3FE Discouraging tale (valves, oil galley, and knocking) (2 Viewers)

[TheWhitefox]

No worries. I'm booked in the city all week, so that's probably not going to work, but I do appreciate the offer.

Gotcha. Usually stay around the meadowlands stadium if we make it into the city ill let you know.

 

[jtmosca]

Does your engine have a knock sensor or equivalent sensor?

The reason why I ask... The past few days I have been fighting with mine on my 97. Obviously mine’s a different engine and guys far more knowledgeable then myself have already weighed in, but my symptoms were similar. At startup/idle it sounded fine and power appeared normal, but halfway down the block (or as the engine warmed up) the power would start to diminish rapidly. Apparently the bad sensor told my engine to retard the timing and go into “limp” mode to protect the engine from potentially “knocking”. With the pedal floored I could barely get up the hill to my house. Anyway, each time I restarted the engine when it was cold, the power appeared normal at first, but would quickly degrade as the engine warmed up. Replacing my knock sensor has fixed the issue.

Anyway, perhaps this info leads to something helpful. Wish I knew this engine better. Either way, good luck figuring this out.

 

[lt1fire]

No knock sensor on the 3FE

 

[TheWhitefox]

First thing I would do is check the EFI temp sender. Make sure it specs out. Second is I would find another ecu and give it a try.

3rd you have sludge in your motor. It's going to cause the black oil until it's all gone. Seafoam can help over a long period of time.


On the cats. Get a shop vac or leaf blower and put the tube on one side of the cat and fee your hand at the exhaust tip. Do both cats flow the same? If so is the flow fairly close to what the leaf blower or vacuum is reading? Could mean a cat is clogged or you have a restriction in the muffler. Have you tested the EGR? Also look at wire harness going through top of motor. Does moving it cause any issues?


Lastly what are your compression numbers?

Been awhile since I have posted/updated. Past year, moved to Myrtle Beach and sent the rig off for restoration (to a shop I thought I could trust). Basically gave them @Trollhole suggestions and a rundown of the issues. After 5 months I finally went by to check on it and a bunch of parts have been replaced but after a test drive the truck is no better than before. $500 for a new mass air sensor unit and still seems the 3fe is running in limp home mode. And the work I really wanted done to diagnosis and fix the engine problem haven't been done. Seems true expert knowledge of the FJ80 3fe is very hard to come by, and it baffles me what went so wrong with this motor with only 130k original miles. New O2 sensors, new mass air, new plugs, 2 valve adjustments and still knocking with 87 with absolutely no power. Can't seem to find the knowledge needed to repair it anywhere in NC/SC. At this point I'm debating on trying to drive it all the way to ACC garage in ATL for pure engine work. Any thoughts or suggestions? @GLTHFJ60 looking for a new project

 

[TheWhitefox]

Does your engine have a knock sensor or equivalent sensor?

The reason why I ask... The past few days I have been fighting with mine on my 97. Obviously mine’s a different engine and guys far more knowledgeable then myself have already weighed in, but my symptoms were similar. At startup/idle it sounded fine and power appeared normal, but halfway down the block (or as the engine warmed up) the power would start to diminish rapidly. Apparently the bad sensor told my engine to retard the timing and go into “limp” mode to protect the engine from potentially “knocking”. With the pedal floored I could barely get up the hill to my house. Anyway, each time I restarted the engine when it was cold, the power appeared normal at first, but would quickly degrade as the engine warmed up. Replacing my knock sensor has fixed the issue.

Anyway, perhaps this info leads to something helpful. Wish I knew this engine better. Either way, good luck figuring this out.

Even when my engine is cold I still get the "not enough power to get up a hill" syndrome. But sounds similar.

 

[lt1fire]

Could you post up a new check list of everything that has been checked and ruled out and another for everything that has been checked and or replaced.

 

[angerhater]

cracks on the accordion intake pipe ? or maybe a chafed wire.... maybe the ecu is going....

 

[TheWhitefox]

Could you post up a new check list of everything that has been checked and ruled out and another for everything that has been checked and or replaced.

Fixed and ruled out:
1 Exhaust leak repaired (custom cat back system)
2 Cats have good flow (previous owner put dual high flows) tested at time of exhaust repair
3 O2 sensors replaced by previous owner with non OEM, replaced with exhaust repair back to factory
4. Header has no leaks
5. Plugs replaced, old ones showed even and normal wear, were not very old
6. Distributor cap inspected
7. Valves adjusted (some too loose some too tight)
8. Valves readjusted less than 50 miles later by dealership, 3 found to be over tight
9. Mass air flow sensor unit replaced
10. Wiring to mass airflow inspected but not tested
11. Leaks in filler neck repaired, leak in gas tank repaired with replacement tank

Symptoms:
After both valve adjustments power gains were noticed that were more akin to engine swap, power gains lost the next day
Knocks with 87, not 93
Runs rich
8 mpg on highway at 65 with 93
Not enough power to sustain 40 up a hill with truck empty
Engine light came on after first valve adjustment 2 days later, codes lead dealership to mess with wiring harness going to tranny but nothing was ever found, nobody understood the codes

 

[mtweller]

Did you replace the EGR valve? If it got stuck open, it could cause that rich condition, thereby causing the ECU to try and lean things out and possibly go into limp mode. That's a cheap and easy sanity check I'd start with. I think it was recommended earlier, but I don't see it in your list above of actions taken. Conversely, if stuck closed, will cause the power loss and knock. It could be sticking open some and closed some even... Definitely worth the few bucks and few minutes if not done yet.





