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Distributor timing issue?

Tiny
95SEIRRA
  • MEMBER
  • 1995 CHEVROLET TRUCK
  • 5.7L
  • V8
  • 2WD
  • AUTOMATIC
  • 308,350 MILES
I replaced my distributor because the old one failed. Now I'm having great issue with trying to get it timed, I went and bought a timing light, and I followed the instructions in the manual. While in neutral I place first cylinder at top dead center and continue to hand crank engine till the mark on the dampener is liked up with the zero, I unplug the tan and black wire under my dash and set up the timing light. I start the truck while still in neutral and check the mark with the light and rotate distributor accordingly so mark lines back up with zero, then I put truck into park and shut it off and plug the wire back in, pull the two ECM fuses from the fuse box located under the hood and wait 30 seconds before installing them to reset the fault code. I then tighten down the distributor and I start my truck again and check with mark one last time with the light just to find the mark to be way out to lunch. I've tried the same procedure while in park, I've tried unplugging the wire while the truck is running, in neutral and in park. It doesn't seem to matter which way I do it the outcome is the same, the mark is other nowhere to be seen or way before the little plate with the numbers or way after the plate. What am I doing wrong here? I followed the procedure of how to properly install the distributor and made sure they were exactly the same before installing, so I don't get it. Also when I installed the distributor the first time and did the timing I never checked it after I started it again to see if the mark was still correct ( didn't think I had too) the only reason why I checked was because the truck was shooting out codes 35 & 42 and started running rough and had no power while accelerating. I changed the fuel filter, the fuel pump just recently and replaced the fuel injectors and pretty much all the sensors but crank sensor and o2 sensor. If you can tell me what I'm doing wrong, it would be appreciated. Thanks
I have a 350 v8 5.7l TBI engine in my 95 Chevy 1500.
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Saturday, March 30th, 2024 AT 7:15 PM

13 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 42,924 POSTS
This is how the book says to do the timing. Can I ask if the engine was running the same way with the old distributor?

IGNITION TIMING ADJUSTMENT
WARNING: To prevent possible personal injury from a moving vehicle or operating engine, do the following before performing the checks:

Engage the parking brake and block the wheels.
Place the transmission in neutral.

1. Refer to the Vehicle Emissions Control Information label under the hood. Always follow the Vehicle Emissions Control Information label procedures first before using the following procedure.

2. Put the IC system in the bypass mode by disconnecting the "set timing" connector. This is a single wire sealed connector that has a tan with black stripe lead. This connector breaks out of the wiring harness below the heater case in the passenger compartment.

3. With the ignition switch "OFF, " connect the pickup lead of the timing light to the number one spark plug. Use a jumper lead between the wire and plug or an inductive type pickup.

DO NOT pierce the wire or attempt to insert a wire between the boot and the wire. Connect the timing light power leads according to manufacturer's instructions.

4. Start the engine, and aim the timing light at the timing mark. The line on the balancer or pulley will line up at the timing mark. The timing should be O° TDC. If a change is necessary, loosen the distributor hold-down clamp bolt at the base of the distributor. While observing the mark with the timing light, slightly rotate the distributor until the line indicates the correct timing. Tighten the hold-down bolt, and recheck the timing.

5. Turn "OFF" the engine and remove the timing light. Reconnect the number one spark plug wire, if removed.

6. Reconnect the "Set Timing" connector.

Preassembled replacement distributors are not available. Components are available to assemble a new distributor. Some components, such as the air cleaner, may need to be removed to reach the distributor. The distributor has a separate ignition coil that mounts to a bracket on the top of the engine.

REMOVE OR DISCONNECT
Make sure the ignition switch is "OFF."

1. Air cleaner and hoses.
2. Electrical connectors at the side of the distributor cap.
3. Two screws on the sides of the distributor cap.
4. Ignition coil wire and spark plug wires on either the left or right side of the distributor.
5. Distributor cap and move it aside.
A. Use chalk to note the position of the rotor in relation to the engine.
B. Use chalk to note the position of the distributor housing in relation to the engine.

6. Distributor bolt and hold-down clamp.
7. Distributor.

INSTALL OR CONNECT
1. Distributor.

A. To ensure correct timing of the distributor, it must be installed with the rotor correctly positioned as noted in step 5 of the removal procedure. Line up the rotor to the mark on the engine, and the mark on the housing to the engine.
B. If the distributor shaft won't drop into the engine, remove the distributor, insert a screwdriver into the hole for the distributor and rotate the oil pump driveshaft so it lines up with the distributor drive gear.

2. Hold-down clamp and bolt.

Tighten
Bolt to 27 Nm (20 lbs. In.).

