Engine momentary power loss

[Mauritian Maestro]

Got a 1.6 R series 84 maestro with only 34k on clock, that refuses to behave itself. Originally used in UK, was exported to Mauritius 10 years ago by 1st owner and serviced by the local rover dealer (what a ******g joke) until I took ownership recently.
When beginning to labour, up hills etc, engine loses power momentarily, creating slight lurching and general annoyance of driver *GGGGGGRRRRR*. Had it down to local mechanics who've given it usual full servicing and checkup and can't seem to find any problem. Anyone able to suggest what it could possibly be? I'm starting to wonder about its automatic choke system from seeing forums here, but happens on a warm engine also, and thermostat recently changed and checked. Carb problem? though after thorough cleaning and tune, no change.
Fuel was recently changed here from leaded to UL without LRP being made available, instead just a lead substitute additive which seems to be working fine. could this be the problem? If so what can I do?
Apologies if ridiculously obvious, but I'm a LONG way from being mechanically competent (as apparently is my mechanic), though I hope to learn soon, cos I ain't paying people to fail to fix my car for much longer.

[Beaker]

You tried the distributor cap?

My 1.3 used to lose power when it was warm momentarily, you'd shove your foot down to clear it then end up racing down the road. (It wasn't fun when there was ice and snow on the road) It normally happened after wet weather.

I changed the distributor cap and its been fine ever since.

Lindz

[threelitre]

Hi!

I could imagine another reason: The carb could be adjusted to too lean mixture. This could lead to some hesistation on picking up power. Did you have it on a CO-tester? It shouldn't read below 2.5%. The other (simpler) reason could be that the dashpot in the carb is not sufficiently filled with oil (look in your driver's handbook for that). But I would assume that the garage would have looked after this.

Regards,

Alexander

[E_T_V]

Yes agreed. First check dashpot has oil in.

After that check vacuum pipes are all ok and attached
Then check mixture is ok.. (which way is to remove spark plugs, if they are white then the mixture is too lean, they should be light brown/grey)
Check the distributer and rotor arm, and then check timing is ok.. For unleaded it may need adjusting by 4 degres I think

All easily fixed in a few minutes by DIY or mechanic

[MaestroMatt]

If you don't want to fiddle with the timing them avail yourself of some octane boosting lead additive which will increase the unleaded petrol's octane rating to that of the leaded. This could well be your problem. If it turns out to be a worn dizzy cap / rotor arm then fire your mechanic as this is a basic servicing procedure!

A vital piece of servicing on the auto-choke is the replacement of the O rings. Search the forums for the word "viton" and you will find the correct seal size. Elsewhere there are instructions on how to do it (takes 10 mins tops). It makes an immeasurable difference to the running of the R series.

[Mauritian Maestro]

Thanks for the help guys,

am changing mechanic, but now intend to learn to do as much as poss myself. Ordered Haynes today.

will be changing O ring just in case - cos so many appear to have had problems with it.

Have checked vacum pipes and dashpot - would you beleive mechanic that had it apart, didn't fill it properly at all, but still have problem (though apparently less), and now not idling very well any more. odd.

CO testers here are few and far between sadly, and often those that have them never bother learning how to use them, but am looking for someone that does. Meanwhile back to the good old days of mechanics. LOL.

Having investigated distributor cap, I don't think it is this, (hope not anyway as replacement been quoted 6 week delivery - I can get any maestro part imaginable, apart from what I need. LOL)

Cheers guys. I'll let you know what happens

[Mauritian Maestro]

well, finally turned out to be the ignition coil. Only problem now is the poor baby refuses to idle cold. Still that should be an easy fix (hopefully) as soon as I get a dry day to look at it!
thanks for your advice and suggestions!

[Mauritian Maestro]

aaaaaaaaarrrrrrrrrrrggggggggHHHH!!!!!!!!

Its happened again. after 1 week of nice running its gone again.
surely electrical. something burning the coil!

[G Force]

Hi there, sorry to hear about your on going problems.

I think one thing that would be worth checking is the pick up winding inside the distributor. On the early Lucas electronic ignition as fitted to the R series and some very early 1.3 A series maestro’s (non modular type), because the pick-up coil moves with the base plate and vacuum advance mechanism, the wires from the pick-up eventually used to break inside and go open circuit. The problem would first manifest it’s-self as a misfire, as in your case, then eventually the car would not start.

You can check the pick-up winding quite simply with a multi-meter as follows. Disconnect the wires at the blue plug next to the distributor, then check the resistance between the two wires in the plug at the distributor end, I’m not sure of the exact reading but I seem to recall around 2.5K ohms is somewhere near but check the manual if you have one. Then remove the distributor cap and rotor arm and dust shield, then disturb the pick-up coil wires where they are bent double and see if the meter reading goes open circuit. If it does go open circuit then the pick-up coil used to be available separately.

This type of fault seems to tie up with your symptoms, because your misfire happens just as you put your foot down to climb hills, assuming the vacuum advance is still working on your car then at this point the base plate would be moving to retard the timing and thus disturbing the wiring for a split second.

Cheers Gary.
] ;)