Adjusting auto tranny fluid pressure [ Archive] - GasSavers.org - Helping You Save at the Pump

My wife has a 2003 Honda Accord with a 5-speed auto. The fuel economy on it is not optimal on the thing, and I think part of the problem is the lag in shifting. I know that in some VWs and in the Toyota Camry, there's a way to adjust the transmission fluid pressure to make the transmission shift sooner. This results in better fuel economy since the engine won't lag in a lower gear.

I was wondering if anyone knows if it can be done for the Accord.

Thanks,
Jeff

I would start by checking the transmission fluid levels and making sure everything is fine there. If there is too much or too little it will affect your shifting.

Yeah, the fluids are all good. This is just how the transmission has behaved since day one. It's slow to switch from 1-2 and 2-3 but is okay with 3-4 and 4-5. It could probably be better, though.

Jeff

there should be a huge resistor right next to the tranny that controls your line pressure. Some people disconnect it when racing and they get fast hard shifts.

By using a different resistor or modding the current one you can change the line pressure and affect your shifting. By disconnect it for regular driving will kill your tranny over time. It can't take full line pressure for a long time.

The 1-2 shift just blows on the new accord. It feels as if you lose all power then all of a sudden you're in second.

Wish I could give you more of an expert response. All I can say is that this is a common gripe with auto trannies. They're usually designed for "mushy" shifts so that average drivers won't complain that shifts are too hard. Imagine you're driving a stick-shift, and you're taking a looong time to bring the clutch all in after you shift, letting it slip so you don't feel a "bang" into the next gear. That's what it's doing.

The good news is that it's an old problem that most likely has a fairly inexpensive aftermarket solution. You need a shift kit. These will change/modify the valve body in the tranny, usually by replacing some parts. These are widely available for older domestic trannies, I'll bet you can find one for the Honda.

If the vehicle has a kickdown cable, it can be adjusted to change the shifting characteristics somewhat.

Maybe try tightening it a little and see if you like the effect better.

I did this on a Toyota and it made it more eager to change down and the changes were harder.

If the vehicle has a kickdown cable, it can be adjusted to change the shifting characteristics somewhat.

Maybe try tightening it a little and see if you like the effect better.

I did this on a Toyota and it made it more eager to change down and the changes were harder.

This is a good idea as it's easy to adjust and easy to change back if you don't like it. It's basically a throttle reference so if it thinks you're deeper in the throttle it will shift differently.

The Accord may be fully electronic though...

On the '98 Integra:

Earlier this year, I discovered that my throttle linkage pulled loose and only provided enough fluid pressure for a partial TC lockup -- after increasing the amount of engagement significantly, FE went up and I get TC at exactly 35 mph MOST of the time... More on that in a moment.

The side effect is a hard shift. To me, this transmission always shifted hard, but more so now than before. I "shift" the car myself like most auto drivers, lift the throttle and it upshifts.

When I do this, it usually results in a hard shift and loud "clink" sound and something you can definitely feel. On auto 3-2 downshifts it does this too with an annoying lurch and clunk.

So the question: is this worse for the transmission than loosening the cable tension/travel?

With the TCU and hill-logic BS, the kickdown cable only provides performance-oriented kickdowns and fluid pressure regulation -- the chip takes care of the rest. In other words, it doesn't downshift too soon like other vehicles with tightened cables. It does just the opposite: TC locks up sooner.

What I've noticed this summer:

Unfortunately, the TCU doesn't like EOC-ing. It generally confuses it, resulting in delayed TC lockup under normal circumstances. Basis for this argument: Hill-logic calculates speed change, load, TPS, coolant temp, etc. to decide on TC engagement and/or gear hold. When EOC-ing with the key-on, the calcs become skewed, and it refuses to engage the TC until the equation is satisfied (still using "bad" data from the coast). Bottom line, throttle cable position is moot in this situation.

The goal with this car is to have everything last as long as possible while still achieving good FE. That includes the tranny (even though I'd love to swap a manual in there, but money is what it is)...

RH77

From my personal experience with GM auto trans particularly the 4 speeds found in the 88-95 Grand Prixs (specifically the Turbo Grand Prixs of 89-90). We would always install an adjustable vacuum modulator to firm up the shifts on a stock trans. In an automatic trans like GMs, if the shifts are soo smooth that you can't feel them...that is bad. It means that the friction plates and steels are sliding on each other way more than they need to. This creates a lot of extra heat and wear on the trans parts. In fact, 4th gear would usually melt/fuse together causing the trans to stay locked in fourth gear so when you came to a stop, that was the end of the trans.

The faster/harder (to a point) the discs lock together when shifting, the better for longevity of the trans. We would adjust the modulator so that shifts were on the edge of what most people would consider firm. you could feel the car engage into the next gear solidly.

My Hyundai shifts way to smooth. If anyone knows about Hyundai autos please share. Otherwise, I'll look for a resistor near the trans. or see if a Hyundai mechanic has any tricks to get this thing to shift firmer. When I find out, I'll post the info here.

What should firm up anything is putting a bottle of "Lucas Transmission Fix" in it. Or changing out the fluid for Universal Tractor Fluid.

Line pressure on hydraulic automatics usually has something to do with the governor so a valve associated with that with a screw adjustment is probably the line pressure.

Shift overlap may be controlled by an accumulator, blocking it off may de-slush it.

