Thread: How to: Adjusting Ignition Timing

I recently replaced my failed distributor and figured I'd check and adjust my timing afterwards. Great write up and very easy to follow instructions. However, once I had warmed up the vehicle and disconnected the TPS sensor, my idle dropped down to like 500rpm. I thought it was maybe going to stall but it didn't. I tried to adjust and turn the idle screw on the IAC but it didn't appear to change anything. Granted it's also plastic that dumb screw and mine looks a bit chewed up from the previous owner.

Could it mean that I have a bad TPS sensor? Or bad IAC Valve i.e. the idle screw adjustment. When I did check the timing it appeared to right around 15 degrees so I think I'm okay with that. Also, when you mention making marks on the distributor for different degrees, do you need to repeat this procedure to change it? Or could you simply loosen the distributor with the car off and turn it changing the timing?

If your idle and acceleration is fine with the TPS hooked up and then almost stalls when you unhook it, the TPS should not be the problem. IACV or fast-idle adjust may be an issue....

I'd be tempted to bump the idle up a bit closer to 750 rpm (+/- 50 rpm) and then re-check the timing. You can use the fast-idle adjust on the TB to slightly raise the idle or you can cheat and shove a screw driver against the TB stopper to temporarily raise the idle to appx. 750 rpm, while you re-check the timing with a timing light.

The marks on the distributor are for quick reference so that you don't have to use the timing light every time you adjust your mechanical ignition timing. You absolutely do need to put the car in timing mode each and every time you adjust via the distributor. Personally, the marks on the dist. don't really save you much time as it only takes a few seconds to go one step further and hook up the timing light. I use a light each and every time, just to be sure.

On a side note, if you are curious about the functionality of your TPS, put a volt meter on it. Check the output voltage at closed throttle, throughout the entire range of the throttle plate opening and for WOT as well. You can check the values for closed and WOT against values stated in the FSM for your car.

I know this is old and you already found the solution instead using the good old rain dance method

Actually its a combination of the two they both go hand in hand when setting base idle and base timing, you will need to mess with the IACV to obtain for a B13 800rpm @ idle @ 15degree.....once base idle and timing are done correctly if using the consult method or Nissan Datascan when you go to hit the bottom to set base idle you will not notice a difference in the idle rpm.


p.s. very important to hit the mark of 800rpm and at least hit 20% AAC Duty while at 15degree timing.

Idle duty is fixed (at 20% for B13) while in "set timing/idle speed" mode. Revving the engine (aka "rain dance") is not necessary to enter "set timing/idle speed" mode.

Dave

That whole "rain dance" is merely a system "check" (as you can see in the FSM procedure) to make sure your car is not a vacuum leaking POS.

Via dyno, the dyno operator and I adjusted timing simply via unplugging the TPS, and checked with a timing light for the crank pulley hash marks and adjust accordingly. No rain dance required, I have tried to spread that little gem since the "rain dance" is so widely known.

However, I utilize a combonation of Nismotronic/NEMU for one car and consult via Nissan DataScan v1.4 freeware for the other three cars without a kick-ass NEMU ECU.

Mr. Dunn already touched on the other part I would have addressed so cheers!

I wasn't sure it was actually locked at 20% when in "timing mode" but I came to the conclusion it was because out of timing mode I was able to get my setup to to show 20-22% while at normal idle, and basically when I enter "timing/idle speed" mode there is no change now, but if you where to be way outta wack you would notice a big change, here are 2 videos but this after getting everything set right.



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What mods could potentially affect your timing/when should you re-check your timing (besides the totally obivious)?

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Underdrive crank pulley. Messing with cam gears. Wiring aftermarket ignition setups. ECU reflash or upgrade. Lots of stuff.

I guess it is fairly obvious. Anything that effects ignition timing. Duh. But actually, wouldn't there be a possibility of something effecting the advance only that may not be so very obvious at first?

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I suppose so, maybe here and there, depending on the modification, it if more air is taken in or more fuel can be absorbed or less, the ECU can and will sometimes alter to adjust..