Bad MAF??

I've got an 84 pickup with a 95 3rz swap. Finally got it running and it has a CEL and what I would consider an intermittent miss at idle and from idle to 3k rpm it stumbles horribly. Above 3k rpm it clears up and runs seemingly flawless.

Edit: I should add that I am not driving this truck right now as it hardly gets out of its own way under power.

-I do not know what the CEL is. I've been unable to get my scanner to connect through ODB2 port and nothing via the TE1-E1 CEL flash method.

NEW PLUGS AND WIRES
NEW CAP, ROTOR, COIL
NEW CRANK SENSOR

-Due to the fact it runs great above 3k rpm, I ruled out essentially anything in the fuel system unless you can convince me otherwise.

-Checked for vacuum leaks and found none.

-Cleaned MAF (CRC MAF cleaner only, didn't touch it) no change

I've cleared the CEL a few times via the EFI fuse and it does run slightly better, and I mean SLIGHTLY. The idle mostly clears up and the stumbling from idle to 3k is better but still bad. Eventually the CEL comes on again. However when I unplug the MAF the truck will start and run "fine", the missing and stumbling is gone. This what leads me to believe that the MAF is indeed going bad. Am I wrong here?

If it is time to replace the MAF whats my best option outside of new OEM that are over $1000?

 

My experience with a bad MAF usual affect all RPM range but more noticeable in the higher end range. Low RPM will hesitate. And during high RPM, the truck will bog down.

 

I suspect the throttle position sensor I had a similar issue on a 00 5VZ odd occasional stumble found the resistance way over range and would occasionally just drop completely out.

Changed TPS and ran perfect.

You can verify with sewing needles tapped into the wires and a meter but will need the OEM repair manual to get your ranges.

 

I just bought a new oem maf for my 01 for like $79

 

This probably just means that the ECU is using a default fuel/timing map with the MAF unplugged, which is usually gonna be conservative/rich. It doesn't necessarily mean that a bad MAF is causing the problem, but some sensor is likely feeding the ECU shitty information...knowing which sensor is the culprit is a guessing game without good data.

Scanner danner has some good youtube videos on diagnostics, although as you can guess by his handle, he relies pretty heavily on ECU data. If you can't get your OBD port to work, then you may need to fire the parts cannon (start with cheap sensors).

 

Same here. Bought a Denso MAF for my 3.4 for $75.00

 

Where did you get that???

Edit: A quick google serach shows a 3rz and 5vz (assuming your avitar is accurate to what you bought), MAP sensor are VERY different in price....

 

This is pretty much where I'm at unfortunatly.

 

Definitly a possibility, allthough a TPS on a 5vz is far more common than on a 3rz.

 

Not a 3.4....

 

This is what you suggest may be the issue…
A mass air flow sensor from a Toyota dealership is around $100
Try Mcgeorge parts online

 

I'll throw another one at you: knock sensor

 

Once again my truck is not a 3.4. Its a 2.7 (3rz) 4 cyl. OEM MAF's are not $100.

 

Replaced the MAF, IAC, and TPS. Also cleaned the TB and intake and replaced all seperated gaskets. I changed each of the MAF, IAC, and TPS seperatly to rule out and confirm which one was the culprite, unfortunatly no matter what I did the symptoms only got WORSE!!!

I am at a complete loss and just about ready to burn the truck to the ground. Not sure at all where to go from here....

 

Don't burn the truck to the ground!!

 

Actually its $98



It’s probably not your problem though.

 

pulls timing and will have little power but will still run fine.

 

have not seen you mention the o2 sensor. i had similar issue to this and thats what it ended up being. under 3000rpm the truck is running in closed loop and basing fueling off the o2 and maf. above 3k its based mostly on maf.

 

Could be the coolant temp sensor as well. But I would try and get that obd port working, did you do the swap your self or did you buy the truck this way?

 

From what I can find Googling it looks like OBD2 was introduced widely in 1996. Would a 3rz from 1995 be outputting OBD2 codes? Have you been using an OBD1 adapter or a different, make-specific OBD1 reader? Personally I'd prioritize figuring out what's going on with the diagnostic port and figure out what codes are being thrown.