1999 sd discovery high rpms.

[valkrie]

good day all
got a question, my discovery one sd series runs at high rpms
even after its warm up. i pulled the idle air control valve and cleaned
it out. ,i sprayed the engine front area around the fan let it set
just a few minutes then rinsed. waited for the engine to dry. now it runs
around 1500 rpms. any suggestions would be great. i have the rave cd
and i considered my self a fair mechanic. when i was in the army i worked
12 cylinder air cooled twin super charged diesl engines.


thanks/valkrie

[osiristheclown]

Did this start before or after you cleaned the IAC?

[valkrie]

Originally Posted by osiristheclown

Did this start before or after you cleaned the IAC?

no after i cleaned around the front end ofthe engine. the other day i drove it to my doctor appointment and on my return the idle went down to under a thousand rpm's. i removed the idle air control vavle, i saw no serverable parts. i wiped both surfaces clean and reattached. still runs high but sometimes it will the rpm's will go up then idle down, still between thousand and fifthteen hundred.


thank, buck

[osiristheclown]

Check your coolant temp sensor, the one for the ECU. It's on the front of the manifold, maybe you got the connection wet while hosing off the engine or the sensor is just bad. The sensor tells the ECU the engine temp and has a 2 wire connector like the ones on the fuel injectors. Don't confuse the sensor with the coolant temp sender that operates the gauge in the dash, 2 different parts with 2 different functions.

[valkrie]

Originally Posted by osiristheclown

Check your coolant temp sensor, the one for the ECU. It's on the front of the manifold, maybe you got the connection wet while hosing off the engine or the sensor is just bad. The sensor tells the ECU the engine temp and has a 2 wire connector like the ones on the fuel injectors. Don't confuse the sensor with the coolant temp sender that operates the gauge in the dash, 2 different parts with 2 different functions.

thanks for the info. I pulled the wrong part and was confused as to which was which. I finally puled the right one and boy was it carboned up. I cleaned off all the carbon i could with solvent, but had to resort to my dremmel tool. finished cleaning with the dremmel and also cleaned the port where it goes. cranked the engine and ran like new.

Thanks again for the info if you need anything i have been doing alot of research and have alot of info will be glad to share.