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RWD - Slow Cold Start, 1992 Volvo 940 Rex Regina, Normally Aspirated

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Slow Cold Start, 1992 Volvo 940 Rex Regina, Normally Aspirated 900 1992

I am experiencing a slow start or long crank (3 to 4 second) when the engine is cold. Once started the engine runs fine. Once started and shut off, the engine restarts quickly without delay. However, if the engine is off for a few hours the slow start is experienced. Any thoughts on what is the root cause of this problem?

A fuel smell is present after the slow start or long crank. For some reason the engine seems to be calling for excessive fuel when the engine is cold.

It is important to note that the cold start occurs when the engine is cold. The situation is experienced in warm and cool air temperatures.

The following preventive maintenance (PM) and replacements, that may be pertinent, have been completed:

New Fuel Pump Assembly 5/2013 old one died
New Fuel Filter 5/2013
New Fuel Pressure Regulator 6/2014 PM (This is a 3.0 bar FPR should it be?)
New Air Filter 4/2016 PM
Cleaned Idle Air Control Valve 9/2016 PM
Replaced RPM Sensor 10/2016 (in search of engine shut off at 60 MPH issue)
Replaced Power Stage (non-blue box) due to engine shut off issue 11/2016 PM (fixed problem)
Cold Start problem may have started around December of 2016
Bosch Distributor Cap 7/2017 PM
Bosch Rotor 7/2017 PM
Bougicord Class E Wires 7/2017 PM
Cleaned Throttle Body 7/2017 PM
Cleaned Air Temperature Sensor 7/2017 PM
New Volvo Plugs 7/2017 PM
New Engine Coolant Temperature Sensor (experienced two ECT 2-2-4 codes) 7/2017
Vacuum line hose connections to plastic line replaced where visible 7/2017
Engine Sensor connectors cleaned with Deoxit 7/2017
Engine Ground connections removed and cleaned 7/2017
Fuel Injectors Professionally Cleaned by RC Injection 9/2017
Intake Manifold Gasket replaced 9/2017

I searched multiple forums and found a few similar Rex Regina situations, but no root cause defined. Please let me know your thoughts as to what the root cause of my slow start problem may be.





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    Slow Cold Start, 1992 Volvo 940 Rex Regina, Normally Aspirated 900 1992

    It may be the FPR a new bosch type is $28 on ebay,,it maybe the cap & rotor,, when my 93 starts quiting or failing to start I replace the cap & rotor & it starts really quick,





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      Slow Cold Start, 1992 Volvo 940 Rex Regina, Normally Aspirated 900 1992

      I replaced the FPR approximately 1,200 miles ago. The Rex Regina uses a 2.5 bar FPR which was difficult to find. I used a Bosch P/N 0 280 160 227 which is 2.5 bar. By the way I mistakenly had a 3.0 bar FPR in there for approximately two years which was close to when I started to notice a slower start. Changing to the 2.5 bar FPR didn't seem to change a thing in the way of performance. However, when I realized I should be using the 2.5 bar FPR I found one on line and installed it hoping it would maybe reduce the pressure and fuel volume to the cylinders at start up. I was wrong, as I still have the slow start and running rich problem.

      I changed the cap and rotor about 5,500 miles ago, I'm thinking I am ok there. My original post defines the preventive maintenance items I have taken care off recently.

      Thanks for your thoughts...





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    Slow Cold Start, 1992 Volvo 940 Rex Regina, Normally Aspirated 900 1992

    A recent check of the Ignition Fault Codes shows: No Faults (1-1-1)

    However, I am now getting the following Regina Fuel Injection Fault Codes:
    2-2-1 = Oxygen Sensor not operating
    2-3-2 = Self Adjusting Oxygen Sensor not operating
    3-1-1 = Signal missing from speedometer (This is from the bad capacitor speedo issue)

    The question I have is whether the oxygen sensor could be the root cause of my slow start (long 4 second crank) problem, or a significant contributor?

    I apologize for the long delay, but my son’s purchase of a 2005 S60 R with manual transmission has pushed this starting issue (on his 940 hand me down) down the list of priorities.





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      Slow Cold Start, 1992 Volvo 940 Rex Regina, Normally Aspirated 900 1992

      The question I have is whether the oxygen sensor could be the root cause of my slow start (long 4 second crank) problem, or a significant contributor? Would an open from the O2 sensor provide an incorrect resistant to the computer and cause a long crank?

