Jared Posted February 23 Report Share Posted February 23 Experiencing a random issue with my idle. Car has been running perfectly fine for many months, put new plugs in it today and this happens... Start the car, it idles perfectly. However, on revving the engine or driving it, idle will only return to around 800 rpm higher than its set idle, almost as if the throttle is stuck slightly, yet it isn't. When driving the car, if keep the car in gear and use the brakes to bring the rpm down near idle rpm, then put the cutch in or take it out of gear, it'll idle perfectly. As soon as I rev it or accelerate again, rpm will stick again. On logging this, TPS is reading zero at both regular idle and and when it sticks. Any ideas? Engine is a Mazda 20B PP. Log 2024-02-23 6;28;49 pm.llg Quote Link to comment Share on other sites More sharing options...
Toona Posted February 23 Report Share Posted February 23 i guess you are have sticky throttle body. please check for dirt in throttle if you are using original throttle body from 20B there will a screw behind it you can adjust it to bring to not sticky and calibrate back tps Quote Link to comment Share on other sites More sharing options...
Jared Posted February 24 Author Report Share Posted February 24 On 2/23/2024 at 8:28 PM, Toona said: i guess you are have sticky throttle body. please check for dirt in throttle if you are using original throttle body from 20B there will a screw behind it you can adjust it to bring to not sticky and calibrate back tps That's what I initially thought too. However, while it was sticking at 2800rpm I inspected the throttle body and it wasn't stuck, resting perfectly on the throttle stop as it would when it idles correctly at 2000rm. Throttle body is an aftermarket 90mm. Quote Link to comment Share on other sites More sharing options...
David Ferguson Posted February 25 Report Share Posted February 25 Have you check the manifold for leaks? A missing /broken vacuum hose or cap will cause this. I bet it will keep running even if you completely seal the throttle with your hand over it. Toona 1 Quote Link to comment Share on other sites More sharing options...
Adamw Posted February 25 Report Share Posted February 25 I think you probably just need to close the throttle a little further. Before the blip your idle speed is being controlled by idle ignition control, the advance is bouncing between -10 and +20 which is fairly extreme, but say the average is around 0. When you blip the throttle the idle control disables so ignition is controlled by the main table which has ~27deg advance in, this prevents the RPM from dropping back below the idle speed RPM lockout. Depending how the ignition table is set up you may be able to manipulate the advance around the "transition to idle" area to encourage it to come down, but if it has worked ok as is previously then I would just close the throttle a little extra. Quote Link to comment Share on other sites More sharing options...
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