Sages,

Background: 1989 Volvo 245, 339K + miles, M47 transmission

So in May of 2015 I posted the following call for help: https://www.brickboard.com/RWD/volvo/1615300/220/240/260/280/engine_running_rich.html

With not much to go on I replaced the ECTS in September of 2015. I did not notice any improvement in MPG. What I did notice was a more steady MPG, like rock steady at 26 MPG, give or take a couple of tenths.

Now this is not horrible by any stretch, but my 1991 gets 30 MPG consistently. It does have a M47 and I drive it mainly on the highway. It only has 177K on it.

So at first my thinking was, well its an old engine, it has a lot of miles on it, it won't get as good MPG as the 91. I also noticed that the 1989 had become sluggish while accelerating, so I'm now starting to think I'm gonna need to rebuild the engine and freshen everything up. Ok, I can live with that, no biggie.

Well yesterday it finally threw a check engine light. I'm thinking now what do I need to fix. So I plugged into socket 2 and get a 1-1-1. I'm like WTF? No codes. So I plugged into socket 6 and get 1-4-3, "Knock sensor signal absent or faulty". So I'm like, ok, I can live with this. I can fix this.

So my question is this, is this model year a EZK 116 or Regina Rex Ignition? I've always thought it was something else. Where should I look to find out for sure?

Thanks in advance and sorry for the long post.

Regards,

Matt

While I cannot get a straight answer from anyone, I have read in a repair manual (Chilton's) that the first thing that happens when a knock is sensed is that extra fuel is added to cool the combustion chambers.

After all, if the engine is knocking, changing the timing won't help as ignition is happening before the spark.

This could be the cause of poor mileage and performance.

I would not go crazy until your knock sensor is up to snuff.

I actually observed this on a trip through Canada - I purchased fuel in French and got regular instead of high test!

I got 2 MPG less on that tank full than on every other tank full on a trip from Massachusetts to Saskatchewan and back. LOTS of highway at steady speed.

First thing is to inspect the sensor visually and confirm it is intact. Then remove it, clean it and the block, and reattach it with the correct torque specs (which varies depending on which style of sensor--see the FAQ!). Make sure the connector contacts are clean and tight. Testing the wiring correctly requires checking values at the ignition computer, which is a PITA. But with the ignition off you can at least use an ohmmeter to check to make sure pin 2 in the connector is properly grounded (zero resistance between the connector and a good ground, like the ground wires attached to the nearby fuel rail).

I went thru Knock sensor hell on my 940 until I rerouted the wiring to eliminate induced currents. That is a design fault afflicting some 940's, nobody has experienced that on the 240's.

john
--
1989 245 245K / 1993 945 131K

dinomartino,

Thanks for the help!

I'll have to find time once the blizzard passes to investigate this more.

The FAQ is good and should help me diagnosis this quickly and thoroughly.

Matt

a 1989 240 should have the Bosch EZ116K ignition, which was used with both Bosch LH 3.1 and LH 2.4 injection. At least in the North American market, Rex/Regina was only on the 7/9 series cars.

john
--
1989 245 245K / 1993 945 131K