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Rover K electrics - Misfire under load?


Steve Day

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Calling for help regarding a potential electrical problem.

 

My car - fitted with Rover K / DTA ignition - is misfiring under load. By this I mean that it is OK if the engine is blipped from tickover but pops and bangs if held at say 4000 RPM and then gradually increased. The peak revs it will achieve in this situation is around 6500 (usual 8K plus)

 

We have checked fuel flow etc and all seems OK wrt to this plus the injection system / throttle pots all seem OK too.

 

There was a question regarding the battery (and a new one is on its way) and if this doesn't cure it then maybe it could be the Alternator.

 

My question is this - is the car likely to misfire as above if the battery shows an OK state when not connected? (i.e just off of the charger). Is there any battery only condition that would allow the car to start run at tickover but yet not produce full 'clean' power...or does this suggest the alternator?

 

Sorry if I seem dense, but I am not an auto electrician...or an auto anything come to that! wink.gif

 

cheers

 

Steve

 

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A buggered battery can show good voltage at zero current and then drop rapidly as current is drawn. Your alternator is responsible for the current delivery - the battery just buffers it. If the alternator is OK then it isn't the battery. Measuring the voltage across the battery when running will tell you if the alternator is OK.

 

I would check the spark plug gaps and possibly invest in a new set. This tends to have rev-limiting propensities.

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Hi...thanks!

 

John - yes - I will call Ian

 

Tony - Don't think it's pre-ignition, although RRoad will test this on 15/4 - fuel is new

 

Peter - is it safe to do this with a standard voltage meter? and what plugs would you run...currently have some form of NGK (not with car so can't tell exactly) I think they are EP 8 R (or something...?)

 

Dave - Thanks I will check the cap!

 

Cheers to you all!

Steve

 

 

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Hi Steve

Going to France again this year??

I had this problem with my car, 1.6K & GEMS ECU: persistant misfire at 6000 rpm in 5th & 6th. Mapping was OK as was the alternater, battery, leads, coil, dis. cap, rotor arm, plug gap as all were checked/changed! It was completely cured by changing from Bosch FR7DC(new plugs) to NGK BCP7ES plugs.

Mick

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  • 2 weeks later...

Hi

 

Just thought I would feedback on the problem. It was the battery!

 

Amazing...I changed to a new one and the problem was sorted! Just shows how sensitive these ignition systems can be to a drop in electrical power!

 

Thanks to you all for your help! thumbsup.gif

 

The R/Road session was enjoyable and the car is now going quite well! wink.gif

 

Cheers

 

Mick - I am going to France, but not in the Se7en!

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