not a noob question, no spark no fuel....

[97-TSi-Hx35]

so I just got done building my car and getting ready for a tune, and I cant get fire, so I checked my 6 bolt cas wiring according to rre im good to go but I have no check engine light coming on my dash when I turn the key. so I did some trouble shooting with some ecu pin outs. so all the ecu grounds are good less than .004 ohms resistance and backup power (pin 80) is reading 12 volts, pins 12 and 25 are supposed to be 12v switched power but my readings actually came back 0v (I jumped power now) and cas is working



TURNS OUT MY IGNITION CIRCUIT ON MY ECU CRAPPED OUT REPLACED ECU AND IT FIRED RIGHT UP

 

[SubversionX]

I'd like to see some progression on this thread. I'm having very similar issues. If you can find the MFI SYSTEM in your service manual, it shows that pins 89 and 88 lead directly to your CAS/CPS.

When you checked the continuity of the CAS, did you turn it by hand to check for 5VDC pulses? Or are you not getting any power to the CAS at all?

Another common thing you may want to check, is your power transistor. I've talked to a handful of people who have seen this as their main issue.

Like I said, I'm having similar problems and would like to see some help from the DSM Gurus. I'm not getting 12VDC from pins 12 or 25 either and was wondering what could be triggering this? They both lead to the MFI Relay onto the entire ignition switch. However, this is foreign territory for me, and I hope some of this helps, and I hope you have better luck than I am. Let me know what you find out!

 

[97-TSi-Hx35]

last night before I left my house for school I pulled the engine harness and I did some diagnostics found the problem with the cas, it was completely disconnected the white and red wire was cut and so was the white and blue? so now I have continuity on both wires. I think also my mfi relay is shorted because when I plug it in, pin 12 and 25 become grounds and they are suppose to be 12v switched power?

so I still didn't have power to the ecu so I jumped power to pins 12,25 and I got the injectors to pulse. so I checked for spark and I had spark on 1&4 so i swapped the coils out with a spare I have and still 1&4 only, I tested continuity from the ecu and the ignition transistor and both a and b coils have communication from the ecu to the tr plug, I got the cas working now, along with injector pulse but still no check engine light!?

oh and btw after I played with the multimeter on the ignition wires now I have no spark!!!????


what else can I test and what should I look for?

this is my 5th dsm and I have been building this purpose race car for 10 months and this electrical problem is getting really old I just wannna hear my hard work pay off with the first start up!

 

[sniver]

Hey I figured I'd chime in. I got your message, but haven't been online in a few days. Soon as I get off my phone and on to a computer I'll read this and see if I can help.

Edit: Looking over your post there I'd say the ignition system or the mfi system could be at fault. Pins 12&25 get 12v from the MPI relay. This happens by pulling the pins 8&38 (allows power to pass the the mpi relay coils)to ground after the ecu gets ignition switch power. Which in turn connects pins 12&25 to the positive battery power.

Not sure if you got this running yet, but I'd check all fuses, battery connections, and grounds(stated these are good). then I would test the mpi relay as per the FSM, and then the ignition switch as per the fsm. After that I would break out the schematics and test each wire. If you have nothing obvious here, then you have to options, swap ecus and see if that makes a difference, or load test the wires. Load testing is good for spotting poor terminal retention, and chaffed but not shorted wires.

Since it doesn't take much to ignite an ageing car without fused protection, I am hesitant of posting a how to load test wires on here ,due to the fear of someone melting there car down. The idea involves using the questionable wire as a ground lead for something like a brake light bulb, which has power to one lead, waiting for its ground. One strand of wire can have no resistance, but have no ability to carry current.

If you don't have the fsm, search my posts, it's around;or if you want it explained, let me know, and I'll see what I can do.

 

[97-TSi-Hx35]

so i figured out that i have a 95 harness and a 95 mfi relay... what wires do i jump to get power to the ecu off the mfi relay plug ir its bad?