I got my car back yesterday from the tuner.

On the way back I noticed it quite frequently stumbles off idle. When taking off from stop you suddenly lose power and then it kicks back in and drops out again.

The tuner is going to have a look on Sunday but I would be interested to know if anyone else has had these kind of problems. It has the E-manage, a SARD regulator (although this shouldn't make much difference at low revs/boost) and 440cc RC Eng injectors. It is Comptech SC'd but was running fine before I added the injectors, E-manage and Sard so I think it is a tuning issue.

I suspect the ECU and E-manage are fighting over the injector cycle and MAP signal at low RPM.

Anyone with FI and the E-manage come across this issue?

 

we need more data. Get an obd-2 reader and look at the signal reaching the ECU for MAP sensor, and check the TPS.

 

No OBD-2 on Aus S2000s. I was quite surprised after I bought my cable and software and couldn't find anywhere to plug it in!

I can get both of those from readings from the E-manage monitoring set up, but the buggers at the tuners have password protected the settings. I am waiting for them to get back to me with the password.

 

doh!

wow that sucks. report back when you have some more data... do you have a wideband? I wonder if the fuel trims in closed loop get applied the same way to open loop in the non-obd2 cars...

 

What rpm does it stumble at? Sounds like it could be an interaction between the stock ECU going out of idle mode, and the E-Manage going out of idle mode. Of course, you can't tell what the E-Manage settings are until they give you the password. Presumably they must have setup the E-Manage round idle - you don't mention problems at idle, so the correction for the injectors must be working there.

-Brian.

 

I've got the password now and can see the settings. What map should I be looking at?

Idle is fine. Apply some revs and she just dies.

 

There is no injector size correction. Apparently this didn't work for them (??). But the MAP settings down low are -50. But pop back up to -15 with some throttle.

 

What I find strange is that the high rev/WOT (bottom right) of this table is still negative. As I'm not using the Comptech FPR I would have assumed that you'd be adding fuel at this point. And the Additional Injection map shows that we are.

The only reason I can think of to hold back the MAP signal but upp the injection phase is to add fuel but stop whatever effect the MAP signal has on timing. I believe at the high end it retards timing and I guess this ahs been done to keep the timing up.

 

Is the anti-stall feature turned on? From Wesmaster's thread about that clamping map, if it's turned on it might be clamping the results from the table, so interfering with the tuning full stop.

There's a very fast ramp in the correction, and a lot of correction. Gives me an uneasy feeling - you've gone from stock to 440cc injectors right? So the corrections in the main area of the table would seem to make sense. But the more extreme corrections at very low load make me wonder if the stock ECU's maps will extend to that adjusted map signal range. If not, then couldn't the problem come from trying to correct for the injector size change purely by map signal changes. All speculation - I'm just thinking out loud here. But that's my guess. The map correction being too large at low rpm / zero throttle as a consequence of not having the injector compensation working. Might be as simple as reducing the correction at low rpm's. Reducing it should only make it run rich (okay, perhaps rich enough to foul plugs etc.), so you might want to try adjusting it yourself. Emphasis on the might.

-Brian.

 

No the anti-stall feature is not enabled.

That is my thoughts. At low RPM/0 throttle you are at -50. The ECU is in closed loop so is adjusting for it. But as soon as you touch the throttle the correction is dropping to -15. Perhaps the ECU can't compensate quickly enough, or it's seeing sudden air and retarding ignition massively.

These are all things we can test safely tomorrow with a laptop and lambda sensor on the road.