Problem after transmission fluid change

[Francois850]

AW50-42LE / AW50-40
The transmission above is a front wheel drive 4 speed automatic transmission. This style transmission is computer and throttle pressure controlled. Common symptoms are transmission shifting erratic, slipping or not shifting at all. Also the check engine light can come on.

External sensors like the throttle position sensor, vehicle speed sensor or output speed sensor quite often go bad, causing these symptoms. Always check your throttle pressure cable adjustment to see if it is causing the problem. On most of these models, they have a diagnostic box you can retrieve codes with. The location of this box should be in your owners manual. If you don't have a diagnostic box then run a scanner. Always check these items first before your purchase a transmission.

Check the shift solenoids that attach to the valve body, sometimes they can go bad.

Found this...

[jblackburn]

If it was definitely a solenoid and the transmission knew it, the flashing arrow would be on. I would think the same for a speed sensor though.

If you go into "3" or "L" DOES the light actually come on, or is it burned out?

Sounds like a valve body or line pressure problem honestly. I kinda wonder if the filter screen inside picked up some junk dislodged by the flush and isn't allowing full pressure when warm.

Pressures will always be higher when cold due to the thicker nature of the cold oil.

[Francois850]

If it was definitely a solenoid and the transmission knew it, the flashing arrow would be on. I would think the same for a speed sensor though.

If you go into "3" or "L" DOES the light actually come on, or is it burned out?

Sounds like a valve body or line pressure problem honestly. I kinda wonder if the filter screen inside picked up some junk dislodged by the flush and isn't allowing full pressure when warm.

Pressures will always be higher when cold due to the thicker nature of the cold oil.

Yes the light comes on (arrow) if I switch to 3 or L, definitely.
I replaced all the warning lights bulbs a month ago or so...
I guess I can't access that filter screen, can I ? Do you suggest more fluid draining and refill?

[mercuric]

Pressures will always be higher when cold due to the thicker nature of the cold oil.

That's a really good point I hadn't thought of, but seems quite obvious now

Also sort of supports one concept I had pondered, that running without a cooler caused rapid wear of some sort of seal and/or the rubber check balls in the valve body -- things that would logically misbehave worse when the fluid is thinner.

I'm not sure I'd bother throwing more fluid at it if the fluid that's in there still looks and smells new. Can't hurt, but I'd probably be more inclined to donate that $$ to the local brewery...

[Francois850]

Pressures will always be higher when cold due to the thicker nature of the cold oil.

That's a really good point I hadn't thought of, but seems quite obvious now

Also sort of supports one concept I had pondered, that running without a cooler caused rapid wear of some sort of seal and/or the rubber check balls in the valve body -- things that would logically misbehave worse when the fluid is thinner.

I'm not sure I'd bother throwing more fluid at it if the fluid that's in there still looks and smells new. Can't hurt, but I'd probably be more inclined to donate that $$ to the local brewery...

Oh I see, you mean put Bud in the trans instead of fluid? Yup, probably would work as well as it is now

[mercuric]

Oh I see, you mean put Bud in the trans instead of fluid? Yup, probably would work as well as it is now

Ha! If the tranny had any taste it'd explode and spontaneously combust

[regent]

put Bud in the trans instead of fluid?

When your transmission gets pulled over and ticketed for DUI, try telling the judge that the viscosity in there was still correct... He'll understand

[Francois850]

You know guys, the more I drive around the block the more I think that maybe I went the false route with the transmission story,
The engine just seem to maybe be the culprit when under load, if I try to gain speed, the RPM does not really increase much... what I interpreted as slippage is probably the fact that the more I push the gas pedal the more I get close to kick down and suddenly the RPM jumps... Maybe the transmission is adapting to a lack of power!
To help you visualize : let's say I am at 20mph, if I press the gas pedal both MPH and RPM needles will move increasing at the same rate, but the gain is SLOW! I hope you see what I mean.
I will get the trans tested this week but something tells me that there is another issue to prevents the engine from giving power.... an issue that does not trigger the CEL... so, if you guys have any idea of things I could check... just shoot!
A few things, since I have to push the gas pedal way too much to actually get some speed, the fuel consumption is super high which is logical. Also, don't know if there is a possible link but I forgot to mention that the ABS light is on since a month..... probably has nothing to do with the rest... but... ???
So, just to make sure, ever heard of any condition that would compromise engine power without triggering the CEL? Just wondering. I wish I could make a short video of the dashboard indications while I drive...
Thanks!

[erikv11]

Aha, maybe we're back on page 3!

Lots of possibilities for weak engine with no CEL.

Bad oxygen sensors, bad ECT, clogged cat come to mind first. Water or oil in the distributor cap, water in the spark plug wells (e.g. https://www.matthewsvolvosite.com/forums ... =1&t=54761). Fuel delivery problem (check fuel pressure), but that seems less likely.

These malfunctions should throw a CEL, but they don't always. I don't remember what all was done recently on your car but I'd start with a full look-see on the ignition system.

[Francois850]

Both sensors are new (OEM Bosch to fit), this is how I passed inspection 3 weeks ago. Everything was "READY including the CAT. So I can assume it's fine?
Distributor cap is very likely dirty, yes from oil contamination from the past.... but I have no misfire issue as far as I know... think it would possibly create a weak spark?
For the fuel pressure, don't know but I changed the filter 3 weeks ago as well.... I can't spot any leak.
ECT is new as well.
Thanks