Problem with Rev Counter and Lost of Power

[chrisb1357]

Hi all,

I have a 306 1.4 8v LX (1998 Reg) which has a strange issue.

I could be driving along and all of a sudden the rev counter will stop working but then the car will also start to feel like there is a lack in power to the car when I put my foot down. Also sometimes when this happens and I put my foot down on the throttle and take my foot off and the rev's will stay high.

After parking up and then starting the car the next day the rev counter works and the car feels fine until it happens again which could be next day or a few days.

The clutch has started to slip but someone suggested to me that a slipping clutch would not stop your rev counter from working.

I have also changed the throttle cable, rev counter sensor, throttle postion sensor,idle control valve and crank sensor and removed the throttle body to clean with carb cleaner but again I still have the problem

Chris

[Peter.N.]

Its possible you have a faulty connection from the sensor, don't know where it is on a petrol engine, on the diesel its just below the gearbox end of the cylinder head. The slipping clutch won't affect it but if you let it slip it will wear rapidly, if you can bear to drive it gently so it doesn't slip it could last for many more thousands of miles.

Peter

[chrisb1357]

I know where the connection is as I changed the Rev counter sensor on the gearbox last week. What would it cause the engine to lack in power when the rev counter stops working

Chris

[Peter.N.]

I would think that the ECU uses the rpm signal in engine control.

Peter

[chrisb1357]

So if the connection is not good to the sensor giving the ECU a false reading?

Shame its a 1998 car as I cannot connect a reader to it

Chris

[spider]

On a petrol engine the TDC (crank) sensor is vital for it to run.

[Peter.N.]

Apologies, I haven't run a petrol vehicle for about 30 years.

[spider]

Sorry Peter, I did not read your post that way. ie as a bad post.

With modern units it has to have a crank signal (or cam signal) to know where "everything" is for both fuel and sparks etc as you know with no distributor etc only the ECU has to rely on receiving something from a engine speed sensor to know where it is, usually there's a slight cut out (no pun intended) with the teeth etc so a 'missing' tooth the ECU will know that point is TDC etc.

[chrisb1357]

Hi
What would I be best to do or check next.

Chris

[Peter.N.]

The last petrol vehicle I ran had a carburettor and a distributer - with points.

Peter

[spider]

The last petrol vehicle I ran had a carburettor and a distributer - with points.

Peter

Nothing wrong with carb + points at least its easily fixed. As my dad once said "does not matter really, even if everything else electrical packs in you can wire the battery to the coil (and distributor) and get home"

Hi
What would I be best to do or check next.

Chris

Try a wiggle wire test. With it idling locate the (sometimes grey) plug for the TDC sensor and wiggle the wiring around. See if you can provoke it to cut out or misfire etc. Its on the transmission side so you should be clear of belts etc, watch out for the rad fan though.

Planet should connect to a 98 car (even a diesel so it can read ABS/AirBag/Immobiliser etc) so a petrol one should not be a problem. Diag 2000 more suitable for that age though but Planet should work.

I'd go for a diagnostic to see what is present. Even if the 'k' light is not on it may have stored a silent code.

[chrisb1357]

Sorry what's the TDC sensor

[Hell Razor5543]

TDC usually means Top Dead Centre, usually on the crank shaft.

[chrisb1357]

I changed the crank shaft sensor last week