2F '84 FJ60 Hesitation, anyone interested in helping me diagnose? (2 Viewers)

[DieselFJ]

View attachment 3512878

Are you hearing the single click at the fuel cut solenoid when you turn the key? Or when you directly connected 12v to it?

One other thing that causes a hesitation is the EGR modulator. Your EGR can be clean and functional but if the modulator is not delivering vacuum signal to the EGR it won't work when it's supposed to. Test for this by holding steady on the accelerator pedal in a certain RPM range roughly 1500 rpms to 2000 WHILE GOING DOWN THE ROAD. Don't test this with your choke or while idling at park. The hesitation will go away while excelerating hard through this rpm range or while above or below those rpms. There are tests in the emissions FSM to determine if the EGR modulator is bad. Also the check the EGR VSV. both the modulator and the vsv send vacuum signal to the egr to tell it to turn on and off while going down the road.

Definitely hear the click from the solenoid with 12v connected, I haven’t verified with the key switch, but will verify with the key switch this weekend.

I did run through the EGR tests per the FSM, but will test again per your instructions, and verify the modulator and VSV again. Thanks!

 

[g-man]

I'd only test the modulator and VSV if I had hesitation IN THAT RPM range! I found a mityvac is a great vacuum testing tool.

 

[OSS]

It’s super easy to rule out if the EGR system is causing hesitation:
Just disconnect the vacuum hose that plugs into the top of the valve. (And plug that hose). That will disable it.
You’ll notice that the engine accelerates much better on light throttle — but it will ping at certain RPMS & load.

 

[DieselFJ]

It’s super easy to rule out if the EGR system is causing hesitation:
Just disconnect the vacuum hose that plugs into the top of the valve. (And plug that hose). That will disable it.
You’ll notice that the engine accelerates much better on light throttle — but it will ping at certain RPMS & load.

I performed that particular test when I was working on passing Utah emissions. I was verifying functionality of all systems and that was one of my tests for the function of the EGR, at that time everything was functioning correctly which was about two months ago. I don’t mind verifying it again just to rule it out.

 

[Mark W]

FWIW, the idle circuit cut off solenoid in the FJ60s has two wires. One is switched 12V. The other is the ground. But the ground wire does not run straight to ground but instead passes through the emissions computer. This collection of not very smart electronics will cut the ground under certain conditions. Throttle closed engine braking above (???) rpm IIRC. Toyota's thinking was that this would reduce emissions a bit. Don't know if it did or not. But I do know that it is a common trouble point as the little box of transitors and diodes that we so lovingly call a "computer" is prone to failure over the years. this particular circuit especially. The common solution, either after or before the failure occurs, it to route the current from the solenoid straight to ground, bypassing the emissions box so that the solenoid works as it did in the earlier vintage Cruisers.

From you symptoms as described I am not strongly suspecting this as the problem. But it *might* be. Sometimes symptoms observed and relayed do not come across the same as symptoms observed first hand.

And it is a problem that can be proactively addressed in just a couple of minutes with no real downside to make sure it never bites at you in the future even if it is not part of your current problem.

My inclination is to agree with those who are suggesting lack of fuel one way or the other as your problem. Primary or idle circuit, rather than secondary circuit. (The idle circuit provides more fuel during mid rpm/load operation than may be expected.)

Mark...

Mark...

 

[DieselFJ]

It’s super easy to rule out if the EGR system is causing hesitation:
Just disconnect the vacuum hose that plugs into the top of the valve. (And plug that hose). That will disable it.
You’ll notice that the engine accelerates much better on light throttle — but it will ping at certain RPMS & load.

I believe we have a winner!!! I had to go pick the 60 up from my daughter a couple days early so I thought I’d run this quick test and sure enough the problem disappeared. I still need to troubleshoot the system again to find the actual failed component, but at least it’s pinned down to the EGR system. While im troubleshooting the system I’m going to advance the timing and verify a couple other systems that others pointed out could be the problem or could cause future problems then give it another run. Looking forward to getting it fixed and back on the road. Thanks for all the insight and help!

Scott

 

[DieselFJ]

Well, did some further testing and everything looks to be pointing towards the modulator. I had a spare old one in my parts bin which did function better than the original one, but it's still not as good as disabling the EGR all together. I was looking to purchase a new modulator to eliminate the possibility that the modulator is only marginally working, but it looks like the modulator is no longer available anywhere OEM or Aftermarket. Does anyone have any alternate part numbers that would work and function correctly in this application?

BTW, I advanced to 13 degrees and without the EGR working and it drives amazing.

Is there anything I could hurt by just leaving the EGR disabled? ie. catalytic convertor etc...

Thanks
Scott

 

[OSS]

Does anyone have any alternate part numbers that would work and function correctly

The EGR modulator used on the FZJ80 LANDCRUISER works fine. Two of the pipes are oriented differently but that’s easy to re-route.
I used it on my FJ60 and I can verify it’s the same. It was available 5 years ago new - not sure if it still is.
See my picture of it for its part number on the top.
It snaps right in where the original goes.

 

[OSS]

Even with a brand new FJ60 with everything working properly, disabling the EGR system will give an immediate impression of improved acceleration and power — for a little while.
The spark advance curve built into the distributor is calibrated to an EGR diluted fuel mixture. The charge burns slower when EGR is active which requires a more advanced spark. When the EGR is disabled, the fuel mixture burns much faster (and hotter) which will cause a normal new engine to ping under certain loads and RPMs.
What’s happening now though with 40 year old 2F engines is that the compression is much lower on an old engine which pretty counteracts the pre-ignition problem of disabling the EGR.

You’ve got to pay close attention to the engine when EGR is disabled. A sloppy workaround is to move the inner vacuum advance vacuum hose on the distributor to the outside actuator (which is normally used for HAC). Doing that will provide only 7° of vacuum advance instead of the normal 15° or so — which should prevent pinging.

 

[g-man]

I bought one of those 80 series modulators in May of 2022 from Partsouq. It worked fine. Around $87.00 USD then shipped. The ports are nicely labeled on the decal. Easy swap.

MINE:

I used this VSV bought off Amazon. Pull the filter off the back side to expose the vacuum barb that the 2f routes to the air cleaner.

Amazon product ASIN B0814MPNFB
I did have to put smaller terminal ends on my wiring to fit on the small male barbs in the VSV. I also removed the housing and used the original VSV housing.
Mine:

smaller barbs required switching terminal ends:

 

[DieselFJ]

Even with a brand new FJ60 with everything working properly, disabling the EGR system will give an immediate impression of improved acceleration and power — for a little while.
The spark advance curve built into the distributor is calibrated to an EGR diluted fuel mixture. The charge burns slower when EGR is active which requires a more advanced spark. When the EGR is disabled, the fuel mixture burns much faster (and hotter) which will cause a normal new engine to ping under certain loads and RPMs.
What’s happening now though with 40 year old 2F engines is that the compression is much lower on an old engine which pretty counteracts the pre-ignition problem of disabling the EGR.

You’ve got to pay close attention to the engine when EGR is disabled. A sloppy workaround is to move the inner vacuum advance vacuum hose on the distributor to the outside actuator (which is normally used for HAC). Doing that will provide only 7° of vacuum advance instead of the normal 15° or so — which should prevent pinging.

This would be the same issue for those that desmog and remove the EGR without modifying the distributor, correct?

 

[OSS]

This would be the same issue for those that desmog and remove the EGR without modifying the distributor, correct?

Correct.
The proper way to do it is to have the distributor timing re-curved for non EGR use. By someone who knows how to do it.