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240 Disconnect O2 = running uber lean?

The Spirit Of Rolling

The Spirit Of Rolling

Volvos, VWs, & NO Vagina
Joined
Jul 22, 2010
Location
OKC, OK
My understanding is that this is NOT what should happen, but it's happening... '86 245 LH 2.2, mostly stock. Runs poorly at start up, sometimes requires a second start to keep running, absolutely fine when warm. Prefers the cold ambient air, does not run as well when it is say 70 or warmer. Have a new engine temp sensor in place, but have not yet confirmed what readings it has cold/warm through the harness. Harness has been replaced sometime, so nothing weird there. MAF tested fine.

Thoughts?
 
RE: Runs poorly at start up

I would not think O2 is related to this issue...in GM designed, one has open loop and a closed loop, where open loop is running a default program. I think many, if not all, have open/closed loops.

Maybe idle value is having an issue...choke it, and see.

RE: running uber lean?

This condition may point back to AMM/MAF, unless ECU has a circuit flaw, or idle circuit is by-passing too much air.
 
From experience in other cars go grab the CTS you removed and try that one again. If the lean out was from a vacuum leak it would run really bad once its warmed up. The O2 has no function until its in closed loop.

The reason I suggest the CTS is because its very common for them to fail or be junk out of the box. Most of them for older cars are cheap Chinese copies that don't hold up in quality compared to the OEM ones 20 years ago.

In your case it could be telling the ECU the engine is warmer than it actually is and its not getting enough fuel. And this doesn't necessarily extrapolate to it getting way under fueled when the engine is warm. They can loose sensitivities in specific ranges. I just tested 2 brand new Chinese CTS's, a 20 year old OEM, and a brand new OEM out of a VW using a few glasses of water, a thermometer and resistance checks. The old OEM one worked more consistently than the new Chinese ones and was closer to the readings of the new one outside of the icey cold water where it read lower resistance than just cold tap water.


Takes a few min to test a CTS but it is worth checking, even if its brand new. I know guys that will buy 4, put the best one in the car and take 3 back.
 
84B23F said:
Maybe idle value is having an issue...choke it, and see.
Click to expand...


Damn it. Why didn't I ever think to clean the damn thing? Nearly three years of ownership... JUST cleaned it, and it did indeed start nicer, rock steady idle when cold. GOOD! And now, to fix the lack luster performance when cold...

Thanks, Shanks. The original one was broken, the wiring was holding the center electrical connection is place. Do you think it had too much resistance? :rofl: The one I installed came from either FCP Groton, or IPD (I think it was the former). I will check it today. Am I more than likely to get a good one from the dealer?

Andy- may have to change the MAF just to check and see if there was any difference. Can't find a cheap (& good) one locally yet; trying to be cheap, unemployed ATM.


I will continue to look further into this.
 
I'm not sure if the current dealers would have a CTS for a 240 in stock. Im also not sure that most parts guys know what a CTS is or where to find it ;)

I would get a hold of IPD. Those guys don't piss around by the looks of things.

Also if it does end up being the AMM before you spend hundreds of bucks look up the Bosch part number and find out what other cars it came on. A great deal of fuel and ignition parts that Volvo uses are also OEM on VW/Audi. Opens another avenue to find one online, a part out and or at the wreckers.
 
Looks like the Vacuum line to the AC controls was leaking, plugged it for now. The weird thing about this car is that I can connect a VOM to the O2 and it won't range until I adjust the MAF to a -very- small range of adjustment. It's ranging now, which is better than it was, but it still doesn't seem right.

As you adjust the MAF screw, should you be able to see movement of the screw either up or down in the MAF body? I am still wondering if this stupid thing works correctly.

Testing the ECT today.
 
Hoping I did this right, searched around and could not confirm if Pin 13 on the harness at the computer was the spot to check resistance for CTS (LH 2.2, 86 245). Scanned the Greenbook for LH 2.0, but I wonder if it is the same for my 2.2? If it is, my CTS is crap.

2033 Ohms at 75*F
2038 Ohms at 115*F
2038 Ohms at 170*F

Temps are approximate, using an IR Thermometer as close to the sensor as I could get it.

1 Did I do this rite?
2 It is indeed FuBarred, ja?

Also of note; I tested resistance at pin 11 and 25 as the greenbook stated; 11 was under an Ohm, but pin 25 was 345 Ohms?
 
That shows pin 2 is the signal from the CTS; mine is pin 12... What in THE hell?

Got pissed off and tore off the intake to get at the sensor; disconnected the plug at the sensor and tried to verify the wire back to the computer; looking at that connector, if I put a lead at the left side connection of the two, and go back to the computer, pin 12 is the only one with a reading, 0.6 Ohms.

Harness had been replaced sometime in the cars' life, wonder if it is the right one? 351(6?)364.
 
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The diagram Mick posted shows the wider of the two banks at the top, reading right to left. I have my plug oriented correctly, but mine has a signal at pin 12 instead of 2.
 
I figured out where to test BOTH connections for the CTS, and it reads properly in relation to engine temp. O2 is good, I had a bad vac leak at the AC controls. Plugged that, and it runs better. Will next replace the MAF, seems like the most likely issue now (cold start probs, fine when warm). More as I discover it.
 
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