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Discussion Starter · #1 ·
Ok,
My 81 Turbo is malfunctioning. The timing is bizerk, about 50degrees BTDC. The factory specs are supposed to be 20 degrees BTDC. I had a question about the detonation sensor. Could the detonation sensor cause these symptoms if it goes bad??? I know that this is a safeguard against motor meltdown and that it is supposed to retard the ignition if this detonation would ever begin. How far does it retard and could this be my problem???? How do I test this thing, nothing in the Haynes manual???? Or could this just be an extremely stretched or jumped chain???? I would think that at this extreme I would start banging parts(valves and pistons) and that has yet to start.
Someone HELP----point me in the right direction!!!!!!!!!!!
Thanks Scott
 

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The timing is adjustable w/a bolt located on the pickup of the crank trigger (the sensor). You will need to loosen the bolts in order to adjust. However, be careful that you do not change the relationship of the sensor to the trigger wheel on the balancer. You should only mover the sensor up or down to adjust the timing. The distance between the sensor and the trigger wheel is also adjustable, so don't do that.

Now, the question I have is, how did the timing become wrong in the first place? Are you sure you are looking at the correct marks? Due to the nature of the timing controls, the timing doesn't usually become wrong. I don't think that the knock sensor would have anything to do w/it. If the engine doesn't knock, then I would suspect that the timing is correct and the knock sensor is working correctly. You may be able to check the knock sensor by rapping on the block w/a hammer as the engine idles. Observe the timing marks and it should retard.

I also doubt that the timing chain has jumped. This would cause the engine to run very badly or not at all if severe. Here's the solution; if it runs ok, then don't worry about it. If not, then post its symptoms here on the forum. Good luck.

Ian
 

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Discussion Starter · #3 ·
Well Ian,
This timing is something that I have known about for a while and figured that this was the reasoning for my lack of horsepower. No, I did not do anything prior to this.
However, I do know about the lower Crank angle sensor and when I adjusted that to either extreme the timing only moved one way and that was to advance it to about 10 degrees to 40 degrees BTDC. When I move the distributor to either extreme the timing does not move either. Yes, I know where the timing mark is. The reasoning for this inquiry is about the detonation sensor. I know that it is supposed to send signals to the ECU to retard the ignition when detonation occurs. How much does it retard the ignition? I will try the beating on the block thing, but if the sensor is bad would it not keep the ignition retarded to its extreme which is set in the ECU? I am just confused.
 

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Where are you from?
it seems that all the 280ZXs don't like cold air
they are all on the west cost
Im on the east cost and don't know anyone with a 280ZX

Jeff 280ZX
 

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Discussion Starter · #5 ·
> Where are you from?
> it seems that all the 280ZXs don't like cold
> air
> they are all on the west cost
> Im on the east cost and don't know anyone
> with a 280ZX

> Jeff 280ZX

Well, Jeff I am out on the west coast in CA. The car and myself residing in FL for most of its life til the move 3 yrs ago to So. CA. I just wish somebody could help me with my problem.
 

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I'm sorry, but I don't know how much the knock sensor retards the timing. However, from what you have written, I doubt that this is your problem. You have stated that the timing is over-advanced, however the job of the knock sensor is to retard the timing. If the timing is that far advanced, the engine should be detonating. Is this the case? Detonation would also occur if the knock sensor was faulty. The timing should be set to 20 like you said, and this is a baseline. The ecu would do the advance curve from there and then retard as needed per signals from the knock sensor. However, in reality, the ecu does not advance the timing, it retards it from a high setting to a manageable level for running conditions. You may have a fault in the ecu. However, if you still suspect the knock sensor, the best way to check it is to replace it w/a known good one. Or you can try rapping on the block like I stated before. Good luck. Please be patient, there are those of us who are trying to help.

Ian
 
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