Rob Kuhlman Posted March 7, 2006 Share Posted March 7, 2006 I'm starting to work through the list of 'things to do' on this new 2.2L 5-speed Legacy wagon which I bought from my son, and am down to this one: Car starts right up when cold (teens to mid-20s in the mornings; 40s in afternoon), but tends to be lumpy for the first 3-4 seconds, then smooths right out. However, when taking off, for the first maybe 60 seconds, the pickup is mildly alternately surge-y and hesitant. If I didn't know better, I'd suggest one side is fighting the other. Once the motor warms up, it runs like a champ. No codes are displayed. Brand new NGK plugs didn't change the behavior. My son noticed these symptoms for about 6 months before he sold it to me. It's got ~120,000 miles. I can certainly live with these symptoms, but it's clear to me that something isn't right and its fix shouldn't be too ellusive. So I'm thinking coolant temperature sensor. Is there any way to test this with a VOM -- resistance when cold, for instance? Or is it simply a matter of swapping in a new one. Thanks in advance! Rob Quote Link to comment Share on other sites More sharing options...
cookie Posted March 7, 2006 Share Posted March 7, 2006 I'd just swap in a new one as they are cheap and easy. I've had a couple of friends that tested thiers and were convinced they were good. Swapping the sensor fixed the problem and I have no idea why they seemed good. Perhaps it was fixed by removing and installing the sensor? Quote Link to comment Share on other sites More sharing options...
WAWalker Posted March 7, 2006 Share Posted March 7, 2006 IF you find the problem be sure to post an update. I lost big $ trying to solve this issue for a customer this winter. And every 95 manual trans Legacy I have had in the shop since is the same way. The Subaru tech at the dealer didn't have a clue, the other independent Subaru shop in town didn't have a clue, and IATN (Internatianl Automotive Technicans Network) has been no help. After testing and retesting everything, I then swap tested everything that could cause it. Nothing changed. I don't think this will be a problem if you drive the car enough to get it good and warm after start up. This customer hardly ever drives her car and when she does it very seldom leaves town, and this is a small town so the trips are short. Quote Link to comment Share on other sites More sharing options...
cookie Posted March 7, 2006 Share Posted March 7, 2006 That's interesting WA. Could this be a programing issue on 95s? Quote Link to comment Share on other sites More sharing options...
WAWalker Posted March 7, 2006 Share Posted March 7, 2006 That's interesting WA. Could this be a programing issue on 95s? That's what I'm thinking. Haven't paid the $500+ for a brand new ECM, PN superceded 2 or 3 times, don't know what changes were made. But the ones I have tried and tested, this is what I have found. The fuel enrichment duration on a cold start seems quite long. Up to 6 seconds. And the fuel injector PW quite high on really cold starts, have seen it spike to 84 ms. These cars are overfueling. That is why they run a little "lumpy" at first. You can watch the fuel inj. pw and as soon as it starts leveling out in a more normal range the engine smooths out an comes up on high idle the way it should. If car is not drive enough to fully warm up for any period of time, plugs get carbon build up, oil gets diluted, converters start stinking................ Only 95's with manunal transmission. Ones with auto's don't seem to have this problem. ECM PN are different too. Quote Link to comment Share on other sites More sharing options...
cookie Posted March 7, 2006 Share Posted March 7, 2006 If it happened to me I would have been replacing the sensor first and then cussing quite a bit. Not much you can do about overfueling these days, no choke to adjust. Quote Link to comment Share on other sites More sharing options...
WAWalker Posted March 7, 2006 Share Posted March 7, 2006 Fuel injected cars have a "clear flood" mode programed in. Hold gas peddal to the floor, crank engine. Computer sees WOT and low RPM (cranking) and decreses amount of fuel injected. These problem cars will start fine like that. Funny thing. Would think that Subaru would know whats going on with these things. They don't even tell you what the normal fuel enrichment should be on a cold start. I just came to the conclusion that 6 seconds is way to long since nothing eles seems to be causeing the problem and 95 auto's don't have that kind of cold start enrichment. I'm no electronic engineer so........................... Quote Link to comment Share on other sites More sharing options...
cookie Posted March 7, 2006 Share Posted March 7, 2006 Do they have altitude adjustment? Are you high enough that this could have an effect? Quote Link to comment Share on other sites More sharing options...
