Farmer needing help

Long story short.
Needed a new daily, bought 06 tacoma access cab with 160k miles. Some underbody rust on rockers and cheap metal brackets but decently solid for what I paid. After about 300 miles CEL came on. Getting couple different codes. One was for bank 1 below efficiency, and one was for a wheel speed sensor. Now here's the tricky part. It's a 6 speed manual, clutch is a little worn and probably needs replaced, but it shifts fine and doesn't slip... until... I will be diving and maintaining speed, say 55mph, all the sudden with no peddle movement or more pressure applied to gas the truck will accelerate a noticeable amount.. after that happens it acts like the TPS is acting up and won't idle down when I engage the clutch. In fact it revs up when changing gears like I'm not letting off the gas. I have to come to a complete stop for it drop to idle rpm 800-900rpm. I park the truck and a little while later it drives fine again. Sometimes it will go 5-600 miles without doing this and sometimes it will do it everyday after about 20 30 min of driving. I drive 400-550 miles a week. Should I start with replacing the clutch and the catalytic system or should I be looking into ECM problems.

Thanks in advance.

 

Since the truck is running I would start with inspecting the clutch system and replacing the faulty parts.

 

Are those the only two codes?

 

Last time I ran codes that was it. I'm getting a snap on dyno from my brother tomorrow to run again.

 

Start simple by cleaning the throttle body and MAF with the proper cleaners and see what happens. At that mileage it likely needs it anyway

I'm not reading any clutch symptoms in your post

And I'll guess the low efficiency code may be an O2 sensor

 

I don't remember if there is a way to test wheel speed sensors so may just have to replace them and see if it helps.

Doesn't sound like clutch is a problem to me.

Surging throttle can possibly be TPS or something in the gas pedal assembly itself. (accelerator pedal position sensor) Price isnt too bad on TPS, but pedal is like $200+.

Generally, how do spark plugs look, have you cleaned MAF, clean throttle body, air filter, look over vacuum hoses for cracks or holes or not fully connected, replace PCV valve,... . Those are all items that wouldnt hurt to check with 160k miles on it anyway and not expensive.

Like if something is odd with MAF or throttle body, system may be trying to compensate to maintain AFR. Just a guess.

I think TPS is most likely. I'm no expert though. Your choice in the end.

 

Sorry I ment to add after the tps problems start. The clutch starts slipping in every gear If you don't baby it. But if its not acting up it doesn't slip at all. I know the emc shouldn't effect the clutch but that's what happens. I will clean that up and run codes again and see. Thanks

 

So if the clutch is slipping I'd address the first.
It's pretty normal for the 4.0 to hang around 1000-1200 RPM when the truck is rolling.

You didn't post code numbers but I'm assuming P0420 and maybe P0500?

 

Do all the easy maintenance, then start delving if needed.
Check free-play in the clutch pedal, and make sure nothing is sticking on your gas pedal.
Bleed all brakes, end with clutch.
Make sure the connections are good on wheel-speed-sensors.
Change plugs, oil, and all driveline fluids.
Clean maf, TB, and change air filter.
This shit solves so many issues.

 

Dm93 it only slips when that problem starts. That's what's got me. The clutch ain't that bad otherwise. Just thowout bearing is rattling a little. This weekend I'm going to change all fluids and replace mass air sensor and tps and filters and fill it with premium and run it a week and clear codes and see what happens.

 

The TOB is a real thorn.
I think the deeper secret about it is to shift well.
When I drive poorly, and shift out of accordance, she starts to rattle a bit.
When I hauled a 6.1k manlift 65mi she had no issues till I had to stop up a steep hill. Eased into first gear, and on she chirped.
The only real annoying piece of these MT trucks is the TOB.
Good luck, keep us posted.

 

I wouldn't replace the MAF sensor "just because", it's not an inexpensive part (don't use cheap/aftermarket or Amazon/ebay "OEM" ones) and it will almost always set codes when it fails.

Certainly wouldn't hurt to clean it and the throttle body, unhook the battery for a few min, reconnect it, start the truck, and let it idle up to oprating temp to relearn the idle (minimum coolant temp for idle learn to start is 174F).

The clutch slipping is a separate issue, that could either be an issue with the hydraulic side (pedal/linkage adjustment or master cylinder/slave cylinder not fully releasing) or a mechanical issue with the clutch itself (worn clutch disk, weak pressure plate, TOB binding, etc).

 

MAF cleaner spray on MAF.
Throttle body cleaner on throttle body. Different sprays.

 

The way I read it sounds like the clutch is a problem as well.

 

Got home and ran code. Have p0420 and p0500.
Started looking around under it more and noticed the downstream o2 sensors have already been gapped so im going to try and replace those along with cleaing TB and MAF. Then replace the clutch master cylinder and the slave cylinder and see if that can buy me a little time on replacing the clutch. As for the p0500 it seems like it can be anywhere between the wheel sensors to the cluster to the ecm.

 

Look closely at your wheel speed sensors and the wires leading up to them. Sometimes the damage is obvious when you get under there and have a look.

 

So bank 1 catalyst efficiency and vehicle speed sensor.

In all likelihood it's a failed converter, you can prolong keeping the code off by gapping the sensor with a defouler but if the cat is completely dead that usually won't work. It's very unlikely replacing the downstream sensors will get rid of the code, in actuality new sensors may make it set easier because newer O2 sensors respond quicker than aged ones and oxygen storage of the cat (measured by varying the Air/Fuel ratio and watching the length of time it takes for the downstream sensor to respond to that change) is the primary test used to determine if it is functioning or not.

An 05 manual uses a Vehicle Speed Sensor for vehicle speed, this signal is fed to the Combination Meter (Instrument Cluster) which sends it to other modules that use it.

If your speedometer always works then in all likelihood it is the Combination Meter, we have determined it can be bypassed by cutting the Violet/White wire at C9 Pin 19 of the Meter and jumpering it to the Red/Yellow Wire at C9 Pin 6 if that is something you wish to do. See the posts linked below for description of the code, troubleshooting and the bypass.

https://www.tacomaworld.com/threads/2nd-gen-information-diagnostics.784008/#post-28042157

https://www.tacomaworld.com/threads/clear-a-single-code-to-pass-inspection.802680/

 

05 Manual Transmission doesn't use ABS for vehicle speed, only autos do and all 12-15s do.
https://www.tacomaworld.com/threads/2nd-gen-information-diagnostics.784008/#post-28042157