lewisd Posted November 3, 2009 Share Posted November 3, 2009 while driving along, accelerating or cruising, the engine just cuts out and drifts abrubtly and then kicks back in. After reading, other threads, I've replaced the TPS, replaced coil, plugs and wires, air filter. I'm thinking maybe the PCV or O2 sensors now. car has 233k mile on it. Right now just trying to get this throttle issue cleared up and then work on the engine light. dang Maryland emission testing is a pain in the butt. no state safety inspections required but you better have emissions test done every other year. hey everyone, this place is great for help. I've been able to search and find solutions before but I'm stuck this time. just frustrated. Quote Link to comment Share on other sites More sharing options...
Legacy777 Posted November 3, 2009 Share Posted November 3, 2009 Welcome to the USMB. What year and model subaru do you have? Is the CEL on? If so, what codes are stored? Based on your description of the problem, I would suspect the MAF sensor. Quote Link to comment Share on other sites More sharing options...
EVOthis Posted November 3, 2009 Share Posted November 3, 2009 +1^...year and model? My first thought was the fuel pump..as mentioned get the code (s) read first than we will go from there.... Quote Link to comment Share on other sites More sharing options...
Fairtax4me Posted November 3, 2009 Share Posted November 3, 2009 That engine light will probably lead you right to the source of the problem. Get the codes read and post the numbers here. I had a similar problem that was due to an internal break in the MAF sensor circuitry. Grabbed one at the junkyard and it was cured. Quote Link to comment Share on other sites More sharing options...
lewisd Posted November 3, 2009 Author Share Posted November 3, 2009 (edited) forgot to mention, 1999 legacy brighton wagon, 2.2 4cyl, automatic. changed the TPS last night and during the test drive it still cut off/on. wife drove it today and says it ran okay, no cutting out... I'd pull my hair out if I had any. CEL is on, I don't have a code reader, relied on what mechanic diagnostic told us. just got Diagnostic codes, PO 325 knock sensor circuit bank1 sensor 1, PO 122 TPS sensor (already replaced), P 1507 vehicle control auxillery inputs, P 1700 transmission control. the transmission one doesnt make sense as it seems fine. Edited November 3, 2009 by lewisd just got codes Quote Link to comment Share on other sites More sharing options...
Fairtax4me Posted November 4, 2009 Share Posted November 4, 2009 Oooh, where's that Endwrench article about the P1507 code... ? The P1507, I think it was only for manual transmissions that the article applied, but it seemed that that code was usually present with a ton of others if the neutral position switch was bad. P1700 is Throttle position sensor circuit malfunction. That's a manufacturer specific code, and though several manufacturers use that code, each one has a different definition for it. P1507 Idle control system fault. This, again, is a manufacturer specific code. P0122 is TPS sensor circuit low input. I'd be willing to bet all this can be cured by replacing the neutral switch, but I'll let another more informed member post their opinion. Quote Link to comment Share on other sites More sharing options...
lewisd Posted November 4, 2009 Author Share Posted November 4, 2009 after replacing TPS, cleared faults and then driving, mechanic reran scanner and still got the knock sensor code PO 325. Hopefully that should be it. Bosch knock sensor for $75 online. I'll check locally as well. junkyards are hard to come by here let alone a subaru in them. Quote Link to comment Share on other sites More sharing options...
lewisd Posted November 9, 2009 Author Share Posted November 9, 2009 I now have a CANOBDII reader (craftsman 14063) for $50. my codes now are P1700 Throttle position sensor circuit malfunction (A/T) and P1507 Idle Control System malfunction (fail safe). I replaced the TPS so after researching some more I'm leaning towards measuring knock sensor (intermittent code) resistance and then cleaning the PCV valve (if possible) before replacing and if that doesn't work, then the IAC valve. engine idle fluctuates intermittently and after letting off gas it sometimes almost cuts out entirely. Quote Link to comment Share on other sites More sharing options...
