Cracked Exhaust Manifold, bad MAF & O2 sensor.

I have had my Tacoma for about 1 year now, I had some issues at first getting it to pass the smog, after sitting for a couple months it finally passed.

So last week I went for a drive it was fine, then I made a stop and it didn't start right away. I was able to get it on by giving it a little gas, at this point i realized the check engine light was on. I got it home, connected the OBD reader and it gave me:

P0100 MAF or VAF A Circuit Malfunction

P0130 O2 Sensor Circuit Malfunction (Bank 1 Sensor 1)

P0133 O2 Sensor CKT Slow Response

So I was planing on ordering those sensors and starting with that, after checking to make sure all the wires were properly connected.

This morning I finally had a chance to take a good look under the hood and I noticed the Exhaust Manifold has a decent sized crack. The truck won't stay on anymore.

Is this normal under the circumstances?

I zoned in and forgot about the sensors, I started taking things apart and I am pretty close to taking off the exhaust manifold. Is rockauto.com a good place to buy the manifold? What about the sensor? Are the sensors what is causing the car to not run at all?

Sorry for all the questions, I don't work on too many cars. I'm just hoping I'm heading in the right direction.

 

I like rockauto for the parts I have needed in the past.

Bad sensors will be a culprit, esp that old.

Cracked manifold though, depends on the history of the truck.

 

Cleaning the MAF and sensors may be a quick fix, too.

 

That's good to know about rockauto.

I had read something about cleaning the sensors, I'll try that before I replace them.

From what I know the truck hasn't had any problems, I was just worried because it won't even stay on anymore. From what I've read on here trucks are still running even with a cracked manifold.

 

Depends on the motor's need for back pressure, the cracked manifold is more a hazard than anything else. The sensors may put the truck in a limp mode type of thing or give it codes saying to shut down due to lack of air. Clean everything and start replacing the cheaper parts if it comes down to it.

 

Maybe I will put the manifold back and see if cleaning the sensors will get it running, meanwhile I buy a new manifold.

 

Post your results as you go

 

So I decided to focus on the MAF sensor and cleaning the O2 sensors. The MAF sensor was hard at all now the O2 sensors are giving me issues. I just sprayed WD40 not sure if its going to help. I'll post some pictures so you guys can see whats going on.

This is the first O2 sensor, very rusted. I'm not sure if I will be able to get it off.



Here is the second, pretty much the same story.



This is where I was working on the exhaust manifold









The crack in the exhaust manifold.





Any help is greatly appreciated.

 

So lots of WD40 and this is where it got me..



I had to upgrade my vice grips and I was able to get the o2 sensor off.





This is what was left of the nuts.



Dirty o2 sensor



Clean o2 sensor



also here is the clean maf sensor



Any way to tell by looking if either sensor is still good?

By the way the new vice grips worked like a charm.

 

Sensors definitely look cleaner. The MAF should be fine but the O2 you can only tell when you try to use it again. Any old O2 sensor will be a prick to get out. Try using anti seize when you install anything back on, it'll help you next time to need to do maintenance. Can't tell how deep that crack is. If it's superficial or from the casting then you have time. Good work so far.

 

I was under the impression I would be able to get the nuts for the O2 sensor and the exhaust manifold at the dealer without an issue. I was wrong they have to special order them. Does anyone know the demensions on them? Also the for the 2 studs on the backside of the manifold, they connect the ERG line?

 

I got it all put back together with the new exhaust manifold, cleaned o2 sensor and cleaned MAF sensor. I cleared the codes and the check engine light is still on giving me the MAF sensor code p0100. It was smoking at first, now the engine seems to be running fine. I decided to take it for a little drive and it won't accelerate, hits about 20 or 25 mph.

I was thinking it may be a clogged catalytic converter now, any thoughts?

 

It is hard to say without being there. A clogged cat would choke the motor. You could try diconnecting the cat and taking the truck for a drive. It will be loud with no mufflers on but you will be able to see if you can climb over 25 mph.

But if you are still getting P0100 then your ecu thinks your MAF is bad. Recheck all the connections on the harness, clean the sensor again and make sure it is dry when you put it back in. If it is still bad, trying pulling one from a wrecker and seeing if that fixes it before dropping $$$ on a new one.

If you still need new nuts...that sounds bad...take the old ones to Home Depot (i forget what yall call them in Cali) or Ace Hardware and get new ones. They have pegs there that will tell you size and thread count of your old hardware.

Hope this helps.

 

I'm having a difficult time getting these bolts off, I was very generous with the WD-40.
I went to Home Depot as well as Ace and I didn't have any luck with the Nuts. The thread is some what damaged so I'm sure that has something to do with it.

I'm going to try to get to the junkyard to see if I can find a MAF sensor.