3vz-fe backfiring, hesitating etc

[vienta97]

hi, I drive an Australian 1997 Vienta, which is pretty much the 93 American camry with the 3vz-fe
and decided to take it upon myself to lean out the fuel via the AFM as pointed out in this guide http://mr2wiki.com/MKII/3vzfetune
so I sliced and pried open the AFM, and dialed it counter clockwise that another guide specified, turned out that was the opposite effect and ran it richer, so I ran it clockwise with the intent to lean it out. eventually I encountered problems when starting it cold and it's now hesitating, making loud popping noises and more, so I assumed it was somehow still running rich, so I ran it back to the stock setting and left the cap off for easy access

the problem is still occurring even though it's at stock ( I marked it with a marker), it seems to resolve when the car heats up and runs quite well, but until then it makes the loud backfire noise and runs like hell.

Anyone know what I've done wrong? am I up for a new AFM?

[BMR]

No check engine light is on, I assume? I'm thinking the ECT sensor. It's on the driver's side of the engine, sticking up vertically out of an aluminum pipe attached to the engine block. It's got a green 2-wire connector on it. Try checking its resistance with the engine cold and hot. Should be about 4k ohms cold, 400 ohms warm.

FWIW, I've done this adjustment on mine, and never had problems like yours is having. I went as high as ~6 clicks lean. It seemed to be losing power, so backed down to 3 or 4 clicks. So I don't think the AFM adjustment is the culprit.

OH, and welcome to TN!

[vienta97]

thanks for the welcome and the advice, I assume you meant opposite to drivers side for Australian cars :p but yeah it would have made a lot of sense if it was the ECT, I was poking around in that whole general area prior to changing the AFM, and I was quite careful with the AFM so it seemed to make no sense to me.

Anyway the problem seems to have resolved, I was about to start diagnosing properly and figured just for good measure I'd blow some dust out of the AFM and make sure no silicon fragments fell in or anything, and I figured I'd reset the ECU for good measure, disconnected battery, cleaned it out and came back in half an hour.

Started it up, all fine, put it into gear completely cold and no problem at all, gave it a bit of throttle and no previous symptoms so I'm pleased but confused.

To celebrate I drove down to the wreckers bought some screws and clips I'd lost in my travels, and a new master power window unit for 20 dollars, and tested out the new rear sway bar around some sharp corners.
Highly recommended to anyone trying to improve their handling.