Topic: A340 to R150F trans swap 2001 tacoma dbl cab

[09roramo]

I have a rpm/speed issue with the truck I bought and I wanted to see if any toyota gurus know what is going on

TRUCK
2001 double cab tacoma 3.4L V6 auto A340 swapped for manual R150F

Issue: due to the difference in the auto and manual trans my tachometer is off by a ratio of 4.22 / 2.393 = 1.76.

I got my data from the REV column in the transmission table of marlin crawler's website.

This is the only explanation of why the tachometer reads about 3k in 5th gear at about 50mph when it should be reading 3k in 5th gear at 82 mph. Also used marlin's calculator for this and confirmed that I have 4:11 R&P.

I could be wrong in what I am saying, but if I am not, does anyone know how to fix this?

[redneckcustoms13]

It may need to have the ecm from a manual shift truck. All i can figure is that the ecm is reading shift fault codes and therefore going wacky with the tach signal. Have you plugged in a decent scanner to see why rpm the ecm sees compared to the gauge on the dash?

[Lewis Hein]

You may also be able to figure out what connections need to be made to fool the ECU into thinking it's getting a shift signal from an automatic transmission. Then install a rotary switch on the dash to set to whatever gear you're using .

[09roramo [OP]]

It may need to have the ecm from a manual shift truck. All i can figure is that the ecm is reading shift fault codes and therefore going wacky with the tach signal. Have you plugged in a decent scanner to see why rpm the ecm sees compared to the gauge on the dash?

Thanks for the idea redneckcustoms. I only have a basic obdii scanner and it doesn’t give me the rpms. I will see if I can ask my friend with a scanner that can do that. I must add that although the tach rpm is off, it is consistently incorrect and doesn’t jump around. There are expected shift solenoid CELs as you said. I would like to splice a manual exam in, but I don’t want to open a can of worms just for a correct tachometer reading because the motor runs fine. I am still trying to figure out if the ECT button does more than change shift points because I swear it seems like there’s more power with the button on, but that could be in my head.

[09roramo [OP]]

You may also be able to figure out what connections need to be made to fool the ECU into thinking it's getting a shift signal from an automatic transmission. Then install a rotary switch on the dash to set to whatever gear you're using .

I guess that could work except you would have to change the rotary switch every time you shifted. Haha. Maybe use that just to troubleshoot my issue?

I have read using the 3rz auto engine/ecm with a manual trans is impossible to fool, per the 3rz post on here. And with that logic, I assumed it was impossible to fool a 5vzfe ecm. I could be wrong though. I haven’t spliced a ecm loom myself yet.

[redneckcustoms13]

Have you tried swapping the cluster with a friend and see the results?

[09roramo [OP]]

I haven't tried swapping clusters. Are you thinking it's a bad tach gauge in my dash?

Thanks for any and all replies guys!

I just got this truck a couple month's ago and it was running like crap, out of alignment, had a body lift, bad trans, and no 4wd due to front diff not actuating. I had a '95 parts truck and replaced clutch, trans, ADD hubs with manual hubs, steering rack, removed body lift and fixed some engine issues. it's running better and the 4wd is working.

I know the diff drop lift is crap, but I couldn't say no to the pretty paintjob. haha. it goes anywhere I take it on the beach, but hopefully I can get it to climb some real areas in the mountains one day.

[gnob]

The trans is in no way operating the tach.  The tach wire goes straight from the ignitor to the ecm and dash.  End of story.

[redneckcustoms13]

I would atleast try swapping the cluster to eliminate that as a possible issue.
When you say it was running bad but now running better what have you changed?

[09roramo [OP]]

I changed the iac valve. The engine would idle at 1.7-2k until I changed it

[redneckcustoms13]

Any other fault codes?

[09roramo [OP]]

I can check when I get home from work, but the only fault codes were related to shift solenoids and the transmission. I did have and probably still do have P1135, which is my o2 sensor.

[09roramo [OP]]

Any other fault codes?

12/14/17
P0710- trans fluid temp sensor
P0753- shift solenoid
P0758- shift solenoid
P0773- shift solenoid
P1135- o2 bank 1 sensor 1
P1700- neutral switch
P1780- park/neutral switch
P0773p
P1780p

The trans is in no way operating the tach.  The tach wire goes straight from the ignitor to the ecm and dash.  End of story.

I get what you’re saying. I just don’t know where the issue could be. The vehicle speed matches with the signs that tell you how fast you’re going so I ruled out the VSS.

Do you have any ideas on why I am revving 3k in 5th gear going 50 mph?

