Help 1996 4Runner 3.4 Engine hesitation, no power over 2000 rpm
- Thread starter werminghausen
- Start date
werminghausen
New member
head gasket leak.... interesting.
Unfortunately my new scanner Innova 3040d does not read Live data on my
1997 4 runner...grrrr
Martin
werminghausen
New member
I changed the fuel filter yesterday...
Nothing changed
The engine is still sputtering beyond 3K rpm. Won't rev any higher.
I put Seafoam in the tank...things you do when you start being desperate.
In the old fuel filter (cut it open) I found some brownish stuff, could be rust particles.
Could it be that I have rust in the tank (would not surprise me) and this influences the injectors badly?
Another preventive action:
I ordered denso plugs and NGK spark wire set for the 3.4 engine.
What about the PCV valve: should be closing one way like a check valve?
I am running out of options slowly...
Martin
Nothing changed
The engine is still sputtering beyond 3K rpm. Won't rev any higher.
I put Seafoam in the tank...things you do when you start being desperate.
In the old fuel filter (cut it open) I found some brownish stuff, could be rust particles.
Could it be that I have rust in the tank (would not surprise me) and this influences the injectors badly?
Another preventive action:
I ordered denso plugs and NGK spark wire set for the 3.4 engine.
What about the PCV valve: should be closing one way like a check valve?
I am running out of options slowly...
Martin
weekendclimber
New member
I had some sputtering similar to what you described at one point. It ended up being a bad MAF sensor. Maybe worth a try to test it to see if it's good.
It takes near zero power to rev the engine in Park. Plugged exhaust will manifest itself under load. Doubt backpressure is/was your problem here.
My first bet was the TPS but you changed it with little improvement.
Now my bet is on the plugs/wires. Although they will have to be bad to have that dramatic an effect. I changed my plugs and the ground electrodes were burned off such that the gap was in the 1/8" range (.0125") on all plugs and it still ran fine.
The wires will have the coils included. Might just take care of it although I don't know why a severe misfire hasn't thrown a code.
Just had a random thought: Have you looked at your air filter and intake tract for blockage?
My first bet was the TPS but you changed it with little improvement.
Now my bet is on the plugs/wires. Although they will have to be bad to have that dramatic an effect. I changed my plugs and the ground electrodes were burned off such that the gap was in the 1/8" range (.0125") on all plugs and it still ran fine.
The wires will have the coils included. Might just take care of it although I don't know why a severe misfire hasn't thrown a code.
Just had a random thought: Have you looked at your air filter and intake tract for blockage?
werminghausen
New member
Thanks Zorrata,
indeed you are right.
I am playing the try and error game.
What happened so far:
The old cat converter was not the problem. I knew it after I removed the old converter (no signs of decay). But it was so rusted outside and the upstream O2 sensor port was very damaged. The new converter is investing in future.
Upstream o2 sensor looked bad... so this was a good to change. I can imagine that this O2 sensor threw the code.
The fuel filter was about time to change (5 years now) but it was not the problem.
I changed the MAP sensor (another used unit) but it did not change things dramatically.
Drivability improved some after changing these units ...so I can drive (driving slowly only but I can drive at least)
There were meany opinions from people, all with good intentions but I haven't found the real problem yet.
I canceled all OBD codes today...and I will see if somethings will pop up in the near future.
As the initial problem showed up during heavy rain it might well be that some electrical part is the problem (part getting wet... well I exchanged the TPS and MAP already...) I ordered the PCV and new spark plug and wires.
However I really doubt that these severe problems are from spark plugs.... wire set...maybe but why did the problem not go away when dry again?
You said the plug set has the coils? I doubt that coils are in the plugs wires.
Bad coils could that be a problem?
Then my last item on the list was fuel injectors.... If they were clogged/contaminated... there might be a problem but I have no experience if that problem would trigger my problems (Idle and engine fine up to 3K ... then bad and sputtering... no way to rev beyond 3500)
OBD codes not very helpful... why is there no CEL with these kind of problems?
Well... code 0420 might still exist... I'll see if it shows up again, I 'd need to get a new/new unit or the computer connections are bad (wires or computer)
I need more words of wisdom from the experienced people here.
Martin
* airfilter: I had the filter out and there is no indication that it won't work (also this problem would show itself slowly over time and not all of a sudden when super wet). Air intake is fine.
Last edited:
The plug wire set on these is the damndest setup in the automotive world. There are 3 coils, all on the passenger side plug boots in a standard coil-on-plug configuration, with old style plug wires going to the driver's side plugs. Each coil fires two plugs at the same time (they call it a lost spark) with one spark at the right time and the other at the top of the exhaust stroke. Make sure you get the driver's side wires on the right plugs.