Fairtax4me Posted November 9, 2009 Share Posted November 9, 2009 There is a procedure for setting the TPS that has to be followed for it to work right. You have to check the voltage feedback from the sensor at the ECU connector and adjust the TPS until you get it within the correct range. The idle code could just be a dirty IAC valve that needs to be cleaned. That's simple, requires nothing more than a $3 gasket, a can of cleaner and an old tooth brush. There are several threads here on the board about cleaning those. Takes about an hour at most. Quote Link to comment Share on other sites More sharing options...
lewisd Posted November 15, 2009 Author Share Posted November 15, 2009 (edited) Hey everyone, I'm back with an update. I've taken off the throttle assembly and (I believe) the MAF sensor that is bolted to the top of the throttle assembly and cleaned both thoroughly. I replaced the PC valve. I then did the IAC Valve cleaning procedure listed on theendwrench.com about spraying engine cleaner (i used seafoam recommended also) down air intake while running engine. I also read the voltage going to the IAC solenoid valve (good) but the resistance check showed an indication of an open (infinite resistance). I"m thinking replace the IAC sensor solenoid thats attached to the metal assembly? Could it really be this neutral switch? ALso someone mentioned TPS adjustment but after reading other threads, I don't believe that applies to my 99 2.2 (CAlifornia emission). My chiltons mentions it for earlier models. ANyhow after the codes were cleared, engine ran great for a while. idle was better and no throttle cutting out while running. now a couple days later it's back. The CEL does not always come on while it cuts out. when it does I get the P1507 code again. I'm having trouble attaching my Throttle body cleaning pictures Parameter Description Value DTC for which Freeze Frame was Stored P1507 Fuel System 1 Status Closed Loop Fuel System 2 Status Not Supported Calculated LOAD Value 8.63 % Engine Coolant Temp 195.80 °F Short Term Fuel Trim - Bank 1 -3.91 % Long Term Fuel Trim - Bank 1 0.00 % Intake Manifold Absolute Pressure 8.88 inHg Engine RPM 1,691. not sure why engine rpm says that high. doesn't sound like it's that high, at least not at idle. it doesn't want to fluctuate or cut out until I apply gas. Edited November 16, 2009 by lewisd update Quote Link to comment Share on other sites More sharing options...
Legacy777 Posted November 16, 2009 Share Posted November 16, 2009 The MAF sensor is not located near the throttle body. It is near the airbox by the fender. Here's a few pictures http://main.experiencetherave.com/subaru/images/mafsensor.jpg http://main.experiencetherave.com/subaru/images/mafsensorpins1.jpg Quote Link to comment Share on other sites More sharing options...
lewisd Posted November 17, 2009 Author Share Posted November 17, 2009 I don't have anything that looks like that. there is nothing but plastic tubing from the air intake up to the filter box. I probably just did the IAC Valve that's attached to the top of the throttle assembly. Quote Link to comment Share on other sites More sharing options...
Legacy777 Posted November 17, 2009 Share Posted November 17, 2009 Hmmm....that's odd. Any chance you could snap a picture of your engine and intake setup? Quote Link to comment Share on other sites More sharing options...
lewisd Posted November 18, 2009 Author Share Posted November 18, 2009 (edited) Okay, finally figured out how to attach pictures. the chiltons mentioned taking a resistance reading on the IAC valve sensor plug. I believe I got the right plug, the one above the plug closest to the throttle cable. Voltage was good in cable to the sensor and three pins should be 9 ohms across 1 and 2 and across 2 and 3. I read infinite (open) across all of them. is this what could be causing the P1507 (fail safe) code? I'm checking local junkyards for the sensor attached to the IAC Valve assembly. Edited November 18, 2009 by lewisd Quote Link to comment Share on other sites More sharing options...
Fairtax4me Posted November 18, 2009 Share Posted November 18, 2009 Infinite resistance means an open circuit, so yes, that could very well be the problem. Be sure to stop by the Subaru dealer and get a new seal for the IAC. Quote Link to comment Share on other sites More sharing options...
lewisd Posted November 18, 2009 Author Share Posted November 18, 2009 (edited) I replaced the IAC valve gasket after cleaning. I thought I coule just replace the sensor attached to the metal assembly. Edited November 18, 2009 by lewisd Quote Link to comment Share on other sites More sharing options...
