Intermittent Starting, Rough Idle, Fuel Smell, White Smoke – 1998 80 Series 1FZ-FE

[reecef10]

Hey all,

Hoping someone can help me troubleshoot some ongoing issues with my 1998 Toyota Land Cruiser 80 Series (Aussie spec) running the 4.5L 1FZ-FE petrol engine. It’s mostly stock. And apologies I’m pretty amateur at all this and by no means a mechanic but hopefully save a few bucks.

Here’s what I’m experiencing:
Symptoms:

Intermittent starting – sometimes cranks for a long time, usually if I key out and crank after a long crank it fires straight away.

Turns over better when engine cold.

Rough idle when it does start, occasional. Maybe a slight misfire.

white smoke from exhaust but smells more fuel than sweet. And goes after 3/4km

Strong fuel smell, constantly.

Oil pressure light flickers intermittently but I believe this is a separate switch issue.

What I’ve Done So Far:

Replaced the fuel pump
Replaced the fuel pressure regulator
Installed a new battery
New sparks
New MAF
New coolant temp sensor

Despite those, the issues persist.

Possible Leads I’m Wondering About:

• Leaky injectors?
• Ignition coil or sensor issue?
• Small vapour locking?
• Blown head gasket, unlikely I think.

Any other key culprits you can think of?

Thanks in advance!

 

[LongDuck]

Is Fuel Filter on your list anywhere? There's one near the Upper Intake Manifold that is often missed. When Fuel Filters clog up, they can lead to poor flow resulting in lean ignition, intermittent fuel flow (*which changes when driven as the sediment moves around), and could significantly impede the fuel circuit resulting in fuel leaks ahead of the filter.

 

[reecef10]

Is Fuel Filter on your list anywhere? There's one near the Upper Intake Manifold that is often missed. When Fuel Filters clog up, they can lead to poor flow resulting in lean ignition, intermittent fuel flow (*which changes when driven as the sediment moves around), and could significantly impede the fuel circuit resulting in fuel leaks ahead of the filter.

I’ll look into this thank you

 

[landtank]

Engine harness with short to ground. Pull the plugs and compare them to each other. One is likely wet.

 

[reecef10]

Engine harness with short to ground. Pull the plugs and compare them to each other. One is likely wet.

Hi mate, bit confused by this? What do you mean? Sorry I’m a novice at best, I can do sparks and a service ahaha

 

[Malleus]

I'd look at the Idle Air Control Valve. If it's stuck in the fully retracted position when the engine is warm, it's letting air bypass the throttle body and the plenum is too lean. This causes the ECM to dump more fuel and results in exhausting fuel on startup. I'd bet on this as you say you have no problems sarting when cold, which is when the IAC is suppose dot be retracted.

There is a bypass galley in the throttle body which is open when the engine is cold (and the throttle butterfly valve is closed). The IAC is an electronic choke control; it lets metered air into the plenum when the throttle butterfly is closed. It's supposed to be fully extended, to close off the bypass galley, when teh engine is warm, so that only the butterfly can meter air into the plenum. This, in concert with the VAF and oxygen sensors, is what determines how much fuel goes into the combustion chamber. If the IAC isn't communicating its position to the ECM correctly, the ECM doesn't know how much fuel to mix with the incoming air.


There are two procedures for confirming correct operation, both are explained in the service manual. I would think you could use the US 1997 version; it's in the Resources forum, 80 series section.

It could also be a shorted fuel injector lead, as @landtank suggested above. If that's the case, you'll see and smell gasoline on the spark plug tip when you remove it. On US models, the typical problem is the EGR valve gets hot and burns the insulation on the number 6 wire, shorting it to ground. You have to unwrap the wire harness (from the injector end) to see this. The common solution here is to rewrap the harness under the EGR valve with heat protective tape. Not a big deal, but a little tedious.

 

[Malleus]

That's a very clean truck, BTW. I'd give real money for those headlights.

 

[Malleus]

Here's what the IAC circuit looks like:

You may, or may not, get a DTC. I never have on any failed IAC I've replaced.

 

[reecef10]

That's a very clean truck, BTW. I'd give real money for those headlights.

Hi mate,

All your replies was super helpful, I’ve had the IAVC off and cleaned it but didn’t test with multimeter etc, it’s old so might just replace anyway for peace of mind. Do you happen to know part number?

The truck is super clean, thanks! The inside is like it rolled off the line 2 weeks ago not 27yrs!

 

[Malleus]

IAC is 22270-66011 and the O-ring is 90079-60004. If you need new screws, I usually have to replace at least the lower one, they are 90079-11022.

Make sure you're sitting down when you look up the valve price.

 

[petegangies]

Hey all,

Hoping someone can help me troubleshoot some ongoing issues with my 1998 Toyota Land Cruiser 80 Series (Aussie spec) running the 4.5L 1FZ-FE petrol engine. It’s mostly stock. And apologies I’m pretty amateur at all this and by no means a mechanic but hopefully save a few bucks.

Here’s what I’m experiencing:
Symptoms:

Intermittent starting – sometimes cranks for a long time, usually if I key out and crank after a long crank it fires straight away.

Turns over better when engine cold.

Rough idle when it does start, occasional. Maybe a slight misfire.

white smoke from exhaust but smells more fuel than sweet. And goes after 3/4km

Strong fuel smell, constantly.

Oil pressure light flickers intermittently but I believe this is a separate switch issue.

What I’ve Done So Far:

Replaced the fuel pump
Replaced the fuel pressure regulator
Installed a new battery
New sparks
New MAF
New coolant temp sensor

Despite those, the issues persist.

Possible Leads I’m Wondering About:

• Leaky injectors?
• Ignition coil or sensor issue?
• Small vapour locking?
• Blown head gasket, unlikely I think.

Any other key culprits you can think of?

Thanks in advance!

View attachment 3944974

View attachment 3944976

Gotta be a Novacastrian with those plates!

 

[reecef10]

Gotta be a Novacastrian with those plates!

Ahaha from Durham originally!

 

[petegangies]

Ahaha from Durham originally!

Haha wrong Newcastle then!

 

[reecef10]

Haha wrong Newcastle then!

Yeah, from sunny NE England but living in WA now