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Discussion Starter · #1 ·
Hello everyone.<br>Question regarding the existing sensors on my 240 Volvo -91. My cold start seems a bit off, and I know that there are sensors involved in the management of the cold start hence my question to you all.<br>The car starts fine in cold weather, but has rough idling for the first 10-15 sec. Then the idling goes up quiet high, too high in my estimate (this is my 3rd 240, and I have not had this happen before).Is there a good post, a description of the sensors the 240 has (air flow sensor, Co2 sensor etc), what they do, how to replace them (if possible), and where they are located ? Is my cold start experience familiar ?? A sensor problem perhaps ?<br>I guess that was 2 questions I had....<p>Thanks for your help and input.<p>Anders
 

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Re: 91 240 Cold Start Question (anders57)

Dump the OBD codes and post them here so we can guess at the problem(s).<p>George Dill<p>
 

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Re: 91 240 Cold Start Question (anders57)

I have a 91 240, so am very familiar with its systems.<p>Checking the OBD-I codes is always a good idea, but rarely helps to pin-point an idle problem. The OBD-I system isn't that complex. You really need to get into the guts of it (there are different dump modes) for it to be of any diagnostic use.<p>What I'm about to describe falls under the rubric of basic, regular maintenance that needs to be done every 2-3 years. Regardless of OBD-I codes.<p>1. Remove and clean the throttle body. You'd be surprised the effect this has on idle quality;<br>2. Replace the throttle body gasket. It's an inexpensive part that prevents air leaks;<br>3. Remove and clean the Idle Air Control Valve. Test to confirm it functions, as this part tends to go after 10 years or so.<br>4. Ensure that the plugs, rotor, distributor cap are in good working order. <br>5. Confirm that the air filter is still OK.<br>6. Set the Throttle Position Sensor. It should click if you move the throttle arm a few mm. If it does not make this noise, it is out of adjustment. When out of adjustment, the ECU turns off the idle air control valve. <p>Don't worry about the Mass Airflow Sensor. If it works, it works. No adjustment necessary. There is no such thing as a CO2 sensor. <p>There is a Heated O2 Sensor. It is located at the catalytic converter (this MY had them screwed into the front portion of the cat). If it hasn't been replaced in the past 10 years, do so.<p>
 

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Re: 91 240 Cold Start Question (RearWheelPaul)

I have a 1992 240 that I purchased in 2000. I've never had the O2 sensor replaced, and assume that the first owner never did so. I checked the owner's manual. It says nothing about replacing the O2 sensor.<p>Does the O2 sensor fail suddenly or does its function degrade over time? What happens when it fails? <p>It is my understanding that engines with 3-way catalyst run slightly rich, and the O2 sensor is used to adjust the air flow. Is that correct?<p>Thanks
 

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Re: 91 240 Cold Start Question (pjf)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>pjf</b> »</i></TD></TR><TR><TD CLASS="quote">I checked the owner's manual. It says nothing about replacing the O2 sensor.</TD></TR></TABLE><p>It probably doesn't say anything about replacing the engine either. But, in time, wear takes its toll on every component. The trick is knowing when to replace components as they near the end of their service lives.<p><TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>pjf</b> »</i></TD></TR><TR><TD CLASS="quote">Does the O2 sensor fail suddenly or does its function degrade over time? </TD></TR></TABLE><p>It's function degrades slowly over time. They only fail suddenly if subjected to mechanical shock (such as removal of the O2 sensor or impact with road debris).<p><TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>pjf</b> »</i></TD></TR><TR><TD CLASS="quote">What happens when it fails?</TD></TR></TABLE><p>It's ability to detect oxygen degrades. This usually results in the engine running lean. NOx readings rise. (I'll explain how this occurs later in this post.)<p><TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>pjf</b> »</i></TD></TR><TR><TD CLASS="quote">It is my understanding that engines with 3-way catalyst run slightly rich, and the O2 sensor is used to adjust the air flow. Is that correct?</TD></TR></TABLE><p>3-way catalysts are designed to operate along a <U>very narrow</U> air:fuel range. This range is ~14.5 to 14.7:1 air:fuel. <p>The O2 sensor doesn't adjust airflow. It sends a signal to the ECU, which controls the delivery of fuel according to the mass of air the engine is consuming.<p>The system is close-loop. The throttle plate regulates the flow of air into the engine. The MAF tells the ECU the mass of air coming into the engine. The Heated O2 Sensor tells the ECU how much of that air remains after combustion. Fuel is progressively added until there is an absence of O2. The system then leans-out the mixture until excess air is detected. The system cycles between slightly rich and slightly lean over and over again. <p>The average is 1.45 to 14.7:1. This average allows the catalytic converter to reduce and oxidize three emission types: CO, HC and NOx.<p>Over time, the O2 sensor loses its ability to both detect oxygen. It also loses its ability to react quickly to changing conditions. When this occurs, the ECU no longer receives the signal it needs to cycle between rich and lean. It usually defaults to lean. <p>This drives combustion temperatures up, causing a host of other problems. Some of these problems, such as ping, are compensated by ignition timing. This reduces engine output.<p>Catalyst efficiency and life also suffers.<p>That's why it is a good idea to periodically replace an O2 sensor. This doesn't need to be done very often and there are tests that can confirm the O2 sensor's functionality.<p>O2 sensor degradation is inevitable. Like shocks and brakes, this sensor has a finite life span. This life span isn't normally discussed in the owner's manual because it occurs very late in the car's life -- after 10 years. Since the average North American car's life span is less than that, there's little point devoting much ink to the subject.<p>240s, however, last a long time. So it's wise to think beyond the book...<p>Hope this helps.
 

