Yogi Posted November 29, 2006 Share Posted November 29, 2006 02 Forrester, auto trans. Need help on this. It started stumbleing while the cruise was on (only once in awhile), and it would stumble after slowing down to where the rpm was somewhere around 2000-2500 and getting back in the gas. I took it back to my machanic and they could find nothing wrong. They did do a fuel system cleaning and the engine ran better for a while, about 250 miles before it started again. The car ran fine before the timing belt was replaced. Quote Link to comment Share on other sites More sharing options...
porcupine73 Posted November 29, 2006 Share Posted November 29, 2006 Hi yogi and welcome! Are you maybe feeling a little driveline shock with the TC locked up when the agressive cruise control gets back on the throttle after coasting? Quote Link to comment Share on other sites More sharing options...
Yogi Posted November 30, 2006 Author Share Posted November 30, 2006 Hi yogi and welcome! Are you maybe feeling a little driveline shock with the TC locked up when the agressive cruise control gets back on the throttle after coasting? That very well could have been the problem,but it was doing it under normal driving and not coasting and I don't think it would explain the lower rpm stumbles. The lower rpm stumbles happen more often and when it happens there will be a clunk to the drive line as power is lost and then reaplied. Also I have noticed that at WOT there seems to be a miss or it seems as if it's not getting gas, I guess you might call it "little quick surges". Quote Link to comment Share on other sites More sharing options...
porcupine73 Posted November 30, 2006 Share Posted November 30, 2006 How many miles are on the vehicle? If anything like plugs, wires, air filter, fuel filter, o2 sensor, etc. are due for changing or are suspectable I'd change them out with OE components. How's the throttle butterfly look? I peek at mine by taking out the air filter, opening the throttle a little and looking in there with a mirror and shop light, of course maybe your year has drive by wire? Does this vehicle have a MAF or a MAP? Quote Link to comment Share on other sites More sharing options...
fishy Posted November 30, 2006 Share Posted November 30, 2006 How many miles are on the vehicle? If anything like plugs, wires, air filter, fuel filter, o2 sensor, etc. are due for changing or are suspectable I'd change them out with OE components. How's the throttle butterfly look? I peek at mine by taking out the air filter, opening the throttle a little and looking in there with a mirror and shop light, of course maybe your year has drive by wire? Does this vehicle have a MAF or a MAP? I'm thinking ignition would be a good place to check as well. I had the tip of a sparkplug burn off in my old Lumina and it acted just like Yogi has described. Replaced the plugs and she was smooth as silk again. I wonder if your wires were brittle or something and got beat up a little during the t-belt work. Quote Link to comment Share on other sites More sharing options...
Yogi Posted December 6, 2006 Author Share Posted December 6, 2006 Thanks for the responce guys. I took the car to the dealer to check for any codes stored in the ECU and they found while checking for codes that the O2 senser was not reading right. It was well below what it should have been. By the way; there were no codes. I replaced the sensor and will see if that was the problem(I'm pretty sure it was). Quote Link to comment Share on other sites More sharing options...
DerFahrer Posted December 6, 2006 Share Posted December 6, 2006 If the car ran fine before the timing belt was changed, and now it runs bad, then you can be pretty sure the timing is now off. Quote Link to comment Share on other sites More sharing options...
ferret Posted December 6, 2006 Share Posted December 6, 2006 You got it already...Front O2 sensor. 01/02 Subarus are known for this, but only by sevice dept's who have tripped across it. They gave you the answer when they said no codes, but the from O2 sensor was not reading correctly. It intermittently thinks the engine is running too rich and cuts the fuel way back or even shuts off completely. That's why it doesn't set a code. Feels like you have a tank of bad gas. Usually fine at startup, but acts up after warmup. Another reason to have more than a code reader if you are a serious Do-It-Yourselfer mechanic. Quote Link to comment Share on other sites More sharing options...
Yogi Posted December 6, 2006 Author Share Posted December 6, 2006 I've drove it up to 250 miles at one time and had no problems and then it would start doing it's stumbleing act. Like you said; when it was acting up, it seemed to have bad gas or not enough at WOT. Now it seems much more responsive and needs very little touch with the gas pedel to maintain hwy speed. Quote Link to comment Share on other sites More sharing options...
Yogi Posted December 10, 2006 Author Share Posted December 10, 2006 Well another update.... I replaced the O2 sensor and it ran fine for a couple of days. Was heading back home from a short trip and she started doing it again. I'll report back when I find something else, so as to help the next guy. Quote Link to comment Share on other sites More sharing options...
Petersubaru Posted December 10, 2006 Share Posted December 10, 2006 What would you recommend to have more then just a code reader... You got it already...Front O2 sensor. 01/02 Subarus are known for this, but only by sevice dept's who have tripped across it. They gave you the answer when they said no codes, but the from O2 sensor was not reading correctly. It intermittently thinks the engine is running too rich and cuts the fuel way back or even shuts off completely. That's why it doesn't set a code. Feels like you have a tank of bad gas. Usually fine at startup, but acts up after warmup. Another reason to have more than a code reader if you are a serious Do-It-Yourselfer mechanic. Quote Link to comment Share on other sites More sharing options...
ferret Posted December 10, 2006 Share Posted December 10, 2006 Some OBDII scan tools only display a code or 2 and then reset the Check engine light. What I refer to is a tool which allows you to view the 'freeze frame' data that was taken at the time the error code occurred. As well as displays stored codes ( codes which did set the check engine light but are not acting up right now ), or the engine 'readiness' cycles which may states now require to be set to good during an inspection. As well as current live display of more than 1 sensor that you can monitor as you drive to allow you to troubleshoot slow or intermittent sensors and signals. This to me is what is needed to fix many reoccurring check engine lights when changing the first thing called out doesn't help. Quote Link to comment Share on other sites More sharing options...
OB99W Posted December 11, 2006 Share Posted December 11, 2006 It's also useful if the scan tool will display pending codes. Such codes are set by faults which have not yet caused the CEL to light, since the protocol for them is that the fault has to occur "x" times before the CEL is turned on but there haven't been "x" occurrences yet. You might wonder why being able to read pending codes is important. Well, let's say you're working on a fault that requires a few cycles before the CEL lights. You think you've found and repaired the cause, and have reset the CEL. With the ability to read pending codes, one drive cycle that duplicates the conditions that originally set the code will allow you to check if the repair has been successful. Otherwise, you have to wait for whatever number of cycles the particular fault requires for the CEL to light. Quote Link to comment Share on other sites More sharing options...
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