1fz-fe rough idle/misfire no CEL - Help (3 Viewers)

[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)

 

[Malleus]

FWIW, the ECM doesn't wait until the engine "warms up" to start "reading" the sensors. The sensor output is fed to the ECM when the engine is running, regardless of operating temperature.

Two questions:
1. How do you know the MAF is reading a higher temperature, and higher than what?
2. You say you've checked "everything" against the FSM. Did you start with the troubleshooting procedure and find no faults?

I'm not trying to be critical, just trying to understand how you've gotten to where you are. I sympathize, troubleshooting can be frustrating.
Given that you have a large number of new parts, are they all Toyota parts?

Finally, you mentioned that you think there might be a VSV fault (I assume you mean the emissions VSV, there's more than one). What makes you think that? FWIW:

 

[Malleus]

Here's another VSV (for fuel pressure)

There's also one for the EVAP, but I doubt that's causing your misfire/rough idling.

 

[GRN bastard]

FWIW, the ECM doesn't wait until the engine "warms up" to start "reading" the sensors. The sensor output is fed to the ECM when the engine is running, regardless of operating temperature.

Two questions:
1. How do you know the MAF is reading a higher temperature, and higher than what?
2. You say you've checked "everything" against the FSM. Did you start with the troubleshooting procedure and find no faults?

I'm not trying to be critical, just trying to understand how you've gotten to where you are. I sympathize, troubleshooting can be frustrating.
Given that you have a large number of new parts, are they all Toyota parts?

Finally, you mentioned that you think there might be a VSV fault (I assume you mean the emissions VSV, there's more than one). What makes you think that? FWIW:
View attachment 3453046
View attachment 3453047

FWIW, the ECM doesn't wait until the engine "warms up" to start "reading" the sensors. The sensor output is fed to the ECM when the engine is running, regardless of operating temperature.

Two questions:
1. How do you know the MAF is reading a higher temperature, and higher than what?
2. You say you've checked "everything" against the FSM. Did you start with the troubleshooting procedure and find no faults?

I'm not trying to be critical, just trying to understand how you've gotten to where you are. I sympathize, troubleshooting can be frustrating.
Given that you have a large number of new parts, are they all Toyota parts?

Finally, you mentioned that you think there might be a VSV fault (I assume you mean the emissions VSV, there's more than one). What makes you think that? FWIW:
View attachment 3453046
View attachment 3453047

Good to know about the sensors.

The MAF was reading 1.5 kilo ohms approx 104 degrees when it was 40 degrees outside. I'll check again to confirm because it was a warm engine.

I've been going through the FSM and checking sensors mainly, checking the resistance. Since I don't have a CEL I can't really pin point a certain area or thing.

Hey I appreciate it, I know trouble shooting involves a lot of information and back and forth.

Yes all the parts are OEM minus the ones stated otherwise.

Yes, the VSV from the intake manifold "fuel valve" to the fuel regulator. I took some extra vacuum line and ran directly from the manifold to the fuel regulator. It ran a little more smoothly but still had slight misfire.

My EGR system has been deleted so there won't be the exhaust gas issue. Also there are and have been no EGR related codes. I had a shop the specializes in Landcruisers do the engine rebuild and EGR delete.

 

[GRN bastard]

FWIW, the ECM doesn't wait until the engine "warms up" to start "reading" the sensors. The sensor output is fed to the ECM when the engine is running, regardless of operating temperature.

Two questions:
1. How do you know the MAF is reading a higher temperature, and higher than what?
2. You say you've checked "everything" against the FSM. Did you start with the troubleshooting procedure and find no faults?

I'm not trying to be critical, just trying to understand how you've gotten to where you are. I sympathize, troubleshooting can be frustrating.
Given that you have a large number of new parts, are they all Toyota parts?