WAWalker Posted March 7, 2006 Share Posted March 7, 2006 No baro sensor. Quote Link to comment Share on other sites More sharing options...
cookie Posted March 7, 2006 Share Posted March 7, 2006 That would be too easy anyway. Quote Link to comment Share on other sites More sharing options...
WAWalker Posted March 7, 2006 Share Posted March 7, 2006 Keep the ideas coming. I'd like to be able to rectify this issue. I've wondered if being a Mass Air Flow system, when they start getting up there in milage and the volumetric efficiency starts dropping if the fuel map is just to agressive in open loop. Once they are warmed up the grams/second are right in line with what Subaru says is good for a normal engine so..........................I donno. Some of these "Tuner" guys should be able figure out how to reprogram the computer to tone down the cold start enrichment. Quote Link to comment Share on other sites More sharing options...
cookie Posted March 7, 2006 Share Posted March 7, 2006 At this point all the sensors and the MAS are at thier sell by date. You don't really want to change everything on an old car. The real worry is what is a 95 legacy worth? I seem to remember when we sold a 93 Legacy wagon that looked pretty good with no real dents, no rust, ran fine, new brakes and clutch, we only got $14 or $1500 dollars. At that point you don't want to put a thousand bucks worth of sensors and other parts in to cure something that you can just let warm up. Quote Link to comment Share on other sites More sharing options...
WAWalker Posted March 7, 2006 Share Posted March 7, 2006 I'm with ya. That is why that car didn't get a new ECM to see if that would change anything. List price, $620. But the burning question is, did they change the cold start fuel map in the newest computers? Quote Link to comment Share on other sites More sharing options...
cookie Posted March 7, 2006 Share Posted March 7, 2006 Sure would be neat to try switching if you just had a used one around. Quote Link to comment Share on other sites More sharing options...
Smarty Posted March 8, 2006 Share Posted March 8, 2006 Just for the record I have a 95 2.2/MT wagon with 95k miles. Same thing - when it's below about 30 degrees it starts out way rich with a low rpm. After a few seconds it pops up to normal cold start revs then a bit of hesitation until warm. It's been like this for a few years. I replaced the temp sensor and no change. It always starts and I always forget about it in the summer.... Quote Link to comment Share on other sites More sharing options...
Chef Posted March 8, 2006 Share Posted March 8, 2006 I have a similar problem on my 92 legacy, with an intermittent hard-start when cold. The first crank will seem normal, then following cranks sound different (slightly faster?). The car will only start if I give it gas, but not if I floor it - rather if I feather it quickly. Then it runs lumpy and stinks of gas, sometimes for a few seconds, sometimes for a few minutes. I figured it must eb flooding, and know I should change the coolant temp sensor, but because it is intermittent I keep putting it off. The worst time this occurred was after I hadn't started my car for a week in -20°C temps - had a real hard time starting the car and it wasn't just from the cold. Quote Link to comment Share on other sites More sharing options...
WAWalker Posted March 8, 2006 Share Posted March 8, 2006 Just for the record I have a 95 2.2/MT wagon with 95k miles. Same thing - when it's below about 30 degrees it starts out way rich with a low rpm. After a few seconds it pops up to normal cold start revs then a bit of hesitation until warm. It's been like this for a few years. I replaced the temp sensor and no change. It always starts and I always forget about it in the summer.... Interesting.........these '95 MT Legacy's. That is exactly what I found. Once engine temp was above 40 the problem went away. So I figured that these cars never have a problem in the summer time. Funny I have never got any other complaints about this, and every other auto tech I've talked to said they've never ran across this problem. I'm starting to feel better about not being able to fix the problem, sounding more and more like a poorly programed computer. Still don't feel good about the time and money lost though. Quote Link to comment Share on other sites More sharing options...
Rob Kuhlman Posted March 8, 2006 Author Share Posted March 8, 2006 You folks have been terrific -- what neat insights! Just to see if the 'initial rich' explanation made any sense, I did what WaWalker suggested -- I floored it when I cranked it, and the lumpiness and mild surge/hesitation was almost non-existant. Fascinating. Here's what the owner's manual says, "In case of a flooded engine, turn the starter motor for five seconds with the accelerator pedal fully depressed. ...Release the ignition switch and accelerator pedal as soon as the engine starts." I wasn't aware of the computer's ability to detect WOT and make fuel mixture adjustments accordingly. Pretty clever. And pretty clever way to work around it. Thanks again for all your wisdom. Rob Quote Link to comment Share on other sites More sharing options...
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