heckler Posted September 3, 2009 Share Posted September 3, 2009 I have bit of an weird and intermitted idle problem - the car idles like normal, go for a drive and it behaves its self, the come to a stop, and its idling anywhere 1500 - 4000rpm - jab the throttle and goes back to normal. I've stipped the throttle - cleaned it - makes no difference, done the same for the IACV thing. Now, if the TPS was er... faulty and giving a false signal to the ecu, would it increase the idle? Quote Link to comment Share on other sites More sharing options...
Ian C Posted September 4, 2009 Share Posted September 4, 2009 I have bit of an weird and intermitted idle problem - the car idles like normal, go for a drive and it behaves its self, the come to a stop, and its idling anywhere 1500 - 4000rpm - jab the throttle and goes back to normal. I've stipped the throttle - cleaned it - makes no difference, done the same for the IACV thing. Now, if the TPS was er... faulty and giving a false signal to the ecu, would it increase the idle? Shouldn't do. It might have the opposite effect, as the TPS has a switch in it to tell the ECU that the throttle is "shut" and it should start using the ICV to control idle. It also tells the ECU it can cut the injectors on coastdown, so if it's not working right, or the TPS is adjusted to the point that the switch isn't activated even with your foot off the accelerator, you'll get popping and banging on coastdown as the injectors aren't turned off. TPS's are easy enough to check with a multimeter and I believe you might know how to use one Can you get it to act up while stationary, and then poke around under the bonnet, see if the throttle is stuck open or something is fouling it? -Ian Quote Link to comment Share on other sites More sharing options...
heckler Posted September 4, 2009 Author Share Posted September 4, 2009 Shouldn't do. It might have the opposite effect, as the TPS has a switch in it to tell the ECU that the throttle is "shut" and it should start using the ICV to control idle. It also tells the ECU it can cut the injectors on coastdown, so if it's not working right, or the TPS is adjusted to the point that the switch isn't activated even with your foot off the accelerator, you'll get popping and banging on coastdown as the injectors aren't turned off. TPS's are easy enough to check with a multimeter and I believe you might know how to use one Can you get it to act up while stationary, and then poke around under the bonnet, see if the throttle is stuck open or something is fouling it? -Ian yeah, i'll give it another go... a multimeter you say... Quote Link to comment Share on other sites More sharing options...
caseys Posted September 4, 2009 Share Posted September 4, 2009 The throttle cable isn't fouling on anything and not getting fully back down when you let off maybe? Quote Link to comment Share on other sites More sharing options...
GreaseMonkey Posted September 4, 2009 Share Posted September 4, 2009 (edited) Just A thought. With reference to the Toyota Engine Manual (RM354E). Following the "MATRIX CHART OF PROBLEM SYMPTOMS" (Inspections in the following order as recommended in the manual) Poor Idling- High Engine Idle Speed: 1. Switch Condition Signal Circuit * Air Condtioning Switch Signal * Throttle Postion Sensor IDL Signal 2. ISC Valve Circuit * Check the ISC Valve Operation (With Multimeter & 12v Power source). * Open or Short in Harness and connector between EFI Main Relay and IAC Valve, IAC Valve and Engine ECU. 3. A/C Signal Circuit (Compressor Circuit). 4. ECU Powersource Circuit. 5. n/a 6. Back up Power Source Circuit. Edited September 15, 2009 by GreaseMonkey (see edit history) Quote Link to comment Share on other sites More sharing options...
heckler Posted September 12, 2009 Author Share Posted September 12, 2009 Right, had a bit of a poke around, now have a throttle position display which monitors the TPS, when ever the high idle occurs, the TPS is reporting that the throttle is slightly open. Now I can see anything fouling the butterfly in the throttle body, if I open it by hand it returns to the closed position. I've had the TB in piece all cleaned up/greased etc. So I'm currently ruling that out, the fact the throttle is open at the increased idle rules out the IACV. All I can think of it's the cable, anyone else got ideas? Quote Link to comment Share on other sites More sharing options...
heckler Posted September 14, 2009 Author Share Posted September 14, 2009 after having yet another poke around... I noticed that when the throttle is opened, the whole bar (bit with springs on etc..) moves to one side due to the nature of the springs, I checked this on my spare TB and it did the same, so bit of fettling (taking apart and putting a rubber O-ring between the where the cable attaches at the body) - open the throttle and it stays central. Put it back on the car went for a drive - all sorted. I think what was happening was when the butterfly opened, it mover slighty to the side and was catching on the wall of the the TB and getting stuck. Quote Link to comment Share on other sites More sharing options...
4packet Posted February 15, 2010 Share Posted February 15, 2010 Hi - could you describe your issue/fix in more detail please? My throttle quite often sticks open (anywhere between 1100 and 1800rpm). If left for a minute or 2 it does appear to drop back to normal. I can always force the TB closed with my fingers and restore normally idle speed. I've not noticed the shaft skewing, but will check this. In the past I've 'fixed' this concern by spraying GT85 on the mechanism (v short term fix) and winding back the plate that contacts the damper (removing damping makes it unpleasant to drive round town though). Really keen to fix this once and for all now. Thanks Martin Quote Link to comment Share on other sites More sharing options...
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