3. Distributor cap with two screws.
4. Wiring harness connectors to the sealed ICM connectors at the side of the distributor.
5. Spark plug wires and coil wire.
6. Air cleaner and hoses.
Check the ignition base timing.

Please go over this guide and get back to us.
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Sunday, March 31st, 2024 AT 6:55 PM
Tiny
95SEIRRA
  • MEMBER
  • 9 POSTS
I have done that procedure, the exact steps for distributor installation and timing. The truck runs great no misfiring, no back firing, everything sounds and looks like it should but it's when I restart my truck after I do the steps and procedures it runs rough and you can hear it misfiring and the mark on the dampener will be completely out to lunch, it will start roughly and will barley move in drive or reverse until it warms up.
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Monday, April 1st, 2024 AT 1:34 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 42,924 POSTS
That's a good one I have seen engine coolant sensors short out when cold. Let's run the codes to see what is stored.

https://www.2carpros.com/articles/buick-cadillac-chevy-gmc-oldsmobile-pontiac-gm-1983-1995-obd1-code-definitions-and-retrieval-method

Please go over this guide and get back to us.
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Monday, April 1st, 2024 AT 7:28 PM
Tiny
95SEIRRA
  • MEMBER
  • 9 POSTS
Shows no codes just blinks 12 which is normal diagnostic system. Also has no power on acceleration, when I drove it back to the shop after starting it again and discovering the issues listed in previous post.
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Tuesday, April 2nd, 2024 AT 3:14 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 42,924 POSTS
It sounds like the cat might be clogged or the fuel pump is going out.

This guide can help with testing the catalytic converter:

https://www.2carpros.com/articles/how-to-test-a-catalytic-converter

This will help test the fuel pressure:

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

Ignition ON Engine OFF .................... 62-90 kPa (9-13 psi)

Please go over these guides and get back to us.
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Tuesday, April 2nd, 2024 AT 8:44 PM
Tiny
95SEIRRA
  • MEMBER
  • 9 POSTS
I don't have a "cat" so that doesn't apply, and I just replaced the fuel pump about 4 months ago roughly, but I will check and test the fuel pressure as soon as possible and let you know what I find. I don't see how either of those things would apply to my timing issue, how I can set it and then become out of time the next time I start the truck.
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Wednesday, April 3rd, 2024 AT 11:12 AM
Tiny
KEN L
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I have seen the distributor gear roll pin shear and allow the gear to "slip" on the shaft changing the timing, or you have a bad PCM.
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Thursday, April 4th, 2024 AT 7:34 AM
Tiny
95SEIRRA
  • MEMBER
  • 9 POSTS
Change the timing? As in the chain? How would that exactly happen? Faulty parts or? Is there a way to tell if it's the PCM like a diagnosis process? Could it only be those two things or are there other things that I can check first before ripping apart my engine to fix the timing chain? Or finding a used PCM?
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Thursday, April 4th, 2024 AT 8:25 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 42,924 POSTS
There is a roll pin at the bottom of the distributor gear which can "shear" allowing the gear to slip on the shaft which will change the timing. Just to confirm you say the timing changes after you run it, correct? For the PCM you will need to send it in for testing.
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Friday, April 5th, 2024 AT 8:55 AM
Tiny
95SEIRRA
  • MEMBER
  • 9 POSTS
I installed the new distributor while in neutral, with battery unhooked, first piston @ TDC, tighten down distributor bolt & finish hand cranking engine so line on dampener lines up with the zero on metal tab, unplug the little wire under dash then put spark plug back in, plug in the wires at back of distributor, hook up timing light and battery cable and put on shroud. Start truck letting run 2-3 min then check mark with timing light and adjust by rotating distributor till mark lines back up with zero mark. Turned off truck, tighten down distributor bolt, remove timing tool and on starting truck again the mark on the dampener will not be anywhere near tab, truck runs horribly, rough high idle, misfiring, no reverse no forward until it warms up and has pretty much no power, rpms ore up but I'm not moving anywhere. Yes, after timing it and restarting the vehicle, the timing will be out.
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Friday, April 5th, 2024 AT 7:29 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 42,924 POSTS
Did you have this problem before the new distributor install? If not, it sounds like you may have gotten a defective unit. Does the engine seem to run okay without timing wire connected?
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Saturday, April 6th, 2024 AT 11:04 AM
Tiny
95SEIRRA
  • MEMBER
  • 9 POSTS
Just the ignition module went on the old distributor, so I just replaced the whole thing. So, no. It doesn't make a difference if it's plugged in or not runs the same.
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Saturday, April 6th, 2024 AT 12:09 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 42,924 POSTS
Can I ask which brand you purchased? I have seen bad pick-up coils, modules and main ignition coils cause this problem.
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Saturday, April 6th, 2024 AT 1:14 PM

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