M52 conversion wont rev past 5000rpm

[Spannerste]

I've nearly completed my 2.8 conversion and put an ecu on off an e36 with the ews delete and m50 manifold map. The car revved fine on the spot but when i took it out it wouldn't rev over 5000rpm. I've tried a different ecu and that is fine the car will rev right up .
Just wondered if the ecu goes into limp mode or anything or if it could just be a faulty map and anyone has had the same problem ?

Thanks

[aivaras325]

Kinda sounds does sound like its in limp mode. Diagnostics should show if ECU thinks something is wrong. 2.8 engines have stuff you need to delete, like did you delete rear silencer thingy that makes it open or close if you removed it? Also I read about some Secondary Air Pump and rear exhaust o2 sensor (could be just US things tho).

[DanThe]

Will be speed signal, give me a shout and I can get rid of it on the ECU

[Brianmoooore]

Will be speed signal, give me a shout and I can get rid of it on the ECU

Why not just connect it up?

[aivaras325]

As far as I read:
Speed signal comes from differential. On facelift modles it easy - its in a loom, on pre face lift you need to run custom wire do dash cluster or smth. (I might be wrong, sorry if I am)

[DanThe]

Some E30's dont have the wiring for it, and some clocks dont even have the needed circuit from the speedo to the output pin on the socket. I do agree its much better to have the signal, but not everybody is able to wire it up and most of the time its not worth their time or interest, especially if the ECU fix comes with a remap/EWS delete package anyway

[Spannerste]

Silly as it sounds will it make any difference if the speedo isn't working ? I didn't check that

[Brianmoooore]

The missing signal is processed by most of the same circuitry that drives the speedo, so most likely no speedo = no speed signal to ECU.
Very few clusters in use today will not have the speed signal available.

[DanThe]

Yep, if the speedo is not working the ECU will not be getting the signal so will go into limp

[Spannerste]

Great I'll try that then , failing that it will be coming to you dan , how do I reset the ecu is it the terminals together? Thanks

[DanThe]

No need to reset anything, just give it the signal and it will sort itself out