95 SL Auto Transmission Shifting Delay

Ok, so for the past few months I've noticed my car has started developing a weird delay or sudden quick jump with shifting, -this isn't bad enough to cause the car to be a road hazard or anything, but it's very very irritating when it occurs.

The weird part is, the car only does this once the engine is fully warm or if its a warmer day outside. (like 75+ F outside) (I determined this because it never seems to happen in the morning on my way to work, but it does sometimes happen on my way home from work). So, living in CA, the car has started doing this more now that it's getting warmer outside. What the heck could be causing this? Is there some kind of temperature sensor related to my transmission shifting that could be going bad?

The transmission is perfectly fine when it's not warm out, or when the engine is not yet fully warmed up, so I don't think the transmission itself is going bad. It's got to be something temperature related.... I just can't figure out what it is since I have little mechanical background, and I don't want to take it to a transmission shop until I have an idea what it could be, cause they'd have to keep the car for a day or two to run some tests on it.

Also, I feel like the acceleration is also affected around the time the weird shift problem occurs, like its slightly bogged down. It's almost like a hiccup, then it catches itself, and doesn't do it again until the next day.

try switching from PWR to ECON or vice versa. If this fixes it, it might be a TCU issue. If not--and you're still driving the same way--then it could be something mechanical.

Thanks for the response.

I usually drive in ECO mode but I'll try switching to PWR mode and see if the issue still occurs.

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Originally Posted by 89HatchbackLxi

Thanks for the response.

I usually drive in ECO mode but I'll try switching to PWR mode and see if the issue still occurs.

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Same, but I have noticed at times that ECON seems to act "janky" and PWR seems to alleviate that.

Drove car in PWR mode yesterday and I had no issues with the transmission acting "janky". However, the temperature was a bit cooler yesterday and today so it may have also been that factor which prevented the triggering of jankiness in the transmission. Issue is also intermittent, so I'll keep it in power mode the rest of the week to do more testing.

If this does fix the issue is there anyway to reset the TCU? Or would replacement be the only option?

Also, a bonus question. My gas light seems to no longer be illuminating when I'm low on gas, and so I think it's burnt out. Is this light supposed to momentarily flash when the car is started, as various other lights on the instrument panel do, or does it remain unlit during startup?

Have been driving the car in ECO mode on the way to work in the mornings (since it's cooler out) and then in PWR mode the rest of the day. I haven't experienced the weird shift delay since I've started doing this. Thanks for the suggestion! I'm amazed something so simple actually worked!

However, does this mean my TCU could be going bad? I swear the issue is somehow related to temperature. Maybe a temp sensor that's only used/or is set to check for a different temp when in the ECO setting or something?

I'd prefer to be able to use ECO mode for it's better MPG (as my car never used to have this issue and I almost always drove it in ECO mode before), any thoughts on what the issue could be caused by?

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Originally Posted by 89HatchbackLxi

Have been driving the car in ECO mode on the way to work in the mornings (since it's cooler out) and then in PWR mode the rest of the day. I haven't experienced the weird shift delay since I've started doing this. Thanks for the suggestion! I'm amazed something so simple actually worked!

However, does this mean my TCU could be going bad? I swear the issue is somehow related to temperature. Maybe a temp sensor that's only used/or is set to check for a different temp when in the ECO setting or something?

I'd prefer to be able to use ECO mode for it's better MPG (as my car never used to have this issue and I almost always drove it in ECO mode before), any thoughts on what the issue could be caused by?

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I'm not an electrical engineer. If Shooter83 is around, I'd ask him--he's the only guy I know who keeps electrical diagrams as bathroom reading materials. Perhaps someone with more expertise than I can chime in.

As to the fuel efficiency, this is irrelevant. All ECON/PWR does is change the rpms the transmission shifts at, and its willingness to "kick down" rapidly. If you're driving in a regular, non-aggressive fashion, you should not see any noticable difference in fuel economy in one mode vs the other.

