Surging Idle Problems

[Iron Ranger]

Need some help with some idle problems.

First, some info:

5.0 efi
computer and harness from an 89 Mustang man trans
Manual T5 tranny
computer is A3M
MAF is E9Zf 12B579 AA AFH55 03 9HO1. Maf sensor is clean.
New TPS Voltage closed is .96*(see below)
BBK 70 mm New throttle body
New BP/MAP
New IAC
PCV is not connected to vac lines, just has breather attatched to the end
Timing set to 14 deg
Fresh 91 gas

I have connected all the appropriate sensors(IAT, VSS, ECT, O2's, etc). The only sensors not connected are the smog things (EGR, canister purges, etc).

*Ok, the problem I am having is when I start the engine, the idle surges from 1000 to 500 back and forth until the truck dies. I checked the TPS voltage, it was 1.2-1.3 at idle. I then tried to adjust the TPS to read .9 volts, but I ran out of adjustment on the TPS plate. I then backed the idle screw down and achieved .9 volts, but now the truck idles at 500 then drops and dies.

Also tried to drive the truck yesterday, but it kept dying at stop signs (this was before i re-ajusted the idle screw) Timing was also 10 deg. at the time, but i bumped it up to 14 now. Seems to sound a little better.

When the truck was surging, I unplugged the IAC and it died. Tried again and unplugged the MAF and it did not help.

Also seems like the truck is running pig rich.

Several questions:

1. Any help with the idle problem?

2. Is there a way to adjust the idle screw so the truck idles at 7-800(or whatever it's supposed to be) and still get .9 volts at the TPS?

3. Does the neutral switch that goes to pin 30 need to be connected? I don't have a switch on the T5 housing.

4. Does the cold air intake have any effect on the MAF function?

5. Could the PCV, being vented, cause a "vac leak" even though it's not connected to the vac lines?

6. Could the EGR crap cause any of these problems by being disconnected? I tried the resister jumper at the egr connector, didn't seem to help.


Thanks for any help you guys can provide.

 

[Iron Ranger]

Forgot to mention codes:

23, 31, 67, 81, 82, 84, 85

KOEO

 

[Scrambler82]

Not sue I can be of help to you but here are a few things to check.
The connectors at the rear of the intake, double check them for fit and corrosion.
There is a resistor kit for the EGR removal, although i took mine off completely and did nothing else (93 Mustang harness/engine).
Check the ground wiring, block top battery, body to battery not through the block but it could be.
What injectors are you using ? Are they setup for the 70 mm throttle body ?
Double check the timing, maybe 12 degrees initial
The TPS, don't worry about the voltage, setup the idle so it works.

Just some thoughts, may not work but something to think about.

Luck,

p.s. make sure the computer has a good ground too.

 

[sparky2eh]

Ok the "famous" surging idle problem
Engine off set the TPS to .98-1.0 vdc
Unplug IAC, so computer doesn't control idle
Remove sprout connector, so computer doesn't control timing
Start engine, may need help to keep it running until idle screw has an effect
Turn the idle adjust screw to set the desired RPM
Stop engine
Reset TPS voltage, it will change after idle adjust screw is turned as it is connected to the throttle plate which is moved by the idle screw
Reconnect IAC and sprout, let computer play again
Start engine, all should be well.....
Well this has worked for me numerous times on cars with exactly the same problem, little procedure Ford forgot to tell us about

 

[Teddyzee]

3. The clutch position switch connects pin 30 and 46 when the pedal is pushed, so the Ranger does not need to use the nuetral switch on the T-5 trans.

 

[fordmike1]

In order to set the TPS voltage you must first set the idle screw to factory specs. Using a .010 feeler gauge back out the idle screw so its not touching the throttle blade. Using the .010 feeler gauge between the set screw and the throttle blade stop adjust the gap to .010 and then when that is set turn in the idle set screw 1.5 turns as that will get you to factory specs. Next go to the TPS and set the voltage to .95-1.0 with the key on and engine off. The TPS and idle set screw is now set to factory specs. Start the engine and see if that fixes your problem.

 

[Iron Ranger]

I also posted this on RPS, and with their help, got it figured out. Now the only problem I have is the truck is running super rich. I'm hoping it's the out of place 24 lb injectors when in reality it should be the 19 lb injectors.