SoobrDad02 Posted February 21, 2011 Share Posted February 21, 2011 Hello everyone, I was wondering if anyone could give me some advice pertaining to the issue I'm dealing with in regard to my n/a '91 4EAT Legacy wagon. She starts up and runs fine for about 15-20 minutes, and then she warms up and (when stopped) the idle starts dropping from the standard 750 rpm's to 500 rpm's, and, if given the chance, she'll sputter out and eventually die unless I give it some gas:(. I'm not getting any CEL's and I've swapped out the Coolant Temperature Sensor and did my best to check for vacuum leaks:banghead:. Does anyone have any ideas on wha could be causing this:confused:? Quote Link to comment Share on other sites More sharing options...
MaddCelt Posted February 21, 2011 Share Posted February 21, 2011 My 81 Brat did the same thing. I figured it out to the intake manifold leak. When the engine was cold the leak was closed or smaller. When it warmed the metal expanded and the idle dropped. Check that area. Quote Link to comment Share on other sites More sharing options...
SoobrDad02 Posted February 21, 2011 Author Share Posted February 21, 2011 Here's my idea... If I have a leak somewhere in the general area of the intake that's allowing an excess of air IN, would it be possible to "smoke-test" it using a fog-machine to flood the general area and a timing-light to see where the excess is being pulled in? Quote Link to comment Share on other sites More sharing options...
MaddCelt Posted February 21, 2011 Share Posted February 21, 2011 Try the starter fluid method. That was how I found it. I sprayed everything that had a vacum line and eventually I found it and when I sprayed the valve at the connection you could see it suck it in and the engine sped up. Quote Link to comment Share on other sites More sharing options...
NorthWet Posted February 21, 2011 Share Posted February 21, 2011 Carb cleaner is a much better idea than starting fluid (ether). It is far less flammable/explosive. Quote Link to comment Share on other sites More sharing options...
efseiler Posted February 21, 2011 Share Posted February 21, 2011 I had a similar problem in my 96 outback...very similar symptoms w/ some stalling...it honestly seemed to have something to do with the cooling system...try bleeding air from the radiator or perhaps adjusting mixture. In the colder months I would recommend less water and more glycol (anti-freeze). HTH, Damien Quote Link to comment Share on other sites More sharing options...
MaddCelt Posted February 21, 2011 Share Posted February 21, 2011 That's right! Why I thought of starter fluid I have no idea! Thanks for the amend. Quote Link to comment Share on other sites More sharing options...
efseiler Posted February 21, 2011 Share Posted February 21, 2011 Could be water in the tank due to phase separation...the ethanol in fuel these days can't hold all the water when the temp drops...you must add either more pure ethanol or hope for warmer weather... An enzyme fuel additive may help as well. Right now I'm trying out 'Star-tron'...I'll try to give you people an honest scientific assessment after all the data has been collected (or I run out of Federal funding)... :-) --Damien Quote Link to comment Share on other sites More sharing options...
SoobrDad02 Posted February 21, 2011 Author Share Posted February 21, 2011 I'll try the carb cleaner, and as for water in the tank, I did think of that and have added some of the "super" HEET gas treatment at my last two fill-ups to no avail. As an aside, I do want to say thanks for all of the great advice I've gotten on this forum, everyone here has proven EXTREMELY helpful whenever I've posted with a question/problem, so THANKS EVERYONE!!! Quote Link to comment Share on other sites More sharing options...
bheinen74 Posted February 22, 2011 Share Posted February 22, 2011 MAP sensor.? Quote Link to comment Share on other sites More sharing options...
gadberry Posted February 22, 2011 Share Posted February 22, 2011 could it be something as simple as the idle speed adjustment? if someone set the idle RPM while the engine was cold, then once it warms, it would drop down to nothing and stall the engine.. happened recently to my beater 'yota pickup, so... hope that's all it is... btw- I was gonna say "yep, I know a girl like that.." but that wouldn't be appropriate now would it... cheers man, Quote Link to comment Share on other sites More sharing options...
renob123 Posted February 22, 2011 Share Posted February 22, 2011 btw- I was gonna say "yep, I know a girl like that.." but that wouldn't be appropriate now would it... I was thinking the same thing:lol: OP: When did this start happening, and did you change anything around the same time? Did you swap the CTS with a new one or another used one? Jacob Quote Link to comment Share on other sites More sharing options...
