Just joined. 2nd brick owned - lost timing belt on 1st. Confused by OBD11 READINGS Topic is solved

mopmandan · Post by **mopmandan** » 25 Jun 2018, 09:59

Hello, everyone. Sorry if I get windy... So, this is my 2nd brick - 1996 850T5 wagon. Lost the engine in my first one - a 1997 850T5 - timing belt before I knew enough about Volvos. Backyard mechanic of sorts - went to auto/diesel school in the 70's. Worked in a couple of dealerships. Built engines/did repairs in my own place for a while, mostly GM and Mopar. That's my background - not a novice but Euro cars are strange to me. Been following this site for some time. Car was running fine then started revving to 4 grand on it's own. Discovered daughter let antifreeze get low, uncovering sensor. Found soft, leaking lower hose and replaced it. Cleaned sensor. Replaced overflow tank and cap. Drove it probably 1000 miles no problems. Got in it one day, hard started. Ran fine. Lunchtime, started fine. End of day, really hard to start - flooded? No start at all next day. No codes. Searched this forum...checked fuel pump fuse - good. Checked hot pin on relay - good. Pulled cover over fuel pump and checked for voltage - zip, zero, nada. Jumped past relay - voltage at pump. Replaced relay with new. Car started. Had wife drive it around (work interrupted my repairs). Drove fine all day, but when she went out later, no dice. Flooded! Threw P233 (made sense - all that fuel). Got it started after sitting overnight. Plugged in OBDII reader. Here are the results: Load % 0.8 to 2.0; RPM avg 840, fluctuates 760 to 1120; ECT 44 to 102 C (I think this is the source of issues); spark advance varies from 4.5 to 6 with blips to 3.5 and 12 degrees; MAF generally 3.18 to 3.32, varies from 2.54 to 5.55 (along with rpm and ect); TP % 10.6; 02 bisi 0.310 to 1.060; shrtft bisi % is -4.7 to -2.3 but bouncing down to -12.5 along with other fluctuations. Temperature gauge all over the place but not showing overheat. I'm not ashamed to admit when I'm over my head...

And I'm sure this has been covered here somewhere but I need this car. Thanks everyone. Btw, there is a guy named Robert that does some decent videos for amateurs - knows his bricks!

Post by **erikv11** » 25 Jun 2018, 10:31

Likely the ECT, yes.

If the ECT that was replaced is a cheap aftermarket one, that is almost certainly the cause of the problem just like you suspected. The other thing to check with the ECT is the condition of the wiring at the connector, and the connector itself. They are known to crumble when they get old and give poor connection.

Post by **mrbrian200** » 25 Jun 2018, 10:56

Temp gauge 'all over the place' + intermittent hard start = either the coolant temp sensor is going bad, the wiring to it, or the pigtail has an intermittant break in continuity. ECTs generally like to be replaced about every 100k miles or so. The NTC thermistor element buried inside the thing is starts developing micro fractures after thousands of heat cycles that eventually make the sensor indicate an artificially cold condition to the ECU, flooding the engine at startup. After another heat cycle some of the fractures may regain electrical conductivity, only to open again later. Hence a failing ECT sensor often acts like an intermittent failure.

It is also my experience on this generation of ECU (on a '98 or '99 NA S40) that a combination of failed ECT combined with bad/intermittant signal from the throttle position sensor will result in a racing idle that seems like the car is getting ready to launch into orbit.

Post by **misha** » 25 Jun 2018, 14:57

What obdII codes and live data from a '96 T5 since they have Motronic 4.3?
Unless you have a Motronic 4.4 in it?

Post by **erikv11** » 25 Jun 2018, 17:18

All 1996 850s with an air pump, which includes turbo (T5) and non-turbo models, are Motronic 4.4.

EDIT: as misha posted later in this thread, this is wrong. The 96 T5 was Motronic.

mopmandan · Post by **mopmandan** » 25 Jun 2018, 18:38

Thank you all for such prompt replies. As I recall in reading other posts here and on Swedish Bricks, '96 and forward (and some very late '95s) are OBD11. Means Motronic 4.4. In response to mrbrian200, I did not change the ECT, but only cleaned it. It looked like new, as did the thermostat. Previous owner changed timing belt, water pump, etc. when he switched this engine in for a bad one. I have had it for almost 2 years and it was his wife's daily driver before that. I'll have another go at it. Any brands suggested? Getting ready to change oil and filter. Valvoline 100% synthetic and Bosch filter. Mann air filter and new fuel filter too. She better respond to all this lavish attention. Gave her Pirelli's last year.

mopmandan · Post by **mopmandan** » 25 Jun 2018, 18:41

Sorry, should be responding to erikv11.

Post by **erikv11** » 25 Jun 2018, 18:56

OBDII does not mean Motronic 4.4
96 are maybe half Motronic 4.3, half Motronic 4.4. But every 96 is OBDII.

The easiest way to tell if your 96 is 4.4 or 4.3 is to see if it has an air pump (that makes it 4.4) or decode the VIN (http://new.volvocars.com/ownersdocs/199 ... n1996.html).

I can't remember what the factory ECT sensor brand is, maybe misha will chime back in he always does.

You can ohm out the sensor at diff temps to test it, satisfying and pretty easy to do. Search here for the values or this guy wrote a treatise about it (https://volvo850wagon.wordpress.com/201 ... -stalling/), makes a good read although do *not* get a cheap aftermarket sensor, it will just fail 6-12 months down the road.

Post by **misha** » 26 Jun 2018, 01:18

erikv11 wrote: ↑25 Jun 2018, 17:18 All 1996 850s with an air pump, which includes turbo (T5) and non-turbo models, are Motronic 4.4.

No erikv11....T5 models have Motronic 4.4 only from '98 in s,v70 models.
850 T5 are all Motronic 4.3 from the factory.
Non turbo with an air pump from '96 & '97 have Motronic 4.4 and ALL '97 non turbo(B5254S) are Motronic 4.4.

There is no live data on Motronic 4.3 because it produce flash codes,just like ECC on 850s....S,V70 ECC is fully obdII.
Ect (oem) is SWF (Valeo)....only aftermarket one i would use is Vernet.

Post by **jreed** » 26 Jun 2018, 05:08

Agreed with misha. I tried an FAE brand ECT once and it drifted out of spec after a couple years:
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