      I am now getting the following Regina Fuel Injection Fault Codes:
      2-2-1 = Oxygen Sensor not operating
      2-3-2 = Self Adjusting Oxygen Sensor not operating





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        Slow Cold Start, 1992 Volvo 940 Rex Regina, Normally Aspirated 900 1992

        I replaced my O2 sensor with an NTK-25002 oxygen sensor. After 332,112 miles it was due for a new sensor. The 2-2-1 and 2-3-2 codes have been eliminated.

        Unfortunately, I am still experiencing the fuel rich, 4 second long crank at cold start. However, I also understand that the O2 sensor was not going to correct this situation, since it's signal does not contribute at cold start.





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        Internal engine drag 900 1992

        I noticed that my 940 1994 Bosch the early morning starting seems to be easier after any recent engine oil change. This much more so as currently I'm using the semi-synthetic variety. Internal engine drag seems to be at play here.

        "Would an open from the O2 sensor provide an incorrect resistant to the computer and cause a long crank?"
        No. The ECU sensing circuit has nothing to do with how fast the starter turns. Study the circuit diagram and you'll see there isn't any connection.

        The O2 sensor doesn't operate unless its fully warmed up (thus the need for a heated sensor when its location is far down the exhaust). The internal heater in our O2 sensor provides a much quicker operating time (within 1/2 minute I think) but not immediately after starting. Thus the 940 uses 3 wire heater - 2 wires for heating element, 1 wire (plus exhaust pipe as ground) for sensing.

        For the O2 sensor codes - ensure its wire connection is intact. Use multimeter and check ground resistance from sensor's site to exhaust manifold. Should be less than 1 ohm. If all checks out OK you might need to replace the sensor.

        Regards,
        Amarin.





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          Internal engine drag 900 1992

          Thanks for your insight. I was thinking that the O2 sensor presented some sensing resistance to terminal 24 of the Regina Fuel Injection ECU, even without the heating element impact at cold start up. My problem is an excessive fuel dump into the cylinders at cold start. It isn’t a starter crank problem. I was wondering if the O2 may be contributing. I now have access to the car and will be able to investigate this further.





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    Slow Cold Start, 1992 Volvo 940 Rex Regina, Normally Aspirated 900 1992

    Hello, I have experienced the same with a fuel pump assembly for my 1990 744 Rex-Regina that I installed this August 2017, verbatim. The fuel pump assembly I installed was used, but perfect in all aspects. I might suggest that you revisit the pump assembly in your car, especially if the pump assembly you installed in 2013 was a newer plastic coated top model. I made sure the new fuel hose/line I installed was larger than original and pushed over the barb on the new assembly and connected to the existing line, which I adapt fitted over the original line headed toward the filter, then engine. Not my normal MO, but was in a pinch. Car performs perfect after first starting as you described. You have been so thorough in troubleshooting your problem, but did not indicate on your roster of repair/replacements/upgrades whether or not you changed the fuel line or connection hardware at that time. Good Luck, I hope this helps.





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      Slow Cold Start, 1992 Volvo 940 Rex Regina, Normally Aspirated 900 1992

      Paul, When I replaced the fuel pump assembly in 2013, it was replaced with a brand new Blue Box Volvo part. Other than the fuel lines associated with the in tank fuel pump assembly, I did not modify or replace any other lines.
      I'm not sure I understand the modification you described above. Thanks,





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        Slow Cold Start, 1992 Volvo 940 Rex Regina, Normally Aspirated 900 1992

        I can understand that I was not as clear as I can be, sorry.
        My original in tank pump and total assembly had a banjo fitting
        for the line out. All that is available now is a push on type
        that came out as an original equipment upgrade due to the rotting/
        rusting problem. The long and the short of what I had to do was
        modify the connection with the adapting piece of fuel hose, add
        barbed bends plus clamps and was able to move forward.

        I am theorizing, is that the larger piece of fuel hose I used on
        the line out to push over the barb on the top of the assembly,
        creates just enough pressure variance, so the fuel flows back into
        the tank. Except for what you described, and what I admit
        I experience, the car runs fine. There is a genuine Volvo
        p/n 9142814, that would be more precise and functional...
        I was in the position to improvise...as I live on the
        Spine of the Green Mountains...some days I just need to
        move forward.

        You mention the smell of fuel, but I do know where you are
        experiencing that...in the cabin, under the hood, back of the car,
        etc...and you have done so much...I uphold that you revisit the
        pump connections, go from there...let me know...I am curious.

