Unable to set Timing

Tiny
JOEADAMS1040
  • MEMBER
  • 1996 NISSAN SENTRA
  • 1.6L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 140,000 MILES
Ran perfectly before, I had to replace the distributor and valve cover gasket due to leaking. I ensured the engine was on TDC by inspecting the timing marks and camshaft while the cover was off. I replaced the distributor and set it to 800 RPM but the best timing I can get is ~15 degrees BTDC. I took the car for Smog and it passed with flying colors.

Now it has a very slow throttle response and will not shift until it gets to 40MPH. I confirmed no broken wires, vacuum hoses, etc, and have replaced the Throttle Position Sensor. The distributor can only go in one way, but the top appears to be pointing at #4 wire when in the correct position. I pulled a replacement from the junk yard and had no improvement.
Saturday, April 30th, 2022 AT 1:12 PM

5 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,747 POSTS
Hi,

Is there a mark on the harmonic/crankshaft pulley which is for TDC? I know the timing is not adjustable and is controlled by the PCM. However, the rotor shouldn't be pointing toward the number 4 spark plug wire. It sounds like the distributor is 180 degrees off.

Take a look at pic 1 below. I highlighted the pin to indicate TDC. There should be a mark on the crank pulley. Check that.

Also, pic 2 shows the firing order. Cylinder 1 spark plug wire is on the opposite side of cylinder 4. Please confirm it is pointing toward cylinder 1 spark plug. Also, make sure the rotor is tight. (Pic 3).

Let me know.

Take care,

Joe

See pics below.
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Saturday, April 30th, 2022 AT 9:56 PM
Tiny
JOEADAMS1040
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  • 3 POSTS
10-4. Yes, I confirmed the pointer was pointing to the second mark (from the left) on the pulley (indicating 0 TDC). However, the cylinder order picture you provided is incorrect, I am loading the correct picture for my engine (GA16DE). Sorry I forgot to provide that on the original question.

The Distro will only fit into the cam shaft with the head pointing towards the #4 cylinder. While trouble shooting, I completed the following steps and got lucky.
After installing the Distro it still ran poorly, so I removed it and rotated the distro shaft 360 degrees clockwise, reinstalled and saw no improvement. I repeated this procedure 3 more times and it finally resulted in the engine running correctly. I have the idle set at 900 RPMs, but the timing marks are still not even close to correct, and I can't rotate the distro any more to get it closer to 10-degrees BTC. But the engine is running great again? Not sure what is happening except "maybe" the pully was installed incorrectly, resulting in the marks being off?
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Sunday, May 1st, 2022 AT 5:19 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,747 POSTS
Hi,

I'm not sure what turning it 360 degrees would even do. Basically, you removed it and turned it one rotation back to where it started.

Since there is only one way the distributor can be installed, then it sounds like the engine timing could be off. Is there any chance the timing chain could have jumped a tooth?

Let me know.

Joe
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Sunday, May 1st, 2022 AT 7:17 PM
Tiny
JOEADAMS1040
  • MEMBER
  • 3 POSTS
Yeah, I was thinking about why rotating it 360 degrees would have any effect, but then I was thinking that the Distro head has to rotate 16 times (twice for each piston) before a signal is sent at the exact moment it is pointing to the #1 cylinder. It appears that I got lucky and did not have to do it 15 times. However, the timing marks are still off. One of my mechanic friends found something that I tried.

It appears that in the 1990's some manufacturers would require you to disconnect some wire to properly set the timing. We found a YouTube video for this engine that says. 1) run engine up to normal operating temperature, 2) shut off engine and disconnect the Throttle Position Sensor wiring clip, 3) restart engine and increase RPM to 2,000 2 to 3 times, 4) check timing and rotate distributor until 8-10 BTC is achieved.

I re-read the Distributor Replacement and Timing Setting instructions in my Haynes manual and it says nothing about that at all. Anyway, I tried, and it works perfectly and the timing are right at 8-10 BTC.

I still don't know why rotating the distro 360 degree had any effect, but there must be some mechanical portion of the distro that needs to be aligned for #1 cylinder, like a complex clock work? I guess?
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Monday, May 2nd, 2022 AT 7:04 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,747 POSTS
Hi,

Like you, the rotation of the distributor makes no sense to me either. As far as the timing, I'm glad to know you got it where it needed to be. The issue with my manual is it doesn't explain how timing is set because it is to be controlled electronically, but this is a perfect example of how that is wrong.

Regardless, I thank you for the update. Chances are your power and findings will help others in the future.

Take care and please feel free to come back anytime in the future.

Joe
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Monday, May 2nd, 2022 AT 8:59 PM

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