Legacy777 Posted November 18, 2009 Share Posted November 18, 2009 Looks like you have one of the elusive and few MAP based Subaru's. Quote Link to comment Share on other sites More sharing options...
lewisd Posted November 18, 2009 Author Share Posted November 18, 2009 That would explain why when I get an air filter I have to grab a 2000 year model.. and in the past work done, I've had to tell mechanics (CA emission model). anyways, with funds as they are, I have to try and fix this myself for now. anyways I don't think I can replace the sensor alone on the IAC valve. after some researching it seems they come as a one unit. I'm trying to find one in a salvage yard. I guess I could search for a 2000 or later model as well:confused: Quote Link to comment Share on other sites More sharing options...
Fairtax4me Posted November 18, 2009 Share Posted November 18, 2009 I may be making a junkyard run this weekend. I'll keep an eye out for one if you'd like. The place I go is cheap. Idle motors are $6 and change with tax. I made sure to check that last time I went because a friend of mine needed one for a Honda. Quote Link to comment Share on other sites More sharing options...
lewisd Posted November 20, 2009 Author Share Posted November 20, 2009 I guess that would be great if you don't mind. I'll still look around here. If I end up buying a whole new unit I'll post here. Eagle Salvage in Goldsboro MD says he has a 99 2.2l engine (non-CA emission) but won't part out the engine (understandable). Quote Link to comment Share on other sites More sharing options...
lewisd Posted November 23, 2009 Author Share Posted November 23, 2009 Okay, I"m frustrated. I know I got a bad reading on the three IAC valve pins but when I had the engine running I tried pulling the plug off. The idle went all erratic. turned it off and reattached the plug and then it idled fine. I pulled the air filter back to do another seafoam treatment down the throttle and then took it for a short drive. the cutting out/back in stopped after a short distance. codes stayed out for a while. got back home and then it idled oddly for a moment and I got the knock sensor code. Someone I know mentioned they had a bad knock sensor with similar sypmtoms on their nissan and it took several mechanic attempts to figure it out. I think I'm gonna go with the addressing the knock sensor before the IAC valve. Quote Link to comment Share on other sites More sharing options...
Fairtax4me Posted November 23, 2009 Share Posted November 23, 2009 Apparently the knock sensors on these are pretty finicky. I've though about grabbing one for a Volvo (basic, never break, never have problems) and seeing if it would work on my car just for kicks. No luck on the IAC valve today. Newest Subaru they had at all was a 95 Legacy OBW. Quote Link to comment Share on other sites More sharing options...
lewisd Posted December 1, 2009 Author Share Posted December 1, 2009 I guess I can say this is fixed. Replaced the knock sensor and it's running great. took it to emissions inspection and breezed through it. All the throttle assembly and IAC valve cleaning helped the idle as well. reading the Haynes manual symptoms page it looks like they called the symptoms "Stumbling". Engine would "stumble". anyhow now it runs smooth with no abruptly "cutting out and back on" anymore. Thanks to everyone! Next task, replace timing belt and associated parts, especially after reading everyones write-ups on that. I'm long overdue. Quote Link to comment Share on other sites More sharing options...
Olnick Posted December 1, 2009 Share Posted December 1, 2009 anyhow now it runs smooth with no abruptly "cutting out and back on" anymore. Congrats! Great feeling, ain't it? By all means go for it on the timing belt. As you're doing, read all you can here on USMB and use the links to Endwrench, car magazine articles, etc. That's what I did and believe me, if I can do it . . . anyone can do it! Good luck and be sure to ask questions if/when thy come up. Quote Link to comment Share on other sites More sharing options...
Fairtax4me Posted December 1, 2009 Share Posted December 1, 2009 Good to hear you got it fixed up. Quote Link to comment Share on other sites More sharing options...
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