Poor Highway Performance & Code 25
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Joined: Mar 2002
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Poor Highway Performance & Code 25
My '86 302 EFI has begun to have very poor performance on the highway in overdrive. Lately it has begun to ping under load/accel on uphill grades. I have done many tests and fixes including freeing up a seized EGR and fixing a vacuum leak. As of now the EGR and EVP work fine, but still no luck. The oxygen sensor has been replaced.
I've pulled the codes. I used to have many, but now I have worked it down to only two:
KOEO: pass
KOER: 41, 25
The 41 tells me the engine is running lean. I've had this the whole time. The 25 is related to the Knock Sensor.. "no response or little change" according to Haynes and "knock not sensed" according to Chiltons. Does code 25 mean I definitely need to replace the Knock Sensor? I've heard its a real pain to change. I'd like to confirm this before I make an attempt.
Thanks
I've pulled the codes. I used to have many, but now I have worked it down to only two:
KOEO: pass
KOER: 41, 25
The 41 tells me the engine is running lean. I've had this the whole time. The 25 is related to the Knock Sensor.. "no response or little change" according to Haynes and "knock not sensed" according to Chiltons. Does code 25 mean I definitely need to replace the Knock Sensor? I've heard its a real pain to change. I'd like to confirm this before I make an attempt.
Thanks
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Joined: Oct 2001
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Poor Highway Performance & Code 25
I have a diagnostic code manual in my hands and it says that a code 25 is a knock sensor signal is not detected during key on engine running self test. It also says that a code 41 means that oxygen sensor voltage signal always lean (low value) does not switch
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From: Virginia
Poor Highway Performance & Code 25
The code 41 may be a vacuum leak somewhere. The code 25 can be checked during the "goose test" When the code reader tells you to do the goose test, peck on the exhaust manifold with a hammer. The code 25 should go away. If it doesn't, the sensor really may have a problem.
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Joined: Jan 2002
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From: suburban atlanta
Poor Highway Performance & Code 25
[updated:LAST EDITED ON 11-May-02 AT 10:35 PM (EST)] I'd suggest that the 41 is due to a misfire... leaving excess O2 in the exhaust... excess O2 means there was too much air.. some left over after the burn... or the burn didn't take place... leaving the same O2 in the exhaust... Given that the O2 sensor is new and working.
check the plugs/plug wires/cap & rotor... Knock could also be due to crossover of the plug wires causing misfire/pre-ignition...
tom
check the plugs/plug wires/cap & rotor... Knock could also be due to crossover of the plug wires causing misfire/pre-ignition...
tom
