sanctfy

i have 94 3.0 runner. started hesitating on me and has gotten much worse. seems to be really bad when i first start it up then goes away when warm with a sometimes miss when warm. Does this truck have a coolant sensor i should check or do you think tps?

I'm planning on motor swapping soon and just want it running good so i can try to get rid of it

Ive cleaned air filter, new fuel filter, checked plugs(plugs and wires and rotor and cap new as of about 8k ago) changed afm, disconnected o2. i just seafoamed the tank and it seems to have mostly disappeared but its warm now so i wont know until its cold again. been through 3 tanks of gas with the hesitation. oh and did a starting fluid spray test to check for vac leaks

AKHeathen

you say "disconnected o2" what pre-tell do you mean? the 02 lets the engine know if it's rich or lean, so it never really runs good without them functioning right. next: what plugs did you put in? i've seen a few go bad, like really bad in a couple hundred miles, and the cause was poor cheap champion and autolite plugs, not mixture, etc.

sanctfy

i put in ngk plugs. its running stupid rich. i can smell it. so im pretty sure it is a sensor somewhere. i checked all the plugs and the rotor and they all look good. a bit rich but good.

AKHeathen

again: explain your 02 sensor situation. the engine, as sin=mple as it is, takes fuel map cues from many places, but the 02 sensor sets it for anything like 3seconds or more, so it will idle off (rich?) if it's not getting the mixture reading to the ecu.... keep in mind, the 02 sensors are a tune up item like every other distributor ccap at least.

AKHeathen

and you did good going with ngk plugs. they are great choice for toyota, if not the best.

sanctfy

nevermind the o2, i dont know what i was thinking with that. it didnt make a difference unplugging it but that doesnt tell me much. It could still be bad. im thinking the tps as it will jump rpm up and down if i try to hold it at 1500 rpm. and it wont let me ease into the rpms. i touch it just alittle bit and it jumps up to 2k. just trying to look up the specs on testing it. oh and the problem is intermittent. today i hadnt drove it in 5 hrs and got it in and it was running great. 2 hrs later get in it and its misfiiring again

sanctfy

test 1 is ohm reading from vta to e2 at closed throttle
test 2 is idl to e2 at 62mm
test 3 is idl to e2 @ 90mm
test 4 is reading vta to e2 at wot
test 5 is vcc to e2 @ everywhere

test #1 .086 @2kohm =86ohms?
test #2 32(AND CLIMBING)@200ohm =32ohms?
test #3 36.3 @200 = 36.3 ohms?
test #4 .13(and climbing)@ 20m
test #5 .124@2k= 124ohms?

I dont ever get good readings from ohmeters...im starting to dislike them. I'm assuming im converting these wrong cause they are way off? what do you think?

Janos01

These symptoms could also be the result of:

Bad Ignition Coil
Bad Cold Start Injector
Bad Fuel Injector
Bad TPS Sensor
Dirty Throttle Body
or a Vacuum leak

As AKHeathen mentioned, you might want to either reconnect or replaced you O2 sensor. Running rich wont necessarily be bad for your truck, however it will ware out your catalytic converter faster.

sanctfy

thank you, i pulled tghe plug wires while it was running and the plugs were firing every cycle so i dont think coil. I ran the seafoam to clean injectors and it didnt seem to touch it(doesnt necessarily rule that out either). o2 is hooked up. my buddy just got a parts runner so im gonna swap the tps and o2 and see what happens. i did a leak test of sorts with noithing.

sanctfy

so i replaced the afm again, tps, complete air box, ignition coil and ecu and cleaned the throttle body to no avail. im runnning out of stuff to check. i was not able to get an o2 sensor to check that. its a post cat o2, right? or is there another one? if its post cat then it doesnt have an effect on fuel trims then? its just a cat checker? otherwise im gonna check compression then go after injectors.....getting tired of this thing.

you said cold start injector. that should just be on cold starts then shuts off when warmed up? so if it misfires after warm that can rule that out? anything else it could be? theres no coolant temp sensor that plays a part in fuel trims?

RJR

All trucks have a pre-cat O2 sensor, which is the primary sensor controlling fuel trim when the engine is in closed loop mode. California trucks also have a post-cat O2 sensor which doesn't affect fuel trim, but checks for the presence of a properly operating cat converter.

A defective coolant temp sensor can affect fuel trim, because the ECU will adjust optimum fuel trim based on engine temperature. Also, if the coolant temp sensor always indicates a cold engine, the ECU will never enter closed loop operation, and you'll be chronically running rich. It's definitely worth checking. BTW, this is not the same coolant temp sensor as the one that runs your temperature gauge.