# timing mark jumps around when idling, GA16DE, 94



## kp3ft (Sep 25, 2010)

I've been trying squeeze out the best gas economy from our 94 Sentra GA16DE automatic. I did the usual easier stuff: new plugs, wires, distributor cap/rotor, and adjusted the timing. I also used a diagnostic tool and software, which apparently didn't show anything wrong. The mileage is better, but it still seems low compared to what others are getting. The best we get is around 26 mpg (combined, cit/hwy) with driving carefully. I noticed that the timing mark jumps around when the car is idling, which I think is not normal. Any ideas of where to check first? There's so many sensors, etc. it can quickly become expensive to replace everything, and we are on a very tight and low budget. I'm guessing to start with the upper chain tensioner first...would that cause a jumping timing? The car has a bit less than 100k on it. Thanks for any advice.


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## Sunny (May 6, 2002)

in order to check your timing

warm up engine to operating temp

rev engine 3 times, not exceeding 4,000rpm

shut off engine

pull TPS (throttle position sensor)

Start engine

connect your timing light

check timing

there are 6 marks from left (pulley mark closest to firewall) 
-5 = 0 = 5 = 10 = 15 = 20

set timing at your desired setting and rev engine 3 times not exceeding 4,000rpm

shut off engine

reconnect TPS

start engine and test drive


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## jdg (Aug 27, 2009)

kp3ft said:


> I've been trying squeeze out the best gas economy from our 94 Sentra GA16DE automatic. I did the usual easier stuff: new plugs, wires, distributor cap/rotor, and adjusted the timing. I also used a diagnostic tool and software, which apparently didn't show anything wrong. The mileage is better, but it still seems low compared to what others are getting. The best we get is around 26 mpg (combined, cit/hwy) with driving carefully. I noticed that the timing mark jumps around when the car is idling, which I think is not normal. Any ideas of where to check first? There's so many sensors, etc. it can quickly become expensive to replace everything, and we are on a very tight and low budget. I'm guessing to start with the upper chain tensioner first...would that cause a jumping timing? The car has a bit less than 100k on it. Thanks for any advice.


My book does say that the marks WILL jump around a bit and you have to kinda average the marks out in your head while you're doing the adjustment.
Past that, upper tensioner, good...
Check the distributor itself, specifically try to wiggle it side to side to check the bushings in the middle of the shaft. Kinda doubt they're bad, but ya never know.
What else have you done to the engine (mods, etc)?


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