sounds like an intermittent electrical problem to me. maybe the wiring to the CPS even?

 

It looks like you can read codes from your car. Here's a link:
How to read the engine codes on 1990-1993 Volvo 240 | Volvo How ToVolvo How To

 

Yup, today I'm going to try to gain access to that cps. But how do you get to it? I can follow a wire with my hand down below the #4 spark plug wire and reach in on top of the bell housing I think and feel where that wire terminates and maybe a single hex head from a bolt. Is that is? I can't even get a socket onto that bolt with one hand.

Fochs, currently I'm not getting any codes out of it, from either connect 2 or 6 on the built in code reader. I was getting some type of MAF code out of it this summer but not currently.

Arne

 

just code 1-1-1 ?

yeah, the CPS is in a hard spot. I've never replaced one, so I'm not quite sure what the magic is to get it out... I'd probably be using an inspection mirror and small bright flashlight to get a better look.

 

Fochs, one more time please. You wrote:

To test the engine rpm signal: ( I think it keeps the pumps running)
-1 and ground while cranking the engine. Should get battery voltage, not less than 8V

I clearly came up with a max of 5.4 volts with this test. Is this a problem?
Is this a test for crank position sensor or is there an rpm sensor you're talking about?

Also Pierce, do you have resistance values for testing my coolant temp sensor at the ECU?

Thanks you Guys

 

I wouldn't worry about the voltage at pin 1. its a pulsing signal, so your volt meter is trying to average it.

if your meter has a 'Hz' or 'frequency' mode, you might try that, you'd see a frequency of twice your RPM (since there's 4 sparks in 2 full turns of the motor) divided by 60 to get cycles/second. if we assume cranking is something like 300 RPM, then I'd expect to see 600 sparks/minute == 10/second == 10 Hertz.

for the ECT (engine coolant temp) sensor, I refer you to... Engine Sensors ... down that page a ways is the table.

best place to read it would be at the ECU pin, as that way you know all the wiring is good. the ECU is just forward of the right front door lower hinge... remove the right side foot 'kick' panel, and the fender liner, and its right there. turn the car off, disconnect battery ground. unplug the ECU connector, examine the inside of the plug with a bright small flashlight, and you should see the pin numbers inside. The ECT goes to pin 13, measure the resistance relative to ground (pin 17, or the ground block thats probably close to the ECU).

the ECT actually has TWO thermisters in it, the other one goes to the ICU (Ignition Control Unit), this is the other CU near the passenger footwell, the ICU's half of the ECT goes to ICU pin 2. ICU ground on pin 20.

 

Thanks Pierce,
Is this table and reference you sent me to good for 240's? I thought it looked like 740's and 940's.

Arne

 

Is my 93 240 a 2.2 or 2.4?

Anyway at the ECU harness I get 0 voltage between pin 13 and ground.
Arne

 

This guy wrote:

[Response 2: Steve Ringlee] ECT resistance "cold" should be around 6k ohms at 32 degrees F (0 deg C), 2300 at 68 degrees F (20 C), and 200 at 212 F (100 C). However, try checking your ECT wiring: Between pins 13 and 5 at the LH ECU (with sensor DISconnected) resistance should be infinite. Voltage with the ignition ON and sensor connected, measured between pins 13 and 5, should be:
0 C=around 3 volts +/-.5v
20C=around 2 volts +/- .5v
100C=around .3 volt +/- .1v
If these aren't correct, check the connections in the ECT wiring harness. Check engine ground connections at the intake manifold. If the voltage is zero, your ECU is at fault.


Does he mean, "If the voltage is zero your coolant temp sensor is bad"?
Arne

 

with the ECU unplugged, you'd need to measure RESISTANCE (ohms) not VOLTAGE (volts). the voltage measurements given are with the connector plugged in, and the ignition turned on, probing the connections under the rubber bootie that covers the wiring harness.

any 240 1989+ is LH 2.4

the engine and LH2.4 systems are identical between 240's and 740/940's (some 7/9's have Regina instead of Bosch LH, and of course, anything up to 1988 would be LH 2.2).