I'm not sure on the fuel light, I haven't driven mine in several years (I'm not stateside). I think mine would normally only come on once the needle was pretty much ON the "E".

If someone can chime in on the TCU, I might learn something myself. I had the same problem (still do on occasion), and it was Shooter83 who turned me onto the mode switching.

Update: As the summer begins to approach and the weather has gotten a good 15-20 degrees warmer during the day, the vehicle has started having the same issue again, even with PWR mode on. PWR mode seemed to help originally, however it seems it was only so effective as the outside temperature increases...

It probably wouldn't hurt to bypass the radiator cooler and go with a large aftermarket one.

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Originally Posted by Forest Gump

It probably wouldn't hurt to bypass the radiator cooler and go with a large aftermarket one.

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Agree here. While not a 3S I saw fluid temps drop drastically on my Grand Prix when I installed a Hayden 1403 cooler. The cooler is actually ran in series with the factory cooler too, so if I ran it stand alone I could see even lower temps. It is pretty big, but not even close to the largest they offer. I was barely able to make it work without cutting or modifying anything.

My temps before the cooler would sometimes approach 230* on hot days on certain roads. It hardly ever goes above 200* anymore.

Thank you for the suggestions. However my car has never had any issues with overheating, and the engine temp gauge never has gone past the halfway mark. While it may be a good upgrade overall, I don't think replacing my radiator is going to affect anything in this case. What are you using to accurately measure the heat?

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Originally Posted by 89HatchbackLxi

Thank you for the suggestions. However my car has never had any issues with overheating, and the engine temp gauge never has gone past the halfway mark. While it may be a good upgrade overall, I don't think replacing my radiator is going to affect anything in this case. What are you using to accurately measure the heat?

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I was saying put a bigger transmission cooler on it. There could be a restriction in your old one and its not really big enough anyway.

Yeah, we aren't talking about replacing the radiator, we are talking about replacing the transmission cooler and running it separate from radiator.

Your engine temperature gauge has zero bearing on the transmission temperature. Even if it did, the stock gauges are hardly analytical enough to accurately gauge what the exact temperature range it is operating within.

Regardless of apparent transmission issues or not, choosing to run a separate trans-cooler and--if possible--an inline filter, is always a good idea. The stock filtration on the trans is internal, so it's difficult to change & not easily checked for debris.

One of these:
http://ups.mazda626.net/img-296817-1-1105a.jpg

and something like one of these, depending on if you plan to run FMIC or SMIC (but for N/A's, you can probably just treat it like you're running FMIC, because you have plenty of open space on the sides).

Universal Aluminum Remote Transmission Oil Cooler 15 1 2" x 10" x 3 4" | eBay

New Aluminum External Transmission Fluid Oil Cooler with 10" Electric Fan Towing | eBay

p.s.
I didn't check sizes on this, these are just sample auctions. FYI, I got two of the "with fan" types for my build, one on each side, one for oil, one for transmission. However, my existing build has the other type of cooler, and it's simply bolted in front of the existing radiator.

This is the one I am running on my Grand Prix

http://www.amazon.com/HAYDEN-TRANSAV.../dp/B009TABMMW

No fan needed, and as I said it is still in series with the factory cooler so it is still getting some heat from the radiator in the colder months. Even in the hotter months my trans temp doesn't exceed 200*, and hardly ever goes above 190*. If I ran it standalone the trans temps would probably be in the 160's which is actually a little too cool.

Oh ok, that makes sense... However, my car knowledge/skills all relate to autobody, and i cant really do anything other than the very basics when it comes to doing anything under the hood. How much do you think it would cost to have my transmission cooler replaced with an aftermarket cooler at my usual repair shop? Would it be bolted on in addition to the stock cooler? Or replace the stock one entirely?

You can do a trans cooler install with a few basic hand tools. If you can do auto body, then you can do a cooler install.

The factory cooler in integrated into the radiator. Dependent on what type of climate you live in you can either run the cooler in series with the factory cooler, or you can run it standalone, completely taking the cooler in the radiator out of the equation.

