A Super-Ultimate 3FE Diagnostics Thread - Let the Battle of Wits Begin (3 Viewers)

[60Works]

FYI

Fuel Cut RPM test?

And I found your previous thread about this problem.

3FE- Loss of power/mild stumbling/at mid RPM range (Fixed it Thread) Whew.

So, from a big picture troubleshooting view, you have the same problem with the new engine as with the old. This leads to the tentative conclusion that it isn't the engine. Which accessories or components are common to both your installations? Which sensors and VSV's did you reuse? Or possibly, what procedure did you do incorrectly or omit both times to reproduce the problem?

On my 62 it ran fine when I parked it, then, after rebuilding most of the braking system, it ran poorly. Made me think it was a vacuum issue and I chased all the usual suspects of hoses and intake without finding a smoking gun. I gave up for the winter.

It only stumbles under load and at exactly the same rpm range.

 

[OSS]

Is it possible for an ECU to become senile? That's the one component that has been carried over from one engine to the next - both exhibiting the exact same symptoms.

Electronic components don't last forever. Failure is eminent. Guaranteed (eventually). It's a rather strange coincidence that two members here on this thread have the exact same issue.

I know from experience working at an industrial electronics company that certain components in our products would eventually fail after decades of use. It was inevitable. We weren't Toyota, but ICs are ICs.

 

[Kleatus]

Couple of other things to think about- but I’d really want to hone in on what @Juggernaught mentioned about making a list of what parts/configurations are carried over between old and new engines.

Since you have a wideband, what happens to AFR and is the ECU able to compensate when you pinch off the return line? May or may not tell anything but on mine I can watch it go pig rich for a moment then back as the ECU is able to pull the injectors back to compensate for the increased fuel pressure (65 psi).

What changes to fuel system did you make to “better supply fuel under load?” mentioned in post 1?

What does your exhaust look like and where are your 02 sensors mounted?

 

[FJ40Jim]

Questions that need to be answered:
-If the ECU goes into limp mode, will it always throw a code?

What is this 'limp mode' you speak of? Have never seen that on a OBD1 Cruiser...

-When should the VSV receive a voltage signal?

Which VSV?

-Exhaust pipes from manifold flange to collector are larger diameter than stock. Could a lack of backpressure produce a lean-running condition?

Theoretically, yes. But not in the real world.

 

[mwebfj60]

This might help on setting the TPS. It can be done in vehicle with a little 90 degree philips but I highly recommend doing it on the bench.

 

[lelandEOD]

FYI

Fuel Cut RPM test?

And I found your previous thread about this problem.

3FE- Loss of power/mild stumbling/at mid RPM range (Fixed it Thread) Whew.

So, from a big picture troubleshooting view, you have the same problem with the new engine as with the old. This leads to the tentative conclusion that it isn't the engine. Which accessories or components are common to both your installations? Which sensors and VSV's did you reuse? Or possibly, what procedure did you do incorrectly or omit both times to reproduce the problem?

On my 62 it ran fine when I parked it, then, after rebuilding most of the braking system, it ran poorly. Made me think it was a vacuum issue and I chased all the usual suspects of hoses and intake without finding a smoking gun. I gave up for the winter.

It only stumbles under load and at exactly the same rpm range.

There are all sorts of possibilities that I need to track down. I reused the major ancillary parts from the old engine as they were all either new or checked out prior to the head gasket failure (with the exception of the O2 sensors - those are new Densos). My old thread on the loss of power and stumbling was a little different and it was definitely the TPS out of adjustment. That was more of a jolting cut-out of power as I acellerated. The engine was jolting pretty badly.

Thanks for posting the link to the fuel cut-off test. I'll be doing that shortly.

Is it possible for an ECU to become senile? That's the one component that has been carried over from one engine to the next - both exhibiting the exact same symptoms.

Electronic components don't last forever. Failure is eminent. Guaranteed (eventually). It's a rather strange coincidence that two members here on this thread have the exact same issue.

I know from experience working at an industrial electronics company that certain components in our products would eventually fail after decades of use. It was inevitable. We weren't Toyota, but ICs are ICs.

I suppose anything is possible, but I have a spare ECU that I've tried with no change. The only thing that I keep wondering about with the ECU is the high altitude compensation feature that is supposedly built into the unit. I see no way to check this function provided in the FSM and it doesn't appear to have a corresponding engine code to indicate a malfunction.

Couple of other things to think about- but I’d really want to hone in on what @Juggernaught mentioned about making a list of what parts/configurations are carried over between old and new engines.

Since you have a wideband, what happens to AFR and is the ECU able to compensate when you pinch off the return line? May or may not tell anything but on mine I can watch it go pig rich for a moment then back as the ECU is able to pull the injectors back to compensate for the increased fuel pressure (65 psi).