 

Your car is an lh-2.4. The Test at pin 1 on your car is the same for both systems. I assume it is for the CPS (speed sender), as I understand it, the CPS (speed sender) does what the hall effect sensor does on earlier cars. I am out of my depth in that regard in that all of my cars are older. All I can tell you is that that is the spec from my Bentley manual.

You are looking at the right spot for the speed sender (CPS).

Here is a link on testing and removal. From what I have been reading, this is a fragile bracket with inconvenient consequences if broken.
Engine Sensors

 

CPS is the 'crank position sensor', not speed sensor.

LH2.2 used a hall sensor which issues one pulse per spark, ignition retard/advance was done via vacuum and guesswork.

On LH2.4(and the fairly rare 3.1), the CPS issues both a long pulse once every half turn, and short pulses a lot more frequently. the short pulses tell the ICU/ECU exactly where the crank is within the cycle so it can use that for precise ignition timing, and respond faster to RPM changes (with the old system, the ICU wouldn't know the engine had sped up until 1-2 sparks later, while with CPS it can tell immediately).


and yes, that volvoclub site is VERY useful even for 240's, while it says its a 740/940 site, in fact the 240's have the exact same engines and control systems with only slight differences (240 uses a side mount distributor while 7/9 uses a camshaft end distributor, and 240 doesn't have a 'radio suppression relay' which most 7/9's DO have). the other main differences are the fuse panel and relay locations.

 

OK, cool. So I have committed myself now. I removed the throttle body, drained coolant. removed coolant sensor and the one for the gauge because I remember this gauge was acting up. Tomorrow I'm going after the CPS too.

I have a 1991 240 wagon I bought for parts. My friend sold it to me and drove it here. He said it runs great. Do you recommend pirating some of these parts for sensors and units like the ones we're talking about, since they're free to me? I guess I would call them known working units. This parts car has 197K miles on it whereas my 93 has 150K. I don't know what these sensors cost but I don't want to do the work over again. Also, if I'm buying new parts, can I go to Napa for these or do I need to stick with OEM? Or can I get OEM at Napa?

Arne

 

if I was buying new parts, I'd either go OEM, or OE supplier parts that you'd find at fcpeuro or ipdusa ... unlikely you'll find anything specific for a 90s volvo in stock at a Napa.

I'd inspect the parts you get off your donor car, if the look decent, and the wiring is in good shape, go for it. the CPS itself typically isn't what fails, its the wiring and insulation.

temp sensors can be tested with an ohm meter and dropping them cold & hot water.

 

Very likely you can find the parts you need at Carquest. They own Worldpac, the largest parts distributor to import shops nationwide. I rarely have difficulty getting OEM or OE parts from them, usually same day.

 

IMHO. Worldpac is more likely to ship chinese aftermarket stuff branded 'scantech' or whatever than OEM/OE.

 

That hasn't been my experience.

 

In a pinch, can I build a reliable gasket for the throttle body with RTV? I know I have black hi-temp in stock and probably gold, maybe blue.

Hoping to hear from you on this pronto as I can't get the part till next week and I could conceivable get this trap running today.

Thanks,
Arne

 

I guess I mean intake manifold gasket? Can I make one with rtv?

What is the throttle body gasket anyway. Some triangle thing I've never seen.

Arne

 

I had to move mine around so much, I don't think I could have made one with sealer. The throttle body gasket goes between the throttle body and the intake. If I couldn't take it anymore, I would get a sheet of gasket material and trace the intake, then carefully cut it out with an exacto knife. When cut out, I would tape it to the intake and press the material into the holes to mark them then cut them out, too. But that's me.

Don't know your location, but this gasket should be widely available, I found several at parts stores in my area, and it's not a Volvo area. I personally would not hesitate to put a felpro or whatever on it. But that's me.