Well heres whats going on. For the past few weeks the check engine light would flicker after letting off the gas on a high RPM run. I would tap the gas and it would go off. Well the other day it stayed on permanently and I noticed my tach stopped working. I started the car today and all was fine. While driving, I watched the tach die again, and again the check engine light came on.

My question is what could this be, and what can I do about it. Also, if the ECU and SAFC isnt getting an RPM reading, what will this do for control of the injectors. Im staying out of boost while the light is on just in case. Thanks in advance!!!

 

any help?

 

I do know if the trailing ignitor goes bad the tach does not work. Are you losing any performance? Have you checked the codes?

 

I had an MX6 that did some similar strange stuff when the alternator was going bad.

 

If the check engine light has been on then the ECU has generated and stored an error code. Find out what it is before you start following random guesses...

The tach is driven by the trailing coil pack, so if it stops working it might indicate coil failure. This will also generate an error code.

Do you see the pattern here...?

http://www.johnr.com/cpucodes.html

Fuelling is not affected by trailing coil issues. The ECU gets engine speed and position info from the CAS, and then triggers the coils accordingly, which then drives the tacho. If you wired the S-AFC according the Apexi's wiring diagram, it'll be getting rpm info from the ECU.