97 jeep cherokee sport acceleration problem
i got check engine codes po135 & po138. when i accelerate quickly from a
stop it hesitates badly and shakes and then moves all of a sudden.i changed the 02 sensors but still have the same problem. it doesn't hesitate when i'm moving at a good speed. mechanic is stumped. any help would be greatly appreciated. |
Re: 97 jeep cherokee sport acceleration problem
edfisher wrote:
> i got check engine codes po135 & po138. when i accelerate quickly > from a stop it hesitates badly > and shakes and then moves all of a sudden.i changed the 02 sensors but > still have the same problem. it doesn't hesitate when i'm moving at a > good speed. mechanic is stumped. any help would be greatly > appreciated. http://revbeergoggles.com/Fixes/diagnostics.html WOT does not use the O2 sensor, TPS and coolant temp are the primary two sensors for acceleration mode. So, how's the throttle position sensor doing? It should have three lines. The outer two are 5v and ground. the inner one should smootly move The coolant temp sensor is usually not the problem, and you can check that with the temp gauge. It can also be a failing coil (which sets no codes) or any general problem with the spark side. (coil, distributor, rotor, cap, wires, plugs) I'm leaning toward spark. How long has it been since you put new cap/rotor/wires/plugs? For testing the TPS ---- If your moderatly skilled with electronics and have a digital volt meter you can test the TPS sensor. There are three leads. one is ground, one is voltage, and the other varies as you move the throttle body. Basically: Turn the ignition on but do not start the jeep. back-probe the connector and find the ground and +5v (should be the outside two wires) If there isn't 5v there then you might have a break in the harness or just not a good contact with the wire. Now measure the center wire against the ground. Throttle butterfly Voltage CLOSED >200 mV OPEN <4.8 V The transition between full open and closed should be smooth with no jumps or dropouts. ---- -- DougW |
Re: 97 jeep cherokee sport acceleration problem
edfisher wrote:
> i got check engine codes po135 & po138. when i accelerate quickly > from a stop it hesitates badly > and shakes and then moves all of a sudden.i changed the 02 sensors but > still have the same problem. it doesn't hesitate when i'm moving at a > good speed. mechanic is stumped. any help would be greatly > appreciated. http://revbeergoggles.com/Fixes/diagnostics.html WOT does not use the O2 sensor, TPS and coolant temp are the primary two sensors for acceleration mode. So, how's the throttle position sensor doing? It should have three lines. The outer two are 5v and ground. the inner one should smootly move The coolant temp sensor is usually not the problem, and you can check that with the temp gauge. It can also be a failing coil (which sets no codes) or any general problem with the spark side. (coil, distributor, rotor, cap, wires, plugs) I'm leaning toward spark. How long has it been since you put new cap/rotor/wires/plugs? For testing the TPS ---- If your moderatly skilled with electronics and have a digital volt meter you can test the TPS sensor. There are three leads. one is ground, one is voltage, and the other varies as you move the throttle body. Basically: Turn the ignition on but do not start the jeep. back-probe the connector and find the ground and +5v (should be the outside two wires) If there isn't 5v there then you might have a break in the harness or just not a good contact with the wire. Now measure the center wire against the ground. Throttle butterfly Voltage CLOSED >200 mV OPEN <4.8 V The transition between full open and closed should be smooth with no jumps or dropouts. ---- -- DougW |
Re: 97 jeep cherokee sport acceleration problem
edfisher wrote:
> i got check engine codes po135 & po138. when i accelerate quickly > from a stop it hesitates badly > and shakes and then moves all of a sudden.i changed the 02 sensors but > still have the same problem. it doesn't hesitate when i'm moving at a > good speed. mechanic is stumped. any help would be greatly > appreciated. http://revbeergoggles.com/Fixes/diagnostics.html WOT does not use the O2 sensor, TPS and coolant temp are the primary two sensors for acceleration mode. So, how's the throttle position sensor doing? It should have three lines. The outer two are 5v and ground. the inner one should smootly move The coolant temp sensor is usually not the problem, and you can check that with the temp gauge. It can also be a failing coil (which sets no codes) or any general problem with the spark side. (coil, distributor, rotor, cap, wires, plugs) I'm leaning toward spark. How long has it been since you put new cap/rotor/wires/plugs? For testing the TPS ---- If your moderatly skilled with electronics and have a digital volt meter you can test the TPS sensor. There are three leads. one is ground, one is voltage, and the other varies as you move the throttle body. Basically: Turn the ignition on but do not start the jeep. back-probe the connector and find the ground and +5v (should be the outside two wires) If there isn't 5v there then you might have a break in the harness or just not a good contact with the wire. Now measure the center wire against the ground. Throttle butterfly Voltage CLOSED >200 mV OPEN <4.8 V The transition between full open and closed should be smooth with no jumps or dropouts. ---- -- DougW |
Re: 97 jeep cherokee sport acceleration problem
edfisher wrote:
> i got check engine codes po135 & po138. when i accelerate quickly > from a stop it hesitates badly > and shakes and then moves all of a sudden.i changed the 02 sensors but > still have the same problem. it doesn't hesitate when i'm moving at a > good speed. mechanic is stumped. any help would be greatly > appreciated. http://revbeergoggles.com/Fixes/diagnostics.html WOT does not use the O2 sensor, TPS and coolant temp are the primary two sensors for acceleration mode. So, how's the throttle position sensor doing? It should have three lines. The outer two are 5v and ground. the inner one should smootly move The coolant temp sensor is usually not the problem, and you can check that with the temp gauge. It can also be a failing coil (which sets no codes) or any general problem with the spark side. (coil, distributor, rotor, cap, wires, plugs) I'm leaning toward spark. How long has it been since you put new cap/rotor/wires/plugs? For testing the TPS ---- If your moderatly skilled with electronics and have a digital volt meter you can test the TPS sensor. There are three leads. one is ground, one is voltage, and the other varies as you move the throttle body. Basically: Turn the ignition on but do not start the jeep. back-probe the connector and find the ground and +5v (should be the outside two wires) If there isn't 5v there then you might have a break in the harness or just not a good contact with the wire. Now measure the center wire against the ground. Throttle butterfly Voltage CLOSED >200 mV OPEN <4.8 V The transition between full open and closed should be smooth with no jumps or dropouts. ---- -- DougW |
Re: 97 jeep cherokee sport acceleration problem
thanks doug. i haven't had any kind of tuneup since i got the car 2 years
ago. the cooalnt temp sensor was changed a few months ago along w/ radiator and water pump. i'll check the tps. |
Re: 97 jeep cherokee sport acceleration problem
thanks doug. i haven't had any kind of tuneup since i got the car 2 years
ago. the cooalnt temp sensor was changed a few months ago along w/ radiator and water pump. i'll check the tps. |
Re: 97 jeep cherokee sport acceleration problem
thanks doug. i haven't had any kind of tuneup since i got the car 2 years
ago. the cooalnt temp sensor was changed a few months ago along w/ radiator and water pump. i'll check the tps. |
Re: 97 jeep cherokee sport acceleration problem
thanks doug. i haven't had any kind of tuneup since i got the car 2 years
ago. the cooalnt temp sensor was changed a few months ago along w/ radiator and water pump. i'll check the tps. |
Re: 97 jeep cherokee sport acceleration problem
i forgot to add that the problem only happens when i'm making a turn or
after i just turned. i'm also getting a rotten egg smell. |
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