Engine stalls when put into drive or reverse

[Christopher Bednar]

Hello, I own a 1987 Volvo 740 GLE wagon with an automatic transmission. It has roughly 192k miles on it. Problem is, ever since I owned the car, most of the time when I put it into reverse or drive, the rpms will drop significantly and sometimes it will stall the car(the car stalls a lot more easily when the engine is cold) from months of dealing with this I can tell you a few things. 1.) when I have the brake pressed and in park, it idles fine, at about 1k rpms, sometimes a little higher, soon as it is switched to R or D, the rpms drop to 400-500 and the car will stall in about 2 seconds OR the car will stay on after just barely dying and the rpms will restore to about 1k. like I said before, the car stalls a lot more easily when the engine is cold, almost 100% of the time actually, unless I 2.) switch the shifter to D or R and immediately press the gas a little. The rpms still drop but with more gas, it shudders back up to 1k and idles fine afterward. What could be the problem? My car always has had some sort of exhaust leak, and since I don’t need emissions inspection in my state, I have this weird feeling that my o2 sensor could be going bad, although I don’t really have solid evidence to support my theory, its just my gut telling me. I have no idea when the fuel filter has ever been changed. I was reading online that it could be a fuel filter issue. I don’t think it is the transmission, but I may be biased because I want to think my transmission will never die. haha. if you have any questions to ask me about the problem, feel free to ask. Thanks, Chris Bednar

Topic

[Bill]

Sounds to me like the throttle body is dirty and or the idle air control system is not working correctly.

[Coty Miller]

Yep! idle control valve is sticking or TPS is bad (throttle Position sensor).

I’ll explain why. The Idle control valve is a tiny throttle body that the computer controls to add and drop air flow into the engine(it’s the computers own little gas petal), if it’s going bad and you put stress on the engine aka putting it in gear, the engine will bog down, but since the computer is having trouble giving it some air (from a sticking ICV(Idle control valve)) the engine will stall…

Now if the TPS is bad (throttle Position Sensor) the computer may think your actually giving the car some fuel/air and so it won’t open the ICV, and the engine will stall…

Now another thing to take into consideration, is that both parts could be completely fine, it could very well be caused from a shorted wire that is connected to the two things I mentioned above, especially with the age of the car, as rubber becomes brittle with age.

As a last case result, it COULD be the EGR, but I highly doubt it…

[MARK FELDSTEIN]

Hi Chris. Isn’t a 1987 model right on the cusp of OBD I diagnostics? If so, can you get it to a parts store to have them scan for trouble codes or borrow a scanner OR buy one? It could be lots of stuff. How bout a bad catalytic converter AND a bad fuel filter, OR a bad fuel pump. When was the last time it was tuned up? See what I mean?

I’d see if you can get it scanned and if not, then start by systematically testing one system at a time, ignition then fuel and at this point, I wouldn’t start to sweat the transmission.
Mark

[Coty Miller]

OBD-I cannot use a code reader, it take a much longer and painstaking approach. On most cars you have to use a test light and it would flash numbers out… on a ford you’d jump a terminal and it would flash the codes via the check engine light…

Here is a video to kinda give you an idea on what it takes…

https://www.youtube.com/watch?v=8lkba9CWI6M

[MARK FELDSTEIN]

Well, using a more “painstaking” i.e., methodical approach, with flashing lights for interpretation would, in my view, be a lot easier in the long run then speculating about which part, which system, and what the problem is doncha think? OTOH, he could just start replacing parts and see if anything coincidentally works. B)

Here’s a video that applies directly to Pre OBDII scan codes on Volvos.

Here’s another video that applies to Volvo although I think the first one above is more useful.

If you need help interpreting the blinks you could always call a Volvo dealer.

[ron]

i think you can try and clean the idle air take the spring out use some carb cleaner

[Author]

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