1995 Volvo 940 ignition timing very advanced please help
#1
03-24-2018, 04:14 PM
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1995 Volvo 940 ignition timing very advanced please help
my 95 940 has ignition timing issues, it idles around 1200-1400 rpm has hard start and several new part and things verified such as, new timing belt installed correctly no teeth out, new crank sensor , new dizzy cap and rotor, mechanical timing verified everything lined up perfect on tdc #1, when running at operating tempature and using a timing light the timing mark is about 90 degrees advanced ( a right angle to the left ) from the timing marks on the lower timing belt cover I know that these balances slip as the rubber ages but my car is pinging very bad upon acceleration which tells me it is indeed advanced to some extent to far, moving the dizzy does nothing because the computer is in control of the ignition timing, I have an ase certified mechanic trying to help me as much as he can when he has time he works on foreign most of the time so he is familiar with some Volvo but not as much on these older ones please help any knowledge will help I jus want this ole brick to run right so I can enjoy drivin her she’s been sittin to long...
#2
03-24-2018, 05:53 PM
the timing on LH2.4 is entirely under computer control and has no adjustments. the input to the timing is the crank position sensor and holes drilled in the flywheel (clutch) or flexplate (automatic).
the ICU (Ignition Control Unit) gets inputs from the crank position sensor, from the coolant temp sensor, and thats about it.
pinging on acceleration can also be from bad gas, from overheating, from excess cylinder carbonization.
the ICU (Ignition Control Unit) gets inputs from the crank position sensor, from the coolant temp sensor, and thats about it.
pinging on acceleration can also be from bad gas, from overheating, from excess cylinder carbonization.
#3
03-25-2018, 07:05 AM
My first thought is to verify whether the harmonic balancer has slipped or not as you noted in your post. This means checking the mark on the pulley when cylinder 1 is at top dead center.
If it were me, I would hand rotate the pulley until the distributor points to cylinder 1 wire. Then hand rotate the crankshaft back 90 degrees. Remove cylinder 1 spark plug and feed a short length of rope in there (use the rope trick). Hand rotate the crankshaft forward until it stops due to the rope. This should be just a few degrees before top dead center. Now check the position of the timing marks. If it still shows off then that would confirm that either the pulley has slipped due to separated rubber or that the pulley was not installed properly when the timing belt was done.
If it were me, I would hand rotate the pulley until the distributor points to cylinder 1 wire. Then hand rotate the crankshaft back 90 degrees. Remove cylinder 1 spark plug and feed a short length of rope in there (use the rope trick). Hand rotate the crankshaft forward until it stops due to the rope. This should be just a few degrees before top dead center. Now check the position of the timing marks. If it still shows off then that would confirm that either the pulley has slipped due to separated rubber or that the pulley was not installed properly when the timing belt was done.
#4
03-25-2018, 12:45 PM
#5
03-25-2018, 08:39 PM
Even if the harmonic wheel was bad it shouldn't make a difference on the timing . It would only be detected when you use a timing light. Was there any recent work done on the car like maybe a timing belt change. Do you have any engine codes. Also crank harmonic balance wheels cost between $50-$100 so it's cheap to replace especially if you have over 100K miles on it.
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