        Be Well

        1990 744 Base 126K, 1989 244 DL 101K, 1989 780 T 205K,
        1992 745 T 202K, 1995 944 T 156K, 1995 964 135K...
        all healthy and on the road...





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    Slow Cold Start, 1992 Volvo 940 Rex Regina, Normally Aspirated 900 1992

    Given the fuel pressure observed at the injector rail, I wouldn't dwell too much on the possibility of inadequate fuel delivery - at least not yet.

    I don't see anything in the response thread that indicates that you have really checked for spark when the engine is cold and not wanting to fire up. As was mentioned, the coil/power stage assembly on the Rex's is known for intermittent no-sparks due to oxidation and/or dirty internal connections, both of which are fixable for $0.00. Take the coil pack apart (two torx screws involved) and clean the mating surfaces and the internal connections. Make sure the springy contacts are making firm contact with the pins. You'll see what I mean when you get in there. I would also make sure that the unit's grounding to chassis is good and clean.

    Also, there was a known issue with the Regina fuel system where the cold start injector would flood the engine under certain conditions. A service bulletin issued from Volvo described a fix that was nothing more than snipping the wire that provides voltage to the CSI and splicing in a wire that now provides voltage from the starter motor so that the injector opens only while the engine is being cranked. Once the key is released back into the run position the injector closes regardless of how cold the engine is. If you look closely at the CSI wiring you can see if this TSB was incorporated.
    --
    Current rides: 2005 Volvo S80 2.5T, 2003 Volvo V70 2.4NA, 1973 Volvo 1800ES (getting ever closer to road worthiness)





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      Slow Cold Start, 1992 Volvo 940 Rex Regina, Normally Aspirated 900 1992

      Chris, thanks for the comments. I actually experienced an engine shut down situation which after much reading and some troubleshooting was caused by a failed electrical contact interface between the Power Stage and the coil pack. I replaced both last fall and the problem was resolved. I do currently have good spark at the plugs.

      Regarding the cold start injector, I have read about the Technical Service Bulletin you mention above. The problem is, either I don't have a cold start injector or I certainly can't identify it's location. I understand it is to be located on the main intake manifold line (between the throttle body and where the intake manifold splits off to the four air intakes) on the manifold. Is it possible that my engine does not have a cold start injector? I do have an Idle Air Control Valve.





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        Slow Cold Start, 1992 Volvo 940 Rex Regina, Normally Aspirated 900 1992

        As I recall it's mounted on the underside of the intake between the throttle body and the four-way split. It's probably hard to see. There is a fuel line running from the injector rail down to the Cold Start Valve - follow that hose.
        --
        Current rides: 2005 Volvo S80 2.5T, 2003 Volvo V70 2.4NA, 1973 Volvo 1800ES (getting ever closer to road worthiness)





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    Slow Cold Start, 1992 Volvo 940 Rex Regina, Normally Aspirated 900 1992

    Our '90 745 seemed to start reluctantly when cold compared to the other two 740s that we owned.

    I had our dealer check it twice.

    Eventually I was told that its Regina ignition system needed a complete engine revolution to figure out where it was before it would start.

    I never had a no start situation in the 4 years that We owned this car - this included all sorts of Massachusetts weather from over 100 degrees F to below zero.





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    Slow Cold Start, 1992 Volvo 940 Rex Regina, Normally Aspirated 900 1992

    My cold engine long start issues usually end up being the check valve on the fuel line with the filter and pump in that little caddy under the drivers seat. I went through your list and noticed it being conspicuously absent from the stuff that was replaced. Cheap and easy to replace, but you gotta get gas all over your hands. Well, you know that, you already had it all apart.

    I'd bet the fuel smell is unrelated. Well sort of. I would bet that your orings on your injectors are giving up the ghost, and are letting raw gas blow-by out while you crank. Ask me how I know, lol.

    good luck, post back with your solution





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      Slow Cold Start, 1992 Volvo 940 Rex Regina, Normally Aspirated 900 1992

      Dear Felix_the_Cat,

      Hope you're well. Rex-Regina cars have a single, in-tank fuel pump. The fuel filter is mounted on the underbody, in the same place as it is on cars with the Bosch (dual fuel pumps, one in-tank, one mounted on the underbody).

      While a check valve is part of the Bosch system, the Volvo VADIS parts list/diagrams do not show a check valve for Rex-Regina cars.

      Hope this helps.

