Need Help! rebuilt 3.4 running very rich!! please!

[tommyoquattro]

so the story is I up a 96 4runner for cheap with a tired engine, buring lots of oil, low compression... So i ordered a rebuilt long block for it and i installed it over the weekend...

first startup the engine would not idle ver well and died when the a/c was on. Idecide to clean out the idle valve. took it apart and it was kinda gunky and after cleaning the engine is no idleing about 1500-1250. no lower.

i figure its still gunked but idleing high would be good to break in the engine so i let it run for about a half hour.
i come back and go to give it some throttle and i get a nasty pop from the cat. only when i blip the trottle not when i close it.
so i look under the truck and notice the cat outlet area is red hot and i shut the truck down.
I had noticed the exhaust was rich smelling but thought it was gunk in the exhaust from the old engine and paid no mind untill i saw the cat glowing. I start to look over the engine for a missing plug or something and i find that i routed the fuel pressure regulator wrong. i had it going right to the manifold when the diagram shows it going to the intake silencer.
after fixing that it was slightly less rich but now the popping sound was still there any time igave it any throttle.

So far i have tried:
Cleaning the IAC again.
Testing IAC operation per the FSM - moves freely full open and close.
Testing coolant temp sensor per FSM- in spec
Inducing a vaccuum leak- made it run slightly better, less popping in exhaust.
last dich effort last night i cut the cat out and put a pipe in thinking the cat had gotten coated in oil/fuel somehow, but the cat looked fine and ran no differently without it.

I am going right now with a scan tool to check O2 sensor voltages and fueltrims.

there is no check engine light on...

please anyhelp would be amazing. ive spent about 4000 now on parts and it runs like dump and im out of ideas and energy to think anymore...
ive been working on it for 7 days strait now 8 hours a day after my regular 9 hour work day and im totally spent.

TIA guys.

Tommy O

 

[tommyoquattro]

i thought the FPR might have gotte damaged when i hooked it up wrong but i checked to see and the diaphram is not leaking or the vacuum line does not smell like fuel...

Could a bad O2 cause it to run this rich with no check engine light?

 

[Singtoe]

Sounds like you have leaking fuel injectors.

 

[Singtoe]

i thought the FPR might have gotte damaged when i hooked it up wrong but i checked to see and the diaphram is not leaking or the vacuum line does not smell like fuel...

Could a bad O2 cause it to run this rich with no check engine light?

O2 measures, tell ecm what is going on. If O2 is out of range, Check engine light will turn on.

So the answer is most likely not. Now, O2 sensors can get tired and be at the low end of it operational value giving you poor mileage and won't give you a check engine light.

 

[tommyoquattro]

yes i was thinking that too. the truck is hard to start. it takes 2 or 3 cranks to fire up like the injectors might be leaking down...

i dont have a good way to check fuel pressure to be sure tho.

there is no shrader valve and the manual shows using a banjo bolt fitting to tee into the rail.. i dont got this...

 

[tommyoquattro]

O2 measures, tell ecm what is going on. If O2 is out of range, Check engine light will turn on.

So the answer is most likely not. Now, O2 sensors can get tired and be at the low end of it operational value giving you poor mileage and won't give you a check engine light.

So it most likely wont cause it to be running this rich where i get gunshots in the exhaust...

whats weird to me is the popping on acceleration and not on decel like a rich motor ususally does...

 

[tommyoquattro]

is the fuel pump supposed to prime with the key on engine off? should i have fuel pressure then? or only with it running?

 

[Singtoe]

is the fuel pump supposed to prime with the key on engine off? should i have fuel pressure then? or only with it running?

only when it is starting and when its running.

 

[tommyoquattro]

only when it is starting and when its running.

Good to know. Well off for more diagnosis... wish me luck.

 

[tommyoquattro]

diagnosis update:

I wasnt able to rig up any kind of fuel pressure gauge but i did learn a few things from the scan tool...

first the O2 sensor 1 is not switching like it should. it is staying around .450 volts and will drop some to about .250 when i rev it and when i close the throttle it will go to about .8 for a sec then go back to .5ish...

no normal signs of switching....

second the LTFT is always about 22% at idle and STFT is 0% at idle.
the LTFT will drop slightly as i rev it and the STFT will jump to around 20% also...

seems like its always calling for alot of fuel...

could so much fuel cause those O2 readings? or are the O2 readings bad?

my head hurts....

 

[brian2sun]

Is the engine stumbling like it's missing too or just the high idle and backfiring? The old engine could have screwed up the O2 because it was running dirty for a while. Do you have a warranty on the new rebuilt motor? Could be a timing issue.