SoobrDad02 Posted February 22, 2011 Author Share Posted February 22, 2011 I r&r'd the intake a while back but didn't have any issues until recently. As for the CTS, I replaced it with a used one I had lying around. Quote Link to comment Share on other sites More sharing options...
renob123 Posted February 22, 2011 Share Posted February 22, 2011 I r&r'd the intake a while back but didn't have any issues until recently. As for the CTS, I replaced it with a used one I had lying around. Ok, then you could have swapped a broken CTS with another broken CTS. I've had the water in gas tank, bad CTS and vacuum leak issues before, so I think you're on the right track. You didn't happen to add a lightweight crank pulley lately, did you? I'll also throw TPS in there as a possibility, but I don't have any experience with that. Jacob Quote Link to comment Share on other sites More sharing options...
SoobrDad02 Posted February 23, 2011 Author Share Posted February 23, 2011 I'll swap in a new CTS tomorrow, and do some snooping around the intake as well and I'll post up whatever I may find. Quote Link to comment Share on other sites More sharing options...
renob123 Posted February 23, 2011 Share Posted February 23, 2011 I'll swap in a new CTS tomorrow, and do some snooping around the intake as well and I'll post up whatever I may find. Make sure you "snoop" with some carb cleaner. It's crazy how small a leak can be and still cause issues. Jacob Quote Link to comment Share on other sites More sharing options...
ferret Posted February 24, 2011 Share Posted February 24, 2011 I had a similar problem with MY04 Forester. Many others I have talked to since, and posted on many Subaru boards have now come to the same conclusion. You can read about it: http://www.subaruforester.org/vbulletin/f88/low-idle-stuttering-erratic-jerking-various-rpms-76450/index3.html#post887065 Quote Link to comment Share on other sites More sharing options...
SoobrDad02 Posted February 24, 2011 Author Share Posted February 24, 2011 More to do here in hust a few hours. I'll keep everyone posted. Quote Link to comment Share on other sites More sharing options...
SoobrDad02 Posted March 6, 2011 Author Share Posted March 6, 2011 Just updating... Spent some time(and an ENTIRE can of carb cleaner) looking for the vacuum leak the other day and still couldn't find anything. Removed the airbox/intake tube assembly to allow for further visual inspection of vacuum lines and couldn't see diddly. I am also experiencing a very random/rare issue with the throttle. While attempting to pass in traffic the other day, I found out that she'd get to 3,000-3,500 RPM's and then just kind of top out without gaining any speed. ideas as to what could be causing this? I'm thinking that they're connected, but not sure... :-\ Quote Link to comment Share on other sites More sharing options...
ShagginWagon Posted March 7, 2011 Share Posted March 7, 2011 Could also be the idle air control valve. Quote Link to comment Share on other sites More sharing options...
SoobrDad02 Posted March 24, 2011 Author Share Posted March 24, 2011 Installed a NEW OEM Coolant Temp Sensor...no change. Picked up 2 j/y IACV's today, installed the first one and took it for a test drive...no change. I got back to the house and tried pulling codes and found nothing either by using the green connectors or d-check mode. I unhooked the battery before calling it a night in the hopes that re-setting the system will magically fix everything. in the case that it doesn't though, I'll install the other one and see how it goes. I have spare MAF's sitting around and I'll try installing one of those as well. I DO want to know though, if I install the sensor that sits in the intake, do I also replace the unit that the wires run to that's attached to the fender? Also, what's the recommended technique for cleaning a used IACV? This car's gonna be the end of me... Quote Link to comment Share on other sites More sharing options...
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