Rev limit at 3100 rpm

[March Hare]

Hi
My March 1.3 has a strange fault. Starts and runs fine, but once properly warm (after 15 miles or so) it wont rev past 3100 rpm. It behaves just as though the rev limiter has kicked in.
It doesn't do it all the time, just sometimes for a few minutes, and then clears again. While this is happening it drives perfectly if I keep below 3000 rpm.
I have resoldered the TB joints, just in case, to no effect.

Has anyone else come across this issue?

I plan to cover the hole on the rotating disc inside the distributor, to disable the limiter. However, after removing the dizzy cap and rotor arm, there is a plastic cover plate which I cannot see how to remove without damaging it.
Any tips on getting this off, or another way to disable the limiter?

Advice welcome, thanks.

 

[frank]

you have to take the screw out the side of the rotorarm, then remove it to get the cover off iirc
and i managed to squeeze some tape on with the disc in situ

 

[March Hare]

Hi Frank
yeah, got the rotor arm off.
Is that plastic cover just a push fit? I don't want to lever it off. SNAP!

 

[solarice]

The cover is held down with two (iirc) star headed screws.

 

[March Hare]

Ah, I see. Of course..
Thanks (Y)

 

[solarice]

no probs

btw im not sure, but your problem could be because the dizzy is on its way out...or maybe your getting signal interference somewhere.

 

[Stani1029]

i had this exact problem and i cant remember exactly what it was but i can tell you it either one of the sensors on the throttle body, your ecu or the distributor as said above

 

[March Hare]

Ok some progress.
I had it out for a longish drive yesterday, and when the fault kicked in I pulled up, revved the engine and wiggled cables and plugs.
Hey presto - the fault lies with the throttle body. If I wobble the plug (from Mass meter) the car will either stall or rev correctly. It seems to be an intermittent connection - maybe the famous dry joints.
Any known problems with these connection plugs?
I did have the cover off the TB and resolder 3 joints already, but now I suspect I did the wrong ones...

 

[solarice]

could try wd40ing the connectors...mine after the rebuild had issues and that solved the probs with the loom.

 

[March Hare]

Sorted!
It was the throttle body. This time I took it off, put in on the bench and went at it carefully.
Just to be clear, it is the three joints connecting the board to the plug that needed doing. (Last time I mistakenly did the three on the board itself.)
As soon as I opened it I could see one looked bad. Having it on the bench meant I could get my solder sucker in to it, so I did a proper job :grinning:

The car now runs perfectly.