Road Test, Slow acceleration and valve chatter |
|
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. |
|
Road Test, Slow acceleration and valve chatter |
VA_914 |
Oct 25 2020, 01:12 PM
Post
#1
|
Newbie Group: Members Posts: 4 Joined: 31-March 08 From: Hampton, VA Member No.: 8,873 Region Association: MidAtlantic Region |
I am finally road testing my 2.0 restoration and haven't quite got it right yet. It starts fine, runs smooth idling or revved up in the driveway but on the road test it accelerated slow, with what sounds like valve chatter when I give more gas to accelerate. It wouldn't go over 3000 rpm in 1st, 2nd or third. I tweaked the timing a bit and it seemed to get better, less chatter and almost up to 4000 rpm. Suggestions, comments; am I on the right track?
|
VA_914 |
Oct 25 2020, 08:13 PM
Post
#2
|
Newbie Group: Members Posts: 4 Joined: 31-March 08 From: Hampton, VA Member No.: 8,873 Region Association: MidAtlantic Region |
Yes, I now run premium in it, but that didn't seem to have much of an effect. Also, the injectors were checked when the engine was rebuilt. I have installed both a fuel pressure gauge and vacuum gauge in the engine compartment. The fuel is typically 28, but I have taken it up to 31 at times. My reasoning was that the displacement was 10% larger so I should up the pressure by 10%, assuming the injector pulse width remained the same. The vacuum is typically 10-12 psi at idle and goes up to 16 or so at higher rpm.
For O2 monitoring, I would need to weld a sensor into the heat exchanger? What other tweaks have people done for a 2056? A couple other things wrt the mixture: There are two vacuum ports on the distributor bellows; one for advance and one for retard (I assume). The throttle body I am using only has one port that size, so I connect it to the port on the distributor side of the bellows and leave the other side of the bellows open to the air. Do I have this backwards? The throttle body has an idle adjustment that allows air to pass around the throttle valve through a tube in the body. It also has a small screw that protrudes into the throat and keeps the throttle valve slightly open, depending on how you set the screw. Both effect the idle speed, presumably because they effect the mixture? I have a second throttle body that has two ports the same size as the distributor bellows, one above and one blow the throttle valve. It has the same type idle adjustment but no screw to keep the throttle valve slightly open. Should I try that one instead? Lastly, I have two pressure sensors, one that Greg Robbins sent to Jeff Blysing to recalibrate for the larger displacement when the engine was rebuilt and one from the second injector set I bought. Unfortunately, I have mixed them up and don't know which is which. As it turns out, they perform a little different, but neither resolve the major issues (ping and 3-4000 max rpm). BTW thanks for your comments and I appreciate the advice about the detonation damaging the engine. I have never gone more than around the block and my intuition told me to back off when I heard the "ping". |
Lo-Fi Version | Time is now: 13th May 2024 - 12:50 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 ... |