magnusfeuer Posted August 20, 2002 Share Posted August 20, 2002 Hello, I have a problem with my Zetec idle. Configuration: Standard 2.0L Zetec (2001), stock manifold, modified inlet cams, standard Ford ECU. Supposed to give 175 HP, but I haven't measured it yet. This engine is in the beginning of its migration path to something really fun. Other stats: Engine starts OK warm and cold. Rather poor mileage of 21 on Californian gas. Nice power curve with no flat spots up until about 6000 RPM. Problem: When I step of the throttle, when the engine is warm, the idle initially often sinks too low and sometimes stops completely. When the engine doesn’t stop, the ECU catches it at about 2-300 RPM and gives it a push to 800 RPM. The engine then falls back to 2-300 RPM, goes up again and continues oscillating at about 2 seconds per cycle. There seems to be no leak on the (stock) inlet manifold side. I tried to disconnect both oxygen sensors, to no avail. The harness may be defective since I had to attach a few extra wires to ground in order to make the engine start at all. Any ideas? Tnx! /Magnus F. Link to comment Share on other sites More sharing options...
JamesA Posted August 21, 2002 Share Posted August 21, 2002 Magnus, Were you able to find a Zetec engine manual such as the Countour/Mystique Haynes manual? They list a number of trouble shooting problems like you mention, but the answer would seem to be with checking to see if there are fault codes from the PCU. The manual lists well over 100 fault codes that may help isolate what is causing the hesitation. Also, not knowing how much you have run your engine, there is a process for the PCM to reprogramme itself after power has been disconnected. Send me an e-mail if you don't have the manual and I will scan the page and send it to you. ACJRoberts@aol.com. Link to comment Share on other sites More sharing options...
Blatman Posted August 21, 2002 Share Posted August 21, 2002 Sounds like the IACV is on the way out.......... Link to comment Share on other sites More sharing options...
magnusfeuer Posted August 21, 2002 Author Share Posted August 21, 2002 James, It's on the list to bring the car to a Ford shop and ask them to extract the codes. I will check the functionality of the IACV as well. Tnx. /Magnus F. Link to comment Share on other sites More sharing options...
Peter Carmichael Posted August 21, 2002 Share Posted August 21, 2002 Standard Ford ECU - modified cams? The cams can't be that modified, but I am sure this won't help the idle strategy. Is there an idle switch - a microswitch that tells the ECU that the throttle is completely closed? It does sound like the ECU is trying to keep it alive but doesn't have sufficient capability to do so. Link to comment Share on other sites More sharing options...
magnusfeuer Posted August 25, 2002 Author Share Posted August 25, 2002 Idle problem solved. It turned out that the PCV (Positive Crankcase Ventilation) valve was missing. This valve builds up a slight overpressure in the crankcase which, for magical reasons, has a serious impact on the idling. When I installed a new valve ($2.95), the idle stabilized immediately. Weird. Anyone knows the mechanics behind the PCV? /Magnus F. Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now