low idle making driving unsafe

[XLoudFN97X]

I've put about 50,000 miles on my 97 since I bought it used w/ 53,000 miles. around 100,000 it began to idle low (200rpm) especially at start-up and when stopped. I'd have to keep a foot on the brake and a foot on the gas (<-- not good for car or drivers, or pedestrians) to keep the idles around 800rpms.... It does click and hum sometimes somewhers under the hood for a couple seconds and I dont remember that happening- The low idling happens very intermittently and sometimes wont happen for days. But I have the opportunity to do some things tomorrow and was wondering what I should (and can) tackle in a day. Search says I should clean the throttle body and IAC, check the air filter (its pertty new -OEM-), maybe O2s. Is there anything else fairly obvious that I could check or swap out tomorrow that I've missed? Thanks :roll:
~stu

 

[Mbrooks420]

You likely need a new IAC.

 

[MazdaGreg]

I agree with MBROOKS, you need a new IAC. When they die, they will not open up that air passage, so the only thing your truck is running on is blow by from the throttle plate, and maybe a little past the IAC. Are there any trouble codes associated? the PCM should notice it can't control Idle, and send up a Code.

 

[XLoudFN97X]

yea I got a CEL sometimes (like I said, the problem is intermittent.) I'm gonna go up to the car wash to clean up a bit under the hood and if the CEL is activated, I'll have autozone do a diagnostics check for the code. The IAC is not an expensive part, is it? Thanks again.

 

[XLoudFN97X]

CE codes P1507 and P1405. The guy at Autozone said he wasn't able to diagnose the 1507 code (it was a manfacturer code or something.... right.. ) The P1407 one had something to do with bypass control valve and a new IAC (after an hour long track-down) fixed the idle problem. The CEL is not on anymore and I couldnt be more pleased except the new IAC has a fast tick to it when cold; is that normal? It may just be newness. I got a coupla' quick snaps of the engine, cleaned and lightly dressed. You can see the new IAC along the intake tube by the throttle body. Thanks for the help guys, I've got big hopes for this truck, she just needs a little love.

~stu