1997 GMC Yukon Sport, 198,000 miles. How do I adjust the timing?
Dec 14, 2006 at 10:21 AM
1997 GMC Yukon No Spark Timing
TAYALEX1978
- MEMBER
- 2 POSTS
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Your cars PCM controls the timing for ignition and injectors. There is no adjustment required or allowed. Why do you need to adjust the timing. Is there something wrong that I can help with
Backyardmechanic :D
Backyardmechanic :D
Dec 14, 2006 at 11:12 PM
[quote="backyardmechanic"]Your cars PCM controls the timing for ignition and injectors. There is no adjustment required or allowed. Why do you need to adjust the timing. Is there something wrong that I can help with
Backyardmechanic :D[/quote
We initially took it to a shop to get the fuel pump repaired. We drove it in but had to tow it out. It wouldn't turn over at all. We replaced the fuel pump pressure regulaor, replaced all 4 O2 sensors, throttle positioning sensor, idle control sensor and cleaned the spark plugs. It turns over but seems to not be getting any fire. We were told that the timing was off. Could it be something else?
Backyardmechanic :D[/quote
We initially took it to a shop to get the fuel pump repaired. We drove it in but had to tow it out. It wouldn't turn over at all. We replaced the fuel pump pressure regulaor, replaced all 4 O2 sensors, throttle positioning sensor, idle control sensor and cleaned the spark plugs. It turns over but seems to not be getting any fire. We were told that the timing was off. Could it be something else?
Dec 15, 2006 at 12:42 AM
[quote="tayalex1978"][quote:950f3d2590="backyardmechanic"]Your cars PCM controls the timing for ignition and injectors. There is no adjustment required or allowed. Why do you need to adjust the timing. Is there something wrong that I can help with
Backyardmechanic :D[/quote
We initially took it to a shop to get the fuel pump repaired. We drove it in but had to tow it out. It wouldn't turn over at all. We replaced the fuel pump pressure regulaor, replaced all 4 O2 sensors, throttle positioning sensor, idle control sensor and cleaned the spark plugs. It turns over but seems to not be getting any fire. We were told that the timing was off. Could it be something else?[/quote:950f3d2590]
If your not getting spark then there is a problem with the ignition system. If the timing is off then this would mean the timing chain has slipped and needs to be replaced. Even though the car has high mileage (chain has some wear) I would make sure the car is getting spark before assuming the timing is off. Check the simply things first before moving on to bigger ones. Hope this is some help BYK
Backyardmechanic :D[/quote
We initially took it to a shop to get the fuel pump repaired. We drove it in but had to tow it out. It wouldn't turn over at all. We replaced the fuel pump pressure regulaor, replaced all 4 O2 sensors, throttle positioning sensor, idle control sensor and cleaned the spark plugs. It turns over but seems to not be getting any fire. We were told that the timing was off. Could it be something else?[/quote:950f3d2590]
If your not getting spark then there is a problem with the ignition system. If the timing is off then this would mean the timing chain has slipped and needs to be replaced. Even though the car has high mileage (chain has some wear) I would make sure the car is getting spark before assuming the timing is off. Check the simply things first before moving on to bigger ones. Hope this is some help BYK
Dec 15, 2006 at 8:32 AM
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Suggested Repair
Confirm spark before assuming the timing is off. Ignition timing is controlled by the PCM and is not adjustable. If there is no spark, diagnose the ignition system. If timing is actually off, the timing chain may have slipped and needs replacement.
Conversation Summary
The owner of a 1997 GMC Yukon asked how to adjust ignition timing after a no-start following fuel-pump work. The vehicle cranks but appears to have no spark, and a shop said the timing was off. The expert explained that the PCM controls ignition and injector timing, so no adjustment is allowed. They advised verifying spark and checking the ignition system first; a slipped timing chain would only be considered if timing is confirmed to be off.