johnfmcewan

My 92 turbo legacy has no signal from the ECU to the O2 sensor, and nothing coming from the O2 sensor either. I put a Japanese engine in about 2 years ago. Could the ECU/O2 sensor have been 'switched off' to make it run richer or something? Everything else seems to work electrically. Should I be checking for a signal right at the ECU, not the connector for the sensor? The car has a hesitation in driving sometimes which I was starting to think could be the knock sensor, based on other posts. Which sensors are most important for the car to drive well- presumably the MAF is most important, then the TPS? I once had a check engine code for the O2 sensor some months ago but it never came up again after clearing the code. I have also had a couple of knock sensor codes stored but these don't come up again after clearing. If the knock sensor was faulty should it come up with a code immediately? Also, if I disconnect the O2 sensor no code comes up. Should it? When the car is behaving, it runs really well. When it gets the problem it lacks power, hesitates on accelerating, and appears to 'miss'. Any ideas? Thanks...

I have a 92 legacy turbo with a long term problem. It only happens sometimes but has been quite frequent lately. When starting to accelerate from a period at low revs, it stutters /coughs /missfires /doesn't run properly until it gets a good burst from the accelerator. Then it seems OK again. My feeling is that it is a fuel mixture problem. I have replaced spark plugs and filters. Also have tried another MAF sensor. Could it be the igniter or the throttle position sensor? What about a fuel pressure problem? How can I check these? generally the car always starts well. Sometimes the idle can be a bit variable. Occasionally, if I run the self check on the computer it will come up with an error code for the knock sensor. Could this be related to the problem (the problem occurs much more often than the code comes up (which might be every couple of months)) or is it more likely to be a misfire from bad petrol? Thanks for your help John