to the main PCM harness, check the resistance from the sensor at pin ‘B’ DIRECTLY to the negative side of the battery. Resistance should be than 0.2 ohms.
* Not legal for sale or use on pollution-controlled motor vehicles. **Direct replacement part.
See pages 3-9 for important safety, emissions and warranty information.
EFI TECH