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Car Forum / Volvo Cars / September 2004My Volvo tried to kill me
Well it's not really as bad as all that. The car is 1983 240 Turbo automatic. I did some work over the weekend trying to diagnse and repair a few persistent problems. I have been having trouble with my cruise control not working so, following the troubleshooting guide I received from Grtdane, I checked all the electrical components (all checked out) and reconnected the wires to the governor. I checked the Throttle Actuator hoses (one thin and one fat with a cable running to the throttle body) and found the thin one did produce vacuum (as required) but the fat one wasn't airtight (a-HA!). I wondered where it goes and how to replace it? Then I set to work on figuring out why my car won't idle until it's warm and why it stalls if I'm really gentle on the gas (that is, if I'm coasting slowly and I give it just enough gas to raise the tach a few RPM and then release it the car stalls). The last time this happened I had loose air-hose clamps and tightening them and cleaning the air filter did the trick. Not this time. Then, looking at my Haynes Manual I saw that the Throttle Sensor (which is a small flat box with a copper tab sticking out and resting against the throttle). According to Haynes when the throttle opens there should be an audible 'click' as the copper switch also opens. This has never been the case so I bent the copper tab until it clicked on and off as the throttle left the "zero position". Then I went for a drive. I live downtown in a crowded city. Several times when accellerating sharply the pedal would take off! The car would accellerate wildly and the pedal would pull away from my foot. Braking had no effect on the throttle and yielded the expected "one foot on gas one foot on brake" results. Only kicking down HARD on the gas pedal would free it from this spell. One time I had to kill the ignition because it started racing right before a stop sign. I was able to reproduce the problem whenever I stepped hard on the accellerator. Disconnecting the cruise governor did not solve this problem. I bent the copper tab on the Throttle Sensor back so that there would be no more clicking but, although the problem is gone, I just don't think that was it. What was happening was definitely vacuum at work on the gas pedal so I'm suspecting the Throttle Actuator is a factor but don't understand how a leak can cause MORE vacuum. Should I disconnect the throttle actuator? Could it be the Sensor? I suspect vacuum is at the root of all my problems (cruise/idling/racing)... any ideas on what to check next? Thanks in advance. blurp ps. sorry this mesage is so long, I wanted to get all the details in. > ... any ideas on what to check next? The mechanic! Don't trust your life in someone who doesn't know what they are doing like your are now!!! > Well it's not really as bad as all that. The car is 1983 240 Turbo > automatic. [quoted text clipped - 49 lines] > > ps. sorry this mesage is so long, I wanted to get all the details in. I would check your motor mounts, as if they are broken the engine will torque to the side and put the accelerator cable on a bind and pull it to WOT . This has happened to me on a 240 and the fix was new motor mounts. Harold Good one Mrs. Fricker. Anyhoo, upon closer inspection it became apparent to me that the plastic threaded barrel adjuster through which the cable from the Throttle Actuator passes was broken and folding at 90 degrees to the piece through which it passes. Make sense? I figure when the throttle was applied sharply it caused the cable and housing to back off from the threaded retaining clip and fold over, effectively pulling the cable and applying gas via the actuator cable regardless of the actual position of the gas pedal. Stomping the gas pedal would then return it to its correct position. It has been straightened out but I should probably find a replacement for the threaded plastic barrel. Next question...does that vacuum-powered throttle actuator do anything outside its cruise control duties? Can I safely disconnect the whole thing? Also, I was reading up on the throttle sensor and I suspect someting is up with it. The manual shows it as a small part about the size of a box of matches (which it is) and that it should have 3 connectors on top (which it has). This is where things go astray: 1) Haynes says it's supposed to 'click' as the throttle is opened from a zero position but that was not the case before and it's not now that I set it back. With the throttle at zero you can reach in with your finger and push the switch a bit further and it will click but under normal operation it never gets pushed far enough to click. 2) There are three electrical connectors on the part but only two wires have ever been connected to the thing, the third terminal left unused. 