Darkshot

iTrader: (4)

I've made much progress in tuning my EBL setup. Three issues remain. While the engine is cold, or even if it has been allowed to cool for 4 or so hours, I have issues accelerating. From a dead stop once I ease my foot onto the gas is seems to hesitate and "gargle" and be very slugish until a certain RPM (perhaps around 1200?) at which point it seems to clear up. There is a noticable increase in power when the gargling clears up. This issue goes away once the engine warms up. The longer it sat to cool off, the longer it takes for the problem to go away (only happens in open loop).

Another issue is surging. It only surges at idle while stopped, coming to a stop, or just accelerating from a stop. Also, it only surges in Closed Loop, however the problem will only exist if the car just entered closed loop. After about 3 minutes in Closed Loop and problem goes away. I've had this before and it was a dead spot at 0% TPS, however that is not my problem this time.

Finally my closed loop idle. It is ever so slightly rough. Dont get me wrong, the car runs really great, but when its fully up to temperature you can feel a very faint "bump ba- bump bump bump". Watching the engine idle it goes not bounce around at all but you can feel the slight roughness if you hold your hand on a fender, steering wheel, air cleaner, etc. Its nothing to really worry about to be honest, however I am a perfectionist I want to make my idle smooth as silk if I can. I have stock cam so I might as well make the best of it right? I should add that the car has ALWAYS had that kind of idle, even with the old ECM, different mismatched injectors, and no tune. I have 7mm duralast wires on there with regular duralast cap and rotor with stock dizzy and coil. Is this likely ignition related?

RBob

iTrader: (1)

The cold engine gargle sounds like it is too much AE. If the O2 sensor is active at this time the data log will show it going high. To correct the issue, look at the WUD or a data log and get the engine coolant temperature (CTS).

Go to the 'AE - CTS Multiplier %' table and lower the values to those areas.

Surging when just enters close loop: it just may be that the engine is still a little too cold for closed loop. It may also be related to the next issue. I would first try raising the closed loop enable temperature: 'Closed Loop - CTS threshold.' Can check a data log and see what the CTS temperature is after 3 minutes of closed loop.


The slightly rough idle, this can be a number of things. With it always being like this, over time the common tune-up items have been replaced (plugs, wires, cap, rotor, etc.). It may be that the valve adjustment could be better, or the EGR valve is leaking (exhaust into the manifold during idle). I would work with the EGR first.

Other items could be the alternater (bad diode causing ripple), or the O2 sensor, heater blower motor causing noise.

RBob.

Darkshot

iTrader: (4)

Thanks for the responce. I'm putting the "rough" idle on the backburner for now as I focus on the other issues. I bumped down the AE table a bit and it helped. It is still slightly noticable however much better and some more tweaking and i'm sure I can work it out.

I also bumped up the CTS threshold for CL from 47 to 61. This helped with the surging, it only surged once for a few seconds at 67*C so i'm thinking of bumping it up again to 70*. Any disadvantages to this? Would you definitely recomend WB 02 tuning if I am going to be in open loop that long?

Here is a datalog with a series of markers, there is only one marker and a few seconds that are of interest however. I was able to log one surge. If you look at the 00:06:18 section as well as the 00:06:19 you will see that I am slowing down from about 15 MPH @ 0% TPS @ 66* CTS. Then you will notice that in this area the RPMs drop. My idle speed for that temperature range is 650, and you will see that it drops far below that and right at 00:06:20 the stall saver appears to kick in (judging from my IAC steps). Any idea what could be causing this drop in RPM? Torque converter? I'm sure I could elminiate the surging by raising my CL threshold even more, but I feel that is masking the real problem.

FYI: That runtime is my first startup this morning. So the whole datalog begins with the car stone cold after sitting through the night. Does my warmup time appear to be normal?

RBob

iTrader: (1)

At the time the engine is coming down to idle the IAC counts are high. At the last idle in the log the CTS is 90 C with the IAC at 60+ counts.

The idle range timing also seems low. It is in the range of the stock timing tables. But could be brought up.

Try this: increase the 1200 RPM and lower SA timing by 4-6 degrees. Blend that in from 1200 to the 1500 RPM range (for smooth-ness).

Then on a warm idle (engine up to temperature), open the throttle blade screw for 5-10 IAC counts. With these changes the engine will return to idle in a better fashion.

RBob.

Darkshot

iTrader: (4)

What should my IAC steps be at a 650 RPM idle? I was under the impression that I wasnt supposed to mess with the idle screw on the TB. Are you saying maybe some uninformed previous owner tried to mess with the idle that way?

RBob

iTrader: (1)

Throw old impressions away. Best IAC counts for a TBI at warm idle, no fan, no A/C, no back-light heater is 5-10 steps.

RBob.

zipfast

iTrader: (2)

RBob....... would you also set the Tables>IAC - Minimum Idle Steps @ 80c and 104c down to 5 steps

RBob

iTrader: (1)

Shouldn't need to.The steps in this table can be tweaked a little, but should be left higher then the actual IAC steps at that temperature.

The Minimum IAC steps table is used to reduce the IAC idle steps while the vehicle is moving and the engine is warming up.

To explain this better, without this functionality: after a cold start, as the vehicle is being driven without stopping there isn't any idle learns. So the IAC steps are held at the setting that was required for idle at the cold start. Which then causes a high idle, usually too high, the first time the vehicle comes to a stop. And it takes a while for the IAC to step down and bring the idle down.

So what I did was to add a IAC Minimum Idle steps table along with some code to use it. Now, as the vehicle is being driven and the engine is warming up, the idle IAC steps are being reduced to match the values in that table.

Now when the vehicle comes to a stop the IAC steps are closer to the proper idle steps. And the idle is where it should be with a minimum of further IAC adjustment.

Then once the engine temperature gets above the value at 'IAC - Max CTS for Minimum Idle Adjust', the ECM stops using the Minimum Idle steps table and holds the actual learned IAC steps. Nifty, eh?

RBob.

zipfast

iTrader: (2)

WAY COOOOL