Help 1996 4Runner 3.4 Engine hesitation, no power over 2000 rpm

W

werminghausen

New member
All of a sudden my 4runner was bogged down as soon as I get over 2000rpm... no power to get beyond second gear. With the car parked I cannot get the engine rev beyond 2500 and it is starting to shut off, then come back at lower speeds.
I cleaned the airflow sensor and throttle body but it was clean and nothing changed.

I guess it can be a lack of fuel that is causing starvation (computer?, fuel filter, fuel pump, throttle position sensor) or maybe spark (spark plugs and wires)?
It stared to happen this morning when there was so much rain and I had to go through puddles of water. But now with less water the same thing happens.

Any ideas... I need help

Martin
 
Last edited:
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You mean a clogged catalytic converter? Clogged exhaust you mean?
But what could clog the converter?

I did not get a Check engine light so far. I should probably still try and get readings with the OBD device ?
A clogged converter is a big thing... there should be a failure to be read with the OBD?
How can I test the Converter? Remove and see if it is clogged?


I installed a new exhaust (muffler) not long ago, do you think the new exhaust could do such thing?

Can't believe that the exhaust could go bad this fast.

Martin
 
Last edited:
Yes, a ~22 year old converter can go bad. The honeycomb starts to crumble.
Nothing you did behind the converter affected it. Yes, remove it and see if the
motor revs right.
 
When you say puddles of water did your ignition wires get wet?

Do you have a scan tool that reads live data to check the TPS and make sure it's a linear reading from idle to wide open throttle?

Also use it to check if the ECT and the IAT are close to each other and to ambient temp after sitting 8 hours?

A clogged cat could be. Toyota is poor on detecting a misfire condition. And nerfing puddles could have caused it and the excess raw fuel could have overheated and melted the cat clogging it.


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heat said:
Yes, a ~22 year old converter can go bad. The honeycomb starts to crumble.
Nothing you did behind the converter affected it. Yes, remove it and see if the
motor revs right.
Click to expand...


Remove it meaning removing the catalytic converter? and test drive without exhaust?
Does the converter clog the passage for the exhaust gas if converter is failing?
Then without the restriction the car runs 'normal' again.
If true I would need to find a new converter, correct?

Now I did the failure read out with the OBD today ...

#1) P 0110: IAT Sensor circuit malfunction
#2) P 0420: Catalyst Efficiency below threshold (bank 1)

I don't know what this all means...could #2 be a failing catalytic converter?

Martin
 
19963.4lsr5 said:
When you say puddles of water did your ignition wires get wet?

Do you have a scan tool that reads live data to check the TPS and make sure it's a linear reading from idle to wide open throttle?

Also use it to check if the ECT and the IAT are close to each other and to ambient temp after sitting 8 hours?

A clogged cat could be. Toyota is poor on detecting a misfire condition. And nerfing puddles could have caused it and the excess raw fuel could have overheated and melted the cat clogging it.


Sent from my iPhone using Tapatalk
Click to expand...


Yes our driveway is full of puddle during heavy rain, not sure if water reaches that high but it is possible.

I did the scan today
#1) P 0110: IAT Sensor circuit malfunction
#2) P 0420: Catalyst Efficiency below threshold (bank 1)

Not sure what the interpretation is.

I figured out meanwhile that IAT is Intake Air Temperature Sensor, ECT = Engine Coolant Temp Sensor

You said "Also use it (the UBD? tool) to check if the ECT and the IAT are close to each other and to ambient temp after sitting 8 hours?
I have a simple tool (Maxiscan MS300 OBDII reader) and I don't know if it can read live data...
Is there another way to test what you think should be tested in terms of IAT and ECT?

Martin
 
Drop the catalytic converter, see if the engine will rev right.

I'm too lazy to search on engine codes.

Get a cheap ELM327 OBDII dongle and TorquePro phone app for live data.

The factory service manual would be helpful.
 
DON'T just chop the cat out, remove it with the proper nuts and bolts.
That way if it's still ok, you don't have to buy a new one.
Obvious advice, but still.

