Mk1 1.8i My rev counter packed up and I really need to find out what’s caused it and/or to find someone who knows what they are doing with these in Essex/Herts/East London. It started intermittently ‘flickering’ for a couple of weeks then gradually died a death.
I’ve changed the instrument panel and still dead - so not the dial itself. It’s the 1.8 so doesn’t have the ignitor. Someone suggested the coil pack - but the engine runs sweet and I’d have thought if the coil pack was naffed then the engine would be missing. Any quick fix ideas or know anyone who can look at it?
What year is your car? Halfway through 1995, there was a change in how the rev counter was triggered. Up to around August '95, it was fed from the igniter that was integral with the coil pack, after this date, it was fed directly from the ecu. Earlier 1.8 had 4-pin connectors on the coil pack and a 2-plug ecu, later ('96+) had a 3-pin coil pack and a 3-plug ecu. Confusingly, there was an interim arrangement between mid-'95 and '96, with 4-pin coil packs with only 3 wires connected, and a 2-plug ecu, with the rev counter fed from the ecu. These cars are known as '95.5s. Establishing which version you have will help to figure out where to look for the problem.
Ok, so your rev counter is fed from the coil pack. I guess start with the easy stuff - check and clean the 2 coil pack plugs and check for breaks in as much of the associated wiring that’s accessible. The tachometer wires are the black/white ones, they run from the igniters buried in the coil pack, to the diagnostic port, to the ecu on pin 2i (for a voltage pullup), and to the dash. I have a wiring diagram, but can’t include it here as photobucket won’t host any more. I can email it to you if you pm me with your email address.
Neither had I, until I fitted a Megasquirt 2 PnP to my mid '95 UK 1.8, and lost the tacho. It was quite baffling, since the coil pack clearly had 4 pins, but after a lot of digging on the web i found out about the '95.5 only having the 3 wires connected, and the signal for the tach supplied by the ecu. The solution was a minor jumper relocation in the MS2.
Hopefully it is something simple like a dirty contact on the low tension wiring but I think unlikely.
Easy to swap your coilpack onto another early MK1 1,8 or any Eunos 1.8(popup headlights) to see if the problem is repeated.
No need to remove their coilpack if you can get the low tension plugs off without removing - just rest your pack on a cloth on top of the cam cover and fit the wiring.
Learn something every day with these cars. I thought that the three pin coilpack and ecu driven tacho came in with the BPU2A ecu, Temic immobiliser and transponder key.
Yes, original ecu is BPS4. The coil pack with connectors is exactly the same one as the earlier ones, and presumably interchangeable, it’s just that the black/white wires are missing from the loom. The rev counter is fed from pin 1f on the BPS4, which is redundant on the earlier versions. The immobiliser was unaffected by the ecu change. I believe they only made the 95.5 for a couple of months, but there’s probably quite a few out there still.
Update. So, I had replaced the rev dial, then the whole instrument cluster, then did checked the coil pack connections, then cleaned the various earths, then replaced the coil pack - still nothing …turned out to be a break in the wire that runs through the bulkhead to the instrument cluster. Works now. I’m soooo happy
Thanks to everyone for the advice, suggestions and wiring diagrams.