3) Haynes says that a 4.something current should be detected across two of the terminals at idle and then drop to zero as the throttle opens up (of course that's where it's supposed to 'click'). With mine just the opposite is true. I may have this backwards since it's been a few days but, regardless, whatever Haynes says my readings were the opposite. This leads me to believe that Haynes may not be taking into consideration variances due to age and model. I figure a malfunctioning part would give diminished readings but not the exact opposite. Am I wasting my time even looking at this thing? Could it really have any role in the idling/cruise/racing issue being explored here? Thanks again, blurp ps. WOT = Wide Open Throttle? >> Well it's not really as bad as all that. The car is 1983 240 Turbo >> automatic. [quoted text clipped - 55 lines] > >Harold >Good one Mrs. Fricker. > [quoted text clipped - 104 lines] >> >>Harold As an additional note: The item I've been referring to erroneously as 'throttle sensor' is, I believe, actually a 'throttle switch'. I have been completely unable to locate any picture of a part that resembles the part I'm taking about (!!!) but the part I'm talking about DOES NOT look anything like this: http://www.vlvworld.com/VolvoRepairManual/repair_pics/throttleswitch.jpg Although it's clearly the part in the above picture that the Haynes manual is referring to. I don't have any part under the hood that looks exactly like that. Furthermore I have looked at over 500 images on the Brickboard and cannot find one that shows engine compartment contents identical to mine! None show the Throttle Actuator (next to the fuel filter in my car) and all have a very different throttle connection on the engine (mine is a tall cylinder with layers that move independantly of each other depending on which of 3 cables pull on it). I'll post a picture soon. blurp > As an additional note: > [quoted text clipped - 20 lines] > > blurp 240 Turbos (and other Volvos of that vintage) have a microswitch for a throttle switch. All it's designed to do is signal the idle computer that the engine is at idle. This particular part is actually a standard electronic component, a double throw, single pole switch. Some have the switch closed at idle (use the common (C) and normally open (NO) terminals) and others have the switch open at idle (use the common (C) and normally closed (NC) terminals). The switch should click as you have a transition to and from the idle stop position.  SignatureMike F. Thornhill (near Toronto), Ont. NOTE: new address!! Replace tt with t (twice!) and remove parentheses to email me directly. (But I check the newsgroup more often than this email address.) >> As an additional note: >> [quoted text clipped - 29 lines] >and normally closed (NC) terminals). The switch should click as you >have a transition to and from the idle stop position. As I suspected! So it is unlikely that a modification to this switch to enable that click at "transition to and from idle stop position" could have caused the engine racing. I will, therefore, bend it back to once again operate in this way with some confidence that the engine won't be taking off on me. Thanks, blurp. ps. Re: The leaking fatter vacuum hose running to the throttle actuator... When parked with the engine running I can hear a whistling (vacuum leak) if I race the engine up above 3K RPM. Is this likely to be the same leak or is there another leak I should be tracking down? In other words, what is that fat vacuum hose actually conneced to? (The people who publish manuals with wiring diagrams would do well to publish the vacuum schematic as well!) Have you checked to see if you won a Darwin Award for this? ( http://darwinawards.com/ ) Darwins are awarded to those who die in pursuit of foolish deeds. I'm still alive. Maybe tomorrow... watch the list! blurp >Have you checked to see if you won a Darwin Award for this? > > ( http://darwinawards.com/ ) > As I suspected! So it is unlikely that a modification to this switch > to enable that click at "transition to and from idle stop position" [quoted text clipped - 12 lines] > (The people who publish manuals with wiring diagrams would do well to > publish the vacuum schematic as well!) Keep in mind that maybe the "modification" was done to "solve" or hide the problem you're now dealing with. The fatter hose from the vacuum actuator goes to the brake and clutch pedal switches. This way not only is the cruise control switched off electrically, the vacuum is dumped as well so it loses its "muscle". Disconnect the cable from the actuator to the throttle pulley to make sure this is not the problem. SignatureMike F. Thornhill (near Toronto), Ont. NOTE: new address!! Replace tt with t (twice!) and remove parentheses to email me directly. (But I check the newsgroup more often than this email address.) |
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