Usually ignition timing being off will not create a "bucking, breaking up" condition. If ignition timing is retarded it will create a loss of power under all load ranges, if the timing is too far advanced it may create a detonation issue in which you may/will also encounter a loss of power, if/when the engine controller see's detonation (from the Knock Sensor) it will retard ignition timing until the detonation stops, chances are you will never even hear the detonation (knocking) but it can be viewed using a scanner looking under "Knock Retard". Bucking and Breaking Up under Boost will usually be caused by... 1)Ignition System Problems a)
New parts do not always equal good parts and there is more to the ignition system than hard parts, electrical needs have to be met. b)
You need to simulate the load/boost condition and see if the ignition system is capable of providing the KV needed under those load conditions, this is easy to do and inexpensive. c)
You need an Adjustable Spark Tester, $14.00 from AutoZone.
Remove the spark plug wire from #1 cylinder spark plug, set the gap on the tester to 30 KV, then install the adjustable spark tester into the ignition wire, the clip on the tester needs to be grounded, I usually use a jumper wire from the clip to the - battery cable so you can attach the tester anywhere where you can see it from inside the car.
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Start the car and see if you have a good, strong spark jumping the gap. f)
Reinstall the removed plug wire and repeat the procedure for the other cylinders. g)
If all 4 cylinders are capable of producing 30 KV the ignition system is OK. 2)Fuel Pressure Problem a)
Fuel Pressure increases 1 PSI over static rail pressure for every 1 lb. of boost. b)
Static Rail Pressure (Key On/Engine Off with the ASD Relay manually actuated or with the engine running at idle and the FPR vacuum line disconnected and plugged) should be 53-57 PSI. Example;
You have 55 PSI static pressure, at 7 lbs of boost fuel pressure should read 62 PSI. c)
Rent a Fuel Pressure Gauge from AutoZone (it is free, leave a deposit that is fully returned when the tool is returned.) d)
Connect the fuel pressure gauge to the service port on the fuel rail, start the engine, check for leaks, disconnect the vacuum line from the FPR and read "Static" rail pressure, is it between 53-57 PSI? (static rail pressure will read lower with the vacuum line connected to the FPR, that is normal and we are not concerned with that right now.) e)
If static rail pressure is between 53-57 PSI, attach the fuel pressure gauge to the windshield facing you so you can see it from the passenger compartment. f)
With a helper go for a ride until you encounter the bucking/breaking up condition, what is fuel pressure reading?, It should be steady and reading 1 PSI over static for every 1 lb of boost, is it?
3)Overboost Shutdown a)
*The wiring may be different at the pump and the ASD Relay will be different year to year(84,85-87,88-90,91-up) but the test is basically the same. *MPFI (multi-port fuel injection) works on pressure differential across the injectors. *Since the injectors are exposed to manifold vacuum total...
If you experience Overboost (above 14.7 PSI on a Stock 2 Bar Setup) the engine controller will shutdown the fuel and ignition system until boost levels come down, it will continue this process if boost levels continue to rise. Overboost Shutdown is very violent and it will feel just like the symptoms you are describing. Generally a Code 45 will be stored in memory, but not always. b)
If the car is not equipped with a boost gauge you will need to tee a Vacuum/Pressure gauge inline with a manifold vacuum source and tape it to the windshield as you did with the fuel pressure gauge, you can do both together. c)
You will need a Vacuum/Pressure gauge that reads up to 15 PSI.
Order Actron Vacuum And Pressure Tester, 2-1/2" Face, CP7802 at Zoro.com. Great prices & free shipping on orders over $50 when you sign in or sign up for an account.
You will also need a "Handheld Vacuum Pump" which can be rented at AutoZone for free.
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Checking/Setting Ignition Timing
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Remove the airbox so you have access to the timing window on the bell housing.
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Start the engine and allow to warm to normal operating temp 3)
With the engine running disconnect the Coolant Temp Sensor connector. The Power Loss/Check Engine Lamp will illuminate and the Cooling Fan will cycle on, this indicates that the system is in "Failure/Limp In" mode and ignition timing is at "Base". Pic of the CTS, (Disregard the Multimeter)
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With the timing light connected to #1 cylinder and the battery shine the timing light at the timing window on the bell housing, the mark on the flywheel should be at 12 degrees BTDC (Before Top Dead Center).
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If it is not, loosen the distributor hold down bolt and turn the distributor clockwise to retard the timing or counter clockwise to advance the timing.
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Once you are set to 12 degrees BTDC tighten the distributor hold down bolt, verify you are still at 12 degrees BTDC. 7)
Shut the engine off, reconnect the CTS connector and reattach the airbox. Note:
A Code 22 will be stored in memory, it does not indicate a problem and it will go away after 50 key starts or with battery disconnect.