Question about poor acceleration

[buysell]

Chase,

Ok, so those items are off the list. Check the fuel delivery. There could be a flow restriction for other reasons.

As has been pointed out, your symptoms could also be due to weak spark. You may not need all new wires, cap, rotor, and so on but you need to make sure they are in good condiiton. Make sure everything is clean and dry. Look for cracks, carbon tracks or other evidence of arcing to ground from the high voltage. As the engine speed and load increase the voltage requirement increases. If the insulation on any of the high voltage parts is marginal it will arc to ground before the voltage is high enough to fire the plugs. Make sure the carbon brush in the cap is long enough and moves freely. An old cap and rotor might look good and not have any high voltage leakage but as they wear from use and get cleaned during service the air gap increases which adds to the voltage requriement.

Make sure the primary connections are clean and tight as well. Don't forget the primaray circuit goes through the tach on the early Z so chech the connections there as well.

Set the timing to the factory setting for your car. If you do not have a timimg light dead time it. That is the one upshot to still having points is being able to set the timing without running the engine. Also, if you have a dwell meter check the dwell. If the points gap and the dwell do not agree to a reasonable degree it indicates a problem.

Trouble shooting is a process of elemination. Start with the most likely suspects and work toward the unlikely along a logical path.

Very good BeermanPete,

Also check for vacuum leaks in the engine compartment. You tested the distributer for correct operation, make sure the vacuum hoses are in good working order.

--Justin

[CW240Z]

beermanpete and buysell,

Thank you for your input and suggestions on what to do. I went through the process of checking the ignition components like suggested and could not see anything that was obviously at fault. While doing this I managed to find another coil in my extra parts box for the car I've accumulated. Surprisingly the other coil I had seemed to fix a good portion of the problems. I will fine tune the timing according to the FSM and see where that takes me.

Chase

[madkaw]

Didn't mean to sound like an a$$, but I still stand by my point that to ask us to help diagnose an issue that could diectly related to a simple tune up(Wires), which are 30$, just doesn't make sense. You are NOT "past the point of a basic tune up".

As pointed out-during heavy loading the spark has to be strong and good wires definetly could be the culprit, so I would replace your 27 year old stuff. The coil swap was a good idea, and you might be on to something. I have had coils going bad on newer cars and the car would buck during heavy loading like the trans was going bad, but it would fine everywhere else. Searching , you might find the ohm reading for a stock coil and check that against yours.

Lean condition also fits the your description.

[LeonV]

Didn't mean to sound like an a$$, but I still stand by my point that to ask us to help diagnose an issue that could diectly related to a simple tune up(Wires), which are 30$, just doesn't make sense. You are NOT "past the point of a basic tune up".

As pointed out-during heavy loading the spark has to be strong and good wires definetly could be the culprit, so I would replace your 27 year old stuff. The coil swap was a good idea, and you might be on to something. I have had coils going bad on newer cars and the car would buck during heavy loading like the trans was going bad, but it would fine everywhere else. Searching , you might find the ohm reading for a stock coil and check that against yours.

Lean condition also fits the your description.

He measured wire resistance and found it in spec, as far as he said. Only other thing I'd do is run the car in the dark and see if there is any arcing wire-to-wire.

Checking the coil per the FSM is a good idea...

[CW240Z]

The wires do not have any breaks or damage in the casing, and meet the required resistance spec in the FSM. LevonV I did the test of checking them in the dark while running and no arcing happened.

madkaw what is YOUR definition of a basic "tune-up" New cap, coil, points, fuel/oil filters, fluids flush, SUs rebuilt, new fuel lines, spark plugs, everything gaped and adjusted according to the FSM. That;s just in the engine bay. I don't think I left anything out with the exception of the plug wires but they have already been tested and in good condition.

The new coil seemed to do the trick. No backfiring under deceleration, the car will easily hit 5000 rpm and has the power through the whole power band. Thanks guys for the tips and suggestions.

Chase

[madkaw]

Basic tune up IMHO would include replacing 27 year old wires.

[John Coffey]

Its a fuel problem.

[CW240Z]

Its a fuel problem.

John,

The fuel pressure and filters were checked and verified to be in good shape. My new coil solved the issues and the car will accelerate easily under load up to 5500 rpm with no problems

Chase

[John Coffey]

I missed your post above. Glad its fixed.