 

[tommyoquattro]

its not stubling really at all. no chech engine light even with both o2s unplugged which i thought was strange... just high idle and popping in the exhaust on accel..

i had my scanner hooked up while driving it last night and was watching the
o2 and fuel trims.

on light accel, not letting it pop, the o2 voltage stayed right around .5, no switching. and fuel trims were high around 15 LT and 15 ST.

hard accel with the exhaust sounding like an uzi, the os voltage pins rich like sometimes over 1 volt and you can see the ecu cutting the STFT down to like -10.

so i believe the o2 is working somewhat and the ecu sees the rich condition and trie to correct but it doesnt work...

really does sound like a badly leaking fuel injector or two..
im going to get a master fuel pressure tester to hopefully comfirm this..

but guys please give me all the feedback you can!
I really appreciate it!!!!!

 

[Grezdlitn]

It sounds like symptoms of a fuel injector being stuck open. Perhaps someone can tell us how to test the injectors?

 

[tommyoquattro]

so i replaced all 6 injectors with a cleaned and flow tested set from ebay and there is absolutely no change in the way it runs.....:nono:

im running out of ideas here..

im thinking i missed a ground somewhere. the only one i have is on the passenger side firewall to the head..

am i missing one?

this is driving me nuts.. thanks guys...

 

[Singtoe]

Check your timing belt timing.

Was the 4runner running with the same symptoms before the rebuild?

 

[tommyoquattro]

the timing is perfect. ive checked it a few times.

found somthing interesting when i took the plugs out to do a compression test. Bank 2 plugs were covered in carbon. bank 1 plugswere almost like new.. barely any deposits.. this is only with about 3 hours of run time and no miles...

also when i start to unplug injectors while its running if i unplug 2 4 or 6 the engine nearly dies.. but if i unplug #1 there is no change in idle speed at all...

i cant get to 3 and 5 to try those...
but thats just weird..

how could it be idleing on all 6 cylinders.. not 100% smooth but def on all 6, and then when i unplug #1 there is no roughness???? and these are new injectors.

 

[Baja Runner]

This looks similar to the last thread I was replying too.

It's sad that people here actually told you that it was leaking injectors. Thats just bogus. That is a very uncommon occurrence with Toyota injectors, and will usually throw a misfire code if it IS the problem.

Anyways, did your ODBII program tell if you if it was getting out of open-loop mode? I doubt it is. Have you tried looking through the FSM? It's very helpful, and has a lot of information pertaining to the testing of sensors.

The 4 main sensors, are: O2, MAF, ECT, TPS. Make sure those are all well within spec. Sounds like you've already done that though.

You are sure that there are no codes? Did you get the computer with the new engine?

The last thing you said about unplugging the #1 injector is odd....

Check the FSM and see if you can't find anything.
2001-2004 Toyota Tacoma FSM

 

[Richard808]

if you unplug cylinder 1 and theres no change in idle it means that cylinder is not producing anything. was the plug clean and wet? did it smell like raw fuel? you may not be getting spark to that cylinder. if there is no spark all that fuel runs out the exhaust which would tell the o2's its running rich and the ecu will try and lean it out but it wont be able to. All that unburned fuel will cause your cat to glow red hot. I seen a few people use intake flushes where it sends the carb cleaner like spray into the intake and the cats will light up due to all the fuel and the exhaust will pop because of it. i dont think your exhaust is popping due to timing issues just too much fuel.

 

[Richard808]

i know you said you bought a new long block but i would run a compression check just to be safe. also check to see your getting spark at each plug. make sure your spark plug wires are routed to the correct cylinder also. that could cause backfires like timing issues.

 

[brian2sun]

the timing is perfect. ive checked it a few times.

found somthing interesting when i took the plugs out to do a compression test. Bank 2 plugs were covered in carbon. bank 1 plugswere almost like new.. barely any deposits.. this is only with about 3 hours of run time and no miles...

also when i start to unplug injectors while its running if i unplug 2 4 or 6 the engine nearly dies.. but if i unplug #1 there is no change in idle speed at all...

i cant get to 3 and 5 to try those...
but thats just weird..

how could it be idleing on all 6 cylinders.. not 100% smooth but def on all 6, and then when i unplug #1 there is no roughness???? and these are new injectors.

I agree with Richard808, if the idle doesn't change when you unplug #1, then you aren't running on all 6 in the first place. What confuses me is your statement that you can't get to #3 and #5 injector connectors. The even numbered cylinders are the ones below the intake manifold (driver's side) and are the harder ones to get to. Are you sure you got your cylinder numbering correct? Are the plug wires routed correctly?

Cylinder #s:
Windshield
5 - 6
3 - 4
1 - 2
Radiator

The coil on #1 goes to #4
The coil on #3 goes to #6
The coil on #5 goes to #2

Just thinking of possibilities.