      Yours faithfully,

      Spook





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      Slow Cold Start, 1992 Volvo 940 Rex Regina, Normally Aspirated 900 1992

      Thanks, I agree it could be the check valve since it wasn’t replaced, but I do seem to be holding fuel pressure well on the fuel rail. Given it’s a low cost item I will look into replacing it. In regard to the injector O-Rings, they were replaced when I had the fuel injectors professionally cleaned.





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    Slow Cold Start, 1992 Volvo 940 Rex Regina, Normally Aspirated 900 1992

    Tired battery?
    Dan





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      Slow Cold Start, 1992 Volvo 940 Rex Regina, Normally Aspirated 900 1992

      Dan, the battery seems to spin the engine up pretty well. I was going to discount this as a possible cause, but come to think of it I actually did replace my battery in December of 2016 prior to this situation starting. I’ll have the battery and alternator checked.





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        Slow Cold Start, 1992 Volvo 940 Rex Regina, Normally Aspirated 900 1992

        A quick and easy test for the battery is to read voltage as you crank it over to make sure voltage stays above 12V. Have someone start it while you monitor the battery.
        Dan





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          Slow Cold Start, 1992 Volvo 940 Rex Regina, Normally Aspirated 900 1992

          Thanks Dan, I was at my local Advanced Auto today and had them perform a test on my battery, starter, and alternator. The three checked out OK with no problems.





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    Slow Cold Start, 1992 Volvo 940 Rex Regina, Normally Aspirated 900 1992

    At first glance at what you've done I don't see what I would have jumped on. Rex. Not Regina. Rex.

    The ignition coil/amplifier module is notorious for temperature sensitive poor corroded connections internally. Jump on Rex. Explains fuel smell too, no?

    Edit: On second glance, maybe you did:
    "Replaced Power Stage (non-blue box) due to engine shut off issue 11/2016 PM (fixed problem)"
    --
    Art Benstein near Baltimore

    Real engineers have a non-technical vocabulary of 800 words.





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      Slow Cold Start, 1992 Volvo 940 Rex Regina, Normally Aspirated 900 1992

      Art, yes, months prior to experiencing the slow start I experienced the REX engine shut off issue and (as I work in the connector industry) I diagnosed a poor contact normal force on one of the Power Stage contacts which led to corrosion in the contact interface. I replaced the Power Stage and coil with a new one. Although, I couldn't find new Volvo blue box parts.





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        Slow Cold Start, 1992 Volvo 940 Rex Regina, Normally Aspirated 900 1992

        OK, I see you understood very well and have covered the issue I know about and remain a bit curious about whether the aftermarket parts are up to what Bendix built in the Volvo 25 years ago. I still wonder what it was that forced Volvo to second source the engine management for those brief few years.

        Having experience with the '92's fuel system in the 940 (Notes on Replacing a Regina Fuel PUmp and Why) I would discount the notion the rail is empty on your cold starts for more than two revolutions. That's my experience. No vapor lock potential exists with the main fuel pump submerged in the tank, and no check valve exists beside the inherent seal in the roller section of the Regina pump.

        If you think it is a lack of pressure in the rail, you could bump the key a few times to enable the function everybody calls "priming" before attempting the first start of the day, to see if that has an influence on the trouble.

        Beyond that, I think my next spot to verify would be the voltage on the ECT sensor lead checked by back probing the pin on the Regina ECU. I read that you replaced the sensor, and given your awareness of contact resistance effects, I think you might find this a worthwhile effort. Voltage should not be up toward 4V unless you live up above the Arctic Circle. I can't get much more specific than that without comparing to the Bosch ECT circuit. Maybe the FAQ has something Regina specific. Did you keep the old sensor? Does it look good on an ohmmeter?
        --
        Art Benstein near Baltimore

        Real Engineers repair their own cameras, telephones, televisions, watches, and automatic transmissions.





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          Slow Cold Start, 1992 Volvo 940 Rex Regina, Normally Aspirated 900 1992

          I checked the voltage and resistance at the ECU, by probing the engine coolant temperature sensor contact #13 and ground #5. The resistance (key off) and voltage (key/ignition on) are as follows:

          At 65 degree F ambient air and 56 degree coolant temperature (engine cold): Resistance = 1,665 ohms and the voltage (key on) = 2.47 volts

          At 65 degree F ambient air and engine coolant temperature at 188 degree F: Resistance = 197 ohms and the voltage (key on) = 0.33 volts.

