S70 2.5t misfire

[radek93]

I checked everything. It looks ok. Only after removing the ignition cap did I notice that the distributor's finger had a burn mark from a spark under a metal element, on plastic. As if the spark leaped at the very end.

Sounds like a carbon track. This could have caused intermittent or consistent misfiring. I used to have a hell of a time keeping the distributor cap in my old VW dry. Eventually I used dielectric grease around the seal and at all electrical connections.

I changed the finger of the distributor but it did nothing.

[wizechatmgr]

I checked everything. It looks ok. Only after removing the ignition cap did I notice that the distributor's finger had a burn mark from a spark under a metal element, on plastic. As if the spark leaped at the very end.

Sounds like a carbon track. This could have caused intermittent or consistent misfiring. I used to have a hell of a time keeping the distributor cap in my old VW dry. Eventually I used dielectric grease around the seal and at all electrical connections.

I changed the finger of the distributor but it did nothing.

By chance did you verify the cap didn't have a track too? It doesn't take much. They can literally be microscopic. Also try spraying the engine with a mister bottle towards the distributor and coil. You'll see it arc if you're lucky.

[radek93]

Sounds like a carbon track. This could have caused intermittent or consistent misfiring. I used to have a hell of a time keeping the distributor cap in my old VW dry. Eventually I used dielectric grease around the seal and at all electrical connections.

I changed the finger of the distributor but it did nothing.

By chance did you verify the cap didn't have a track too? It doesn't take much. They can literally be microscopic. Also try spraying the engine with a mister bottle towards the distributor and coil. You'll see it arc if you're lucky.

I will check. Why i have Ignition timing 9-11° when in datashets is 6+-2

[luckykolo]

Anyone has any experience with resetting misfiring codes? How quickly they are coming back if the problem persists? I just want to eliminate the "ghost" code scenario before diving into serious troubleshooting etc. My car is Volvo 98 s70 Base 150 000 miles and has the history of some codes popping up and disappearing. My code was P0302. I inspected spark plugs for torque - (I replaced them about 6 months ago). Spark Plugs Wire Set is old - 16 years old as a matter in fact. No corrosion. Applied some dielectric grease and put some fuel treatment into the tank. I drove so far about 50 miles. No code. Having said that, monitors on the car are not reset fully. It takes log time on this car. Nevertheless I would think, that misfire would pop up immediately, am I right? Thanks

[radek93]

An update on my 10-year battle to find the cause of "misfiring". I recently changed the LPG computer to a newer model from another company. I was surprised when the LPG program showed the error "gas injector fully open" from time to time. It was firing on various cylinders. I thought it was an error of the LPG controller. However, on the built-in oscilloscope I saw, for a fraction of a second, individual petrol plugs drawing pins, suggesting that the petrol injection was fully open. The problem already occurred before the installation of LPG, so it is not from LPG. the petrol injection control on the injector side is cut off and comes from the LPG controller, so it is not the fault of the petrol injection. All that remains from the old car are the knock sensors and the engine wiring harness. Short circuit in the harness? I took it apart in the place where the engine meets the body and it looked perfect. It wouldn't happen occasionally, but probably more often? Can the knock sensor affect the injection time parameter for a fraction of a second?