Odd case of Rough Idling and Misfires on my 96 FZJ80

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Miilkman said:
Yeah I felt like they were trying to hustle me out of money. I cant imagine my car running perfectly fine under load with these issue, but i'm going to see if replacing these with newer OEM parts directly from Toyota will help.
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Purely to satisfy my curiosity, may I ask where you bought the old "new OEM" wires? Maybe I've just been lucky, but I rarely buy parts from Toyota directly, unless I need something immediately, and I can't ever remember having a problem with an authentic Toyota part.
 
I know nobody believes me and its all in my head, (since the fuel filter for 1fz is a lifetime item) :rofl: 👌 :flipoff2: but after replacing my fuel filter my 1fz-fe @354,000 engine runs very smooth and actually has pickup, kick down is working, acceleration is much improved. I did also replace the battery to engine block ground cable on the same day . A few months prior I replaced the fuel pressure regulator and full tune up. I'm in the Bay Area also
 
Malleus said:
Purely to satisfy my curiosity, may I ask where you bought the old "new OEM" wires? Maybe I've just been lucky, but I rarely buy parts from Toyota directly, unless I need something immediately, and I can't ever remember having a problem with an authentic Toyota part.
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I bought my "old" spark plugs on ebay from the Bell Lexus shop on ebay(Security Measure - https://www.ebay.com/str/belllexusnorthscottsdale) and the OEM spark plug wires on Amazon(Amazon product ASIN B00KTJQS1C). Im buying the newer parts directly from Toyota this time
 
calokie said:
I know nobody believes me and its all in my head, (since the fuel filter for 1fz is a lifetime item) :rofl: 👌 :flipoff2: but after replacing my fuel filter my 1fz-fe @354,000 engine runs very smooth and actually has pickup, kick down is working, acceleration is much improved. I did also replace the battery to engine block ground cable on the same day . A few months prior I replaced the fuel pressure regulator and full tune up. I'm in the Bay Area also
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calokie said:
I know nobody believes me and its all in my head, (since the fuel filter for 1fz is a lifetime item) :rofl: 👌 :flipoff2: but after replacing my fuel filter my 1fz-fe @354,000 engine runs very smooth and actually has pickup, kick down is working, acceleration is much improved. I did also replace the battery to engine block ground cable on the same day . A few months prior I replaced the fuel pressure regulator and full tune up. I'm in the Bay Area also
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I hadn’t thought about the battery, but I did notice that my battery cable terminals are really messed up… negative terminal is loosely on so it has me thinking. I’ll look into those.

CA35544A-DD3D-4C2A-89D7-8D90A63EB2F8.webp
 
Miilkman said:
I hadn’t thought about the battery, but I did notice that my battery cable terminals are really messed up… negative terminal is loosely on so it has me thinking. I’ll look into those.

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Fuel filter and pressure regulator easy maintenance items that need replacing regardless
 
FMC80 said:
Based on the issues you both describe, I’d look at the engine harness nearest the #6 area and inspect for any discrepancies there.
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This means cutting open the heat wrapping on it right? I don't see any exposed wiring on it, but i'll give it go... I know nothing about handling electrical issues, but i'll give it a try
 
Mine did the same thing, but mainly only cut out at low idle when the A/C kicked on. While I've had success in the past with Seafoam in the intake and in the fuel tank on other vehicles I saw some tests and decided to try this:
Berryman B-12 Chemtool

Normal use in the fuel tank is 1oz per gallon (per the label), supposedly someone looked up the "Service Shop procedure" and found they recommend 2oz per gallon for better cleaning. Autozone had it on sale, I added 2 of the 21oz cans to a 3/8 tank of fuel, I drove it around for a few days (less than 30 miles) , then filled it with fuel. It hasn't cut out at low idle since.
Maybe it cleaned the fuel injector tips for a better spray pattern, I'm not sure, but at least when using it in the fuel tank, it seems to have worked better than Seafoam.
 
