This last fall we swapped out my 1986 22RET and installed a 1996 3RZ, we also installed an Off-Road Solutions Monster Harness and have replaced these components, Ignitor, Clutch Plate, Throw out bearing, Slave Cylinder, Starter, Spark plugs, Spark Plug wires, Distributor, K&N Filter charger, MAF, Intake Manifold Temp Sensor or External Air Temperature sensor, Oil Pan conversion, Knock Sensor, Water pump, Thermostat with gasket, Tensioner, Belts, Radiator Hoses, Crankshaft Position Sensor, Vehicle Speed sensor Marlin, New headers, 02 Sensors x 2, Exhaust minus cat, Alternator, Power Steering Pump Trail Gear,Bell Housing and have Deleted all smog. It ran fine in my neighborhood after installation.

While at King of the Hammers Everyman Challenge 2021 the engine ran fine while testing prior to the race. During qualifying, the engine started to run rough and then died, we were pulled off the course and back to the pits. We replaced all the fuel components as we felt this was a fuel issue and the night before the race, we had it running again. On the day of the race, the green flag dropped, first gear was fine, second gear was fine, and third gear is where if fell on its face and bogged down. Since then, the engine starts up fine, idles fine and revs fine. Once we put the engine under load, i.e. third gear it severely bogs down, backfires, and doesn’t want to get into higher RPM’s unless you feather the gas pedal. If you have to ask, no, I didn’t finish the race, I barely made it to the first jump before it died.

So, since King of the Hammers Everyman Challenge, this is what I have replaced or installed. Holly Hydr-omat, New fuel hose, Fuel filter, Fuel pump, Engine fuel filter, Injectors, Fuel Pressure Regulator with gauge LCE, New fuel return fuel line, Cleaned Intake and throttle body, Intake gaskets, Idle Air Control Valve, Throttle body gasket, TPS.

After all this, the engine starts easily, revs nicely, first gear runs smooth until you mash the skinny pedal and it bogs down. I have read many forums and they say it’s the MAF, Stuck Valve, Catalytic converter in which I don’t have, etc. Also heard that the speed sensor that installs into the transfer case can cause issues. I am at wits end.

Help,

Joe

 

You certainly haven't been shy with the parts cannon.

It sounds like a fuel supply issue to me, since the motor seemingly makes good power in 1st, 2nd.

First off - I'd look into checking the fuel pressure somehow. See if that's diving down when this happens. I see you mention a gauge on the FPR, but is it where you can see it in motion?

It's hard to diagnose from afar, so I'll just toss out some random thoughts.

I have an old antique car that I restored after it sat in an open sided carport for 17 years. I got it running just fine with a minimal amount of new parts (old Volvo's are tough), but for a long while it would run *perfectly* around town on normal streets, but whenever I got it out on the highway and tried some sustained faster driving, it would bog and die, I'd coast to the side of the road, and it wouldn't restart. I'd try to diagnose it for a few minutes, then it would restart without me finding anything, and continue on like nothing happened. One time while it was dead on the road shoulder I noticed the fuel filter was dry. Opened the gas cap and *WHOOOOSH* a whole bunch of air went *INTO* the tank. Turns out that it was an old style non-vented gas tank system that relied on a vented gas cap, and the previous owner had installed the wrong kind of non-vented cap. So under sustained higher power output, the gas would drain from the tank fast enough to create a slight vacuum, and it doesn't take much at all before the pump can't pull gas. And when it died, slight leaks in the system would gradually repressurize it again.

Another thought is I see a K&N filter and a MAF in your list. I've had a couple of bad experiences with those on my 5VZ engine. When I first got it, the CEL kept popping on, it was sluggish in transitions *(moving the throttle quickly). It cost the seller a few hundred bucks as a negotiating point. Ended up being a somewhat over-enthusiastically oiled K&N filter. It was feeding some fine oil droplets into the MAF, which has a hot wire hanging out in the breeze. The oil would hit it, carbonize, and after a bit it had built up an insulating 'coat' of burnt oil that slowed it's reactions to changing air flows. Not quite the same thing as your symptoms.