Finally, you mentioned that you think there might be a VSV fault (I assume you mean the emissions VSV, there's more than one). What makes you think that? FWIW:
View attachment 3453046
View attachment 3453047if I can get to it I'll check this too.

I also cleaned the MAF and IAC this week to eliminate those. The IAC O ring was hard as a rock so I swapped it for some OEM gasket maker until I can get an o-ring in.

The IAC was ready about 10 ohms too high across the first set of pin you're asked to check in the FSM. I don't remember exactly the pin names off my head but I didn't think 40 ohms instead of 30 ohms was a massive faults that would cause these issues. I could be wrong though.

 

[Malleus]

When the engine idles well cold, but poorly when warm, the IAC is the first thing that comes to my mind, unless it's either new or been verified. There are two performance checks to ensure the IAC is working, only one is electrical. The other is mechanical; it has to fully extend and fully retract. I had one that checked fine electrically, but wouldn't fully close. The truck ran like crap, unless the A/C was on (running the rpm up). Once it was disassembled, cleaned and reinstalled, the problem went away. Not saying that is your problem, but if you haven't verified the mechanical operation, you need to pull the IAC off the throttle body and do that.

If you have no DTCs, the troubleshooting matrix would point you to check each ECM terminal for voltage per the operating parameters. This is what you would do if you had a DTC and couldn't find a sensor fault. The list is in the EG section of the FSM. It's pretty straightforward and not at all hard, you will need a multimeter, though. It's located directly behind the glovebox. It wouldn't take an hour to run through the list.

 

[GRN bastard]

FWIW, the ECM doesn't wait until the engine "warms up" to start "reading" the sensors. The sensor output is fed to the ECM when the engine is running, regardless of operating temperature.

Two questions:
1. How do you know the MAF is reading a higher temperature, and higher than what?
2. You say you've checked "everything" against the FSM. Did you start with the troubleshooting procedure and find no faults?

I'm not trying to be critical, just trying to understand how you've gotten to where you are. I sympathize, troubleshooting can be frustrating.
Given that you have a large number of new parts, are they all Toyota parts?

Finally, you mentioned that you think there might be a VSV fault (I assume you mean the emissions VSV, there's more than one). What makes you think that? FWIW:
View attachment 3453046
View attachment 3453047

I just double checked the MAF and it's reading the right temperature. I checked it with a warm engine last time and it seemed off. On a cold engine it was reading dead on. 5.8 kilo ohms for 32 degrees and it's 34 outside.

 

[Malleus]

34º! I didn't know vegas got that cold this early!

 

[mudgudgeon]

Vacuum leak?
Did you replace all vacuum lines? With the right size tube?
Oil fill cap o-ring fresh? Not rock hard?
PCV valve grommet good? Not rock hard or cracked?
Dipstick o-ring good?
Intake air tube not cracked?

What statoc timing do you have the distributor set at?
Try advancing the static timing to 6-10⁰ BTDC. Some 1fz-fe run great at 10⁰, some will ping. If it pings, back it off to 6⁰
A bit more timing advance sometimes will smooth out the idle, and give them a bit more pep off the line and better pick up from low rpm

 

[mudgudgeon]

34º! I didn't know vegas got that cold this early!

Profile says Tennessee

 

[Malleus]

Local humor... I grew up in middle Tennessee. It's Clarksvegas there... 'cause it's nothing like the real thing.

 

[GRN bastard]

When the engine idles well cold, but poorly when warm, the IAC is the first thing that comes to my mind, unless it's either new or been verified. There are two performance checks to ensure the IAC is working, only one is electrical. The other is mechanical; it has to fully extend and fully retract. I had one that checked fine electrically, but wouldn't fully close. The truck ran like crap, unless the A/C was on (running the rpm up). Once it was disassembled, cleaned and reinstalled, the problem went away. Not saying that is your problem, but if you haven't verified the mechanical operation, you need to pull the IAC off the throttle body and do that.

