1990 1.6 slow throttle response and lower rev limiter

Technical Area Engine, Transmission, Exhaust etc
1

Hi all,

I’ve had a new engine fitted to my 1990 mk1 1.6. It starts and runs fine and pulls well, but does a few weird things and i’m wondering if you can help…

For background Its an automatic engine fitted to a manual car, the wiring loom is a manual loom but all sensors things like the throttle position sensor are from the auto. The weird things it does are as follows:

  1. It seems to, sometimes, hit an invisible rev limit at around 5.5k rpm where it completely and violently cuts power. Sometimes it doesn’t do it all.

  2. When its running fine and i accelerate through the revs, the rpm needle bounces about but the revs climb normally.

and 3. It doesn’t seem to pick up very nicely, if you try and blip the throttle, it faulters for a split second before picking up. Just bad throttle response.

It all got slightly better after I used a tank or 2 of Shell V Power.

Things i’m going to try: Redex (the engine was sat for a while before being used) and a fit a new throttle position sensor as it seems they are different for manuals and autos.

Any advice would be great!

Thanks,

Will

2

That usually has the rev-counter feed from the IGNITER module that sends current to the IGNITION-COILS. Check both those elements and their connections first before spending money! Very fiddly at the back of the engine, but…

See Mellens for the Wiring.pdf etc. A USA site but most of the info applies to both LHD and RHD MX5s.

3

Ahhh thank you! I will look into this, might do the job!