FIXED!!! Bad ECU - Runs rough, CEL and P0304 (1 Viewer)

[Jeff Elliott]

Hi All -

New to the 80 Series (always wanted one, finally got one!) but not new to Land Cruisers. My new to me FJ80 was delivered today from CA and I bought it from a fellow Mud member here: For Sale - 1997 FZJ80, Only 89k Lifted, King Shocks, 35's, ARB...etc

After a PPI at a shop of my choosing, I got the "all clear" and had the shipper pick her up. He had to unload her to accommodate another vehicle and thereafter she wouldn't start. Got another shipper with a winch to pick her up and got her today. After some reading here, I was prepared with EFI relays and fusable links in hand. I'm pleased to say I had her running in about 20 min after installing a new fusable link!

Now for the bad news - she runs like crap... I mean like she was converted to to a 4BT at idle. And she idles low... like 450 RPMs. I initially didn't have a CEL but now I do. Luckily, the PO had left a gauge with a scanner in there and I read the codes - only one, a P0304 (cylinder 4 misfire I believe). I'd appreciate any advice on how to deal with that little gem and get this girl running smooth (and hopefully no more gremlins).

And now to the pics and videos!

 

[Red Merle]

I don't hear it in the motor. This is what mine sounded like after a full top end job and having most of the parts I pulled off to do it replaced with new. I think it sounds about the same as yours.

 

[Red Merle]

Are you having any vacuum leaks? I can hear the low idle in the exhaust. It doesn't sound like it is missing or stumbling though.

 

[Jeff Elliott]

Are you having any vacuum leaks? I can hear the low idle in the exhaust. It doesn't sound like it is missing or stumbling though.

Thanks for the quick reply! Maybe this video will help. The rattling you hear is only under load and it will shake your teeth out... it smooths out completely when the load is removed. Note how violently the side view mirror shakes at 14 seconds... goes away when I lift off the accelerator.

 

[Red Merle]

And it's for sure coming from the motor? Could it be something loose in the suspension? Have you checked the nuts on the trunion beraings and steering control arms on the birfield knuckles?

 

[inkpot]

I would clear the code and then run it for a while to see if it pops up with the 304 again. Guessing that it will. If it feels like a constant miss then most likely isolated to #4 cylinder. Check cheap and easy first. Plug, plug wire, dizzy tower #4. If they test out ok, try compression test on #4. If ok then try to listen to #4 injector. It should click just like the rest of them. You can also try wiggling the harness in several places between the heater valve and #4 to see if that makes any change. Hopefully it is something simple.

 

[Malleus]

The next first thing to is get a copy of the FSM. This will get you started:

Unfortunately, this is only the tip of the iceberg here. These flowcharts assume that everything else is fine. I wouldn't make that assumption, given that you (I) don't know very much about this engine. The first place to start is to check the ignition system and make sure all the parts work properly. Any that don't need to be replaced. This is what most people do to baseline the engine, but you can spend a lot of money for extremely little return on your investment. FWIW, as a for instance, I always replace plug wires when I buy a truck, but I check them and I have never seen a set of OEM plug wires out of spec.

 

[Malleus]

Here are the ignition, fuel and miscellaneous specs:

 

[Malleus]

Check the ignition specs first (you'll need a multimeter), they're the easiest to confirm. Next go to the fuel system and finally set the ignition timing and idle speed.

If that doesn't get you where you need to be, you have other problems. The most important thing is not to skip around, throwing parts at the problem. You'll get as many opinions on how to proceed as posts. This isn't the only way to find and solve your problem. You need to develop (or use) a solid, systematic plan and stick to it.

 

[Trapper50cal]

Was this truck's origin at a much lower elevation? How many times have
you started it and turned it off?

The reason I ask is that I had an fzj80 shipped from Arkansas to ABQ, NM
and at first it ran rough. The computer had to "re-learn/adjust" to the new
altitude.

It ran as you described until it figured everything out.

I'm not familiar with Denver, North Carolina and it looks like
it was a CA purchase so probably not the problem but it may
be if it was started somewhere high altitude during the trip.

 

[Jeff Elliott]

Thanks to all thus far. @Malleus I agree with your view on "we don't know very much about this engine" and that I should take a systematic approach. Following that logic, I have to wonder if the fact pattern would perhaps help narrow the search a bit (recognizing that it could still be anything listed in the FSM). Here's the chronology - maybe it might help you guys might suggest the first place to look?

• Truck has only 89K miles
• PO asserts that it ran well, then developed a stumble at WOT that went away post WOT. PO replaced ECU trying to fix. PO also suggests recent plug, wire, rotor, cap replacement
• I had it PPI'ed at a shop of my choosing who seemed very familiar with these rigs based on their report back. Got a mostly "green light" to buy it (hang ups were leaky valve cover gasket and mixed coolant)
• Rig ran fine on test drive and PPI shop could not replicate stumble
• Shipper picks up the truck where it initially runs fine, then wouldn't start
• I get truck started with a simple change of the fusable links
• Truck runs like crap from first start up - idles like a diesel

No time or ability to trouble shoot tonight - I will crank it up tomorrow, check the ignition system first (#4 plug, wire, etc.) per FSM. After that, I will go through the FSM flow unless someone suggests the next logical place to look given the circumstances.