          The data doesn't seem to be too far off the target information I have:
          At 68 degree F: about 2300 ohms and the voltage should be 2.0 +/- .5 volts
          At 176 degree F: about 300 ohms and the voltage should be .5 +/- .2 volts

          Any thoughts on whether this data is acceptable?





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            Slow Cold Start, 1992 Volvo 940 Rex Regina, Normally Aspirated 900 1992

            "Any thoughts on whether this data is acceptable?"

            Looks beyond reproach to me.

            And thank you for including the resistance readings, because with the voltage measurements you've confirmed the Regina's voltage divider network is at least very close to the Bosch circuit.


            --
            Art Benstein near Baltimore

            Draw your curves first and then plot your data!





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              Slow Cold Start, 1992 Volvo 940 Rex Regina, Normally Aspirated 900 1992

              I am still experiencing the fuel rich, 4 second long crank at cold start. In addition, I am only getting 17 MPG with mostly (75%) highway driving. The car seems to be running rich. Can this be the Bendix/Siemens ECM (Volvo p/n 9146261)??? Is it possible that the unit is failing after 333,797 miles? Is it worth replacing it with a used unit? If so, can I simply disconnect the battery and swap this out or is there some sort of programing or re-programming needed?

              Thanks in advance for feedback/guidance on this issue.





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                Slow Cold Start, 1992 Volvo 940 Rex Regina, Normally Aspirated 900 1992

                Hi
                Two thoughts. 1) Put a set of eyeballs on the ECU and its connector. I recently discovered mine had significant water intrusion and corrosion at the connector, resulting in the engine losing power to the ignition.
                2)Has the TSB been applied for the cold start valve? There should be a permanent 321 code stored if it has. You could also simply disconnect the cold start valve to see if it makes a difference.
                https://www.brickboard.com/RWD/volvo/1579113/740/760/780/hot_start_problem_1990_740_gl_regina_fuel_system_code_321_231.html
                Matt





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                  Slow Cold Start, 1992 Volvo 940 Rex Regina, Normally Aspirated 900 1992

                  Matt, I pulled the connector on the ICU and cleaned the connector with some DeOxit contact cleaner. The connector interfaces looked fine with no noticeable corrosion or distorted contact blades or receptacles. Is it possible the ICU has failed and is causing the rich condition? The car seems to run pretty well except for the slow start and lower gas mileage.

                  My 1992 Volvo 940 Rex Regina does not have a cold start valve or injector under the middle of the intake manifold. It does have an Idle Air Control Valve, but would that impact fuel usage?

                  Any other thoughts? My initial post describes everything I have serviced to date.

                  Thanks,





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                    Other thoughts redux 900 1992

                    "A fuel smell is present after the slow start or long crank. For some reason the engine seems to be calling for excessive fuel when the engine is cold."

                    The fuel odor could be a leaky injector; when I've experienced that, it is not only hard starting cold, but runs a little rough for a minute or so as the excess fuel gets dissipated.

                    With the OBD mode 3 (works in Regina too right?) you can open up the injectors to simulate that. When I've tried that with a gauge connected, the residual pressure shows the drop. Another clue might be the oil smells of fuel; dipstick is high.
                    --
                    Art Benstein near Baltimore

                    This girl said she recognized me from the vegetarian club, but I'd never met herbivore.





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                      Other thoughts redux 900 1992

                      Art, Thanks for reaching out to me. I too thought that possibly one or more fuel injectors were leaking. Approximately a year ago, I pulled all four and sent them to “RC Injectors” to have them cleaned and leak checked. I received a nice before and after report which declared them rebuilt with new O-rings and providing an improved spray pattern and balanced fuel discharge rates.

                      I could pull the fuel rail with all four injectors attached and test these for leaks and operation with the OBD mode 3 feature to confirm there are no leaks. However, keep in mind that my original statement was written before I realized that my overall MPG has dropped down to 17 MPG even with 75% highway driving. I seem to not only be starting rich but also running rich. Maybe I should do this check to confirm no leaks?

                      The oil seems to be fine and there is no dipstick lift or high crankcase pressure. A few months ago I cleaned the flame trap out, related screen, and replaced the larger related hoses and vacuum line to ensure no leaks.

                      Is the ECU a possible root cause or is that highly improbable?

                      Thanks,
                      Vince near Harrisburg… Baltimore is not far away I’m willing to drop it off for you to repair :-) . Plan B is in formulation and involves a brick on the gas pedal and the Chesapeake Bay bridge late at night.





