1990 vert : key turned on until warning lights come on engine not running. I Have a ticking coming from under the lower intake manifold. Really sounds like injectors pulsing... I assume from memory this is the primaries? Unplug the connector on the far left of the ecu and it goes away... so I dont know exactly what injector is pulsing but one of them is. The ecu has been wet and it runs really rough and smells rich as hell. So is this suppose to do this? I remember on my 1988 vert I had, all there is a click and the beep beep from the interior beeper...

 

That ticking is the BAC. Try running the ecu test jumper, I bet the ticking will stop.

Sounds rediculous, but it helps narrow it down.

 

Nope, jumping it doesn't work. Can't get the ecu to even show me the codes. I got a tested and working ecu coming. Check engine light comes on and it smells like gas bad! Ecu smelt funny too and had a large amount of water in it.

 

you fried the Ecu when you put power to it,since it was wet it shorted out **** inside it!
Don't use it any more.Wait until you get a new one...please!

 

I have a degree in electronics kind of curious now ... Is there a schematic available for the inside of the ECU? I see inside 7 hex buffers, 2 PIA, 1 CPU, 1 8 MHz crystal, looks like a 27c256 EPROM the program runs on. Got a whole box of those programmable ic's.

 

You have a degree in electronics and you needed to ask why the ecu smelled funny with water inside it? Wow... just..... wow!

 

Never asked why it smelt funny... I just mentioned it did.

 

Anyway, to end the saga... Just in case someone else wonders... I fixed the ECU, connector pin location 3W (front rotor primary injector) was pulsing to ground at ~ 2HZ (cycles for second). Dumping the entire fuel rail contents into the engine.... Never could find a schematic, so I traced the circuit back to bad HEX buffer 74HC00 chip. 25 cents later and a socket... Runs pretty damn good!

So in closing it wasnt the BAC valve, it was in fact an injector clicking

 

Oh and if anyone wants it, I also dumped the contents of the EPROM... Be nice to have some of those 'speed' chips and see what they changed in the program. Of course I think all the chips are for T2's but anyways. If someone has a chip laying around and needs them copied (for backup purposes only ) I can do it, I have a programmer and a stock pile of reusable 27c256 eproms

 

Hey Mike! My car has these same symptoms with the front rotor primary injector. I took the intake manifold off and with the key ON can hear and feel the same injector clicking rapidly and intermittently. My ecu on the other hand doesnt smell and isnt wet. But Im stumped once the cover is removed from the ecu, what and where is a "HEX buffer 74HC00 chip" on a rx7, and how can i tell if mine needs replaced? Thanks!