Rpm switch problem car won’t start
 

Hi guys I’m kind of stuck

New RPM switch part of a kit with Leask WUR

All wired per instructions verified connections with MM..Power to solenoid check power to RPM switch check ground check

Car cranks fires stumbles tach jumps up to 7000 RPM and back...will not run

Disconnect white signal wire from the switch to black and Violet tach signal from CDI car starts normally runs normally

Disconnect ground from RPM switch car starts normally tach doesn’t work(white wire connected to black violet)

Since I had black violet wire exposed checked voltage to ground with ignition on ...six-ish volts not sure if this is significant normal etc.

Any ideas

Sorry I can’t help but I’m following- I have one in the box and was figuring on installing it once I’m back together. Is BL himself responsive?

Bought the kit from Brian at rarely l8 he’s been great and both of us scratching our head after I described to him the situation.

I believe he forwarded info to BL. I believe this is something in my electrical system but just speculation at this point. Everything seems to operate normally I did end up troubleshooting the yellow relay that was letting my pumps run during ignition on .....had a spare that solved the problem.

Also thanks for chiming in Ken ... looking forward to see your build.

I’m 600 miles plus into initial break in with my engine so kind of a bummer ....didn’t want to keep dumping 10 to 1 AFR during mid range...I haven’t adjusted the WUR threshold yet so may try that as an interim Band-Aid

I can send you my unopened one if you want to swap it in and see if it’s the unit itself.
I’m weeks from roadworthiness...
LMK

Awesome thank you Ken...sent you a PM

Replied and just saw your tools/stomski offer on my build thread. Thank you back!

found this on page 3 - may confirm my 6V measurement of blk/vlt tach signal wire with ignition on
http://forums.pelicanparts.com/911-930-turbo-super-charging-forum/489392-tach-not-responding-3.htmlhttp://forums.pelicanparts.com/uploa...1588000937.jpg

Tried another new rpm switch (thanks Ken!)..same behavior.

Went back to my sometimes working MSD box ...fired up normally although I didn’t test it driving. May have to go MSD route.

Unfortunately no solution to the original problem with the stock CDI.

Sorry to change the subject but I noticed your condenser without a fan and wondered if ac performance is as good as it could be.

http://forums.pelicanparts.com/uploa...1588423738.jpg

Yeah I definitely was thinking about it but other priorities took over if I’m moving AC is decent sitting in traffic hot weather it goes off on high head I just open the windows. But definitely something to consider for the future

Ok got rid of my German hillbilly test rig and buttoned Everything up MSD box switch solenoid good..... went for a 50 mile drive yesterday before the rain hit. Had a 4200 rpm chip...It’s working ...especially noticeable upon boost threshold car is much more responsive hi 11s AFR instead of immediately dropping to afr 10/high nines at about 3000 3300 before switch install. Appears to get richer 3500 to 4500 with a drop to low 10’s after switch opens solenoid.

Tough to watch all the gauges at once and the road...I’m going to take my youngster out for some observations...so far so good

So, your Leask RPM switch is working but only with the MSD CDI and not the original factory CDI box?

What do you think made the difference with the Leask RPM Switch working or not?

Thanks,

Rahl

Hi Rahl...that’s correct..msd6al2 yes..porsche CDI no....unfortunately I didn’t have the skill or the time to properly troubleshoot why it wouldn’t work with the stock Porsche CDI. maybe some thing with my stock box ...who knows?

Just a follow up..with the switch active ..boost enrichment delayed at 4800 rpm ...the afr drops as Soon as system goes from closed loop lambda control to open loop 14+ to 10s about 3000 rpm...Starts running out of fuel 6000 RPMAFR at low 13s....Time to start thinking about EFI in the near or intermediate future

If the only problem is running out of fuel then the fuel distributor can be swapped out for a Euro model or modified for more flow.

That sounds familiar....

Incredible difference in every respect. My only regret is not doing it sooner.

Appreciate your input Brian and Spuggy...this was not unexpected based on my engine build...I’m at the well traveled crossroads of mod CIS vs EFI...but have a few leaks I’m chasing...also I have some suspension stuff to take care ofhttp://forums.pelicanparts.com/uploa...1589745569.jpg
Will contemplate which way to go...Ultimate goals and use for the car....Also time and money factors