It sounds like ti still has a stock ECU on it, does it have the OBD2 port? Even if the codes might not be great, you could still plug into it and get some live readings, see what the ECU thinks is happening when the motor is bogging.

 

Thanks for taking the time to read my post and posting your thoughts. Parts cannon, that makes me laugh but the wife won't find it very funny.
Regarding fuel pump:
I run one Walboro external fuel pump and have swapped it out with my 2 backup Walboro and it hasn't changed the symptoms. The pump running it right now is the brand new one.
I also run a Jaz 32 gallon fuel cell with a vented roll over valve plus my out fuel line and my in fuel line. All of these are cleared of obstruction.
K&N filter is very lightly oiled and no debris or oil inside the MAF. MAF in new from NAPA. But we are still considering this as a possible problem
It does have a stock ECU provided with the Off Road Solutions Monster Harness. The only issue I might see with the ECU is it is a 1996 ECU for my 1996 engine but its for a automatic, my truck is a manual, I am still wondering if the Vehicle speed sensor that I purchased form Marlin might be the culprit.
On that note, a pit crew near us had the same year conversion and he let me plug his ECU into my engine, it didn't change the symptoms. My ECU in his truck and his truck ran fine.
My buddy who is a mechanic is bring his fancy Snap On computer up to the house and we will plug it into the OBD2 connection and see what we can come up with.
Thanks agian.

 

Follow up:
My mechanic plugged his Snap-On computer into the OBD2 Port and we could not find any codes. We pulled the distributor out and retarded the timing by one tooth, the truck ran but then threw the knock sensor code. We then advanced the distributor by one tooth and the engine ran, did not throw a code but the engine light came on. Put it back to TDC and replaced the distributor where it should be. Per his computer, all systems/sensors are working and within normal limits.
Things I have done since:
Replaced the Advanced Auto plug wires and plugs with NGK and properly gapped the plugs.
Removed the in-line fuel filter between the fuel cell and the pump, the pump sounds happier. Still have the filter at the engine, which has been replaced.
Replaced the Speed sensor from Marlin Crawler
Status:
No change, still bogs down under load.
Is there a possibility that my headers and by not having a catalytic converter is not allowing enough back pressure?
Tell me what you think.
Thanks,
Joe

 

Back pressure can certainly cause a bod, jam something in the exhaust pipe and find out!

Does the snap-on read live data? What's it saying when it bogs? Not codes, but anything else showing up as strange?

Can you see the fuel pressure gauge while driving?

 

"Look, man, I ain't fallin' for no banana in my tailpipe!" Ha!
We had the Snap-on running but we did not get it to show what happened when it bogged down.
I will attach a GoPro in the engine compartment and check out the fuel pressure while driving this weekend.
I thought that I had replaced every sensor but I found one I missed, the Engine coolant temp sensor that is found on the back of the engine. The Snap-on read that this sensor was working but we did not look into it deeper and to find out that this could be the culprit somewhat excites me that I found the issue. Not going to get my hopes up.
I will update this weekend.

 

The CLT/ECT/whatever sensor probably wouldn't cause this big of a problem even if it was unplugged. How does it run after it starts bogging and you back off the throttle? It sounds like it like it doesn't recover immediately.

Is it entirely throttle-dependent? Does it do the same thing if you wind-out third gear at lower throttle?

Getting a live data stream out of the Snap-On during the problem would be a godsend in cases like this, although seeing what the fuel pressure does while driving is probably the next logical step. I don't expect it to be the problem though.

That sounds very strange to me. Under normal circumstances the CEL only comes on because a fault was detected and a code was tripped and stored. Really, if something is causing such poor running that the ECU can't compensate, it should throw a code eventually.

No, absolutely not. Engines don't need backpressure of any kind because backpressure is restriction and restriction is bad.

