JulianH Posted August 16, 2010 Share Posted August 16, 2010 OK, again with my wife's 98 Forester. So I've got the engine in and everything hooked up, the engine fires up easily, but it idles at 3500-4000 rpm. The only code I get is an intermittent TPS circuit low, because I haven't readjusted it yet. I tried disconnecting the throttle/cruise control cables to rule those out, it doesn't make a difference. What areas should I be looking at? I am also getting a flashing AT oil temp light, haven't driven it yet to get the error that's being triggered there because I haven't filled the coolant system yet. Thanks, Julian Quote Link to comment Share on other sites More sharing options...
Rooster2 Posted August 16, 2010 Share Posted August 16, 2010 Julian..........I am far from being an expert in this area, but I think your lack of coolant may be a factor in the high idle. I know there is a temp coolant sensor that sends a signal to the ecm that affects rich/lean mixture, and therefore how the engine runs. If all electrical and mechanical connections have been reconnected, then add coolant, and see how the motor runs then. Quote Link to comment Share on other sites More sharing options...
JulianH Posted August 17, 2010 Author Share Posted August 17, 2010 Well, it shouldn't make any difference, this was at 9am on a cold start, the motor and CTS were both around 70-75 degrees. I just got home from work, so I'll fill it up and see where we're at. Thanks, Julian Quote Link to comment Share on other sites More sharing options...
bstone Posted August 17, 2010 Share Posted August 17, 2010 How many times does the AT Oil Light flash? Quote Link to comment Share on other sites More sharing options...
JulianH Posted August 21, 2010 Author Share Posted August 21, 2010 OK, I'm finally back... I've filled the coolant and connected the exhaust, it's now idling at 2500rpm. The CEL is on, right now I'm assuming it's the rear O2(which has needed to be replaced for a while), but I'll pull the code in a bit and see what's up. I picked up a vacuum gauge to check for a vacuum leak, I've got a solid -21 inhg, which I think is about what it should be. The AT Temp light flashes continuously, I stopped counting at 40 flashes. I'm going to check the TCM code in a bit, I can't get up to speed just in the driveway here so it'll have to wait till I can drive it. Thanks, Julian Quote Link to comment Share on other sites More sharing options...
porcupine73 Posted August 21, 2010 Share Posted August 21, 2010 Are you sure all vacuum lines are reconnected and there are no vacuum leaks anywhere? I know you said you hooked up the gauge but it doesn't take too much vacuum leak to really start letting the idle climb. Plus to idle that high it has to be getting enough air to run at that rpm so the vacuum reading almost doesn't matter. There may be other issues in addition considering the flashing ATF light (need to read out the codes), etc. Quote Link to comment Share on other sites More sharing options...
JulianH Posted August 21, 2010 Author Share Posted August 21, 2010 I'm sure that they're all connected, but I don't know how I can be sure that there are no leaks beyond using a tester... I'm heading out to play contra with the TCU. Quote Link to comment Share on other sites More sharing options...
JulianH Posted August 21, 2010 Author Share Posted August 21, 2010 OK, so the CEL was the same TPS circuit low, and front/rear O2 sensor(which I forgot to plug in ). When I drove it around to get it over 12mph, I noticed the speedometer wasn't responding(well, it moved a little, but not like it should), so that's probably the source of the flashing AT light. I'll take a look at the VSS in the morning when I can actually see. Could the TPS and fast idle have anything to do with each other? Quote Link to comment Share on other sites More sharing options...
porcupine73 Posted August 21, 2010 Share Posted August 21, 2010 Not sure, I mean if the throttle isn't completely closed of course that would cause fast idle. But if it is closed and there are no vacuum leaks then the only source of air for the engine when idling is through the idle air control valve, which the ECU will modulate to keep the desired idle rpm. I'm not aware of any reasons the ECU would open the IACV enough to make it idle around 3500 rpm. But if the throttle is not completely closed or there are vacuum leaks, that would do it. Quote Link to comment Share on other sites More sharing options...
johnceggleston Posted August 21, 2010 Share Posted August 21, 2010 this a little ,well maybe a lot, out of my league, but with the flashing AT lite and the other issues, i would check the connectors at the rear of the engine to make sure they are well connected without any bent pins. Quote Link to comment Share on other sites More sharing options...
JulianH Posted August 22, 2010 Author Share Posted August 22, 2010 OK, all the pins on the main harness are straight and clean, and it's seated fully. The VSS is fine, and I should have known that, since a bad VSS throws it's own code. The AT code I'm getting is 31, which is a throttle position sensor problem! Apparently I'm having problems with my TPS reports... I'll test the wiring to make sure the problem's not there, but I suspect I must have damaged the TPS somehow when I put the engine back in. Does Delphi make a quality TPS? Quote Link to comment Share on other sites More sharing options...
JulianH Posted August 23, 2010 Author Share Posted August 23, 2010 OK, problem solved. I guess maybe I did have a vacuum leak, because every thing I did to try to solve the problem dropped the idle speed a little more, and adjusting the TPS dropped it down to normal(750ish rpm). Thanks for all your help, everyone. Quote Link to comment Share on other sites More sharing options...
Fairtax4me Posted August 23, 2010 Share Posted August 23, 2010 No, I have the memo right here... Yes the TPS can cause the engine to idle higher than normal. The ECM thinks the throttle is open and changes fuel delivery and spark advance to accommodate. It can red-line itself with the throttle plate closed in some cases if the TPS fails. Quote Link to comment Share on other sites More sharing options...
porcupine73 Posted August 23, 2010 Share Posted August 23, 2010 Glad you got it working! Hey what's this I hear about you having problems with your TPS reports man? The other seven bosses will make sure you get another copy of that memo, m k? yah. If the TPS has problems and it wants to increase fuel to increase rpm, it is going to have to also increase the airflow in order to keep the A/F ratio correct. And the only way it can do that is through the IACV. Quote Link to comment Share on other sites More sharing options...
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