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E 30


Biggsean

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ran a diagnostic on the 1990 deville and the codes E30 and E48. Any idea what this is

E030 is ISC RPM out of Range, Code E030 is set because the actual RPM never reaches desired RPM signifying a slow or failed ISC motor. ISC is the the Idle Speed Control motor. Faults include checking proper throttle switch, brake switch and park/neurtal switch operation, proper ISC motor operation, and engine and fuel emissions faults may cause unstable idle. My guess due to the E048 is that your EGR is hung open, how is your idle, should be very rough or stalling..

E048 is the EGR system fault. Usually cleaning the EGR system, throttle blades, and checking for vacuum leaks solves this. What engine do you have, 4.5? I am not sure if it has the EGR ports in the intake, if it does a good cleaning of the ports is advised. If your EGR has not been replaced since 1990, try cleaning it and freeing it up, if replacement is necessary use only GM parts they are calibrated for your car, aftermarket EGRs are not adequate. I have been told that EGR valves are near impossible to clean up and its best to replace them. Mike

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does the ISc motor make funny noise AFTER you shut the car out? if so, you have to replace it. push the eng data on DIC several times until you get RPM while idling. Is it too high/low?

The saddest thing in life is wasted talent

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For the EGR code, with the engine off, open the butterfly valve in the throttle body (Either have a helper hold the gas pedal on the floor or hold the linkage by hand).

You will see two tubes - if they are plugged or partially restricted, rod them out with a coar hanger.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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Do you have to do any of this EGR cleaning on a 99?

No - the EGR system on the Northstar is completely different from the 4.x engines. On the Northstars of your vintage, all that is necessary is a cleaning of the pintle/seat on the EGR valve to free it up when you get the EGR pintle position code.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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