Its been a long time since I looked under the hood of a auto 3s so I can't remember how the lines are routed and if they are just soft lines or have a hard line as part of it. That right there will determine the difficulty of the install. If it is soft lines you can just run all new soft lines to the new cooler from the trans and use good clamps.

mine has all soft lines, iirc. and up until the engine swap, the filter was immediately accessible after opening the hood. couldn't have been any easier to work on.

Okay, I thought it was all soft lines. On my Grand Prix it was a little harder because it is a fitting with hardline coming out of the trans, then it goes to soft line, then back to hardline with a fitting to screw into the radiator. I had to cut the factory line at the soft part and using double barbs hooked to it and ran it to the aftermarket cooler that I was attaching to the front of the ac condenser.

With all soft lines the options are much easier. If you want to run it standalone you just need to get enough hose to run from the trans to the cooler, and from the cooler back to the trans. If you want to run it in series you just need to get a section of hose that is long enough to run from the cooler back to the trans since you would use the factory line from the trans to the radiator. Then the factory line coming out can be run to the external cooler. Then the new piece would run from the external cooler back to the trans.

So the best solution would probably be to run it standalone, correct? Since a buildup/restriction in my stock trans oil cooler is what may be causing the issue? Running it in series may run it cooler, but the buildup/restriction issue likely won't change since it'll still be part of the trans fluid cooling system? I'm thinking if I do decide to tackle this I may try to install it behind one of the dual vents on the sides of the front bumper, if it fits.

Edit: then again, if it's temp related, perhaps running it in series WOULD help more...

Actually running in series would make it run a little warmer than running it standalone since the radiator warms the fluid slightly.

Ok. It probably has a reason for warming it though, right? Like in case of extreme cold weather?

What should I use to check the temp of the fluid before I start on anything?

Its technically not supposed to warm it per say, but in extreme cold conditions it does help with that.

As for checking temps you'd probably have to install some sort of aftermarket trans temp gauge. There is a trans temp monitor OEM on my Grand Prix, thats the only reason I know the temps there.

too cold trans fluid. sounds like an N/A problem. :)

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Originally Posted by IPD

too cold trans fluid. sounds like an N/A problem. :)

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Eh, supercharged GP's can still have issues with too cold fluid. Realistically you want to be around 175*. If you live in a hotter climate it probably won't be an issue, if you live in the northeast, winter driving can have issues with the colder fluid.

I kinda figured I'd have to install a gauge. I was kinda just hoping I could use a laser temp sensor or something, but that probably wouldn't be too accurate/accessible for trans fluid.

I live in the High Desert area of Socal, so "extreme cold" here is about 10'F, maybe 0'F at the lowest, and that'd probably only be an overnight temp. Heat, on the other hand....

So, I caved and had my transmission rebuilt about 3 weeks ago. Transmission shop found a problem with 2nd gear sticking, and overdrive sometimes not engaging/disengaging. Said they found it was worse when the car was still cold. Had my front rotors replaced at the same time, as they were causing the car to shake a bit when braking. Cost me a few grand, but my car is now running as it should be again. The shop let me see my parts afterwards, and a couple of the gears were definitely looking pretty worn. Previous owner had the transmission actually replaced back in 2000 according to the pile of service papers that came with the car.

I guess 15 years isn't too bad before needing a rebuild. Everyone tells me the automatic transmissions on these cars aren't that great, so I suppose a rebuild was to be expected by now. Hopefully the engine is more durable though.

Those people have no fucking clue what they're talking about. These transmissions are great. Dodge wouldn't have used them in everything from minivans to the stealth--if they weren't good. You don't see DSM guys bitching about them. I think it's just 3/s owners who don't know any better (because they think it's somehow inferior because the VR4/TT's never came with them stock). Couple that with people who don't know anything about the 3/s--who diss on the platform all around because of the baseless urban myths they hear & repeat. And last but not least, idiot owners who should have bought a fucking manual in the first place--but instead got an ATX & then try to shift it like an MTX, do neutral drops, etc.