I double checked the diff ratio and the test proved 4:11s. I had 18 rotations on the tire and 37 rotations on the d/s. One tire was on the ground and the other was spinning. 37/(18/2) = 4.11

I also eliminated the trans having a change in gearing because I swapped the first one with push button 4wd to a trans with the j-pattern transfer case shifter.

[redneckcustoms13]

Are you actually turning the engine 3k or the tach is just saying that?

[gnob]

You need to get hooked up to a real scanner so you can see what is actually going on.  As far as checking actual rpm vs your tach.

[09roramo [OP]]

Sorry for the late response.

Are you actually turning the engine 3k or the tach is just saying that?

I am just looking at my tach. I can't find anyone that has the more expensive scanners that can read rpms. I have the cheap $20 and so does my friend. Haha

I will update when I can find someone to scan it.

[redneckcustoms13]

If you have an android. Get this, download the torque app. It's about $10 one time purchase.

https://www.ebay.com/p/Obd2-OBDII-Elm327-Bluetooth-V2-1-Car-Scanner-Android-Torque-Diagnostic-Scan-Tool/1707508839?iid=201896889934

[09roramo [OP]]

I have an iPhone...

Asked my cousin and his doesn’t have the tach feature either.

[redneckcustoms13]

I'm sure they make an apple compatible version.

[09roramo [OP]]

Yup. Because of what you sent I searched for one on amazon and got it for $20. It works with iPhones  and has some pretty good reviews👍🏽

Hopefully it comes in quickly. Everything takes extra long to ship to Hawaii on top of everything being closed for holidays.

[09roramo [OP]]

Good/bad news with the obd2 scanner. It just came in the mail and I confirmed that my tachometer in my truck is incorrect.

At idle my truck’s tach is dead center at 1k while my scanner shows 667rpm. That gives me a 1.5 ratio correction factor while I was expecting 1.76. I need to get more data at different rpms, but it’s late here. I will post pics and more data when I can.

Now that I confirmed the problem. The question is how to fix the tach issue.

[09roramo [OP]]

Attached is my screenshots of my OBD2 scanner.
You will have to trust that what I am seeing on my truck tach is when I took the screen shot of the scanner.

TRUCK tach vs. OBD2 scanner (rpm)
1000 vs. 667
2000 vs 1341
2500 vs 1672

They are all off by about a ratio of 1.5.

If anyone has an idea of how to fix this, please let me know

Or if anyone can help me pinpoint my fuel system open loop issue, please let me know. I believe it is due to a bad O2 sensor, but I don't want to spend $100 without knowing for sure.

I'll still be driving it regardless so this isn't a major issue, but it would be nice to fix.

[gnob]

I had a 3rd gen dash, had a factory potentiometer on it. I was able to just adjust to match.
As far as open loop, does your tool show o2 data?

[09roramo [OP]]

I had a 3rd gen dash, had a factory potentiometer on it. I was able to just adjust to match.
As far as open loop, does your tool show o2 data?

I’ve never gotten to the back of the gauge cluster, but if I did, there’s an adjustable potentiometer for the tach? I don’t doubt you, I just want to confirm? Any description of how it looks or location? 

All of my check engine codes are transmission related except p1135, which is bank 1 o2 sensor. I believe the one before the cat con. I know it sounds stupid to question what the issue is in my fuel system when the scanner tells me exactly what the issue is, but I’ve had this code in a previous 3rz before and after replacing the o2 sensor I still had the check engine light on. Waste of $100 at that time. I might just purchase the O2 sensor after all. 

Do you think the $100 is worth the fuel savings? From what I understand, the ecu runs more efficient(uses less fuel) when in closed loop due to it utilizing the o2 sensor signal. When you floor it or rev the motor hard enough, the ecu goes into open loop. I guess what I’m getting at is I don’t know if closed loop saves that much more fuel than open loop. Enough to justify an o2 sensor 

[300k]

I’ve never gotten to the back of the gauge cluster, but if I did, there’s an adjustable potentiometer for the tach? I don’t doubt you, I just want to confirm? Any description of how it looks or location? 

don't know how accurate this is to 2001 but this apparently works to 95

[redneckcustoms13]

Your 3rz probably had issues with the egr temp sensor in the intake. It's common. This one I would replace the 02 sensor.

[09roramo [OP]]

I'll try to take apart the dash when I have some free time and find the pot to adjust. I will update when I get to it, but don't hold your breath.

I believe I found the O2 sensor on Amazon for $105, DENSO 234-9001.

Thanks for the info everyone. I appreciate the help.

[gnob]

I tore into a 3rd gen 4runner cluster i have.  I didn't find an adjuster