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I have an '89 horizon TBI 2.2 and when I stomp on the pedal it has a bog, the A/F guage goes directly to lean, then 1/2 a second or a full second later it rolls itself over to the richer end and I can feel it pulling. How can I richen up the initial throttle response and lean out the higher end. Working on geting d-cal set up, but I can't find a 5 speed TBI computer for cheap in case I break it and need the old one back in. Untill then, any manual tuning tips I could use? Thanks
-Tom
 

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There can be a number of reasons for this. If I were to guess the most likely, it is usually a vaccum leak or some other obstruction that is making the MAP sensors respond sluggishly. Any codes? TPS could also be a culprit...even the injector, which has the FPR built-in, IIRC.
 

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Double check cam timing isn't a tooth late then double check ignition timing.

Advancing ign. timing a couple of degrees can help with a stumble.

Remember to unplug CTS to check/adjust ign. timing.

Thanks
Randy
 

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Double check cam timing isn't a tooth late then double check ignition timing.

Advancing ign. timing a couple of degrees can help with a stumble.

Remember to unplug CTS to check/adjust ign. timing.

Thanks
Randy
It hesitates when it's warmed up. Hit the gas and it just doesn't go like it should. timing cam-crank and ignition is set. it acts like it hits a lean hole then accelerates fine. When it's cold it has good off idle power....
 

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There are a lot of things that can cause your hesitation issue.
You run fine when cold because you are in open loop and the controller is running on a fixed program.
Once warm the vehicle goes into closed loop operation and the controller now pays attention to the O2 sensor.
1)Are any fault codes stored?
2)Cam/Ignition Timing
As already stated above 1 tooth off on the cam sprocket will make a big difference.
3)Ignition System
Weak Coil, Excessive Secondary Resistance (Cap/Rotor/Wires), Worn/Fouled Spark Plugs
KV Requirements increase on acceleration, if the system cannot keep up due to any of the above mentioned items then a hesitation will occur.
I suggest using an Adjustable Spark Tester to check system capability and physically checking the spark plugs.
Open the spark tester to 30 KV (system is capable of 40 KV) and check at each cylinder.
IGNITION - Adjustable Spark Tester.jpg


4)Map Sensor Circuit
The Map Sensor is the Dominant Fuel Control Sensor.
If the Map Sensor Calibration is incorrect (Either Baro or Pressure) or there is a restriction/leak in the Map Sensor Vacuum Reference Line you may/will have the issue you are currently having.

5)Fuel Pressure
Fuel Pressure on a 86 - 91(1/2) TBI is 13-15 PSI and remains steady at all times.

6)Oxygen Sensor Operation
It is rare for an O2 sensor to cause a driveabilty issue (since it is only a fuel trimmer) other than lower MPG and cause high CO emissions, however...
If the O2 sensor is latched above/below .450 volts or extremely slow to respond then yes, it may cause your hesitation issue.
The job of the O2 is to inform the engine controller of oxygen content in the exhaust stream so the controller can attempt to keep the A/F ratio at 14.7/1 (Stoichiometric) in closed loop operation (idle, no load cruise)
The controller makes small corrections in the fuel mixture to try to maintain 14.7/1 and that is why the voltage will constantly cross above/below .450 volts.
Just remember, the amount of oxygen in the exhaust stream is determined by how well the engine is running so O2 voltage will be affected by any of the above items mentioned.
Once you know all of the above items are OK you can check O2 operation.
Tap into the O2 sensor signal line with a digital voltmeter.
On a warm engine voltage should constantly cross above/below .450 volts as the controller makes small fuel corrections.
 

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There are a lot of things that can cause your hesitation issue.
You run fine when cold because you are in open loop and the controller is running on a fixed program.
Once warm the vehicle goes into closed loop operation and the controller now pays attention to the O2 sensor.
1)Are any fault codes stored?
2)Cam/Ignition Timing
As already stated above 1 tooth off on the cam sprocket will make a big difference.
3)Ignition System
Weak Coil, Excessive Secondary Resistance (Cap/Rotor/Wires), Worn/Fouled Spark Plugs
KV Requirements increase on acceleration, if the system cannot keep up due to any of the above mentioned items then a hesitation will occur.
I suggest using an Adjustable Spark Tester to check system capability and physically checking the spark plugs.
Open the spark tester to 30 KV (system is capable of 40 KV) and check at each cylinder.
View attachment 273238


4)Map Sensor Circuit
The Map Sensor is the Dominant Fuel Control Sensor.
If the Map Sensor Calibration is incorrect (Either Baro or Pressure) or there is a restriction/leak in the Map Sensor Vacuum Reference Line you may/will have the issue you are currently having.

5)Fuel Pressure
Fuel Pressure on a 86 - 91(1/2) TBI is 13-15 PSI and remains steady at all times.

6)Oxygen Sensor Operation
It is rare for an O2 sensor to cause a driveabilty issue (since it is only a fuel trimmer) other than lower MPG and cause high CO emissions, however...
If the O2 sensor is latched above/below .450 volts or extremely slow to respond then yes, it may cause your hesitation issue.
The job of the O2 is to inform the engine controller of oxygen content in the exhaust stream so the controller can attempt to keep the A/F ratio at 14.7/1 (Stoichiometric) in closed loop operation (idle, no load cruise)
The controller makes small corrections in the fuel mixture to try to maintain 14.7/1 and that is why the voltage will constantly cross above/below .450 volts.
Just remember, the amount of oxygen in the exhaust stream is determined by how well the engine is running so O2 voltage will be affected by any of the above items mentioned.
Once you know all of the above items are OK you can check O2 operation.
Tap into the O2 sensor signal line with a digital voltmeter.
On a warm engine voltage should constantly cross above/below .450 volts as the controller makes small fuel corrections.
1 no codes besides 12 and 55
2 cam and ignition timing were verified.
3 new cap rotor wires and gapped rn12yc plugs. It doesn't buck like a spark issues seems more like a lack of fuel or some sensor lagging...
4 MAP is new but it came with a retrofit "Bleed" hose to replace the cracked plastic hose.
5 I'll have to check that.
6 I'll have to check that.
 

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1 no codes besides 12 and 55
2 cam and ignition timing were verified.
3 new cap rotor wires and gapped rn12yc plugs. It doesn't buck like a spark issues seems more like a lack of fuel or some sensor lagging...
4 MAP is new but it came with a retrofit "Bleed" hose to replace the cracked plastic hose.
5 I'll have to check that.
6 I'll have to check that.

3)Please verify the system is capable of 25 KV minimum (See post #8)
4)Please verify calibration and vacuum response (See post #8)

Here is Chryslers diagnostic flow chart for driveabilty issues without fault codes.
(Systems/Circuits have to be checked/tested, not just new parts installed)

(5)Test NF1 Code 51-52  1.jpg
 
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