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                        Other thoughts redux 900 1992

                        Hi Vince,

                        Three thoughts come to me:

                        (1) "Fuel Injectors Professionally Cleaned by RC Injection 9/2017 " Blame my reading comprehension. I missed this.

                        (2) You're right, a drippy injector doesn't drop highway mileage that much, just makes for long cranks sometimes.

                        (3) I am much closer than is the Bay Bridge, but not in business. Also, I have very little exposure to 7/9 cars and Rex/Regina.

                        Certainly in theory an ECU could be at fault, and running a nearly thirty-year-old car of any kind would demand I had a spare of anything so unknowable as a fuel computer to swap, however blameless its reputation might be.

                        Were the car mine, I might want to monitor that Titania oxygen sensor voltage to get a clue on how well its fuel/air mixture is being controlled. Of course, an oxygen sensor fault in itself can't cause a hard start. Now that I've said that, I need to re-read the thread to learn if you already have done that.
                        --
                        Art Benstein near Baltimore


                        When chemists die, they barium.





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                          Other thoughts redux 900 1992

                          Art, I was actually throwing an O2 sensor fault (2-3-2) and replaced it with an NTK-25002 for Regina.

                          At this point in the game, I plan on picking up a used ICU. Can I simply replace this item after disconnecting the battery, or is there a special replacement procedure or programming of the new ICU required?





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                          Other thoughts redux 900 1992

                          Dear Art Benstein,

                          Hope you're well. I chase a persistently and steadily high idle (1,700 revs/minute) on a '93 940 (Rex-Regina) concurrent with poor fuel mileage (17 versus 21 miles/gallon).

                          I've just swapped-in a known-good engine control unit, which made little difference to the idle rate.

                          I've swapped or replaced the idle air control valve, MAP (manifold absolute pressure) sensor, air intake temperature sensor, and the engine coolant temperature sensor. None of these changes improved fuel mileage.

                          I'm open to suggestions as to other tests.

                          Thanks for your always-helpful insights.

                          Yours faithfully,

                          Spook





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          Slow Cold Start, 1992 Volvo 940 Rex Regina, Normally Aspirated 900 1992

          Art, in regard to the ECT sensor replacement, once I experienced the ECT sensor codes I thought I had the “silver bullet” to resolve this situation and I simply replaced the sensor. I have the old sensor and took a few resistance readings on it in just the ambient air temperature (70 degree F) state. The resistance at this temperature is supposed to be 2300 ohms and I was reading approximately 1600 ohms on the ECT sensor I pulled out of the car. I’m not sure this explains the codes I threw, but regardless the sensor was replaced.

          In regard to the Bosch vs Rex situation, it was most likely fueled by Volvo’s desire to keep their suppliers “honest” from a purchase price standpoint and possibly the desire to not have the supply chain interrupted by an issue with one of the suppliers. Volvo could play one supplier against the other for price and volume.

          I’m experiencing nice fuel pressure on the rail and it doesn’t seem to drop off, so I don’t believe I have fuel delivery issue, but I could be wrong.

          I have to dig into the current voltages at the ECU.





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            Slow Cold Start, 1992 Volvo 940 Rex Regina, Normally Aspirated 900 1992

            I don't think you're wrong about the fuel delivery if you've measured the rail pressure. The fuel odor could be a leaky injector; when I've experienced that, it is not only hard starting cold, but runs a little rough for a minute or so as the excess fuel gets dissipated.

            With the OBD mode 3 (works in Regina too right?) you can open up the injectors to simulate that. When I've tried that with a gauge connected, the residual pressure shows the drop. Another clue might be the oil smells of fuel; dipstick is high.

            That little bit of resistance difference surely doesn't explain the ECT code being set, so maybe that is a clue. The thermistor doesn't normally fail by changing its characteristic but its packaging and connections fail from the corrosion environment making it intermittent or just plain open circuit, especially those dual units like yours referencing common to the case in the head. I just mentioned checking the voltage because it is easy to do that without disturbing the sensor.

            I figure most second-source arrangements are for competitive reasons, but Volvo's concurrent use of Bosch and Bendix is so short-lived that it makes the Rex/Regina an anomaly. The real story might be an eyebrow raiser. One major difference is Regina's ability to be reprogrammed in the field.




            --
            Art Benstein near Baltimore

            Real Engineers wear badges so they don't forget who they are. Sometimes a note is attached saying "Don't offer me a ride today. I drove my own car".





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