S70 2.5t misfire

[misha]

...It was like this before lpg assembly

Before LPG installation?

[radek93]

...It was like this before lpg assembly

Before LPG installation?

Yes

[radek93]

I found after going over a year with the same issue and replaced everything that the culprit was the thermostat sensor that's at the thermostat housing. A $13 part plus a new thermostat while I was there. ECU reads the temp wrong from the sensor and adds more fuel to the mix to cool the temp.
Also, check that all electrical connections are good and clean. use some dielectric grease. Be sure the wires from the cam sensor are not near the ignition wires. that may cause some em feedback.

I have new temperature sensor

[wizechatmgr]

Did you verify the new parts were good before installation personally? Specifically the Crankshaft sensor & Camshaft sensor - test them again

Occasionally new parts aren't within spec. Bad batches do happen... Sometimes the longevity of a part isn't what it used to be. Also test the supply voltages to sensors and their grounds. Either having an issue will make the ECU go nuts.

Have you checked and verified the voltage at the ECU? These cars get pissy if the voltage isn't within spec.

[radek93]

Did you verify the new parts were good before installation personally? Specifically the Crankshaft sensor & Camshaft sensor - test them again

Occasionally new parts aren't within spec. Bad batches do happen... Sometimes the longevity of a part isn't what it used to be. Also test the supply voltages to sensors and their grounds. Either having an issue will make the ECU go nuts.

Have you checked and verified the voltage at the ECU? These cars get pissy if the voltage isn't within spec.

I have not verified. I put on good substitutes. Delphi and Hella. I improved the grounding of the entire car, also ecu. I checked the resistance of the ecu power cables. The only thing that surprises me is why, even after changing the alternator voltage regulator, finally replacing the alternator with a used one, the charge is still around 13.7-13.9 volts. Usually cars have a charge around 14.4 volts.

[misha]

13.7-13.9v at idle with headlights,heater blower(not on 4th speed) and radio is OK.
Check voltage output directly on alternator b+ and it's casing.
If it doesn't match with battery terminals....cables are bad and voltage drop test should be performed on both....positive and negative side.

[radek93]

13.7-13.9v at idle with headlights,heater blower(not on 4th speed) and radio is OK.
Check voltage output directly on alternator b+ and it's casing.
If it doesn't match with battery terminals....cables are bad and voltage drop test should be performed on both....positive and negative side.

I have so much without anything turned on. With the lights on etc. I have around 200-300 mv less. Wires, of course, checked. Even as a control I added ground and b + to the battery.

[misha]

Check on alternator directly.
If the reading is the same as on battery terminals....voltage regulator is the culprit.
If battery terminals reading is lower than reading on alternator...then cables are bad.

Difference should not be higher than 0.2V.

Do this after driving around 30min and without turning the engine off.
This will allow you to have precise picture of what is going on...when cables and everything under the hood is warmed.

When cables are cold...the readings will be higher than real untill ressistance builds up....and will not give you real results.

[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.

[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.