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94' 940t loses power uphill anytime/engine has power downhill and bogs after going up a hill

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youngvolvo940

Member
Joined
Oct 31, 2024
Hey community I'm a new member but this is my favorite Volvo forums and I figured it was time I joined. Anyway I've gotten this Volvo 940t in June only had 156k and all seemed good until I started it up when I got home and noticed a weird groan or almost sounded like something slowly sliding or trying to get unstuck and I figured that wasn't good. It drove good until I noticed it bogging down going uphill and having no way of going past 5-10mph up pretty steep hills. And the shifts were almost always hard or felt like they shot back a bit at higher rpm like a rubber band sort of Thanks for your time everyone and Im glad to be apart of the community! side note: I've only owned Volvo and only ever will >:)
 
youngvolvo940 said:
Hey community I'm a new member but this is my favorite Volvo forums and I figured it was time I joined. Anyway I've gotten this Volvo 940t in June only had 156k and all seemed good until I started it up when I got home and noticed a weird groan or almost sounded like something slowly sliding or trying to get unstuck and I figured that wasn't good. It drove good until I noticed it bogging down going uphill and having no way of going past 5-10mph up pretty steep hills. And the shifts were almost always hard or felt like they shot back a bit at higher rpm like a rubber band sort of Thanks for your time everyone and Im glad to be apart of the community! side note: I've only owned Volvo and only ever will >:)
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With low power the first suspects I would consider are usually bad fuel pressure or bad timing. Curious if the exhaust smells like fuel/seems to run rich - that would point to bad timing. I'm guessing the hard shifts are a separate thing.
Could also be a boost pipe leaking badly somewhere but I don't know much about the turbos.
 
A bad HG engine will still run, but be gutless. Never hurts to do a compression test to confirm HG and valve/cam/timing belt health & adjustment.

At a higher level, you need to check the onboard LH fault code system and see what error codes it gives you.

Do you know anything about the internal combustion engine?
If YES, find the link to the Volvo 700/900 Maint. Pages, hosted by the UK Volvo club. You will find plenty of diagnostic assistance therein.
 
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I haven't been on this thread in a while but hoping someone sees this, My throttle linkage rod seems to be loose and after reading up about proper throttle adjustment that seems to be just what I need. But does that explain why my car idles right around 500-550 rpms? I just replaced IAC as well thinking that was the culprit to no avail and didn't smooth out idle either.
 
youngvolvo940 said:
I haven't been on this thread in a while but hoping someone sees this, My throttle linkage rod seems to be loose and after reading up about proper throttle adjustment that seems to be just what I need. But does that explain why my car idles right around 500-550 rpms? I just replaced IAC as well thinking that was the culprit to no avail and didn't smooth out idle either.
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Is your idle control valve working? Does it actuate in the diagnostic modes?

An improperly adjusted throttle/sensor/linkage can absolutely result in the idle air control valve not being activated at idle like it should be. Check that everything is in spec.
 
Diagnostic modes as in the thing that reads the fault codes? Sorry I'm not too sure what you mean. And this is definitely starting to make sense if my IAC isn't being activated at all.
 
youngvolvo940 said:
Diagnostic modes as in the thing that reads the fault codes? Sorry I'm not too sure what you mean. And this is definitely starting to make sense if my IAC isn't being activated at all.
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yes, there is a setting that should ping your injectors, idle valve, and some relays under the hood among other things. If you can hear and feel it actuating in that mode then you know the ecu is connected to it
 
NLRegina said:
yes, there is a setting that should ping your injectors, idle valve, and some relays under the hood among other things. If you can hear and feel it actuating in that mode then you know the ecu is connected to it
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Update: everything pinged in order and went off as it should in test mode 3. I ordered the Haynes manual PDF from eBay and I should be able to do the throttle/link arm adjustment by the book. Is there anything else I should investigate for low idle/poor shifting?
 
youngvolvo940 said:
Update: everything pinged in order and went off as it should in test mode 3. I ordered the Haynes manual PDF from eBay and I should be able to do the throttle/link arm adjustment by the book. Is there anything else I should investigate for low idle/poor shifting?
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Just read the throttle adjustment procedure here

Bosch — 1991 Volvo 740 L4-2.3L SOHC VIN 88 B230F Service Manual | Operation CHARM

Detailed repair manual for the 1991 Volvo 740 L4-2.3L SOHC VIN 88 B230F.
charm.li

You can always check it for your model specifically if you go back a few pages but you should be fine with that
 
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