You are right sir! I did measure across the two pins. My first time dealing with a no start so lessons learned.

I also did measure the resistance just like the one in the manual you sent me. Took the ECU plug, took cover off and measured at the tiny square holes under the corresponding numbers. Thanks again!!

Also, thanks for the tip of changing the oil. I smelled the dipstick and it smelled like gas was mixed in with the oil.

 

If you had the sensor in your hand, for example, you would put one test lead to a pin and then the other to the brass threaded section (GROUND!)

That is at least the way the sensor is on this application. It's not always that way. Certain sensors ARE measured across the two pins. Furthermore, if you ever see a one wire sensor (such as oil pressure switch) you know for sure it simply makes a measurement to GROUND.

The fact that your car started with the ECU unplugged makes me wanna guess it was flooded with fuel from the ECT (Or another problem), and then when you cranked it, the spark ingnited whatever fuel was left in the cylinders and ran for a second.

If your car starts with the ECT sensor unplugged, it PROBABLY means the sensor is bad, but it could be the ECU still.... I would triple check that the pins inside the plug are seated properly. They can get pushed back into the wiring harness. Since you already swapped the sensor recently, you should take a good look at the wiring and the plug. Also make sure you have a 1990+ sensor. It should be black. Earlier models use a different one, GREEN? and it is wrong for lh2.4 cars.

You should also find out what pin the ECT goes to on the Ignition Control Unit (ICU). I would take readings there to make sure both computers are seeing accurate values.

Soooooo.....what are your ECT values AT THE ECU?

 

Hey you are doing a good job understanding and learning. The curve is VERY steep at first. I measured that sensor wrong many times before I learned to do it right.

So now, follow me here, you need to also measure the temp sensor resistance at the ICU. Here is a diagram. I am not going to tell you on which pin at the ICU you need to do a resistance test. It's for you to figure out!!!!

 

I re-checked resistance on ECU pins for ECT. It read 951 with engine warm so it's within spec.

So, I drove the kids to school today and car was driving fine until on my way back home. The car started hesitating, made a right turn which involved me slowing down and the car stalled. I was able to start the car and drove it back to my garage.

I pulled codes and only one popped up 232. Cleared it and drove it again.

I went back out and drove to publix which is about 5 miles away. No problem, no hesitations. On my way back, the car started to hesitate. I went and made the same right turn and car stalled. Only code is 232 once again.

Did the test again for the RPM sensor, ground and pin 1. Cranked the car Only got 5v to 6v at the ECU pin. Would this mean my RPM sensor is bad or is it the wring from ECU?

Finally got her to start now THIS!!!!!!

 

do note, a 1991 940SE is actually a transition model in between the '760 turbo' and "960"... the 960 inline 6 wasn't ready, so they one year only, they sold the upscaled '960' as a 940SE with the turbo 4, same as the 760 turbo...... It has the same engine as a regular 940 turbo, but the dashboard electrics, fuse panel, and relay panel, are /completely/ different, including wire codes.

 

I pulled the FPR and it turns out that the return line was completely dry. Not a drop of fuel. Time to get a new one and hope this fixes it for good!!!!

 

FIXED again!!!! It was the FPR. I took the same route to Publix and came back with no hesitations or stalling. Checked codes and it is 1 1 1. Oh yeah!

 

Parts Cannon:1
Fuel Pressure Test: 0!


Curious to hear end result.


oh yes, wire colors vary constantly. There is one constant, however, which is all 2.4 computers have the SAME PIN NUMBERS.; )

 

I honestly don't know. I haven't had a chance to ever find a bad sensor that way. You could always try OBD diagnostic mode 3 (look it up) and there is a test where you hit the starter and it will let you know if you got a rpm signal. Not the most scientific test, but just something else....

Obviously if your car runs the sensor isn't obliterated. Only way to really see if the sensor is working perfectly is with a scope.


I am confused that you say your return line was dry and that was the issue..... yeah if you pull it off the FPR i would imagine the fuel would quickly flow right back into the tank (ie dry?) oh well.

So far you have believed that the problem has been three things:

1.Bad ECT
2. Bad ECU connection
3. now bad FPR....

Doesnt make sense, but as long as the car is running consistently now, who gives a ****!!!!? keep us posted.

 

the signal from a CPS thats not connected to the ECU is only about 1 Volt AC when cranking. as revolv says, if the CPS is broken, it wouldn't start or run at all no way no how (no crank position pulses means no spark AND no fuel injection).

 

have you bothered checking the four ground wire pins at the ecu? What is the resistance on them? if ok, wiggle the harness at places and see if you can get a bad reading.

Have you checked your wiring harness coming up to the injectors and the grounds at the fuel rail?

Have you bothered checking fuel pressure yet? Instead of wasting money on FPR, could have just put it towards the $150 deposit to borrow the fuel test kit from oreilly.

Have you inspected the crank sensor wiring for fraying? It could very well be your issue. It is one part maybe worth firing the parts cannon at.

I think you should just make left turns. ; )

First three things above are listed in the link I provided for ya. Read it carefully. It explains what to test FIRST before you spin yourself in circles firing the parts cannon at the thing.

 

I'm waving the white flag!!! Taking it to my mechanic who is a specialist on Volvos and make my decisions on keeping the car or not.

 

nothing wrong with that. keep us posted. you cant be driving around with kids in the car and have it stalling out!

 

It's heading there tom. I already made a list of what parts I changed in the car. Also, guess what? The car is not starting. Back to no start and engine just turns and turns. FRUSTRATED!!! I'll keep this board posted. Already told him not to fix it if it will be an expensive fix. Plan to sell it as is.


Edit-----

Got it to start by spraying starting fluid in the intake. I had to drive it out of the garage to get ready to be towed tom. It idled rough and had to keep the throttle up. The. It idled for three mins then died.

 

so its probably a fuel delivery problem, sounds like.

 

This is where you ask yourself:

-Does it have spark? unplug wire from coil-tocap and grounding it closely to the driver strut mount and crank the engine. Sprak?

fads,fjads,jfasdkfjsd dont want to type it out anymore....


here is a link from the ol' google search:

http://www.stepbystepvolvo.com/Resou...20No-Start.pdf

That's when you introduce a professional to your car.

 

Yes, I did that test and it is sparking. Also followed that guys suggestions. It's in the shop now. He will let me know tom.

 

so......

 

DRUM ROLL PLEASE!!!! It's the wiring on the radio suppression relay!!! Mechanic changed it and now she is back on the road!

 

Glad you got it fixed!

See post #2. I was right! ------>That is why the FIRST thing I said was to check for 12v at injectors. If the relay is dead, you would NOT see 12v at injector plugs.