P0101 Code

Hey yall, I'm new to this stuff but here's my problem. Lately, 98 2.7L with 230,000 miles has been acting up. Once I start it up in the afternoons, it runs fine. If you let it idle for 3 to 5 minutes, it dies and throws a P0101 code. If you restart and try to back up or pull forwards, it dies again. This keeps repeating until the engine is running and at normal operating temperature, I'm going off of my Water Temp Gauge for a visual guide. I replaced my MAF sensor back in July, replaced Cam and Crankshaft sensors put DI- ELcetric Grease on the connection. The vacuum has been checked, no leaks. I just replaced the connector of the MAF Harness and still haven't fixed anything. Before I spend any more money, I would like some advice, please. Any thoughts.

Thank you

 

What did you replace the MAF sensor with, OEM or aftermarket? Aftermarket sensors don't fare well on these trucks, which sucks because the OEM MAF sensors are pricey

p0101 is a MAF trouble code I think, or vacuum leak but if your certain it's not a leak then I would suspect the brand new MAF that was put in, if it was an aftermarket one

 

P0101 is a MAF circuit code, that means that the problem can exist anywhere between the ECU and the MAF. I would start by conducting a thorough visual check of the wiring all the way from the ECU to the MAF. Highly likely you will find an indication of damage to the harness somewhere; pinched wires, rodent damage, etc. If that doesn't lead you to the cause then, disconnect the harness at the ECU and at the MAF (isolate the conductors) and check for continuity to ground on power, ground and signal lines. If one or more of them is grounding, then you need to find and repair that. If that doesn't solve it, then reconnect the harness, and back probe at the MAF or ECU connector and verify power, ground and signal. Remember when verifying ground you need to use an incandescent test light, of at least a half-amp. Let us know where that gets you.

 

It was an aftermarket, A Standards Product, which I'm not fond of but it was what was in stock. Yes, they are pricey. The aftermarket was like $6o.

 

That could well be the issue; a lot of cheap after-market stuff is cheap for a reason. Try the tests I mentioned above; if they all pass, then stump up the $$ for a 'real' MAF.

 

I would definitely suspect that brand of MAF sensor then. It's well documented on here that aftermarket MAF sensors (and O2, A/F, etc) don't work well on Toyotas

 

When I dropped my truck off to get the Crank and Camshaft Sensors replaced, my mechanic checked all connections and power supply and said it was getting the right voltage. I didn't go into detail with him about what that would have been. But once I get home I'll check the ECU connection. Thank You

 

Probably my best option, but should I check anything else like exhaust?

 

This code is indicating an electrical issue. A multi-meter, test light and wiring diagram, along with patience is all that's needed. Exhaust has nothing to do with it. This is likely a very straight-forward issue to diagnose, but if you're not at least somewhat familiar with automotive electrical systems and test equipment, it may prove challenging and the assistance of a professional sought. If you have multi-meter and an incandescent test light, and are familiar with their use, then likely folks here can walk you through the problem.

 

I have a multi-meter but not an incandescent test light.

 

Cheap to buy at any auto-parts store, Amazon, etc, or to make out of an old bulb and socket around the shop. If you buy one, make sure it's an incandescent, and NOT an LED; LEDs do not draw enough current to let you know if you have an 'iffy' ground.

 

Thanks

 

My mechanic check the power supply and said it was fine. I don't think I mentioned that after starting up and letting it start warming up if you pull out onto the road and try to accelerate, it will lag, you can hear the engine trying to spool up but it won't. It soon catches and bucks and jumps and then it lags again.
Oh, and should I still be able to run my truck even with it unplugged. I can start it up and drive as long as I stay below 1k, Higher would cause it to buck and lag. Would this be because I'm in limo mode or what? Thanks.

 

Yeah, the truck goes into limp mode without the MAF plugged in, that sounds normal.

I am fairly confident if you throw an OEM MAF into this thing it will fix it, but I understand not wanting to drop that kind of $ until you know for sure. Do you know someone else with a 2.7l 1st gen Tacoma nearby that you could maybe swap their OEM MAF in temporarily just to see?

 

I wish I did but I don't, and I made the mistake of throwing away my old MAF. I also looked just for the heck of it at my exhaust manifold and I found a crack. I know that can screw up the O2 sensors and an O2 sensor can throw a P0101. I'm still learning about engines, that's why I got this truck. Thanks

 

Has anyone checked your fuel trims? I don't see the cracked manifold being the sole culprit, but it could be compounding a problem!

 

No, they have not or at least not to my knowledge.

 

Definitely wouldn't hurt to look at. Again, not the sole cause, but it could be an issue.