What changes to fuel system did you make to “better supply fuel under load?” mentioned in post 1?

What does your exhaust look like and where are your 02 sensors mounted?

I'll try pinching off the return line and let you know what the AFR gauge says.

The changes to the fuel supply system were intended to provide better fuel pressure under various operating conditions. My -40 is running a primary tank under the passenger seat and a aux. tank under the rear crossmember. Originally, I was using a frame-mounted universal fuel pump and a 6-pin Pollak valve/Carling switch to select the fuel source. With this old setup I was occasionally getting cavitation and aeration in the fuel line which was wreaking havoc with the fuel pressure to the rail. Several buddies mentioned that I was asking the pump to "suck" fuel from the tank and that the number of connections in the plumbing might be introducing air into the system. They also mentions that most pumps do a better job pushing rather than pulling. Thinking that this was causing some of my problems, I opted to redesign the fuel system. I now have a dedicated in-tank fuel pump for each tank. The fuel pumps, senders, and Pollak valve position are synchronized using a 5-pin relay in the engine compartment. So far, this system has worked well (I think) as I'm able to switch the supply from front and rear tanks on the fly without so much as a stumble or dip in fuel pressure.

Here's a photo of the O2 sensor positions. They are pretty close to the same positions as those on a FJ62:

What is this 'limp mode' you speak of? Have never seen that on a OBD1 Cruiser...


Which VSV?


Theoretically, yes. But not in the real world.

Thanks for the reply, Jim. I think you're right about the limp mode in OBD1. I thought I heard it mentioned in some conversations with other 'cruiser heads but when I referred to the 1988 New Model Featured bulletin it doesn't mention such a thing. I'll modify the original post.

The VSV I'm interested in is the only valve I still have on this desmogged motor. It's the VSV that controls vacuum to the fuel pressure regulator to adjust pressure on the rail. I see precious little detail about how and when this VSV functions or how I can confirm the signals from the ECU to the VSV are good to go.

 

[lelandEOD]

This might help on setting the TPS. It can be done in vehicle with a little 90 degree philips but I highly recommend doing it on the bench.

Thanks!
I wish I had found this video before I spent an hour last night trying to film bench testing of a spare TPS.

It looks like I was performing the adjustment incorrectly. I finally get that the .0366" gauge is half-way between the .0303" and .0429" gauge. So, the goal is to get it to the point where it changes from closed to infinite with the .0366" gauge. This should ensure that there is continuity with the smaller gauge but should be open (infinite) with the .0429" feeler gauge. I'm off to double-check my TPS adjustment!

 

[mwebfj60]

Thanks!
I wish I had found this video before I spent an hour last night trying to film bench testing of a spare TPS.

It looks like I was performing the adjustment incorrectly. I finally get that the .0366" gauge is half-way between the .0303" and .0429" gauge. So, the goal is to get it to the point where it changes from closed to infinite with the .0366" gauge. This should ensure that there is continuity with the smaller gauge but should be open (infinite) with the .0429" feeler gauge. I'm off to double-check my TPS adjustment!

You got it. I’m curious with a desmog if it would be beneficial to set the open point closer to one edge of the range.

 

[lelandEOD]

I'm waiting for the garage to warm up a bit before I tackle that TPS adjustment but in the mean time a couple other things have piqued my interest that I wanted to share. I can't shake the thought that I might have inadvertently mixed incompatible parts and that something I've installed is causing (or contributing) to this problem. Up 'til now, I was thinking 3FE parts are 3FE parts are 3FE parts. This morning, a friend suggested I cross reference part numbers for key components on Rock Auto's website to see if they are interchangeable. Remember, I started with an engine, harness, and computer from an '88 but over time have picked up at three other engines from at least a '90 and '92 from which to salvage parts.

See the parts-hoarder photo below:

Looking at Rock Auto's website, I noticed that the following parts show different part numbers from '88 to '92:

Throttle Position Sensor
O2 Sensors
Ignition coil/Ignitor
Water temp sensor


DO'H!


I'm definitely running the correct coil/ignitor for an '88 but I noticed I have TPS sensors with different p/ns. Dang! I have a Denso 89452-14050 ('89-'93) installed instead of Denso 89452-28030 ('88-'90). "Rut Row, Shaggy."

Along these same lines, I am questioning whether the Denso O2 sensors I bought are correct for the '88 harness/ECU. I bought an installed Denso #234-4051 and #234-4050. I'm going to have to do some more digging to confirm those are correct part numbers for the '88 which should be Toyota #89465-69015.

Geez... Ain't troubleshooting grand!?

 

[WILLD420]

You are on the right track. Consider this though. You took the EGR off it. The computer doesn't know this so it will advance the timing and adjust other parameters based upon the original smogged needs.

