Guest [S]oLiD Posted November 15, 2008 Share Posted November 15, 2008 hi people, I thought i'd ask you UK guys for help, we dont have much experience with VVti's her in OZ... when i start the car up, it idles very low (500rpm), but after driving it for a couple minutes, the idle will go up to what it should be and its all fine from there... it only idlles low when i start it up why would it idle low on startup and be fine after a 2 minute drive??? any ideas ???? Ive tried resetting the ecu but it did no good.. its got me and my mechanic baffled ..... cheers Sam Quote Link to comment Share on other sites More sharing options...
michel lane Posted November 15, 2008 Share Posted November 15, 2008 sounds like the AIT sensor , if this is faulty then when its cold, it gives a wrong reading to the ecu and caused it to run at a lower rpm . After awhile when the engine gets up to temp , then it runs smoother. Also check your MAF sensor, part of your intake where the filter is . Quote Link to comment Share on other sites More sharing options...
Guest [S]oLiD Posted November 17, 2008 Share Posted November 17, 2008 sounds like the AIT sensor , if this is faulty then when its cold, it gives a wrong reading to the ecu and caused it to run at a lower rpm . After awhile when the engine gets up to temp , then it runs smoother. Also check your MAF sensor, part of your intake where the filter is . thanks for the reply but: * whats an AIT sensor ??? wheres it located ?? * I know where the MAF sensor is but how do i check it ??? sorry for the noobish questions... Quote Link to comment Share on other sites More sharing options...
Dave17 Posted November 17, 2008 Share Posted November 17, 2008 Air Intake Sensor i believe Quote Link to comment Share on other sites More sharing options...
Ian C Posted November 17, 2008 Share Posted November 17, 2008 As the VVTi runs off a MAF I think the air temp is sensed within the MAF and not the intake plenum where the J-specs have it. It may idle low due to running too rich, and only once the narrowband O2 sensor has warmed up and the ECU as consequently gone into closed loop does the fuelling get sorted. Is the car modifed and can you check the AFRs on cold start? -Ian Quote Link to comment Share on other sites More sharing options...
Guest [S]oLiD Posted November 17, 2008 Share Posted November 17, 2008 As the VVTi runs off a MAF I think the air temp is sensed within the MAF and not the intake plenum where the J-specs have it. It may idle low due to running too rich, and only once the narrowband O2 sensor has warmed up and the ECU as consequently gone into closed loop does the fuelling get sorted. Is the car modifed and can you check the AFRs on cold start? -Ian its almost stock, only mods are a catback & front mount... are you saying it could be my O2 sensor??? is that part of the MAF ?? could it be a battery or alternator related issue?? Would they affect the idle on startup??? my battery has had a bit of a hard life, ive had to bring it back from death a few times... Ive had it checked out, load tested etc and they say its fine but i still have my doubts... Quote Link to comment Share on other sites More sharing options...
Ian C Posted November 17, 2008 Share Posted November 17, 2008 oLiD;2178288']its almost stock, only mods are a catback & front mount... Those mods shouldn't make any difference to the cold start. are you saying it could be my O2 sensor??? is that part of the MAF ?? No, I'm not. The O2 sensor has to warm up to work properly and that takes a couple of minutes. What I'm saying is that once it has warmed up it then starts being used by the ECU to trim the fuelling to the desired mix, and perhaps that sorts the idle out. The O2 sensor lives in the exhaust pipe, it samples the exhaust gas for the amount of oxygen left in the gas. could it be a battery or alternator related issue?? Would they affect the idle on startup??? I wouldn't have thought so, the ECU compensates for low battery voltages by changing the injector lag times and stuff, but you can check a couple of things easily. One, multimeter the voltage across the battery terminals while the engine is running - it should be between 13 and 14 volts. Two, see if the idle sorts itself out when you start the car and leave it idling until it's warmed up (this will discount additional battery charging caused by higher revs when driving). If you do that test, time how long it takes for the revs to become normal (if they do), see if it roughly matches with how long it generally takes the O2 sensor to warm up. my battery has had a bit of a hard life, ive had to bring it back from death a few times... Ive had it checked out, load tested etc and they say its fine but i still have my doubts... It may not be holding a charge but then I had a battery like that once, when charged it'd start and run the car fine, it just discharged in a couple of days. -Ian Quote Link to comment Share on other sites More sharing options...
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