Recirculation Fail
If the valve is stuck open, exhaust air will flow into the intake before the engine needs it, causing a rough idle, poor acceleration and poor performance overall. The extra air will give you a lean mixture in the chamber, and without the proper ratios of atmospheric oxygen, the combustion stroke will carry less power. Stuck-closed valves won’t prevent the creation of NOx, so the engine will heat to dangerous levels, leave a lot of unburned fuel in the exhaust (you’ll probably notice a strong gas smell) and significantly reduce fuel efficiency. As temperatures reach the point of untimed detonation, you may experience engine knock. Open or closed, your system should notice something is up and alert you via the “Check Engine” light on your dash.

 

[mtweller]

Also, quick search on the 3FE shows there's a EGR modulator as well, that has a cotton filter that can get clogged. Advice: troubleshoot the entire EGR system and replace anything that is a wear item, including vacuum hoses.

 

[GLTHFJ60]

Or eliminate the EGR system entirely.

 

[mtweller]

Or eliminate the EGR system entirely.

Will he have problems passing NC inspections though? If not, that's probably easiest (granted I don't know if the ECU would be unhappy).

 

[GLTHFJ60]

Depends on the county in NC, but in SC (myrtle beach) it doesn't matter at all

 

[TheWhitefox]

Will he have problems passing NC inspections though? If not, that's probably easiest (granted I don't know if the ECU would be unhappy).

SC truck from here on out thus no concerns with inspections. Yet I've discussed removing EGR system and everyone seems to have concerns with 1 how the ECU will react and 2 that the gains would be small compared to either my time spent or money spent at the shop.

But making sure that valve and modulator are working properly is something I've yet to look into, excellent advice. Thanks gents!

 

[GLTHFJ60]

@DeeRex how did your ECU react when you did your desmog? No issues?

IIRC, there is a resistor hack you can do, similar to the 80s, that fools the ECU to thinking that the EGR is working properly, but it's been a long while.

Perhaps @jonheld has a few moments to provide thoughts on the points in post #48?

 

[lt1fire]

Just take the EGR out entirely if it is suspect at all.
Wont really give you a hp increase but it will run smoother and leave off another thing you wont have to worry about.
It didnt affect the ecu on mine at all. Cleans up the engine bay quite a bit also.

I think I got a small bump in mpg but it was so small that it would really be hard to accurately gauge but it did seem the light came on 10 miles later every time...

Also, quick search on the 3FE shows there's a EGR modulator as well, that has a cotton filter that can get clogged. Advice: troubleshoot the entire EGR system and replace anything that is a wear item, including vacuum hoses.

SC truck from here on out thus no concerns with inspections. Yet I've discussed removing EGR system and everyone seems to have concerns with 1 how the ECU will react and 2 that the gains would be small compared to either my time spent or money spent at the shop.

But making sure that valve and modulator are working properly is something I've yet to look into, excellent advice. Thanks gents!

@DeeRex how did your ECU react when you did your desmog? No issues?

IIRC, there is a resistor hack you can do, similar to the 80s, that fools the ECU to thinking that the EGR is working properly, but it's been a long while.

Perhaps @jonheld has a few moments to provide thoughts on the points in post #48?

 

[jonheld]

You mentioned that the ECU was throwing codes that a dealer couldn't diagnose. What were the codes?
For the record, the A440F transmission is not electronically controlled. It is a hydraulic unit.
The 3FE has an AFM (air flow meter) not a MAF.

The valves were adjusted and it ran well, then it didn't. This screams vacuum leaks to me. I'd be willing to bet that unmetered air is getting in somewhere.
The top end of the 3FE wants to be air tight. Leaks can develop from the valve cover gasket, valve cover grommets, side cover gasket, oil fill cap gasket, oil dipstick gasket, PCV valve grommet. All must be air tight.
Any crack/tear or loose clamp on the intake plenum will cause all sorts of issues.

It's a tractor motor from 1986. Always look for the simple things first.

 

[angerhater]

take the time you are spending on this and invest it in planning a 2uz swap... more power, more mileage, many more donor vehicles available. there is likely a good reason the 3fe was forgotten.

 

[TheWhitefox]

take the time you are spending on this and invest it in planning a 2uz swap... more power, more mileage, many more donor vehicles available. there is likely a good reason the 3fe was forgotten.

3fe is excellent with a manual tran and pt. time 4wd. I'd rather tranny and transfer case swap than swap a practical brand new 3fe. That said 2uz would be an excellent option.

Update. Finally got some answers out of the shop who is working the restoration. Vacuum system tested with no issues, going to double-check EGR valve but leaning towards taking a look to see if the valves are not staying in place after adjustment. Seems this would be logical since I had excellent performance after each adjustment so far. Thanks for help, couldn't resurrect this ol rig without this place!

 

[TheWhitefox]

Just take the EGR out entirely if it is suspect at all.
Wont really give you a hp increase but it will run smoother and leave off another thing you wont have to worry about.
It didnt affect the ecu on mine at all. Cleans up the engine bay quite a bit also.

I think I got a small bump in mpg but it was so small that it would really be hard to accurately gauge but it did seem the light came on 10 miles later every time...

Now that I'm in SC I think that is something I'm going to try myself. Seems like a good project in the garage.