What you are experiencing is the same as the older carbed motors . The advance curve and vacuum advance we're calibrated for EGR. They gave way too much timing under part throttle and pinged like mad until you changed the vacuum advance can.

 

[OSS]

Does the 3F-E have a knock sensor?

 

[Kleatus]

Does the 3F-E have a knock sensor?

Negative. I wish it did, then maybe the timing would have some more flexibility beyond a pre-programmed curve; especially for de-smogged engines.

 

[OSS]

Then that's why it's pinging. New engine with great compression but no EGR = guaranteed detonation.
@WILLD420 nailed it
Try racing fuel. Octane 100.

But the correct solution is to install the EGR system.

 

[LAMBCRUSHER]

Those o2 sniffers are about 16” too far forward in your pipes based on my fj62... that should not be discounted.

 

[Kleatus]

Then that's why it's pinging. New engine with great compression but no EGR = guaranteed detonation.
@WILLD420 nailed it
Try racing fuel. Octane 100.

But the correct solution is to install the EGR system. The ECU is programmed for it.

The factory timing spec is very conservative..

I run mine without EGR (and 0.035” taken off the head). Compression numbers around 175 psi at 1000’ ASL. I run 89 or better octane, and have no pinging. With EGR functioning properly I’m sure I could get away with more timing and squeeze a little more out of it at full throttle though.

Timing should be checked but I suspect we have more going on here.. I have had tanks of gas that pinged and I have stopped and adjusted timing accordingly-however none of the other symptoms we’re reading about were present.

You mentioned being at 10:1 during acceleration, that seems overly rich. Not saying mine is a benchmark by any means but it dips down to 12.5:1 during heavy throttle. It should be running in open loop during power enrichment, i.e. no feedback from 02 sensors.

How fresh is the sensor on your wideband? I was warned when I got mine not to leave the sensor threaded in all the time because they wouldn’t last near as long as a narrow band type.. not sure what the lifespan is or if your meter will self calibrate like some do, but it would be good to be reasonably sure we’re working with good data.

[/QUOTE]

 

[tornadoalleycruiser]

O2 sensor difference is probably only the length of the wire

 

[lelandEOD]

Then that's why it's pinging. New engine with great compression but no EGR = guaranteed detonation.
@WILLD420 nailed it
Try racing fuel. Octane 100.

But the correct solution is to install the EGR system.

The pinging I experienced was with the now-dead motor that blew a head gasket. I haven't driven this one enough to notice pinging (that and it's really cold out). If I had saved the smog parts, I'd totally be ok with replacing them if I thought it'd solve this. When I desmogged it, I didn't see anything that indicated doing so would cause problems like this. :/

Those o2 sniffers are about 16” too far forward in your pipes based on my fj62... that should not be discounted.

If that's the case then the motor I had originally must have had non-factory exhaust. I remember looking up tear-down photos to see where they were attached when I had a shop make the exhaust.

The factory timing spec is very conservative..

I run mine without EGR (and 0.035” taken off the head). Compression numbers around 175 psi at 1000’ ASL. I run 89 or better octane, and have no pinging. With EGR functioning properly I’m sure I could get away with more timing and squeeze a little more out of it at full throttle though.

Timing should be checked but I suspect we have more going on here.. I have had tanks of gas that pinged and I have stopped and adjusted timing accordingly-however none of the other symptoms we’re reading about were present.

You mentioned being at 10:1 during acceleration, that seems overly rich. Not saying mine is a benchmark by any means but it dips down to 12.5:1 during heavy throttle. It should be running in open loop during power enrichment, i.e. no feedback from 02 sensors.

How fresh is the sensor on your wideband? I was warned when I got mine not to leave the sensor threaded in all the time because they wouldn’t last near as long as a narrow band type.. not sure what the lifespan is or if your meter will self calibrate like some do, but it would be good to be reasonably sure we’re working with good data.

[/QUOTE]


It's my understanding that the timing cannot be manually manipulated the way it can on a carbureted engine as the ECU will adjust the advance as it sees fit. 10:1 was just a guess. I need to get the O2 controller hooked up to a serial port on a laptop to do some data logging.

 

[lelandEOD]

O2 sensor difference is probably only the length of the wire

You mean the only difference between the O2s on the FJ62 and 3FE FJ80 would be the pigtail length on the sensor?

 

[lelandEOD]

Also, I noticed something peculiar tonight - someone has drilled a hole in one of the spare AFMs I have.

Any idea why someone would do this?

 

[tornadoalleycruiser]

I thought

You mean the only difference between the O2s on the FJ62 and 3FE FJ80 would be the pigtail length on the sensor?

Pretty sure ive used the wrong 02 sensor on the corolla matrix b4 and it was fine just the length. Denso 02 is 4 wire heated all have the same plug and do the same thing. No idea on the afm my spare is intact there just checked.