My 94fzj80 developed a rough low idle out of the blue I was also having trouble with my battery interstate battery was almost 2 years old was dying thought maybe a parasite drain or alternator going to s***. Also noticed when starting cold it didn't have a high idle just straight to 1000 rpm then dropped down to low and rough idle. Went to my buddy automotive shop where I got the battery he had some fancy battery tester battery had high ohm so we switched battery out for new one that had 4ohm new. Now no low idle cold start has normal high idle then drops down slowly then to normal idle. Fixed both problems.
Tommy
 
Miilkman said:
Hey, not yet... I brought it into a local shop that reputable in land cruisers(A+ Japanese Auto Repair) the other day and they said that my spark plug and spark plug wires are worn... He said the spark plug ceramics were spinning and the spark plug wires were arcing. I was pretty surprised hearing this cause i just had these replaced with OEM parts 2ish months ago. I'm going to go get new parts and see if that fixes the issue.

I also found that my uncle who owned this prior, had the back O2 sensor welded on for some ******* reason... The voltage on that o2 sensor was everywhere--ranging from 0.01-.9 which doesn't sound right to me. So after I replace the spark plug and spark plug wires again, I am going to tackle this o2 sensor issue, and if that doesn't work, I am going to replace my distributor--which was recommended by Georg.
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Genuine OEM wires will have the date manufactured printed on the wires.

A properly functioning O2 sensor will have a continuously oscillating voltage output somewhere in the 0-1V range
 
Miilkman said:
This means cutting open the heat wrapping on it right? I don't see any exposed wiring on it, but i'll give it go... I know nothing about handling electrical issues, but i'll give it a try
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Yep. There often isn’t any exposed wiring or any obvious visual cues until you open up the wire bundle and see what’s going on under there. Insulation breaks down over time, it cracks, separates, shifts, and potentially shorts.

Even if there is nothing there, it wouldn’t hurt for you to perform a visual inspection and tidy up the wire bundle while you’re there if it hasn’t been done recently.
 
Some new updates: I ended up getting new OEM spark plugs and spark plug wires into my truck, but it didn't really help that much. I ended up doing a compression test and my results were:
1: 190
2: 190
3: 185
4: 170
5: 195
6: 190
I know the max variance is around 15 psi or something. Since my cylinder 4 is out that range by a small margin, is it worth doing a leak down test to check?
 
Miilkman said:
Some new updates: I ended up getting new OEM spark plugs and spark plug wires into my truck, but it didn't really help that much. I ended up doing a compression test and my results were:
1: 190
2: 190
3: 185
4: 170
5: 195
6: 190
I know the max variance is around 15 psi or something. Since my cylinder 4 is out that range, is it worth doing a leak down test to check?
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I would
 
You need to monitor data and baseline where you're at.

Here are the specs on a recently rebuilt Engine:

2023-05-12_16-39-56.webp


I doubt you have that exact tool, but those data pids are all "Federally mandated" data pids available from nearly any basic scan tool on ALL OBD 2 vehicles.
  1. First step is to perform a VE calculation -
  2. Next you need to know your fuel pressure and volume.
  3. Then you need to perform a smoke test and check for other vacuum leaks.

You may end up having to:
  • Perform a leak down test
  • Check injector spray patterns (fuel trims alone would help point you in this direction)
 
So I had the leak down test performed.

The mechanic said, they heard air escaping from the crankcase. They added some oil to the #4 Cylinder and now the Compression is now at 177 psi from its original test of 170...

They basically said that its an internal issue(long block) and that the rings are worn, and would recommend an engine replacement if I want to fix it. What are y'all thoughts on this? This is out my level of expertise so I'm not sure where to proceed
 
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**edited, thought was another thread**

You're in a very tough place now.

170 to 177 psi really means nothing.

What's the variation in each cylinder from the leak down test? Those are the real results of a leak down test, not compression.
 
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