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Discussion Starter · #6 ·
Re: 91 240 Cold Start Question (RearWheelPaul)

George, I apologize for my apparent ignorance, but I would need to know how I can dump the OBD code.<p>Thanks<p>Anders
 

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Re: 91 240 Cold Start Question (pjf)

Thanks for the detailed service instructions Rearwheelpaul. I will follow those and see what improvement it brings.<p>Anders
 

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Discussion Starter · #8 ·
Re: 91 240 Cold Start Question (anders57)

Where would you find instructions how to replace the o2 sensor ?<p>Thanks<p>Anders
 

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Re: 91 240 Cold Start Question (anders57)

It's like replacing a spark plug. It just requires a special socket (available at most auto parts stores) and an impact wrench (to loosen what will be a corroded sensor). <p>But if you need to have a reference, buy a shop manual.
 

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Discussion Starter · #10 ·
Re: 91 240 Cold Start Question (RearWheelPaul)

will do, thanks for the tip. I got the 122/p1800 manual, guess I need the 240 one as well!!<br>Still... dumping those OBD codes George mentioned, how is that done ?<br>Thanks<p>Anders
 

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Re: 91 240 Cold Start Question (anders57)

FUEL SYSTEM LH 2.4 - B230 F 240 89-92<br>Control function 1 Fault Tracing<p>Open the diagnostic socket cover and connect the selector cable to pin no.2.<p>Turn on the ignition.<p>Enter control system 1 by depressing the button once.<p>Depress the button for at least 1 second, but not more than 3.<p>Watch the light diode and count the number of flashes in the three flash series indicating a fault code. The flash series are separated by a three second interval, making them easy to read.<p>Make a note of the fault codes.<p>If no fault codes are received by the diagnostic unit, the diode will flash 1-1-1 and the fuel system is operating correctly.<p>Check to see if any fault codes are stored in the memory.<p>Depress the button again. Make a note of any additional fault codes.<p>Depress the button a third time to see if a third fault code is stored in the memory.<p>If the code received when the button was depressed the first time is repeated, there are no other codes in the memory.<p>NOTE! The diagnostic system memory is full when it contains three fault codes. Until those three are rectified and the memory is erased, the system can not give any other problems.<p>LH Jetronic 2.4 FUEL SYSTEM B230F 240 89-92<p>The fault code key below shows the fault Indication codes.<p>Fault code key<p><br> 1-1-1 No faults<br> 1-1-2 Fault in control unit ( Change control unit )<br> 1-1-3 Fault in injector ( Break in lead, clogged, etc.)<br> 1-2-1 Signal to/from air mass meter is faulty<br> 1-2-3 Signal missing to/from coolant temperature sensor, possible grounding short<br> 1-3-1 Ignition system rpm signal missing<br> 1-3-2 Battery potential too low or too high ( Check battery and charging system )<br> 1-3-3 Shutter switch; idle setting faulty, possible grounding short<br> 2-1-2 Lambda-sond signal missing or is faulty.<br> 2-1-3 Shutter switch; full load selling faulty, ( possible grounding short )<br> 2-2-1 Lambda-sond not operating.<br> 2-2-3 Signal missing to/from idle valve.<br> 2-3-1 Self-adjusting Lambda-sond not operating.<br> 2-3-2 Self-adjusting Lambda-sond not operating<br> 2-3-3 Idle valve closed. ( possibly leaking air. )<br> 3-1-1 Signal missing from speedometer.<br> 3-1-2 Signal missing for knock related fuel enrichment.<br> 3-2-2 Combustion cleaning of hot wire in air mass meter not operating.<p>Fuel system LH2.4 - 240 Fault tracing<p>Erasing diagnostic system memory<p>Once all fault codes have been read and the faults corrected, the diagnostic system memory is erased as follows:<p>1. Switch on the ignition.<p>2. Read the fault codes again.<p>3. Depress the button more than 5 seconds. Release the button. After 3 seconds the diode should light up.<p>4. Depress the button again for more than 5 seconds. After releasing the button the diode should stop shining.<p>To check that the memory is erased, depress the button once for more than 1 second but not more than 3 seconds.<p>Flash series 1 - 1 - 1 denotes erased memory.<p>Start and run engine<p>Turn off engine.<p>Check if new fault codes have been stored in the memory<p>1. Turn on ignition.<p>2. Depress the button once for more than 1 second but not more than 3 seconds.<p>It the flash series 1-1-1 comes up, there are no additional fault codes.<p> If there are more fault codes, continue fault tracing.<p>Turn off ignition.<p>With regard to the DTCs for position number 6, this position is for testing the EZ 116K electronic spark control in LH 2.4/3.1 cars. The fault messages are as follows:<p>111 No fault<br>142 Control Module Fault<br>143 - Knock Sensor Signal Fault<br>144 Load Signal from MFI absent<br>154 EGR Flow Hihg<br>214 RPM Signal absent/faulty<br>234 Throttle Posn switch signal in idling position faulty<br>241 EGR flow low<br>413 EGR temp sensor absent<p>
 

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Discussion Starter · #12 ·
Re: 91 240 Cold Start Question (RearWheelPaul)

Thanks for taking the time to explain all of that ReerWheelPaul, much appreciated !!<p>Anders<p> <IMG NAME="icon" SRC="http://********************/smile/emthup.gif" BORDER="0">
 
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