1fz-fe rough idle/misfire no CEL - Help (1 Viewer)

[GRN bastard]

My fzj80 isn't running smoothly, slight misfire, ticking from the front/top of the engine. No CEL (sadly) and it runs okay. When the engine is cold, and I first start it up it runs absolutely amazing, no ticking, not misfire, no shaking. Once it warms up and starts reading the sensors it runs rough. Idle settles around 650 + or - 50. Idles around 1000 rpm in Drive.

First off what has been done to the vehicle (348k miles): ALL parts OEM unless Stated:

- Engine rebuild (top and bottom full refresh) 15k ago
- new fuel injectors
-new engine wiring loom
- new cooling system hoses, radiator, thermostat, water pump
- new TPS
- new O2 sensors (denso)
- new Mangaflow y-pipe and second cat (my old ones were shot)
- new distributor (cardone)
-new sparkplugs (less than 1k ago iridium)
- new spark plug wires
-new air filter
- new fuel filter
- new fuel pump and sending unit
- EGR delete
- new ignition coil
- new fuel regulator
- newish belts (20k)
- swapped main pulley
- new fan clutch and blade
- new charcoal canister
- new fuel filter cap
- new knock sensors (2x)
- temp sensor (aftermarket unknown brand)

Now you can see my frustration why this thing isn't running like a top... Everything I can think of has been checked against the FSM. Because it runs good when it's cold I assume it's a sensor... But no CEL so I'm running in circles.

Known issues:
- front exhaust manifold middle bolts are slightly stripped and aren't as tight as the rest
- possible issue with the VSV (THIS WAS THE ISSUE)

Issues listed in the comments (condensed for viewers ease)

- Vacuum leak, cracked tube, wrong size (THIS WAS THE ISSUE - replaced entire vac system)
-Oil filler cap o-ring rock hard (replaced due to age, wasn't an issue)
- PCV valve grommet brittle (was replaced not an issue)
- Dipstick o-ring (didn't have time to check before issue was resolved, will be switching it out)
- Intake air tube not cracked (mine was in good condition)
- Timing off a gear (checked and moved, but wasn't the issue)
- IAC (idle air control valve) - ( checked against FSM was bad, but didn't solve my issue)
- Fuel Octane rating too low (didn't check due to gas prices)


Fixing the Issue: $320.53 (from Partsouq and Toyota parts deal not including IAC approx $400)

I replaced all the Vac lines, switches, couplers, everything that was still on the market in one go. Solved the issue and now runs extremely smoothly.

Parts replaced: FOR 1995 1FZ-FE
9099992002 - Vac line (you'll need about 4 of these)
2582013020 - valve bi-metal
9091710049 - gas filter #1
9091005212 - Large vac hose
9613251100 - larger vac clamps
9092503192 - Valve vac control (the thing with the blue cap)
9533306010 - Evap hose
9091012079 - VSV #1
9091012079 - VSV #2
9033903002 - plug

List does not include:
- intake manifold "gas" valve
- any egr components
-intake manifold gaskets (THESE ARE NEEDED)

 

[mudgudgeon]

3 degrees is 3 degrees, regardless of moving a tooth.

Sure, but if you want 6⁰ and the bolt is at the end of the slot, what are you gonna do?

 

[GRN bastard]

3 degrees is 3 degrees, regardless of moving a tooth.

A moved tooth would've created a lot weirder symptoms, I moved it anyway so I could adjust it beyond 3 degrees.

 

[studawg]

These engines run just fine on 87 octane. Anything above that is a waste of money, unless you have forced induction.

Yes if your timing is set at stock, but when its advanced considerably, it would need a higher octane correct?

 

[jonheld]

Yes if your timing is set at stock, but when its advanced considerably, it would need a higher octane correct?

Depends if your getting pre-detonation with your timing advanced on 87 octane. If it's knocking then yes.
However, if you do cost benefit analysis on running 93 as opposed to 87 over the next 10K miles, keeping gas prices what they are around me today, it will cost me an additional $900. I'll keep FSM timing.

 

[studawg]

Depends if your getting pre-detonation with your timing advanced on 87 octane. If it's knocking then yes.
However, if you do cost benefit analysis on running 93 as opposed to 87 over the next 10K miles, keeping gas prices what they are around me today, it will cost me an additional $900. I'll keep FSM timing.

Is there any benefit to advancing the timing a few degrees? I thought it was giving me better throttle response and/or power but I could be imagining things

 

[mudgudgeon]

Yes if your timing is set at stock, but when its advanced considerably, it would need a higher octane correct?

I run 10⁰ static advance, on standard petrol.

No pre-detonation issues for me.

Runs a bit crisper, more power off idle, and better mid-range pickup.

If it's not pinging, no reason at all to run higher octane fuel.

 

[gaspain]

did you figure this out. I have similar issues

 

[GRN bastard]

did you figure this out. I have similar issues

Still working through it. IAC definitely helped. I'm replacing my entire vac system in a few weeks so I'll give an update on that.

I'd start simple though for your issue. Spark plugs, plug wires, distributor cap and rotor, then vac lines.

 

[gaspain]

Still working through it. IAC definitely helped. I'm replacing my entire vac system in a few weeks so I'll give an update on that.

I'd start simple though for your issue. Spark plugs, plug wires, distributor cap and rotor, then vac lines.

Thank you!