code 49

[bruno]

The car, (91 GT mostly stock) has a bad stumble during idle. I might have imagined it but I think it got worse when I had the engine mounts replaced. I'm sure it's not just more vibration because of the energy suspension mounts, the engine actually stumbles and bucks like it's missing or running out of fuel.

I pulled the code 49, which seems to be distributor related, and changed the rotor and cap. This helped it smooth out some but the stumble is still there. Changed out the sparkplugs, same thing. Smoothed out a little more, but under idle it stumbles and bucks bad, this stumble seems to go away completely when given some gas.

You guys ever run across code 49, any tips? I did a search on here but didn't find any threads with for this specific code.

TIA

 

[jrichker]

Code 49 is rare, you're the first guy tp post a problem with it. It looks like code 49 is a problem with electronic Ignition - spout signal circuit problem, and is similar to code 18. I'll post the code 18 test path and you can use it to check some of the simple things.

Code 18 - SPOUT out or wiring fault - look missing SPOUT jumper, short to ground or open circuit in SPOUT wiring going back to the computer. Possible bad TFI.

The SPOUT enables the distributor to advance the timing beyond the base setting. Without a working SPOUT, you are locked down to the timing you set with the timing light.

Checking the SPOUT wiring
Tools needed:
DVM or Ohmmeter
10 MM wrench
Phillips screwdriver.
6 ft 16 or 18 gauge jumper wire with alligator clips on each end.

Anytime you make resistance checks, the circuit under test must not be powered on. If it is powered up during the test, your readings will be wrong and you may damage the meter. Do not touch the probe tips when making resistance measurements. If you do, your readings may be inaccurate.

Remove the SPOUT connector from the ignition harness by the distributor. Remove the passenger side kick panel and loosen the 10 MM bolt that secures the computer wiring connector. Use your DVM to measure the resistance between ground and pin 36 (yellow/lt green wire): you should see and infinite open circuit. Keep the DVM connected to pin 36 (you may need a helper at this point). Insert the DVM lead you previously had connected to the body ground into the computer side of the SPOUT connector. You may need some extra wire to extend the test lead, so have some 16-18 gauge insulated wire handy. If you extend the test lead, remember that the quality of the connections may affect your readings. You should see 22K Ohms (22,000 Ohms): more than that indicates a wiring problem. The 22K Ohm resistor limits the voltage and provides some isolation between the TFI and computer input.

The following is a view from the computer side of the computer wiring connector.

Diagrams courtesy of Tmoss & Stang&2birds

See the following website for some help from Tmoss (diagram designer) & Stang&2Birds
(website host) for help on 86-95 5.0 Mustang wiring Mustang FAQ - Engine Information Everyone should bookmark this site.

Ignition switch wiring
http://www.veryuseful.com/mustang/tech/engine/images/IgnitionSwitchWiring.gif

Fuel, alternator, A/C and ignition wiring
http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif

Complete computer, actuator & sensor wiring diagram for 88-91 5.0 Mass Air Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/88-91_5.0_EEC_Wiring_Diagram.gif

Complete computer, actuator & sensor wiring diagram for 91-93 5.0 Mass Air Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/91-93_5.0_EEC_Wiring_Diagram.gif

Complete computer, actuator & sensor wiring diagram for 94-95 5.0 Mass Air Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/94-95_5.0_EEC_Wiring_Diagram.gif

Vacuum diagram 89-93 Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/mustangFoxFordVacuumDiagram.jpg

HVAC vacuum diagram

 

[bruno]

Thanks jrichker!

 

[HISSIN50]

I didnt think 5.0's could generate that one.

 

[SMOKEDYA]

You might want to try the pick up inside the dizzy also.Mine was loose and wobbled and it ran like f'n crap!peace











john

 

[jrichker]

I didnt think 5.0's could generate that one.

I haven't ever seen it before, but it is in the Probst book, which is Mustang centric. The note in the Probst book says that the timing is locked at base setting and will not advance.