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Old 11-03-2009, 10:28 AM
Join Date: May 2007
Posts: 84
Unhappy Failed Emissions 1985 240DL- Helppppp!!

MY 85 240 has failed emissions 3 times. Very high HC(hydrocarbon levels)

Have replaced/swapped the following:

plugs, oil, AMM, idle control valve, flame trap, O2 sensor

Seems to have gotten worse since I did the work!

Any suggestions?
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Old 11-03-2009, 01:34 PM
bubba240's Avatar
Senior Member
Join Date: Mar 2008
Posts: 734

I would:

- make sure your timing is 12 degrees at idle, and that it doesn't "jump around"
- measure the o2 sensor voltage at idle, on the green wire, with everything connected. it should cycle quickly between .2VDC and .8VDC
- measure the resistance of the coolant temp sensor at the ECU.
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Old 11-03-2009, 10:09 PM
varg's Avatar
1985 Volvo 244
Join Date: May 2009
Location: West Palm Beach, FL
Posts: 78

On top of the above suggestions, also:

-Pull the vacuum hose from the fuel pressure regulator and ensure it isn't letting fuel into the vacuum line
-Investigate the condition of your catalytic converter (how old is it? does it look particularly rusty and heat damaged?)
The Beige sleeper; a work in progress.
1985 Volvo 244DL, B21FT, ported and polished head, VX3 cam, whitebody injectors
, stock intercooler, EZK swap
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Old 11-05-2009, 12:15 AM
Titan Joe's Avatar
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Join Date: Jun 2009
Location: Utah (for now)
Posts: 752

When you did the AMM job did you adjust the CO content? That kinda calibrates the Lamba Sond (O2 sensor). If you got LH 2.2 FI system that is done by a screw on the AMM (it's covered by a cap next to the plug for the unit). After you've confirmed everything else if is in good shape, that can be adjusted. For a procedure on that... I don't have my manuals with me, but I'll get them at Thanksgiving. Someone else may know too. If you have already checked it, then all of this is old news.

1989 740 Turbo - Parents bought new - 238K miles - Original clutch - 3rd turbo - Red leather interior
Turbo plus system - Aluminum hood - 1" sway bars - Oil pressure gauge - 3" turbo back exhaust with a magnaflow (no cat) all stainless - quad HID projector headlights

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Old 11-05-2009, 02:05 AM
Typhoon's Avatar
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Join Date: Dec 2007
Posts: 909

As you probably know, high hydrocarbons is unburnt fuel exiting the tailpipe.
Check fuel pressure, basic timing, air intake obstructions(clean filter?), air intake leaks after the AMM.
Also replace spark plugs, check leads rotor cap.
Also check for vacuum leaks at intake manifold.
Spark timing is usually not a big factor on HC, it usually affects NOX more.
O2 sensor is not a big part of the picture idling either, although at speed it is. If teh O2 sensor is more than 50k miles old, I'd replace it, they are a wear item.
I'd also throw an oil change at the engine, it helps the rings seal.

Regards, Andrew.
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Old 11-05-2009, 07:04 AM
Junior Member
Join Date: Oct 2009
Posts: 9

A classic trick is to remove the air filter just before test. Check at home first so that you make sure there is no loose stuff in airfilter housing.
This wont fix your problem but it will take it a long way towards a good test, unless its completely off that is.
How far off was the test?
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1985, 240, adjustment, dl, emissions, failed, fuel, hc, high, lamba, pipe, sond, tail, test, timing, unburnt, volvo

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