Rapid thumping noise
#1
Rapid thumping noise
More often than not, when I turn the ignition Off: I hear a quick-time rap/rap/rap coming from the drivers-side lower dash area. It's like it's coming from the brake pedal, but it's not moving. I'm thinking some kind of vacuum motor rapidly cycling? Everything works ok afaik. At a loss to understand this. I haven't been using the AC mode....too cold....using only the Econ for Heat. Any ideas/help/suggestions would be appreciated. Thank you.
#3
Cold engine/no codes/P.01=3.3-3.7 at idle. The rapping noise is from gas pedal movement. I recently installed a new ISC. Went through the complete procedure from the FSM before hooking up the electrical connector. I did notice an odd thing after the installation. Upon easing up the throttle, the idle would be around 950rpm. I would 'burp' the throttle and it would idle down to 750rpm, where it should idle. I thought something was 'hanging' with the isc plunger. It wouldn't idle down to that 750 by itself, only after a little 'burp'......but sometimes it does? The engine(new)/computer doesn't have a lot of miles/time on it....260mi/5hrs. Thanks slowroll for the response
#4
Possible weak return spring. It happens. If you run ISC back so it's not contacting throttle lever, what does TPS read? Does closed throttle / ISC nose switch indicator light come on when gas pedal is released?
#5
When I was doing the installation procedures, I think the P.01 wasn't to spec(I should have written the value down...didn't), but the next step was to read the voltage at the test point. The voltage was in the ballpark and the procedure was that no adjustment was necessary. The OEM isc plunger had thread-lock on it and was damn-near impossible to move. The new isc plunger can be moved(screw'd/un-scrw'd) with one finger.....I don't know if that is/will be a problem or not. It's always in contact with the throttle lever so it shouldn't move/change, but then again.....
I'm also hearing a slight octane-knock which REALLY bothers me.....
Last edited by Dave S Texas; 02-01-2009 at 07:56 AM.
#10
Try 8D or look in index for Computer Diagnostics. There is a page that will show ECC head and what the lights mean when in diagnostics. If ECM see ISC nose switch closed the low light should should come on, when gas pedal is depressed light should go out.