Rev Counter Jumping Up And Down Without Engine Speed Changing

[mikespug 1]

Right where do I start ..... I needed to go to yarnton (24 miles from my house) today so thought it would be a good little run for the pug after all the work that's been done (head gasket/water pump/ ht leads/ coil ect) Was running sweet Sun out music playing and enjoying life got to yarnton all ok jumped out the car left it running with my mate in it done what I needed to do (took about 5 mins) got back in the car to come home but as I was putting my seatbelt on I noticed therevcounterneedlejumping around but theenginedid change !! Worried about it I giveita revSheseemed to missfirea little. ThoughtI would give it a go at getting home but trying to drive was I nightmare as was miss firing like a woof pulled over and turned her off checked everything under the bonnet everything looked good apart from a very small splash of water on the coil. Got back into the car she started and run fine all the way home I then left her running for about anothr 5 min on my drive and she started to do it again (woof)

 

Could this be down to coil? Don't know if I should spray WD40 over it all to waterproof everything ?

 

Anyone else got any ideas or know if it would be ok to use WD40

[DamirGTI 342]

Sounds like ignition issue (bouncing rev needle , misfiring on fully heated engine) , ignition amp and coil would be first on my list as a suspect

 

D

 

.. also , for fine electric components (like the ignition amp. , ECU , various sensors ... and by all means the wiring itself) WD40 is not as good as electric/contact spray ... there's special sprays for fine electrics which does both cleaning oxidized surface , protecting it from further oxidation and also act's as an demister and leaves a mist preventive film on sprayed surface .

Edited February 16, 2013 by DamirGTI

[mikespug 1]

Thanks for the fast reply mate the coil and ignition amp are only a two or three weeks old will have to pull it all off and have a look what is the paste called on the back of the ignition amp as will have to get some more

 

I really don't like electrics lol

[DamirGTI 342]

Which brand is the new coil and amp. ?

 

D

[DamirGTI 342]

checked everything under the bonnet everything looked good apart from a very small splash of water on the coil.

 

Curious about this , as you've said , was a sunny day ... did this come from the bonnet down to the coil during the morning mist or was the day before raining or something ?

 

Water , heat and vibrations are big no for ignition system components !

 

Also id do an quick test with a block tester for combustion gasses , hence the recent HG change , just to rule that out .

 

D

Edited February 16, 2013 by DamirGTI

[mikespug 1]

Can't remember what make will have a look tomorrow and get back to you

 

As for the water I don't know think it mite of leaked out of the water bottle under pressure as the bottle was a little wet did wait for it all to cool down and checked the water and didt seem to of lost any :$

[mikespug 1]

Right no markings on the coil or the amp but have replaced them both with the old ones I took off will.see how she gos tomorrow thanks for your help bud

[DamirGTI 342]

If they're unlabeled/unbranded parts , it's very likely to be some cheap aftermarket ignition parts ... which our 205's don't quite like

 

If you're on for a trip , i'd take with me as an spares : coil , ignition amp (Bosch blue amp is , by far the best) , set of spare spark leads , and dizzy (could be a worn dizzy signal cable ..)

 

D

[ALEX 98 1 Cars]

Check the tachometric relay.

They can get a bit burnt out and still work, giving you the symptoms above.

Do you have a spare you could try?

[mikespug 1]

Tachometric relay ? Where abouts is it ?

 

Thanks for the reply peeps she seems to be ok at the mo but need to take her for a good long drive

What I did find was when I took the old amp off I had trapped a wire behind it (wire not used for anything) but ment that the amp didt have full contact to the plate could this of caused the problem ?

[ALEX 98 1 Cars]

I'm not sure if the ignition module is earthed on to the plate, I think it's just a heat sink, but I could be wrong.

The Tach relay is usually near the ECU above the drivers right knee.

[welshpug 1,661]

yes, its just a heat sink, there's an earth in the multiplug iirc, just happens that the battery to chassis earth is bolted to the plate as well.

[DamirGTI 342]

Yes , the burned out diode inside the tachy relay caused also similar problem to me long time a go ..

 

But it wasn't misfiring , just cut out completely during the driving and restarting back after a few min. of waiting .

 

The non connected wire which you've seen around the coil/amp , it's mostly purple/bluish wire with female single connector - unconnected .. it's for some ignition testing purposes , well was during the 80's with the servicing tools of that time .

 

D