1994 Chevy Suburban timing problem

Tiny
AFIARYTALE4U
  • MEMBER
  • 1994 CHEVROLET SUBURBAN
1994 Chevy Suburban V8 Two Wheel Drive Automatic

vehicle idles rough and hesitates while driving
we replaced the spark plugs, wires, distributer cap and rotor, TPS sensor and other sensors, set the timing for 18 degrees tdc to 4 degrees tdc using alldata instructions for this vehicle. Test drove vehicle and it seemed fine while at low speeds then when trying to cross an intersection and accelerating it began to hesitate and run rough once again. Got the vehicle home and re checked the timing and it was off again to 16 degrees tdc. Tried to reset the timing using alldata instructions again and timing immediately jumped again.
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Wednesday, August 18th, 2010 AT 11:01 AM

5 Replies

Tiny
WRENCHTECH
  • EXPERT
Did you disconnect the timing connector when you adjusted the timing
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Wednesday, August 18th, 2010 AT 11:16 AM
Tiny
AFIARYTALE4U
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NOTE: Timing specifications are listed on the Vehicle Emissions Control Information label under the hood. Always follow the Vehicle Emissions Control Information label procedures first before using the following procedure.

Timing Mark

PROCEDURE:
Set timing under the following conditions:

* Normal operating temperature.
* Air cleaner installed.
* A/C "OFF."
* Transmission in neutral.
* Disconnect SET TIMING connector. The location of the set timing connector is inside the cab where the heater box and the carpet meet on the passenger side floor. Pull carpet back to expose the single wire and connectors on the outside of the control module harness. The wire colors are tan with a black stripe. DO NOT disconnect 4 wire connector at distributor.

Connect timing light and adjust as necessary by loosening hold down bolt and rotating distributor. For specification, refer to SPECIFICATIONS/TIMING MARKS. Tighten hold down and recheck the timing. Stop the engine and connect SET TIMING connector. Clear control module trouble code by disconnecting control module power source. With engine at operating temperature, drive vehicle at part throttle with moderate acceleration and decelerate to idle condition. This will "teach" the control module and return the engine to normal performance.

This is what we did and they didn't give me the option to put the motor type 454 7.4 liter
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Wednesday, August 18th, 2010 AT 11:23 AM
Tiny
WRENCHTECH
  • EXPERT
I know what the instructions say. I wanted to know if you actually found it and disconnected it.

You also have to disconnect it when your rechecking it later.
If you've done all that and the timing is still moving, the you have a problem that could be the timing chain, distributor or distributor gear.
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Wednesday, August 18th, 2010 AT 11:49 AM
Tiny
AFIARYTALE4U
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Sorry was not trying to disrespect. The purpose of the copy/paste was to share what we were reading. There can be changes that maybe we were not aware of. We did disconnect it each time we tried to set it. I am pretty sure it is a timing chain issue as I am a former Chevrolet technician but after trying the things we have I needed to pacify my mother who's vehicle it is. Thank you for your time.
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Wednesday, August 18th, 2010 AT 11:57 AM
Tiny
WRENCHTECH
  • EXPERT
No problem, good luck with it.
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Wednesday, August 18th, 2010 AT 12:05 PM

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