Why did my VDI & Aux port signals just quit?
 

Three weeks ago I pull out on the highway, everything works normal in 1st.
I shift to 2nd and the Aux ports & VDI quit. They have not worked since.

My setup includes an electric air pump that is controlled by a relay tapped off the 6PI solenoid.
I have checked the ECU by tacking a test wire to the 6PI output.
It does clamp, but not until 7500!
I get NO check codes from the ECU
I suspected something in the ECU's internal tach signals, so I put in another ECU -- same problem.

I now suspect an input sensor problem, but the ECU's I/O relationship chart in the FSM points to just about everything.
I don't know what the engineers are smoking when they use signal from the rear defroster switch to control the 6PI??

Here is the list:
Intake air thermosensor (engine)
Intake air thermosensor (AFM)
Crank angle sensor (G+, G-)
Pressure sensor
TPS (full range)
TPS (narrow range)
O2 sensor
Heat Hazard sensor (OK we go slow if the cat gets too hot)
Mileage sensor (Hmm- no VDI for the first 20000 miles?)
Back-up light & 5th gear switch (OK- I suppose I don't need the VDI in reverse)
Rear defroster switch (From here down seems bogus)
Blower switch
Headlight switch
Fog light switch
AC switch

So what can go out enough to kill the VDI & 6PI without throwing a code or causing some other symptoms?

No codes would seem to eliminate a problem with the first seven items on the list. Of course you never know.

My advice is to just go through it one by one, using the FSM's suggested order for "Lack of power, poor acceleration or hesitation."

1 Airflow Meter
2 Throttle sensor
3 Mileage sensor (there's where it gets confusing)
4 Neutral switch
5 Clutch switch
Etc, etc

If nothing seems to work, may be time to have the auxiliaries and VDI work off of an RPM switch and be independent of the ECU.

I just thought of something.
The pressure sensor may be late seeing the vacuum drop under load.

Can someone tell me if the orifice pill in the pressure sensor hose goes near the sensor or the engine?

No luck with the pressure sensor hose.
I checked to see if the orifice pill was blocked- It's OK.
I switched the hose around - still no luck

Still no luck. So far I have checked:
Intake air thermosensor (engine)
Intake air thermosensor (AFM)
Crank angle sensor (G+, G-)
Pressure sensor
TPS (full range)
TPS (narrow range)
O2 sensor
Heat Hazard sensor

I've spent my budget and I'm running out of options.
Any ideas??

I still have not found the cause.
The mileage sensor is closed, but I jumpered it anyway so it will not open at 200,000.

Er, ah, duh, are not the things that effect the 6 port injection the following?: AFM, WATER THERMO SW, CRANKANGLE SENSOR(NE), NEUTRAL SW, CLUTCH SW??????????

I can't jpg the Relationship Chart, but the *O's* are the ones I'd be looking at if I had a problem with the aux ports solenoid not opening.

The X's are the one's that have nadda to do with the problem. Right?

I'd be checking the neutral sw and the clutch switch.

OMG - I was assuming the X's were the relationships.
I will start over this weekend.
I have not checked the neutral & clutch switches yet. They sound like a good bet.

Thanks for the reply. I expect there are others with this problem also.

My wife says I don't need to go fast, so I told her "I'll just put a board under the gas pedal on your 300HP northstar & we will see if you miss your high end!"

****OMG - I was assuming the X's were the relationships*****

Not to worry. I made the same assumption (assume: make an ASS out of U and ME. humor) the first time I saw that chart. The first time I mentioned that chart I got it ass backwards. J-RAT straightened me out real quick on that.

X's should mean that item applies and O's that it does not, in my opinion. In real life it works just the opposite. It's the same problem with reading the ECU pins. They read from right to left. Just ain't natural.

BINGO! - Both switch signals from the tranny were dead.
I had to jack it up, go under & clean all the switch connectors.
The main problem was the bullet connectors in the 12v source wire.
The 6PI & VDI don't kick in at half throttle like they used to, but at WOT I'm in business.
So - I wasted 6 hours chasing X's instead of O's.

;)