 

It's possibly wired up wrong so the ECU loses power when the key is off, so it wipes out codes? Unless you tried checking for codes without turning it off, while the CEL was still on?

 

The night before KOH EMC, we did have an issue where the engine ran fine at idle, put it in the desert and it ran kinda fine until you really get on the gas, 2nd gear, 3rd gear and it would bog down to a very low idle, back fire and then die. We would then tow it back to the garage and it would not start at all for about an hour. After that, we did it all over again with the same exact symptoms and not starting. A nearby team brought his Toyota with the same engine conversion, 1996 3rz and we swapped out the ECU. My ECU worked fine in his truck and my truck still acted the same with his. The ECU issue of not storing a code might be due to the kill switch. Turn the kill switch off and the engine dies. I will have to look at the wiring and see where my hot wire to the ECU is on the kill switch.
Since my last post, I have not been able to reproduce the backfiring and having the engine completely die, but it still has a bogging issue once it gets warmed up to operating temp. I am able to play with the throttle, meaning let off and then back on throttle but still get the bogging.
My fuel pressure is running around 48 via the LCE Fuel pressure regulator gauge. I did pull the valve cover off to replace the fluid temp sensor and all of the valves and head look okay, from what I see. I also noticed that when I removed the valve cover, the bolts were no near where they should be for torque settings. I retorqued them after replacing the gasket. It runs great at idle and revving but still has the bogging issue.

 

Also, no key. Master switch, push button start and race tech kill switch installed.

 

That makes me think it's something to do with the ignition and perhaps heat-related.

 

Ultra4 tech states that a kill switch has to be installed in your vehicle and it has to be able to kill the engine completely when turned to the off position. My kill switch does this. So, I have been in the habit of turning the kill switch off every time that I turn the motor off. Ignition off then the kill switch. After some research, I found that I have been resetting the ECU every time I do this. Over the last 2 weeks, I have left the kill switch in the on position, ran the truck and have possibly put 20 miles on it, can't do more miles due to Nextdoor complaints in the neighborhood. I have seen increased performance and no hesitation or bogging. I am hoping that I figured out the problem.

 

The ECU does "learn" over time. Keeping the keep-alive voltage to it will definitely make a difference in the way the truck runs. The ECU learns the current temperature range, AF and O2 sensor outputs, and so forth, to tune the way it runs the engine to peak the performance.

Good luck to ya!
Pat☺

 

I suppose that could be the issue if you have engine mods that max-out the ECU's trim authority, but there again, resetting the volatile memory wouldn't cause good running, then a failure to recover from bad running under load leading to engine stall followed by a time-dependent failure to restart.

 

I still have not had a chance to get it out and put some miles on it but the ECU is now holding codes, was not before. The codes that are showing are the emissions stuff that I have removed and I can now delete these codes when they show up. It never held a code before this.
Taking it out to IMI this weekend and hopefully putting 50 plus miles on it, wish me luck!
Just letting you know how its going.

 

UPDATE: We put many miles on her and she is running better than ever! No stalling, no bogging and she starts up every time without issue. Per the scanner, all systems are running within normal limits and I can clear all of the smog delete related codes when they appear.
JMach1

 

Glad you seem to have it fixed. I wager that now, it's good to go!

So, take it out and go! These trucks love to be driven, on AND off road. Give it what it wants, and it will treat you well

Pat☺

 

We have been running the truck without killing the ECU and it keeps getting better every time I drive it. Wish us Luck! Heading to Sturgis next week for the Ultra4 Black Hills Throw down! Gonna run the hell out of it! If you are watching the race, my truck # is 4599.
Joe

 

Go truck, go!
Wishing you all the best.
Pat☺

 

Glad you got it figured out!!

I was curious do you have just a bare pick up in the fuel tank?

I had one sometime back where the owner went to an external pump but was drawing through the old pump the sock on the pump was so full of dirt the fact it started was amazing this had issues some what like yours.