1FZ Timing Question, Engine stall (1 Viewer)

[florida95fzj]

When I got my truck the timing was set to 7 or 8 degrees. I can't keep it running well at 3.

I replaced all of the vacuum lines, cracked intake hose, PCV, cleaned throttle body + IAC, replaced broken knock sensor, new wires, cap, and plugs. I also adjusted the timing to 3-4 degrees per the FSM.

About a 100 miles later I stalled out while stopped to make a turn after driving 5 minutes. Engine restarted fine. No codes since then.

Later, I used my OBDII scanner and noticed the timing normally sits at 3-4 but drops to 1-2 degrees when I can hear it about to stall. It seems if I rev engine to 2000 RPM the idle is a bit worse afterwards.

I am going to advance the timing back to 7 but I don't know where to look to actually fix the problem. Using the search engine here tells me a lot of folks set their timing to 7 anyway but I imagine something else is still wrong with my truck.

I'd appreciate any pointers where to look.

 

[ceylonfj40nut]

Running at 7 is done by several. I do. Not because it stalls at 3. Check you IAC sensor and tach sensor to see they are to spec.

 

[florida95fzj]

Running at 7 is done by several. I do. Not because it stalls at 3. Check you IAC sensor and tach sensor to see they are to spec.

Ok, haven't bench tested the IAC yet. Will do. Is the tach sensor the one right next to the IAC? what the FSM is calling throttle position or something like that?

 

[BILT4ME]

Also, or your timing was 7 and now 3, you may need to adjust your idle screw to get it back to 650.

 

[ceylonfj40nut]

Ok, haven't bench tested the IAC yet. Will do. Is the tach sensor the one right next to the IAC? what the FSM is calling throttle position or something like that?

Tach sensor is located at the outside bottom of the oil pan right behind crank pulley. It’s got a protected metal sheath with a wire connected to a plug.

 

[ceylonfj40nut]

Also, or your timing was 7 and now 3, you may need to adjust your idle screw to get it back to 650.

Where is this idle screw? News to me having owned an 80 this long. Learning something new.

 

[florida95fzj]

Where is this idle screw? News to me having owned an 80 this long. Learning something new.

I assume this is the throttle position sensor screw adjustment.

 

[ceylonfj40nut]

I assume this is the throttle position sensor screw adjustment.

Post pics pls of said screw?

 

[florida95fzj]

Will repost when I figure it out.

 

[florida95fzj]

Looks like there is a throttle stop screw, as shown in this FSM picture.

The TPS is slotted so it can rotate and be adjusted to reflect the actual throttle position for the ECU's benefit. I presume if it's off it will screw with the air/fuel mix and the ECU will spend a lot of time screwing up how the truck runs.

I don't see any other screws that adjust the idle.

 

[ceylonfj40nut]

Looks like there is a throttle stop screw, as shown in this FSM picture.

The TPS is slotted so it can rotate and be adjusted to reflect the actual throttle position for the ECU's benefit. I presume if it's off it will screw with the air/fuel mix and the ECU will spend a lot of time screwing up how the truck runs.

I don't see any other screws that adjust the idle.

View attachment 3213360

This is for a 3fe as I recall. In a 1fz idle speed is managed via ECU.

 

[jonheld]

This is for a 3fe as I recall. In a 1fz idle speed is managed via ECU.

Both the 3FE and the 1FZ-FE idle speeds are controlled by the ECU which bumps the ISC valve to adjust idle speed. There is no "idle speed adjustment screw" on either motor.