Again, thanks a ton - this is an incredibly disappointing start to my FJ80 ownership journey so hoping it's as simple as the fusable link!

 

[Jeff Elliott]

Was this truck's origin at a much lower elevation? How many times have
you started it and turned it off?

The reason I ask is that I had an fzj80 shipped from Arkansas to ABQ, NM
and at first it ran rough. The computer had to "re-learn/adjust" to the new
altitude.

Wow, that would be a great problem to have! Given very little elevation difference, I'm guessing i'm out of luck though... Denver NC is 900' above sea level and this rig came from LA which is 300'

 

[JohnVee]

......Again, thanks a ton - this is an incredibly disappointing start to my FJ80 ownership journey so hoping it's as simple as the fusable link!

Nice truck to join your 40, Jeff. We'll be happy to see either when you can finally make an ONSC meeting.

Incredibly sarcastic but tongue in cheek noob-alert middle finger comment: See if it runs better when you call it an FZJ80!

 

[Jeff Elliott]

Thanks @JohnVee - noted for future posting!

I'm anxious to attend a meet up and thought I'd be driving my FZJ80 for my first event and maybe still will... I'm gaining confidence in the FJ40 since rebuilding the front axle and getting rid of the death wobble so maybe I'll bring her. Hopefully see you soon!

 

[Malleus]

Thanks to all thus far. @Malleus I agree with your view on "we don't know very much about this engine" and that I should take a systematic approach. Following that logic, I have to wonder if the fact pattern would perhaps help narrow the search a bit (recognizing that it could still be anything listed in the FSM). Here's the chronology - maybe it might help you guys might suggest the first place to look?

• Truck has only 89K miles
• PO asserts that it ran well, then developed a stumble at WOT that went away post WOT. PO replaced ECU trying to fix. PO also suggests recent plug, wire, rotor, cap replacement
• I had it PPI'ed at a shop of my choosing who seemed very familiar with these rigs based on their report back. Got a mostly "green light" to buy it (hang ups were leaky valve cover gasket and mixed coolant)
• Rig ran fine on test drive and PPI shop could not replicate stumble
• Shipper picks up the truck where it initially runs fine, then wouldn't start
• I get truck started with a simple change of the fusable links
• Truck runs like crap from first start up - idles like a diesel

No time or ability to trouble shoot tonight - I will crank it up tomorrow, check the ignition system first (#4 plug, wire, etc.) per FSM. After that, I will go through the FSM flow unless someone suggests the next logical place to look given the circumstances.

Again, thanks a ton - this is an incredibly disappointing start to my FJ80 ownership journey so hoping it's as simple as the fusable link!

I'm leaning towards an electrical problem, based solely on your description. If you follow the steps I suggested, I think you'll find the problem.

I should also have mentioned that before you start, it's a good idea to thoroughly photograph the entire engine bay (you won't get a chance later, it'll look different); even if you don't think something's related now, do it anyway. Then, with the engine running, pick up the wiring wherever you can, barehanded. Try to move it a little and see if that has any effect. I'm not talking about shaking it like a rag doll, just moving it around a little. If there's a short/open, this may expose it.

 

[Jeff Elliott]

Well, a bit of progress... Had only about 10 min to look at it last night. I started it up and moved the wire bundle above and behind the valve cover - this sent a small spark or two and shut down the engine. I was able to restart the truck though the idle problem remains. From this I suppose we can conclude that I definitely have electrical issues though we can't say that's the misfire issue.

Are the electrical issues independent of mileage? Maybe a function of being 20 years old and living in SoCal heat all that time?

 

[inkpot]

It is a well known problem for the 1fz setup. The heat from the EGR pipe fries the main wiring harness where it comes off of the firewall and heads out around the intake manifold. Kind of awkward to gain access, but some of us have had good results from doing surgery on individual wires in the harness to resolve problems without replacing the entire harness, but that is certainly an option.

 

[Jeff Elliott]

Thanks @inkpot ! A quick google says a new harness is ~$450 or so for OEM and ~$300 for aftermarket. How difficult is the install beyond the obvious (e.g. pulling the old, chasing through firewall, etc.)? Do you need to pull parts off the engine (to get to the injectors for example)? Pull the dash?

 

[Jeff Elliott]

More progress... I have the ECU down - PO said he changed it and in fact he did. It's from a '96 so I guess that works for a '97?

Checked plugs and can't tell much difference... Here are pics of #4, #5 and #3 in that order - how do they look to you??? Keep in mind, the misfire code was on #4:

#4

#5

#3

 

[Jeff Elliott]

It also seems low on coolant - I checked it with a cold engine there's no water in the reservoir and I don't see any at the top of the radiator... Suggestions?