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peterpete190
peterpete190, Auto Technician
Category: Subaru
Satisfied Customers: 29068
Experience:  Auto repair Technician with 17 years experience.Past ASE and other certifications.
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Subaru impreza 2005 1.6ts. What would cause negative timing?

Customer Question

Subaru impreza 2005 1.6ts.What would cause negative timing? Drops from 35 degrees on idle to near - 7 while driving / with load. Timing is accurate (timing belt checked) , cam and crank sensors checked, tps checked, thermostat changed, throttle serviced, injectors serviced.
Submitted: 2 months ago.
Category: Subaru
Expert:  peterpete190 replied 2 months ago.

Hi my name is ***** ***** I will be happy to assist with this today.In some cases I may need more info to assist better.I apologize for any delay.My info is somewhat limited on your model here but I had seen no one else has responded and would like to see if I can help here.If at any time you feel that I cannot help with this please let me know.

My info doesnt cover your engine due to the country difference but what control the timing or aids the computer in controlling the electronic timing is an engine knock sensor.If you have knock sensors on this engine if one is faulty or if you have two that are reading incorrectly then this causes the computer to retard the timing like you see here.I have had to replace several knock sensors for this fault.

If your model does not have these sensors or they were already replaced this can be a fault with the engine computer itself retarding the timing when it shouldnt be since all of these other components have been replaced already.

One of these two components here is usually the cause.

If more help is needed, use the reply tab to continue our conversation. If no further assistance is needed, kindly rate my service,your 5 star rating is appreciated ( should be a link to click on here or above).You can rate at any time and we can continue to work on your question as this will not close out your question.Keep in mind in some cases it can be difficult to fully diagnose or help repair your vehicle without seeing it and I work on delivering the best possible answer from what I see to work with.

Thanks Pete

Customer: replied 2 months ago.
Knock sensor already replaced as well.
Expert:  peterpete190 replied 2 months ago.

Any damage from the knock sensor wiring to the computer at all?

Does the engine have an actual knock to it?

Customer: replied 2 months ago.
5 volts to the pin of the knock sensor.No audible pinging on the engine.
Expert:  peterpete190 replied 2 months ago.

Since the sensor is o.k. check the ground to the engine from the battery and make sure it is o.k.

If this is all o.k. and all of the components you have listed above were checked and/or replaced the only other component I see that can be causing this issue is a fault with the engine computer itself.It may have an internal electrical fault which is causing the timing to act up like this here.I have seen engine computer failure in the past before cause issues like this here with it needing replaced.

Let me know if you need anything else and feel free to rate my help here or above ( should be a link to click on ) as this is how I receive credit for my time.Your 5 star rating is appreciated

Thanks Pete

Customer: replied 2 months ago.
Can fuel pump / pressure be a cause?
Expert:  peterpete190 replied 2 months ago.

If you have a pressure issue due to pump issues or a restricted fuel filter this can cause the computer to try and compensate for a lean running condition which can cause the timing to retard like this here.This is a very good possibility.

Let me know if you need anything else and feel free to rate my help here or above ( should be a link to click on ) as this is how I receive credit for my time.Your 5 star rating is appreciated

Thanks Pete