58veedub

Hello everybody!! thanks in advance for any help. i have a 1998 tacoma, 3.4L v6. when accelerating or putting the truck "under a load", it sputters, hesitates and backfires (or pops). ive searched every where i can think of. check engine light was on, came up with bad O2 sensor and TPS, replaced O2 sensor and TPS, checked spark plugs they seem to be ok. replaced fuel filter (thinking it may be starving for fuel). nothing has worked. ive checked the MAF, and i cant take my sensor off to clean it, but i did take the whole unit off and it seemed farily clean, (wiped off any dust i could see). any help and/or ideas would be much appriciated! thanks!!

58veedub

also, some stuff i found pointed me to the EGR valve, not sure if im blind or what, but i dont see any lines or anything coming off my exhaust or manifold to an egr...

Superpilot

Don't know if you fixed it, but the 5vz-fe doesn't have a egt. I learned that after a lot of searching and a AutoZone guy who didn't know what he was doing with his computer.

res@wesco.com

i have a 99 v6 doing the same thing, what did you do to fix this problem ? please reply need urgent help on this
thanks

Garfleck

1996 4Runner 3.4 acting the same way. I tried Seafoam, and symptoms disappeared immediately. Then after 3 more Seafoam influenced tanks of gas, symptoms returned. I am getting consistent 0304 CEL codes. Will update this thread as my diagnostics continue.

HappyCamper

i read before (can't remember poster) that under load it's more likely to be ignition than fuel -- and since that's easier to check, i'd recommend starting there

check and replace your spark plugs, cap and rotor (cheap!). make sure your ignition wires are fully connected

HappyCamper

EGR is in the back of the motor; see FSM for picture. if your EGR is clogged or the vacuum switch isn't working, then you'll have higher NOx. you can rule out EGR by loosening the bolts, slipping in something to block the passage (e.g. rectangle cut out of a soda/beer can), and tightening the bolts back down. see here for the complete details: http://www.22reperformance.com/22RE_...ce_-_FAQs.html

75w90mantraN

0304 is a misfire code, of the #4 cylinder in particular. Something with the ignition coil /fuel injector/sparkplug/wire that feeds that one perhaps. Wonder what's been replaced or needs to be...never had that code but ran across OBD codes when I dealt with 0420 and 0171 not too long ago.

75w90mantraN

Can rule out the EGR issue, because there is none on these engines. I read around and found the same posts from other owners.

This is a fairly old post, so hopefully this problem got figured out. Would be helpful to know the code that was pulled. For MAF sensors, it can be difficult to remove without taking out the airbox assembly. The screws that hold the sensor in place are easy to strip...had that issue with whoever owned it before me, so I ended up extracting them and replacing the airbox. Multiple posts on correct cleaning of the MAF.

Garfleck

Sorry for delayed reply. Life is .. just that way. So .. I took the universal YotaTech advice and installed all new NGK BKR5EKB-11s. And because I had $80 to throw away, I bought a new coil pack for cylinders 3/4. No more sputtering or hesitation. Backfiring still happens as a local mechanic discovered two broken studs on passenger side exhaust manifold to downpipe connection. So, thank you all for the advice and encouragement.

Terrys87

iTrader: (1)

I don't know the 3.4 to well so am always eager to see some of its problems and fixes for it. Great to hear you got it running.

Garfleck

Just to add additional information:

My younger son took the 4R to the local Toy dealer about 6 months previous. $150 later (diagnostics fee), they told him it had to be injectors. They told him that they swapped out the coil packs, checked the high power leads (plug wires), connected the diag computer to the diag connection in the engine compartment, etc, etc, etc.

Their final conclusion: pay us $2500 and we will fix it for you.

This solution was much better

Thanks to all but, mostly, Happy Camper & 75w90mantraN, since their suggestions pointed to ignition.