Surging only in CL and codes P1133 & P1153

[dvx]

I have a persistant problem and really hoping someone can help. I have been working for months off and on trying to tune my car. This is the first one I've done so I'm still learning. I have adjusted idle airflow, done AutoVE (multiple times), recalibrated the MAF (2 passes), RAFIG, RAFPN, worked with the cracker and follower tables, and experimented with timing trying to get rid of all surging. I also went through the idle tuning sticky and have spent hours reading here, and it was a big help in getting to where I am today. A big thanks to everyone here for all the great info.

When I am in open loop, with the MAF enabled, the car drives great. My wideband shows AFR in line with commanded and I have almost no surging, and it idles very well.

As soon as I go back to closed loop, it idles lean but the LTFT's are negative. This seems odd, but eventually idle AFR settles down very close to commanded (14.63). At this point it idles OK but not quite as smooth as when in open loop. I can live with this.

However, I am getting an annoying light throttle surge in the 1,700 - 2,200 rpm range, and it only does this in closed loop and in this range AFR looks good. I can not get rid of it by adjusting the timing or the throttle follower. I've had the follower all the way from 0 grams/sec to 20+ grams/sec and it has very little affect on it. After a while running closed loop, it also throws codes P1133 and P1153 (insufficient switching for 02 sensors) for both sides. At this point I'm convinced these problems are related and the surge is coming from fueling. I have also recently replaced the factory sensors with Bosch 13111's thinking the originals were just worn out. But it didn't change anything.

What can I do to fix this? If I can get these problems to go away I will be very happy with the driveability of my car. Thanks in advance.

Dave

[rally1]

Hi there have you had headers fitted? if the O2 sensors are to far down stream they can get to the point where they are not hot enough work 100% under light load.. can you post a log of the surge? with injectors, O2 switching, map etc..

[dvx]

Thanks for the response. I do have headers, off road Y, cam, heads, bigger injectors. I have read about the problem with the 02's resulting from the long tubes but not sure if this is the entire problem. I will try to get a log posted up later in the week when I have time to get the car out again. I'm wondering if I can alter the 02 switch points to compensate but haven't found much info on this.

[rally1]

You could just run open loop and see if that fixes your surge...

[vxleather]

Having the same problem with mine, run similar set up, 232/ 234 cam, 225 heads etc etc... but i do not run a maf, or use o2 sens... Mine surges at about 80klm, very light throttle... by richening the Ve table around there seems to help as well as not letting the convertor lock up until higer up the speed range... Screws your fuel economy but does minimise the shakes...

[dvx]

Mine doesn't surge in open loop. Idle and driveability are both very good. But I've only run open loop during VE and MAF calibration. I'm not against running open loop all the time if my AFR will stay in line with weather changes. Can anyone shed some light on this? If I run OL all the time will my tune change with the weather? And if I decide to go this route, can someone tell me how or point me to a thread that explains how to go about setting it up to run OL all the time so that commanded stays where it should including PE mode?