If you have no DTCs, the troubleshooting matrix would point you to check each ECM terminal for voltage per the operating parameters. This is what you would do if you had a DTC and couldn't find a sensor fault. The list is in the EG section of the FSM. It's pretty straightforward and not at all hard, you will need a multimeter, though. It's located directly behind the glovebox. It wouldn't take an hour to run through the list.

I'll check that, I cleaned it and everything looked good but I didn't test it's operation.

That's too easy. Really appreciate the information. Mechanical stuff I'm okay with but all the electrical systems go over my head.

 

[GRN bastard]

34º! I didn't know vegas got that cold this early!

I need to change my location, I just moved to Alaska. Lol

 

[GRN bastard]

Vacuum leak?
Did you replace all vacuum lines? With the right size tube?
Oil fill cap o-ring fresh? Not rock hard?
PCV valve grommet good? Not rock hard or cracked?
Dipstick o-ring good?
Intake air tube not cracked?

What statoc timing do you have the distributor set at?
Try advancing the static timing to 6-10⁰ BTDC. Some 1fz-fe run great at 10⁰, some will ping. If it pings, back it off to 6⁰
A bit more timing advance sometimes will smooth out the idle, and give them a bit more pep off the line and better pick up from low rpm

I tested with soapy water for vacuum leaks, nothing that I could find and no hissing sounds.
All the small lines have been replaced recently with OEM vacuum line. A few larger ones haven't been but again no hissing or bubbles.

I can check the oil cap, I believe it's fine, but I'll add it to the list, I'm sure it's original.

PCV valve, hoses, and grommet have been replaced in the last 30k and cleaned recently. No issues found there.

Dip stick o-ring unknown, I'll have to check.

I didn't see any cracks in the intake tube, I just it's still soft and no noticable punctures.

Timing is set at 3°. Good to know, my distributor is maxed out on adjustment at 3° so I'll have to remove it and reinstall it with more movement.

 

[mudgudgeon]

Timing is set at 3°. Good to know, my distributor is maxed out on adjustment at 3° so I'll have to remove it and reinstall it with more movement.

If it's maxed out, sounds like you're one tooth off on the distributor gear.


Not sure soapy water helps test for vacuum leak? Unless you're pressurising the system so it blows bubbles?

I recently re-did vacuum lines on mine after finding aftermarket vacuum tube was too loose for my liking. Was dubious when I fitted it, but it was all I could get at the time

 

[GRN bastard]

If it's maxed out, sounds like you're one tooth off on the distributor gear.


Not sure soapy water helps test for vacuum leak? Unless you're pressurising the system so it blows bubbles?

I recently re-did vacuum lines on mine after finding aftermarket vacuum tube was too loose for my liking. Was dubious when I fitted it, but it was all I could get at the time

I was already planning on removing my distributor and adjusting it so I'll make sure it's correct.

I had it running and sprayed down the hoses and didn't see anything abnormal, there's no hissing either.

 

[studawg]

Bad gas?
Octane too low?

Mine started running really rough just recently. I had gotten through about a half tank of 87 when it started. I refilled with 93 and its been running fine since. Im not sure if it was just bad gas, or if it was the octane. I do have my timing advanced over stock so maybe it was the octane.

 

[jonheld]

Bad gas?
Octane too low?

Mine started running really rough just recently. I had gotten through about a half tank of 87 when it started. I refilled with 93 and its been running fine since. Im not sure if it was just bad gas, or if it was the octane. I do have my timing advanced over stock so maybe it was the octane.

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

 

[GRN bastard]

Bad gas?
Octane too low?

Mine started running really rough just recently. I had gotten through about a half tank of 87 when it started. I refilled with 93 and its been running fine since. Im not sure if it was just bad gas, or if it was the octane. I do have my timing advanced over stock so maybe it was the octane.

I have had bad gas before, but I don't believe it's that. I've ran though a lot of tanks and have had the same issue.

 

[inkpot]

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