Bouncing tacho in 5 litre

[vsv8berlinawag]

Only happened the other day, but while the engine is warming up and while it is being driven the tacho moves erratically and the engine looses power at the same time especially when you floor it. I have replaced the leads dizzy cap and rotor button approx 2 - 3 years ago and the plugs only the other week. Once the motor has warmed up to normal temp it is not as bad, but it still seems to be not there. Any advice would be great !

 

[Boonz]

check the negative terminal on the coil:thumbsup:

 

[vsv8berlinawag]

If the coil was on its way out what dare I ask is it like to replace and how ?

 

[Cursed CX8]

isnt the tacho in the vr/vs computer controlled?

My boss recently had very similar problems in his mazda 6, the tacho would bounce and stop working and when cold the car was crap

turned out the alternator was gone and was not supplying enough power to run everything

 

[KRUPTD]

Easy fix mate replace the ignition leads.You mentioned you replaced them 2 or 3 years ago.Thats a long time.Well on the 5L's its very common for this to happen.I had a VR 5L stato and whilst cruising the tacho would flicker not like in big rates but if you watched the tacho needl cruising at 50km or 60km it would fluctuate.So i replaced my leads and problem was fixed.

 

[383 hatch]

Ignition module could be on the way out. They generally make the tacho bounce when they are on there way out!

 

[vsv8berlinawag]

If the coil was on its way out what dare I ask is it like to replace and how ?

Well I thought I'd start with replacing the coil. Far out how do you get these buggers out. I managed to take the bolt out that holds the coil but after that........ there is just far to much plumbing and very little room to get you hand in to undo the +ve and -ve leads let alone taking the coil out. Apart from cutting a huge hole thru the dash and firewall are there any secrets, hints, tips etc to get this out ?:bang:

 

[vsv8berlinawag]

Update -> managed to get coil out and replaced it with new. Did zip so replace leads and plugs or just pay the man bucks and get it diagnosed ?

 

[vsv8berlinawag]

Easy fix mate replace the ignition leads.You mentioned you replaced them 2 or 3 years ago.Thats a long time.Well on the 5L's its very common for this to happen.I had a VR 5L stato and whilst cruising the tacho would flicker not like in big rates but if you watched the tacho needl cruising at 50km or 60km it would fluctuate.So i replaced my leads and problem was fixed.

Thanks man, you theory was basically spot on. I bought a coil to cap lead and presto no more flickering needle and the ol' 5 litre purrs like a Lion ! Cheers Ron

 

[ElDubya]

How did you end up getting the coil out? I am having similar dramas and can't even see the bloody coil, let alone take it out.