Sent from my VS986 using Tapatalk
 
werminghausen said:
Yes our driveway is full of puddle during heavy rain, not sure if water reaches that high but it is possible.



I did the scan today

#1) P 0110: IAT Sensor circuit malfunction

#2) P 0420: Catalyst Efficiency below threshold (bank 1)



Not sure what the interpretation is.



I figured out meanwhile that IAT is Intake Air Temperature Sensor, ECT = Engine Coolant Temp Sensor



You said "Also use it (the UBD? tool) to check if the ECT and the IAT are close to each other and to ambient temp after sitting 8 hours?

I have a simple tool (Maxiscan MS300 OBDII reader) and I don't know if it can read live data...

Is there another way to test what you think should be tested in terms of IAT and ECT?



Martin
Click to expand...



You need to fix you IAT malfunction code


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AntleredRuin said:
DON'T just chop the cat out, remove it with the proper nuts and bolts.
That way if it's still ok, you don't have to buy a new one.
Obvious advice, but still.

Sent from my VS986 using Tapatalk
Click to expand...

Does the engine run without the O2 sensor when cat is removed?
I have the most rusty 4Runner on Earth, I hope I can cut out the bolts easily. Thank god i have a lift.
If the engine should run normally without the catalyst ( if it is the catalyst) I’ll give it a shot.
Martin
 
heat said:
Drop the catalytic converter, see if the engine will rev right.

I'm too lazy to search on engine codes.

Get a cheap ELM327 OBDII dongle and TorquePro phone app for live data.

The factory service manual would be helpful.
Click to expand...

I am lazy too :bravo:
I'll get the ELM327 and the Torque pro... hope it works for the Iphone.
I'll remove the muffler and CAT , see if it runs... obviously no O2 sensor during the test?
Would you see the damage to the CAT?

Martin
 
werminghausen said:
I am lazy too :bravo:
I'll get the ELM327 and the Torque pro... hope it works for the Iphone.
I'll remove the muffler and CAT , see if it runs... obviously no O2 sensor during the test?
Would you see the damage to the CAT?

Martin
Click to expand...

No, you'll need iphone specific stuff. There's a current thread on that in this
forum.

You're just trying to see if it'll rev above 2500 rpm.

You might be able to stand the cat on its front end and shake bits out of it
 
Last edited:
Hi Heat,
Thanks, very helpful.
Seems I need this App: OBD Fusion by OCTech, LLC https://itunes.apple.com/us/app/obd-...650684932?mt=8
For the iPhone.
Seems I can’t read trans temp in my 1996 3.4. But hope to read what you suggested.

I ordered the dongle on Amazon and get the app so I can read IAT and ECT.
Meanwhile I get the car on the lift and try my best to get the Cat out.
My underside is so rusty that it did not happen often that I found remove a bolt without destroying even if I am using heat. I welded 50 pounds of steel in Frame and redid both rocker panels. Love the car too much.

Martin
 
I really would fix the IAT trouble code before dealing with the CAT.

My 96 all the bolts broke or the nuts ripped all the threads off the studs to drop the cat to pull the engine.


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19963.4lsr5 said:
I really would fix the IAT trouble code before dealing with the CAT.

My 96 all the bolts broke or the nuts ripped all the threads off the studs to drop the cat to pull the engine.


Sent from my iPhone using Tapatalk
Click to expand...

I would agree with this, as the cat is a beotch to remove, and definitely the more expensive fix, if you stay OEM.

Also, a way to tell if your cat is clogged; use a laser thermometer on it with the truck running. I forget the details, but you can Google it. The rear will be a whole lot cooler than the front, or something to that effect.
 
jgue467 said:
FSM says P0110 = intake airtemp circuit malfunction.



Possible causes: 1) open or short in intake airtemp sensor 2) airtemp sensor (built into mass airflow meter) or 3) ECM.



Page 202 and on in the FSM instructs on how to test. https://drive.google.com/open?id=0B20d86M4DqTrVU5wUHhyUVN4OWM



:cowboy:
Click to expand...



I never realized the IAT was part of the MAF sensor. On all my previous vehicles it was a separate sensor in the intake or on the throttle body.


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