Surge / Idle |
|
Porsche, and the Porsche crest are registered trademarks of Dr. Ing. h.c. F. Porsche AG.
This site is not affiliated with Porsche in any way. Its only purpose is to provide an online forum for car enthusiasts. All other trademarks are property of their respective owners. |
|
Surge / Idle |
lsintampa |
Dec 22 2014, 08:53 AM
Post
#1
|
Senior Member Group: Members Posts: 520 Joined: 28-January 13 From: Tampa, FL Member No.: 15,441 Region Association: South East States |
75 2.0 FI
I'm in Florida - so the weather outside is somewhat warm (50's maybe right now). I'll try to be as detailed as I can. I've had this issue since I started driving the car - about 8 months ago. It underwent a motor rebuild - along with some other mechanical repairs. All hoses are new (air supply, and fuel). ECU and other FI components are original - best I can tell. When I start the car - it starts right up. At idle RPMs go to about 1500 with a very slight surge (maybe 1450 - 1550). If I pull the air supply that goes to the AAR from the air filter and plug it, the idle goes down to what I'd expect - about 900 RPM still with a little surge. This is while the motor is "cold" - so to speak. Within like a minute of starting. As the car warms - just at idle, the RMPs start to come down and the vacuum from the AAR isn't as strong - but still present. However now the surge is crazy - like from almost a stall up to maybe 1200, back down, back up, etc. Pulling the hose from the AAR - does nothing - I can plug it or leave it and the air filter wide open and there is no change. I put the hose back on - again no change. I did not let it get to a full warm state - IE the temp gauge just started to move up. I've heard there are three states (cold, pre-warm, and fully warm) that come into play. Various tinkering, like turning the air mixture valve to a total closed state, and mucking with the ECU dial has had some success, but at BEST, I get like a 1200 RPM idle still with some surging. To the best of my knowledge there are no air leaks - at least not from any hoses. I've some concerns that the air plenum may have some stress cracks around the support studs. But I don't know that would cause the surging? I'd think the idle would just be high - period. YES / NO? I don't know where to begin to figure out why it behaves this way. Thanks, Len |
lsintampa |
Jan 1 2015, 02:22 PM
Post
#2
|
Senior Member Group: Members Posts: 520 Joined: 28-January 13 From: Tampa, FL Member No.: 15,441 Region Association: South East States |
Recap 75 2.0 d-jet - was a California car, cat deleted by some PO, new (used) FI harness for a non California car.
Latest update... Following Rich's guidelines.... Day 1: 1) Set idle - motor warm, RPM's at 3200, pulled vac lines off dizzy, plugged the holes to the throttle body. Timing mark did NOT move - held steady. 2) Turned ECU knob full clockwise - to full rich position. 3) Adjusted TPS - per the Pelican site. Car now idles very low - most times it will eventually stall out. Day 2: Today the motor was cold. I didn't know what to expect, but leaving everything as was, I just went for it. Car started. It took a few tries - maybe three. But it had a hard time staying running. The AAR valve was full open because I could here it sucking air. The extra air had NO effect on the idle at all. After a while the car will run, but the idle is just above stall point - and it catches itself most times, but eventually will stall out. I have a new TPS coming in. Most likely it will get here sometime next week. For what it's worth, I've never seen the ECU knob have any effect on the idle - ever. I laugh every time someone tells me to adjust it, because I know it's not going to do anything. Maybe it is broken, or the idle circuit is fried, or the TPS is shot. I think when the day comes that the knob actually has an effect on the idle, I'm gonna fall over. And yes I did try to turn ONLY the ECU knob (day 2). I'd turn the motor off, move the knob like 1/4 turn - restart. I went from full rich to full lean - no setting had any effect. I've put the knob back now to full CW (rich) position - as it was this morning. (IMG:style_emoticons/default/dead horse.gif) |
Lo-Fi Version | Time is now: 15th May 2024 - 10:20 PM |
All rights reserved 914World.com © since 2002 |
914World.com is the fastest growing online 914 community! We have it all, classifieds, events, forums, vendors, parts, autocross, racing, technical articles, events calendar, newsletter, restoration, gallery, archives, history and more for your Porsche 914 ... |