Not your normal erratic RPM problem.

[Ken555]

Thought I would share this for those that might have the same problem.

In the last few days I have been chasing a erratic RPM reading problem.

First noticed when the car started to hit the rev-limiter at 3000 rpm, along with the shift lights flickering.
On plugging in the Computer I was getting readings of between 900-10000+ Rpm, causing the problems.

So I started on a VR sensor gap checking, followed by a wiring check, then EDIS swap, VR swap, MJ check for "dry" joints, the full works.
Nothing made a difference !

Then for some reason I remembered that I had swapped the sparkplugs from a set of Champion RN9YCC to NGK BP6E S

Swapped the old plugs back in, problem disappears.

My guess is its something to do with the suppression resistor. But open to idea's.

[NITROPIXIE]

According to http://www.mister-solutions.co.uk/bp6es ... -194-p.asp there is a 5K resistor built into it. NOt sure about the NGK as yet but looking. So not sure if this has something to do with it or not.

[NITROPIXIE]

And found this concerning Champion plugs but no specific data as yet. Use the numbering chart on the bottom of the page, left hand common to findout what the lettering means.

[Ken555]

The NKG BP6ES isn't a resistive plug the BRP6ES is whats needed.

With the Champion RN9YCC is resistive.

Reference here:-

http://www.spark-plugs.co.uk/pages/tech ... l_code.htm

http://www.spark-plugs.co.uk/pages/technical/ngkjpg.htm

http://www.spark-plugs.co.uk/pages/tech ... l_code.htm

[NITROPIXIE]

Makes sense and some good info. I wouldn't of thought of that.

[Ken555]

Makes sense and some good info. I wouldn't of thought of that.

Neither did I, I just went with what MED recommended back in the 90's, when the engine was built..
Of course that was for the original distributor system.