Hi there, just tuning the 245 I am overhauling for winter use and today doing some tune up work. Result, I have a few questions:

-How do you know IF a spark plug wire is bad? Is there a way I could test with a voltmeter?
-Car seems to be running too rich, the car is a 1988 with fuel injection, this is my first fuel injected car (don't ask, I just like old things), where do I start to troubleshoot to find how to lean it out? (Symptoms: dark spark plugs little fouled, have replaced these, also the exhaust is a little dark, if I quickly rev (blip) the throttle then let it idle down, there is a minor backfire, very slight)

Thanks.

Chris

 

You can OHM the wires but I forget the spec's

Check the timing make sure it didn't jump.

Also make sure the O2 sensor is working. Put the positive from the meter to the single wires and the other to ground and watch it. It should sweep between 0-12 Volts when in open loop.(Warmed up)

 

Tech,

Isn't the O2 sensor voltage 0 to 1.2?

 

Could very well be. My meter may be reading a very low range and it may look like 12V.

 

Resistance, including the cap, SHOULDN'T be over 35,000 ohms and 50,000 ohms is the limit. When I didn't have a ohm meter on hand, I'd start the motor and pull the plug wires just far enough off so they can still arch from the wire to the plug, then I'd look at the color of the arch. You can only do one at a time, and they should all be close to the same color. Wires that aren't secure are often suspect, the exess vibration will cause tiny fractures in the wire core which turn into breaks, ultimately raising the resistance and reducing the spark.

Is your exhuast darkish black, or darkish blue?If its blue(oil) your intake valve guides might be loose so when you rev your motor, they suck a small amount of oil in to the chamber making a blue puff when its winding down. I'd suspect the O2 sensor though, that would make a black(excess fuel) puff. Hope that helps

 

coolant temp sensor to ecu has a very large effect on inj pulse width. check grounds and connections on engine, fuel inj, and connections on temp sensor. O2 sensor will try to compensate. Use only digital volt/ohm meter on o2 signal wire .1-.9v .9 being rich and .1 being lean If it varies .1-.9 this is normal.