Manual Swap Problems

[merlinx454]

I completed the swap on the 94 I rescued from a guy's yard. I had some problems with it because it sat for 10 or so years but I thought I was past most of them. I still have an issue where the truck bogs down under load for exactly 10seconds then feels like a valve is opened and I get full power. The EGR valve and EGR pressure sensor are new. Also when it bogs down, I get a check engine light. I cleaned the MAF sensor and the IAC. The weirdest part is that when I push the clutch in, the check engine light goes away. When I start in first and the light is off, 1st doesn't bog down. Did I miss something in my swap? Why would the clutch relieve the check engine light?

 

[Fix4Dirt]

are the o2s slow to respond? can tou get live data and the codes that show up wuen that happens?

 

[merlinx454]

Both are new Bosch but I don't have the ability to see the live data like I normally can on an OBD2.

 

[410Fortune]

You need to check the code
There should be a code in memory

Could be issue with speed sensor
Was this truck an automatic? Did you keep the auto computer?

 

[Fix4Dirt]

You need to check the code
There should be a code in memory

Could be issue with speed sensor
Was this truck an automatic? Did you keep the auto computer?

ive been wondering this: what are the differences between the auto and manny pcms? i know the auto compensates for the TC so it idles a hair higher, how many wiring differences were there? i assume ford would have made them swappable and interchangable for the most part.

 

[Gadget X]

The idle speed was the only difference that I noticed when I did mine. I have heard that there are slight differences in timing advance or something, but I'm not positive. I eventually located the appropriate pcm and replaced the auto one, but I never had any CELs or anything.

 

[Fix4Dirt]

The idle speed was the only difference that I noticed when I did mine. I have heard that there are slight differences in timing advance or something, but I'm not positive. I eventually located the appropriate pcm and replaced the auto one, but I never had any CELs or anything.

10-4! good to know! maybe one day ill get me a 1st gen to mess around with! first priority: finding me a 2nd gen v8 that i can take all the stuff out of my sohc 98 to make that my primary wheeler

 

[merlinx454]

Mine has been all over the place. This is the first set of codes I pulled:
335 EGR valve position/ pressure feedback voltage > or< expected
566 3-4 shift solenoid fail
629 Torque converter clutch solenoid fail
10 separator code
Then I replaced the EGR presser sensor and I have the same condition but new codes
2 trans codes and
113 IAT Circuit max voltage
118 ECT max voltage
123 TP circuit max voltage
157 MAF circuit min voltage
337 EGR valve position max voltage
542 Fuel pump circuit open PCM to MTR GND
543 fuel pump circuit open bat to PCM
Then I would disconnect random things and all went away when I disconnected the intake air temp sensor, they all went away except for the trans codes.
After that I replaced the IAT sensor. Currently I still get a check engine light most of the time but it always goes away when I push the clutch in.
410Fortune, it was an auto and I still have the auto ECM.
Also, I have the clutch switch installed and the 2 wires for the neutral safety switch connected..

As I typed this, I wonder if I got a wire swapped on the EGR pressure sensor since it is the Motorcraft that requires a plug change.

 

[merlinx454]

Update: The day I did the swap, I spliced 2 wires together at the neutral safety and drove the truck. A few days later, I removed the resistor for the clutch position harness and installed the clutch position switch. Today, I disconnected the switch and reinstalled the resistor like the truck came from the factory. Crank but no start. After that, I disassembled the clutch position and moved the contacts to the "clutch depressed" position. With this, all hesitation and bogging down ended. I have no idea why, but it appears to work.

 

[Fix4Dirt]

nice!!! not sure why either!!! glad its fixed though!

 

[merlinx454]

I am looking at the schematics and only finding 2 features of the clutch triple function switch. One is for starting. The other is a grey and red wire that links to a light blue and yellow wire when the clutch is depressed. The grey wire is ties into almost all the sensors and goes to the ECM. With what I called the resistor in (actually a clutch position jumper) that connection is there at all times. When the clutch switch is installed, that interrupts that. It has to be something in the programming of the ECM that if I got a manual ECM, it would not be a concern. Still scratching my head on this one.

 

[410Fortune]

3 position clutch switch

1 neutral safety circuit for starting
Clutch pressed in allows starter to run

2 four low shift
Clutch pressed in truck at stop allows low range shift for ESOF system

3 cruise control
Press clutch in de activates cruise control otherwise engine would rev to the sky

The grey with red is called sensor signal return it is one wire that feeds many sensors, the computer reads the voltages on this wire and can determine the position of many switches.

 

[merlinx454]

410 Fortune, I suspect that sensor return wire was the problem. Why the stock jumper did not work is a mystery to me. Sliding the clutch position switch to the depressed position took away the codes to include the ABS warning light and the buzz from the radio. My plan is to isolate the two wires from the clutch switch and connect them then re-attach the clutch switch as designed. After that I will build a two pieces of harness to replicate the auto trans solenoids.

 

[410Fortune]

That’s a wild one for sure! Good job actually figuring it out!!