California Emissions

[Kurt Franz]

Hello,

First time here ..... hopefully someone can shed some light on this one:

I have 2 4Runners - a 1990 model that has the 31" tire package with 4:56 gears and a 1994 model that is plain jane from California with whatever stock gearing came on that year model and 30 inch tires. I am fairly certain that it is not 4:56 though.

When driving the 1990 at 70 mph I am right around 2400 RPM

When driving the 1994 at 70 mph I am a right about 3000 RPM

I realize that the tire size differences will have an impact, but not to this extent.

Also, on the 1990 the rpm drops more in overdrive than the 1994 does.

So, I am wondering - did toyoya do something to California vehicles with regards to gearing/shift points or something to make the engine rev higher and hence hotter to burn off more emissions or something?

Last year on a trip in the 1990 I set the cruise control at 65 mph and got a tad over 300 miles on a tank of gas

On another trip in the 1994 I set the cruise at 62 mph and the best I got was 220 miles on a tank of gas.

Also I notice that on the 1990 when overdrive kicks in the rpms drop about 600-700 rpm, but on the 1994 the drop is only about 400 rpm. What gives here?

My speedometers are correct on both vehicles.

Both vehicles are stock with no performance modifications.

Both vehicles are tuned properly and running properly

In summary, It would seem that all things considered, the 1994 should get better mileage than the 1990 due to the higher gearing - regardless of the 1 inch tire size difference.

My theory is that the CA emissions are causing the issues, but I can't confirm this. Hoping someone can chime in with some real facts about this, and also with a possible workaround if necessary.

Best,

Kurt F

 

[JP4RNR]

Do the 90 and 94 trucks have the same powertrain? engine transmission and differential?

I would tell you with 100% certainty that emmissions are not the cause. You may have a problem with your lock-up clutch on the torque converter. The lockup clutch eliminates the slippage between the engine and transmission by locking the engine to the transmission also reducing engine speed by about 600 RPM's. The purpose of the lockup is to increase mpg's and reduce heat by eliminating slippage.

Early transmissions lockup only engaged in O/D while today the lockup engages from 2nd to O/D gear depending on the transmission model and vehicle application

 

[toto]

All other things being equal, you're burning more gas per minute at 3000 RPM than you are at 2400 RPM. I don't know enough about the differences in the gear ratios in the two model years, so I can't explain why the 94 is running so much higher at a given speed.

An interesting experiment would be to get in the 94 and cruise at whatever speed makes it run at 2400 RPM, and then check the gas mileage.

 

[MichiganFan82]

This is a topic I would like further information on if possible from others.

I also have a 1994 4runner SR5 from California. I live in Minnesota but I bought it from a guy a few months ago who moved here from California.

My 4runner also runs at 3000 RPMs at 70mph which seems kind of high. I am starting to think they are geared to run that high. Howerver, I also have my check engine light on, which I then used the paper clip trick on the diagnostics to narrow down the problem. I think what it is saying is error code (71). Which this website (http://www.off-road.com/toyota/tech/codes/index.html)
says its the following:

EGR VALVE MALFUNCTION--EXHAUST GAS TEMPEATURE BELOW SPEC. FOR EGR CONTROL

--EGR SYSTEM

--EGR GAS TEMPERATURE SENSOR/CIRCUIT

From what I have read, that error code has to do with Cali. emmissions maybe? Not sure if that code is what is making my RPMs run so high...

Anyone else have comments on this topic?

 

[Kurt Franz]

Is it possible to setup a poll to ask folks with 90-95 4Runners with 6cylinder engines to post their RPM at 70 mph? And how much the RPM drops when activating the OD button at 70?

This might help to determine a baseline of some sort.

I am somehow convinced that the CA models do have different shift points than the federal models OR there were changes made sometime between 90 and 95.

Like i said - my 90 is right around 2500-2600 at 70 mph - with 4:56 gears. It just seems that the overdrive on my 94 (which is the basic model with higere gearing) is not as drastic as that on the 90 - by that i mean the rpms drop more significantly on the 90 than on the 94.

I don't think I am nuts.....

thanks

 

[Kurt Franz]

I dont think the egr would play a part in this scenerio, as the issue is definitely gearing related. Also i don't thin it is a coincidence that we are both experiencing the same thing with CA models. My 94 is in mint condition with no mods and in perfect tune so it can be considered exactly normal for a standard CA model.

This is a topic I would like further information on if possible from others.

I also have a 1994 4runner SR5 from California. I live in Minnesota but I bought it from a guy a few months ago who moved here from California.

My 4runner also runs at 3000 RPMs at 70mph which seems kind of high. I am starting to think they are geared to run that high. Howerver, I also have my check engine light on, which I then used the paper clip trick on the diagnostics to narrow down the problem. I think what it is saying is error code (71). Which this website (http://www.off-road.com/toyota/tech/codes/index.html)
says its the following:

EGR VALVE MALFUNCTION--EXHAUST GAS TEMPEATURE BELOW SPEC. FOR EGR CONTROL

--EGR SYSTEM

--EGR GAS TEMPERATURE SENSOR/CIRCUIT

From what I have read, that error code has to do with Cali. emmissions maybe? Not sure if that code is what is making my RPMs run so high...

Anyone else have comments on this topic?

 

[Kurt Franz]

I would tell you with 100% certainty that emmissions are not the cause. You may have a problem with your lock-up clutch on the torque converter. The lockup clutch eliminates the slippage between the engine and transmission by locking the engine to the transmission also reducing engine speed by about 600 RPM's. The purpose of the lockup is to increase mpg's and reduce heat by eliminating slippage.

[/B]

Yes I agree that emission controls would not solely cause this - I should have stated the thought more clearly - my bad - I was wondering if possibly there was something in the electronics that is telling the CA models to shift at a different point to meet CA emission standards. Of course this is just a theory, which is what led to my initial posting in the first place.....

thanks for the feedback

 

[MichiganFan82]

bump