JMat
New member
I had a problem with similar symptoms present itself once after going through a lot of water during heavy rains.
The symptoms I had would only start up once the engine warmed up and were almost non existant when cold. Once the engine warmed up and I started to put a load on the engine I couldn't get it over about 2000rpm. Turns out my issue was caused by water in two of spark plug tubes that would turn to steam when the engine warmed up and allow the spark to ground to the head. Apparently the wire boots on those two cylinders didn't seal enough to keep a little water out of the tubes but sealed enough to keep the water from escaping as steam.
May not be your issue at all but when I saw that it started after some heavy rain I thought I would share just in case.
The symptoms I had would only start up once the engine warmed up and were almost non existant when cold. Once the engine warmed up and I started to put a load on the engine I couldn't get it over about 2000rpm. Turns out my issue was caused by water in two of spark plug tubes that would turn to steam when the engine warmed up and allow the spark to ground to the head. Apparently the wire boots on those two cylinders didn't seal enough to keep a little water out of the tubes but sealed enough to keep the water from escaping as steam.
May not be your issue at all but when I saw that it started after some heavy rain I thought I would share just in case.
werminghausen
New member
Thanks JMat for sharing
I'll change the plugs and wires for sure and then I will see what happens.
I am thinking probably changing injectors (reman Denso for $60) while I am digging in there.
Question: could there be a damage in the ignition coil that causes such problem? Just in theory. ohoh.. Denso coils are expensive I see.
Just thinking...don't want to exclude anything at this point.
Martin
I'll change the plugs and wires for sure and then I will see what happens.
I am thinking probably changing injectors (reman Denso for $60) while I am digging in there.
Question: could there be a damage in the ignition coil that causes such problem? Just in theory. ohoh.. Denso coils are expensive I see.
Just thinking...don't want to exclude anything at this point.
Martin
werminghausen
New member
?? 3 coils total and only 3 ignition wires??
oh I ordered 6 NGK wires (2x3)... damned.
Probably I should order 3 coils instead?
Martin
https://toyotapartsestore.com/2001-...tomatic_4-electrical-ignition_system-8414160/
Here's what it looks like installed. The coils with boots sit on the passenger side plugs. There are wires that attach to the coils that go on the driver's side plugs. I like the other poster's thoughts about trapped moisture. Changing plugs and wires will get you in to where this moisture may lie.
And this is just me but I don't think I'd change injectors just yet. If you're shotgunning parts (and we've all been there) just do one at a time or you'll never know what fixed it. Not to mention the co$t of the injectors.
BamaDrewski
New member
If you can afford to be without the T4R for a few days, send the injectors for testing and cleaning rather than purchasing new....I pulled a spare set at Pull-a-part just for this purpose as a plan B....
werminghausen
New member
Thanks so much, moisture trapped inside was mentioned once before. At least there is a connection to water. That is where the problem started.
I’d also like to know peoples input here. The symptoms getting slightly better with new cat and MAP sensor installed... hm that might have been just time delay and some drying out of moisture?
As the problem has nothing to do with engine load/ output but rpm only I was stupid to think it is a clogged fuel filter or exhaust... because in park reving the engine or driving on the highway would make a difference?
So now... how can it be that moisture gets in there ( water from the road?) but not out? If I was driving a lot with engine hot the moisture should go away over time? Where are the spots wires?
Martin
19963.4lsr5
New member
To me the only place to trap any kind of moisture in the ignition system is between the coil itself and the spark plug boot.
I had that problem 1 time after washing the road grime from the engine compartment. And I tried being careful and only mist the coil area.
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I had that problem 1 time after washing the road grime from the engine compartment. And I tried being careful and only mist the coil area.
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werminghausen
New member
Thanks, between coil and spark plug wire... is there a rubber boot than fail?
Is there any replacement boot or seals that can be used to reseal this part... or new coils?
Martin
19963.4lsr5
New member
If you remove the coil from the right hand valve cover you will see the rubber boot that attaches to the underside of the coil and pushes onto the top of the spark plug. Should be plenty of pictures on the Internet of what it looks like. I have a few spares but am not near them to snap a picture.
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werminghausen
New member
Probably a wise idea to change the boots. Any idea where to get these?
Any other seals inside there?
Martin
sleepydad
Senior Member
A340F transmissions are pretty universal for all the 3rd gen years. A 99 limited should be a direct fit into a 97.
There are some differences in valve bodies but I’m pretty sure the valve body in 99 is the same as the 97.
19963.4lsr5
New member
My wire set from autozone came with wires and boots. Most sets do. I bought the autozone set because I wanted a mag core set and they stopped selling the Bosch brand I always bought.
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