I've been having this low kPa vigorous jerkiness since I've put in the Link Plus in my car (N/A and Turbo'd) and I've talked to AMR and skywalker about this a few times and they've been a great help but I still cannot solve this problem!
I thought it would be a tuning issue but now I'm not sure. This is happening to another friend of mine Bigbird who has a Link Plus as well. We both have our cars tuned with a wideband to a 13.5:1 in vaccum, rich but not tha rich.

Both our cars run fine now in boost but we both have this low kPa bucking that gets wild from 2000-3000RPM with kPa reading of >45kPa. During datalogs I noticed that ignition is cutting. Fuel is fine and throttle reads 12-16 but ignition advance goes from 20 to 0-4 untill I open the throttle a bit more to increase MAP to above 50kPa.

Has anyone else had this problem? Could it the spark plugs (BKR7E-11)? They fire fine in boost so I dont see why they wouldnt at such a low MAP.

Here is the Datalog
I tried to post it in here but it looks very confusing.

Notice when MAP is below 50kPa things get crazy. OXY readings go to 0 and the advance gets all random and TPS is always above 10. I try to ignore the OXY readings because the sensor is pretty old and is narrow band. I have my car tuned below a 14:1 overall in vaccum so the readings will not be that accurate.
Advance was supposed to be 14 in that zone, I have changed to 20 since this datalog but the problem still exists.

I thought I was the only one with this problem but my friends Link Plus on his MY01 has this very same problem which leads me to believe that it could be a tuning issue if no one else has this problem. At least I hope its a tuning issue.

 

Advance is not consistant. Very odd.. Also, why the hell is the radiator fan kicking on and off in that short interval? Trace that down...

CT

 

I did the datalog in idle so the radiator was not getting air. During run datalogs though the engine temps are fine.

This timing problem happens when I am in gear and in idle. In idle if I rev it up, right when it reaches 2000RPM, the problem starts occuring.

 

Let's see your map. I have had the same problem also and it has to do with timing and fueling. I have played around with low MAP and RPM levels righ in the area you are talking in and have gotten it quite a bit smoother.

So let's see what we can, do.

Bill

 

You still have a problem. Even at idle the Radiator fan should not be kicking on and off in that short of a duration. Worth checking into.

CT

 

I will email you my MAP this evening. I have made several changes to timing and fuel at those zones but have not had any improvement. Did yours do this while in idle as well? For instance your in idle and rev it up slowly and when RPM reaches 2000 it starts to misfire.

From what I can tell, its cutting fuel before throttle is actually released. That could exlpain why I get ignition cut. Similar to decelerating except it is on/off and thats why it gets violent, sorta like pressing and depressing the gas pedal very rapidly.

I appreciate your help!

 

I'll check into that. Thanks.

 

Try turning off the fuel cut, and change the injection to Group.

That got rid of my low MAP jerkiness.

 

Running in group is not the best option though. It does work well, but you really want to use the capability of the Crank sensors and Cam sensros in order to use sequential firing. It will really improve response time, and over power of the car. That is the one drawback of group injection, though it does solve a lot of those jerkiness problems. It is a trade off.

 

Yeah I prefer running sequential and have fuel cut on decel. I dont see why this could be a problem when the Link can perform so many other complicated taks such as boost control etc.. and not be able to provide the fuel and timing needed at such low kPa unless there is a minor hardware glitch that cuts fuel a little to early when TPS is between 11-18.
Thas what my take is on this. I guess some boards came with this glitch and some didint. Simliar to the few boards that had idle problems.

 

I agree.

FWIW, I have two very similar maps for me car, one that I use on the street, and on that I use for auto-x. The biggest difference is that on the auto-x map, I have the fuel cut turned on and the injection on sequential.