No RPM Signal In MT
 

I finally decided to tackle a parrallel MSI build on my '97, but I'm having some issues.

I built and modded the board myself. Everything checked ok w/ the stim. Being a bit of a wuss (and its my DD) I'm connecting all the sensor inputs first to double check everything, then I'll add the fuel and spark outputs when its all settled.

I hooked up most of them w/ no issue. I soldered everything into the stock harness such that they are shared with teh stock ECU. (Boomslag parts on backorder) Down to the last one, RPM input. No start. I attatched the grey shielded wire to the position shown in Braineak's big DIY MS thread (white wire on the stock ECU). With the MS plugged in, the car won't start. When I disconnect it everything is normal.

I've checked that all my jumpers an mods are in palce and correct. I checked the schematic for the '96-'97 models but it doesn't look like there's an RPM input to the ECU.

Am I pulling the signal from the right place? Or should I look to MS hardware issues?

I am running COPs if that makes a difference....

Thanks.
--Alex

There are two inputs for the tach, CKP and CMP. Do you have both connected?

Yes, just confirmed.

CMP - Yellow / Blue wire to pin 25 of DB37
CKP - White wire to pin 24 of DB37

--Alex

Are your codebase outputs setup correctly? Reference the MSPNP msq for the correct settings.
mspnp.com

They should be. I've loaded the PNP base maps.

I'm thinking it's got to be a hardware error for it not to start on the stock ECU. Can the CKP, CMP signals be shared with the ECU and MS?
--Alex

probably not your problem but i had been having problems with mine getting tach signal, ended up fixing it by reinstalling megatune, at the very least it's quick and easy

Tried again, not luck. Double checked the input mods. They all look and measure ok. D1 and D2 are jumpered.

CMP is hooked up with not issue. When I connect the CKP to pin 24 I get a no start. I tried disconnecting the stock ECU to see if signal sharing was the issue, but no RPM in MT.
--Alex

Just checked through the U3 opto isolator circuit. Seems to be good.
--Alex

Edit: Nope thats not it.

Ill think about it and get back to you. I also have a 97. But I made sure my tach worked with the stim prior to modding it.

Yea, mine worked prior to the mod. I used the stim 2.1 not the Jim stim though. Couldn't test it after the mods.
--Alex

will the car not start or do you not have a tach signal?

From how I read it, Alex can't get his tach signal to read. He also can't start his car when the MS is plugged in. The MS is not hooked up to control anything, but just to read sensor inputs.

Perhaps you've wired one of your sensor inputs to the wrong wire and it's wired to an output of the MS, causing the signal to the ECU to be extremely wrong and the car won't start.

As it turns out there was a single strand of shield grounding the CKP signal. Should have known to check that sooner. It's almost aways a silly little problem. All is good now.... On to outputs.

Thanks for the help.
--Alex

Been there done that :)

...and she's running fuel only now. Started as normal on the PNP map. Time do do a bit of tuning and set up for ignition control. Thanks again.
--Alex