i have a 94 4 runner 3.0l v6 with 138000 miles on the body and motor... only 2k on new heads. This truck has had a major isssue with losing power under 2500 rpms... its almost like i have no throttle just go or stop. It got real bad last night driving to santa cruz, i could not maintain speed on the hills... at one point i was going 40 oh the highway trying to climb a hill that even big rigs can maintain speed on. I though i had this issue resolved with some injector cleaner and a tank of premium. but after last night it is for sure getting wrose. any thoughts? tps maybe? how would i test the tps?

 

does it idle right? and what do you mean by you lose power? do you mean like the car just doesnt pull anymore, or is it like if it went into neutral?

 

idle is fine, car wont pull any more... its a 5spd if that helps i only notice it in lower gears

 

have you checked your compression?

 

the problem has been intermittant so no, it seems to becoming more often now though. you think a compression check would be in order?

 

well you did say that you just got your heads done 2k miles ago, so that could always be a problem as to why you're losing power.

 

Are they actual brand new heads? and has this problem been since install or just recently?
What was wrong with old heads? Need more info on what else was done.

 

the heads are new heads I bought from a shop in austin, they are still under warranty. I did it because i had a burnt valve, it ran great for 2k miles and now seems to be crappin out on me. it started about a week ago with about 2k on the new heads. It started as just a chuggalugging feel while in 2nd and 3rd gear, it did this intermitantly for a week or so and yesterday all went to ˟˟˟˟. now it still does the chuggaluging but it just feels gutless at low rpm. it goes, but like i said low rpm no matter how much or how little throttle i give it, it just goes at its own pace, after 3k rpms its quick

 

are sure its your engine? maybe a tranny problem?

 

i would maybe suspect the tranny if it were an auto, but its a stick... (i have felt autos slip but never a manual, can that happen?) and it is going speeds that i would expect for the rpms... it feels like a miss fire but ive got spark... i have not checked the timing but i would imagine the timing should be fine (i had a timing belt done with the heads 2k miles ago) im going to be working on it tomorrow and might even be able to recruit some help, so im going the do a battery of tests, tell me if this order sounds good

1 compresson
2 TPS
3 MAF
4 Fuel pressure & filter
5 injectors (i used a lucas injector cleaner and it made my problems go away for a few days)

that sound like im on the right track or should i maybe be looking at something else too

 

oh and if it helps i passed smog with FLYING colors a three weeks ago

 

The 3VZE doesn't have a maf. And unless you've played with it, then that shouldn't be a problem. And I believe it doesn't even have a tps. But I'm not sure. Fact is though that the vafm isn't the problem

 

It does have a TPS and yes start with those test's and also re-check for vacuum leaks.

 

Pull your plugs and check them.
Verify your ignition timing is correct.
Perform a leak down test, if possible. If not, do a compression test.
Check that your cam belt hasn't slipped.

 

ok thanks i will do the compression test today... any one know if my motor should die when i pull the oil cap off??? just found out it did this... doesnt seem right, any other EFI car ive had has no problem when i do this.

 

3vze has a tps asuarez. I'm having similiar issues with my rig also christopher. Brand new motor to boot. Just dogs on the incline at around 2800-3000 RPMS in second and third gear and then opens up with a kind of bucking acceleration. OBD1 scanner picked up codes 41, 42 and 43, TPS, VSS circuit, and Starter signal circuit. My TPS is new though and not faulty. Did you check for codes?

 

Mine did that. when cold, the motor just felt like it was bogging down under 3000 rpms. No matter how much pedal I gave it. Then at about 95% throttle, it would come alive and go wide open, on/off switch like. TPS and ignition timing. If they arent working together youll get this. If one is out of whack and you adjust it, check the other to make sure it didnt change during the adjustment. If you are adjusting your TPS and restting youridle while doing so, you will have to adjust your timing afterwards. Its a ˟˟˟˟˟ty balancing act but once it right youll run great. I dont know the setting for the V6, but this happened with my 22re and i lost alot of hair getting this right.

 

Cool thanks for the insight. I replaced all my spark plugs, the wires had 2k miles on then so i left them... it didnt work... so i checked then resistance on my wires... ˟˟˟˟ed up all over the place replaced the wires and it stopped bucking durring acceleration. But its still a little sluggish, lots better though. I am going to test the tps and check the timing next weekend... any ideas on correct timing, ive heard factory is supposed to be 10... but ive heard if you advance it a little to 12 or so the motor seems to be happier.

also:
i had a shop do the install on my new heads timing belt distributor etc... is it possible that the shop put in defective wires unknowingly and then wound up setting the timing wrong either a: to compensate for whatever misfires the wires were causing or b: assuming the wires were good when the timing was set could the timing have adjusted to maybe compensate for a faulty tps?

I just dont know how to two would or could relate on the 3vze

I also have not checked for codes, I dont have the code puller, any one know where i can get one cheap? None of my local parts stores have them for anything pre 96...
my dad has a 02 tacoma but i dont think his reader will work?

 

code puller for cheap is a paper clip. put it in the proper terminals on the diag check connector and the codes flash at you through the check engine light.

Oh, and you do the same thing, putting the jumper in those terminals, in order to set the idle speed and ignition timing.

 

how do i do the paper clip thing?? I tested all my spark wires and they were ALL way out of spec... so i replaced those and the plugs... the problem persisted... It was a little better.. but recently i went right back to how it was... this time i bought a full tank two weeks ago... I drove it bone dry... didnt run out but ran it all the way to the bottom and it seemed the lower it got the worse it got... i got a new full tank today and its still kindof ˟˟˟˟ty... but its better, so im thinking maybe this is a fuel delivery issue?