Loping with the brakes?
11-14-2009, 05:00 PM
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Loping with the brakes?
Help please,
I had this same issue with my 22re, but my 3.slow 4 runner now is loping when I step ion the braskes. Also the brake light on dash glows dim and occasionally gets brighter and dimmer. I thought maybe I had a vacuum leak but cant seem to find one. Any ideas? All input is aweesome. Thanks.
Rift
I had this same issue with my 22re, but my 3.slow 4 runner now is loping when I step ion the braskes. Also the brake light on dash glows dim and occasionally gets brighter and dimmer. I thought maybe I had a vacuum leak but cant seem to find one. Any ideas? All input is aweesome. Thanks.
Rift
11-14-2009, 05:53 PM
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Loping? You mean pulsing? If so does it feel more in the floor or steering wheel? If wheel, I'd say get your rotors trimmed. If floor (or I like to use the e-brake trick) get the drums trimmed.
11-15-2009, 12:46 AM
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Loping engine when stepping on brake pedal is brake booster issue. Not real sure about Yotas, but on Full Sized Jeeps there's a check valve that can be replaced. My Grand Wag's idle would increase when I hit the brakes. I couldn't find a leak, but I replaced the booster anyway. I hadn't realized how bad my brakes sucked until I drove it with the new booster, and my idle smoothed out. I'd download the FSM that's available on this site, get into the brake section, and troubleshoot the booster. Or just replace it.
Last edited by aerocorey; 11-15-2009 at 12:48 AM.
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11-15-2009, 07:58 PM
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Thanks
I am not sure what the idle is set at, it idles about 1200 even after its warm.
It should idle about 900-1000. When I swap the booster Ill post my results.
Thanks
It should idle about 900-1000. When I swap the booster Ill post my results.
Thanks
11-15-2009, 08:29 PM
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Umm... if it idles at about 1200 after warm, that's where the idle is set at. If you think it should be 900-1000, you already know the idle isn't where it's supposed to be, right?
For the record, it should be around 850. 800 is too low, 900 is too high.
Set the idle and ignition timing before you change the booster. You might be pleasantly surprised.
For the record, it should be around 850. 800 is too low, 900 is too high.
Set the idle and ignition timing before you change the booster. You might be pleasantly surprised.
11-16-2009, 09:53 AM
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11-16-2009, 12:36 PM
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Here's the reference Junkers is talking about:
"Assuming there are no vacuum leaks, such as in the brake booster, it’s likely because your idle speed is set too high. I can exactly duplicate this “problem” in my ‘85 by bumping up the idle speed to a bit over 1000 RPM and it’ll act as described. Turn the idle speed back to normal, and it works fine. It’s really not a problem, its supposed to work this way and if everything is set properly, and you won’t have the “problem”.
Why is this the case? Because the ECU has logic built in that says if you hit the brakes and the engine is turning over 1000-1100 RPM, it’ll cut the fuel to the injectors in an attempt to help you stop faster. After all, no sense pumping gas into the engine when you are braking to a stop. So idle rises, fuel is cut, idle falls, fuel restored, idle rises, etc. Turn the idle back to 850-900 RPM where it’s supposed to be and it’ll get back to normal. Idle speed is adjusted with the large slotted screw atop the throttle body. Turn it in to lower the amount of air passing through the throttle body at idle (and thus lower the idle speed)."
"Assuming there are no vacuum leaks, such as in the brake booster, it’s likely because your idle speed is set too high. I can exactly duplicate this “problem” in my ‘85 by bumping up the idle speed to a bit over 1000 RPM and it’ll act as described. Turn the idle speed back to normal, and it works fine. It’s really not a problem, its supposed to work this way and if everything is set properly, and you won’t have the “problem”.
Why is this the case? Because the ECU has logic built in that says if you hit the brakes and the engine is turning over 1000-1100 RPM, it’ll cut the fuel to the injectors in an attempt to help you stop faster. After all, no sense pumping gas into the engine when you are braking to a stop. So idle rises, fuel is cut, idle falls, fuel restored, idle rises, etc. Turn the idle back to 850-900 RPM where it’s supposed to be and it’ll get back to normal. Idle speed is adjusted with the large slotted screw atop the throttle body. Turn it in to lower the amount of air passing through the throttle body at idle (and thus lower the idle speed)."
Last edited by aerocorey; 11-16-2009 at 12:38 PM.
12-08-2009, 01:51 PM
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Ok that was cool. but another problem arose with it. I set the idle to about 850-900 and the problem went away. About a week or less of normal driving and the idle adjusts itsselt to about 100 (one hundred) RPMS. I reset the IA to about 850-900 again and in about 50 miles the RPMS just back up to 1200. The problem instantly returns. I did not reset the ECU when I made the initial adjustments. Should I have?
Gonna try it and Ill see what happens. Thanks for the help.
Gonna try it and Ill see what happens. Thanks for the help.
Last edited by RiftRider; 12-08-2009 at 01:52 PM.
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