This is how we do it on a Chrysler 3 speed transaxle (A404, A413, A470, A670, 30TH, 31TH) ...
http://members.firststep.net/stevien1/trans/valvebod.html

Type F ups the pressure

Type F ups the pressure
But don't mix type F with other types... I've heard that's bad. I know a guy that runs type F in all of his cars and trucks. He says the transmissions last longer too.

My understanding of the sitch is...

Type F has friction modifiers that make clutch packs grab harder, doesn't necessarily increase line pressure but may give better performance on some trannies.

Type F mixes fine with regular ATF if you don't need that much extra grab 1 quart in a normal fill is plenty for most folks, BUT if you put anything but type F in a tranny that NEEDS it, it will slip like hell and go nowhere.

My understanding of the sitch is...

Type F has friction modifiers that make clutch packs grab harder, doesn't necessarily increase line pressure but may give better performance on some trannies.

Type F mixes fine with regular ATF if you don't need that much extra grab 1 quart in a normal fill is plenty for most folks, BUT if you put anything but type F in a tranny that NEEDS it, it will slip like hell and go nowhere.

ATF + has the modifiers in it

My understanding of the sitch is...

Type F has friction modifiers that make clutch packs grab harder, doesn't necessarily increase line pressure but may give better performance on some trannies.

Type F mixes fine with regular ATF if you don't need that much extra grab 1 quart in a normal fill is plenty for most folks, BUT if you put anything but type F in a tranny that NEEDS it, it will slip like hell and go nowhere.
So if you have a slipping tranny you can make due for a short time with type F? If so I should have done that with my old Pontiac wagon. That was starting to slip by the time we got rid of it.

-Jay

Yeah, it's been known to work. However, that "Lucas Transmission Fix" also does the job. Had a Tempo in the family with the ford ATX it was slipping, was a 200,000+ mile tranny, Transmission fix held up for 2 years and another 50,000 miles. However, if you do this BEFORE it starts slipping, you help the frictions live wayyyyyyy longer, and it also runs cooler, because the quicker grab means less heat as things mash together, due to shortening the time they're grinding against each other. For an example of that, stand a bike upside down and spin the wheel, first stop it by slowly applying pressure to the tire with your thumb, probably gets too hot to bear before you stop it, whereas if you jab your thumb into the tire hard, you stop it while only feeling a brief flush of heat on your thumb. (Make sure there's no sharp bits of gravel or glass shards stuck in the tire before you try this)

So if you have a slipping tranny you can make due for a short time with type F? If so I should have done that with my old Pontiac wagon. That was starting to slip by the time we got rid of it.

-Jay

add the + (atf plus)

Is the Lucas transmission fix compatible with synthetic fluid?

Don't know, but if you've got a transmission that needs a special synthetic like Mercon V or a 7176, ATF +4 spec fluid, then don't mess with it. If it takes regular ATF, then it's probably not so fussy.

Actually if you're using a synthetic "just because" you might want to try some of the synthetic chrysler ATF +4 which has larger amounts of friction modifiers than "regular", then at least you're blending synthetics.

Don't know, but if you've got a transmission that needs a special synthetic like Mercon V or a 7176, ATF +4 spec fluid, then don't mess with it. If it takes regular ATF, then it's probably not so fussy.

Actually if you're using a synthetic "just because" you might want to try some of the synthetic chrysler ATF +4 which has larger amounts of friction modifiers than "regular", then at least you're blending synthetics.

my T-350 takes 10qts ,,i have 8 Dext/mercon 1 type F and one ATF +4 in it :thumbup:

I'm using "practically synthetic" TDH UTF (Universal Tractor Fluid) made out of high grade high VI group 3 base stocks (Which some motor oil manufactures claim they can call synthetic these days) that has friction modifiers intended for heavy duty wet brake and wet clutch use in industrial and agricultural transmissions... plus it's only $7 a gallon :D

I'm using "practically synthetic" TDH UTF (Universal Tractor Fluid) made out of high grade high VI group 3 base stocks (Which some motor oil manufactures claim they can call synthetic these days) that has friction modifiers intended for heavy duty wet brake and wet clutch use in industrial and agricultural transmissions... plus it's only $7 a gallon :D

you using that in the Ford and the Dodge ?

Just Marvin so far. Wile-E was doing great with fresh ATF plus a dose of Lucas, when his motor is back together, I'll probably consider it next spring. Might need to use lucas in it to color it for him (it's clear) he has some optical sensors for clutch pack modulation.

Just Marvin so far. Wile-E was doing great with fresh ATF plus a dose of Lucas, when his motor is back together, I'll probably consider it next spring. Might need to use lucas in it to color it for him (it's clear) he has some optical sensors for clutch pack modulation.

where did you buy it ??

At the evil emporium of he who must not be named, ummm *cough*walmart*cough* :D Actually always seem to end up there for my fluids when nothing is on sale anywhere else. Supertech/tech 2000 synthetic oil is a good bargain too.

At the evil emporium of he who must not be named, ummm *cough*walmart*cough* :D Actually always seem to end up there for my fluids when nothing is on sale anywhere else. Supertech/tech 2000 synthetic oil is a good bargain too.

i agree ,,,i hate the place ,,,,,,,,,,,,,,,,,,,,,,,,,but i go cause of some good deals ,,,thanks