09 tacoma 2.7 starts, dies

No i havnt done that,ill try if it warms up enuf. Thank s

 

Ok load test and its fine have voltage at maf under load as well as just key on ? I guess ill get rebuilt ecm?

 

I really doubt it's the PCM unless it somehow got water in it, I'm still thinking we have an input problem. It seems to be related to the MAF sensor but it may not be, I need to go back over this tonight and see if I can come up with something we may have missed.

Have you checked powers and grounds at the PCM and the ground (Pin 5 (Brown)) at the MAF?
Do you have an oscilloscope?

 

I dont have a ocilliscope, i checked grds at ecm but not brown at maf, it has no codes now at all? It runs with maf unplugged, with it plugged in only way to get it to run is hold throttle to floor but it revs up to bout 3500 then down to bout 500 over and over if i let off slowly revs will get lower til eventually dies.

 

Have you checked the housing that the MAF sits in for any debris, damage, or blockages?
Everything seems to point to a mis-reporting MAF, trying to figure out why though.
Is your intake piping stock?

 

Definitely a software issue. Not necessarily the sw itself,but suffers from bad data input. Unplugging the maf may just branch to a less sophisticated code branch that doesn’t use a different sensor that is feeding bad data. Likely the pcm falls back to throttle position data when maf data disappears to keep the engine running. This explains how disconnecting the maf gives good results. Could also be you are very unlucky and got multiple bad maf’s. Could be a lot of things but just really feels like the pcm is getting bad data from a sensor somewhere. Just not much else that can make an engine oscillate between 3and 3.5k with a fixed load and throttle position. As mentioned, there could also be a wiring issue on the maf circuit.

have you observed maf data on a scanner as you rev to 3500? If the reported maf volume drops off with the engine rpm, that means the maf input is the culprit. If it doesn’t, you can stop looking at the maf. I would also not rule out the cps, as they can create really strange problems when they start to go.

 

The intake is a k&n intake, the filter is clean, the pipe is totally clean, the mounting hole for maf is totally clear and sealed no leaks, it has had this intake on it since 2 -3 days after purchased pickup new,zo its not something just caused, its ran since 2010 with no problemz and this intake. The maf readingz drop off with rpms? Ill check again in a bit to make sure again but i know in a earlier post i posted that the maf readings fluctuate with rpms

 

Ok key on eng off maf is at .90gm/s , on cold startup eng will rev to 2000@ and down a few times then die, after doing that til eng warms a bit then it will rev to 3500@ and down to @ 500 and not die. But maf readings while revving are from @ 24gm/s down to @ 2-3 gm/s

 

I'm not a fan of aftermarket intakes on MAF vehicles because they tend to skew MAF readings although most will run ok they alot of times will set codes.

Do you have the sensor oriented correctly?

Do you have the factory intake still to try?

 

Ok, this is hard to admit , but im going to, i put new sensor in oriented like the one i took out, i dont know if old one was taken out and put back in or what before i got picckup, anywhoo, i put new one in the same way not paying attention to the sensor side! It was ass backwards! Dammit, sorry for wasteing every ones time! Very sorry for a stupid mistake. Now after driving about 15 mi i get eng light and trac skid lite code c1201, it runs fine with code, but with all ive checked now wtf! Again very sorry for wasteinv everyones time but i really appreciate the help! Very much!

 

Nice I kept thinking it had to be something simple then when you said it had an aftermarket intake I thought of the sensor being installed backwards.
The C1201 is most likely stored because the engine had a code, just clear it and carry on.

 

Clreared, and runnin, again i apologize. Thank u very much for the help. Have a merry christmas. Thanks again

 

Never in a million years would I have figured that out.

 

No worries, I'm just glad we caught it before the parts cannon started getting fired at it.

 

Lol for sure!