Timing adjustment
05-31-2016, 08:53 AM
#1
Timing adjustment
So don't know me on this one to bad but some one has borrowed my timing light and I will probably never see it again. Out of desperation I marked my starting point on the distributor and rotated it clockwise and listened for the the RPMs to go up. Checking the tach I adjusted the distributor about 1/4 of the adjustment area clockwise and the Rpms went up from 500 to about 850-900. The 4Runner is now running a lot smoother and definitely feels like it has more mid range power. I have also noticed it starts better and doesn't bog or jerk at low RPMs. I am definitely shifting sooner at around 3200 vs about 4000 before.
Now I was under the impression you rotated clockwise to advance timing and this would account for the idle increase. And yes I plan on checking timing with a timing gun the first chance I get. So far it has a lot of adjustment left and I am running 87 octane so I don't want to push it any more until I verify timing.
Now I was under the impression you rotated clockwise to advance timing and this would account for the idle increase. And yes I plan on checking timing with a timing gun the first chance I get. So far it has a lot of adjustment left and I am running 87 octane so I don't want to push it any more until I verify timing.
Last edited by cbr600rx7; 05-31-2016 at 10:27 AM.
05-31-2016, 05:14 PM
#2
Verified timing with a timing gun. It was initially set low at around 6 degrees so this explains the sluggish response. When I adjusted by ear and test driving she was around 14 degrees and seemed to really run well at that setting but just to be safe I backed off just a little more. I have it currently set at roughly 13 degrees and it is definitely a huge improvement L. This is all on 87 octane with a working knock sensor and no check engine lights.
06-01-2016, 02:30 PM
#3
13 degrees? with efi, the computer controls the timing... on the 22re, timing gets set at a base level, i think that it's 5 degrees, and it's set with a jumper that stops all timing advance.
06-01-2016, 04:44 PM
#4
Sorry should have been clear. This is a 3VZE and base timing should be 10 degrees at 800 RPMs with the TE1 and E1 jumped to set the base timing. The computer is limited to what it can control and depends on the knock sensor to detect ping and pull timing. From what I have looked at online 12-14 degrees seems to be a common happy spot that a lot of people tend to like. A few have pushed it far past that point but I would be worried about any thing over what I have mine set to with out running higher octane. This is just my 2 cents so take it for what it is.
Last edited by cbr600rx7; 06-01-2016 at 04:48 PM.
06-01-2016, 07:54 PM
#5
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A couple of things that may help clear up how this works.
- First, unlike newer engines, on the 3vze the ECU gets its TDC information from the distributor, not the crankshaft. So, by rotating the distributor to an advanced timing setting, you are essentially lying to the computer about where TDC is.
- The ECU will take the various inputs (rpm, throttle position, air flow and temperature, and coolant temperature) and compute a timing advance from where it thinks TDC is. Then it will listen for the knock sensor and continually advance or retard timing from that computed setting until the engine is running just on the edge of knocking.
- If the ECU doesn't get a signal from the knock sensor regularly, it will assume it's not working, retard the timing significantly to protect the engine, and set code 52. With the retarded timing your engine will run poorly.
By advancing the distributor, you are biasing the ECU to run the timing more advanced, but ultimately the knock sensor has the last word on where the timing actually ends up. Where you'll most notice the effects of advancing the distributor is under quick throttle changes and acceleration, where the ECU has to make a quick estimate of the optimum timing before it has time to collect good knock sensor data. That's likely why you feel the engine is more responsive with the distributor advanced.
At steady rpm's the knock sensor will override most anything you do to the timing. If you run higher octane fuel, the ECU can advance the timing further before knocking starts, so you get somewhat more power and/or improved fuel economy. On mine, I pick up about 1 mpg by using midgrade instead of regular.
- First, unlike newer engines, on the 3vze the ECU gets its TDC information from the distributor, not the crankshaft. So, by rotating the distributor to an advanced timing setting, you are essentially lying to the computer about where TDC is.
- The ECU will take the various inputs (rpm, throttle position, air flow and temperature, and coolant temperature) and compute a timing advance from where it thinks TDC is. Then it will listen for the knock sensor and continually advance or retard timing from that computed setting until the engine is running just on the edge of knocking.
- If the ECU doesn't get a signal from the knock sensor regularly, it will assume it's not working, retard the timing significantly to protect the engine, and set code 52. With the retarded timing your engine will run poorly.
By advancing the distributor, you are biasing the ECU to run the timing more advanced, but ultimately the knock sensor has the last word on where the timing actually ends up. Where you'll most notice the effects of advancing the distributor is under quick throttle changes and acceleration, where the ECU has to make a quick estimate of the optimum timing before it has time to collect good knock sensor data. That's likely why you feel the engine is more responsive with the distributor advanced.
At steady rpm's the knock sensor will override most anything you do to the timing. If you run higher octane fuel, the ECU can advance the timing further before knocking starts, so you get somewhat more power and/or improved fuel economy. On mine, I pick up about 1 mpg by using midgrade instead of regular.
06-03-2016, 08:16 AM
#6
Thanks for braking that down so clearly.
I am still running 87 and playing around with it a little bit. It seems to really like 14 degrees even on the lower octane fuel. The 3.0 is all stock with the exception of a cat delete pipe but still 2 inch exhaust into stock muffler.
I may continue to dial it in on the 87 and then start running 91-93 for security but so far MPG and drivability have noticeably improved. It's still a 3slow by all means but no longer feels like it's struggling.
I am still running 87 and playing around with it a little bit. It seems to really like 14 degrees even on the lower octane fuel. The 3.0 is all stock with the exception of a cat delete pipe but still 2 inch exhaust into stock muffler.
I may continue to dial it in on the 87 and then start running 91-93 for security but so far MPG and drivability have noticeably improved. It's still a 3slow by all means but no longer feels like it's struggling.
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