Problems with 90-93 MSPnP
 

Alright so here is the deal. MS has been driving me nuts. I will just let everyone know what the current symptoms are and see what the suggestions are to fix this mess.

MS turns on like normal most of the time. Every once in a while you have to tap the gas and the ECU will turn on. When I am in realtime display the second you turn the ignition to run the TPS signal starts climbing without touching the gas pedal. It seems to go up in 3's ex: it will start at 6 when you first turn the ignition on the it will go 9,12,15 etc. The car cranks very slow no matter what battery I use.

Things I have checked so far:
all grounds
starter connections
TPS (I am a little lost as to what this should test out to)
all harness connections

I hope some one can help me on this.
Rich-

what model year car is this going on?

if it's cranking slow, check your cranking rpms under cranking settings in megatune.

Cheap, I'b obviously start by disconnecting the TPS itself to see if this changes the character of of the problem. It's not impossible that something inside the MSPNP is malfunctioning, but it's also possible that you car has some unique pre-existing wiring problem.

It's my understanding, from talking with the guys at DIY, that the MSPNP for 90-93 does not use the stock TPS at all. Thus, this busines of TPS causing the ECU not to start is indeed puzzing, and its removal is warranted as a troubleshooting step.


N3v, are you implying that the MS controls the speed at which the engine cranks?

Braineack- it is a 90 chassis with a 1.8L swap

Joe Perez- I will try disconnecting it and getting back with what happens

i have a settings page in my software for the cranking speed under 'more cranking stuff'. I figured it probably can't make it faster but i assumed it could make it slower.

Nope.

The connection to the starter from the battery does not go though the ECU. You turn the key and depress the clutch pedal and full battery power is supplied to the starter motor. The speed at which the engine cranks is determined entirely by the state of charge of the battery, the condition of the cabling and connections in the starter system, the temperature of the engine, etc.

The field in MT where you enter cranking speed describes to the MS what rpm condition it should consider to be cranking. It doesn't know when you're turning the starter directly, yet it needs to know when to switch to the cranking advance and cranking fuel settings. Whenever it determines that RPM is at or below the cranking value, it assumes the engine is cranking and adjusts fuel and spark accordingly.



I suggest you study your wiring diagrams (and for that matter, how cars work) a bit more closely.