DNBishop

iTrader: (3)

Can you post a screen shot of the modded table? There seems to be quite a few with this problem. I have been keeping up with this thread and appreciate the efforts being put into it.

thanks

Dynotech Tuning

iTrader: (12)

What trouble are you having? More has to do with timing and fuel than it does with the ISCV. If you have adequate fuel and the RPM is too high, a mixture of less ISCV demand and less ignition timing may help. If rpm is too low and fuel is sufficient, more timing and greater ISCV demand is the solution.

Once SD came around, I have seen some screwy VE tables in that area that can cause all sorts of fuel and load variances. Lack of understanding of SD has added greater headaches to some DIY tuners that are beginning to learn it more.

-Jamie

catman78

iTrader: (15)

Car basically dies after around 10 seconds of cold start.
Idle dips real low then dies.


Timing
10 20 30 40 50 60 70 80
500 17 17 17 17 18 19 19 18
1000 17 17 14 14 14 18 18 17
1500 20 20 20 20 20 18 16

AFR's all 14.7 in area above

VE
500 75.7812
1000 75.7812
1250 81.25
1500 90.625

Don't know how screwy this is.

@ this point I'm gonna start with a fresh ROM.

thanks for your help

Dynotech Tuning

iTrader: (12)

Do you have a log showing your actual AFR when it stumbles and stalls?

-Jamie

Dynotech Tuning

iTrader: (12)

Whats the highest ISC Steps anyone has logged? The most I can get it to do is 120 steps. I'm just trying to figure out the 0%-100% range of the ISC steps. I set the entire Idle Stepper Table to maximum values and the highest I get its 120 thus far.

-Jamie

domyz

iTrader: (6)

Jamie, according to a toyota ISCV guide I have here:
"The pintle valve has 125 possible positions"
Not from Mitsubishi but still, it could be a standard.

There is a lot of basics but there is also some good info in this file, take a reading when you have time: http://www.autoshop101.com/forms/h26.pdf

catman78

iTrader: (15)

Hey Jamie,

I think it ended up being an issue with Vacuum Leak.
Seems to be fine now.
thanks

ExViTermini

iTrader: (25)

I'm having an odd cold start issue. Once it crosses over ~115F or so ECT, it does ok. Upon startup it will idle a little low for a few seconds, then climb up to 1800, then back down to normal, then back up, then back down and smooth out. All this happens over the course of a minute or two. Quite annoying, but otherwise ok. Have played with IACV initial some but it wasn't seeming to make too much diff.

Log posted below...would love some input. Rename to .csv before viewing.

Raptord

iTrader: (10)

ExViTermini, I graphed your RPM vs ISCV demand and steps just for the heck of it. Certainly seems ISCV-related. Question now is finding out what's doing it.

domyz

iTrader: (6)

It's acting like the ISCV itself would be sticking (very unlikely). Something else makes the RPM change...
At #721 to #1250, steps go from ~72 to ~83 with virtually same idle RPM, then suddenly go up to 1800rpm...
You get like 100rpm for 11 steps, in my car 11 steps yield at least 200rpm in those conditions.
ISCV system seems to work smoothly, RPM rise and steps do not overreact. The STFT demand quickly starts to lower the steps to reach target....

Did you do a boost leak test ?

Raptord

iTrader: (10)

Did a bit of testing on my own car tonight. Basically I copied over my tune and tables that weren't in any way related to idle to a stock v7 rom and started fresh. First cold start I did, rpm shot up to over 2k rpm, then slowly started coming back down. I lowered demand by 5% in the CTS Adder AC Off - neutral table, then reflashed. Next start went up to about 2k rpm, then slowly started coming down again. I lowered demand in the same table by another 5% (which corresponded to 5 steps at the coolant temp I was at on the car). Started up again and got this:



After starting rpm still went up higher than I want, though not quite as much as before. This could just be the higher coolant temp accounting for this though, and not so much the changes to the map. The more interesting part for me though is what happens to rpm after the initial spike, and comparing actual rpm (blue) vs target idle rpm (purple). It looks like the stock ISCV correction settings are too aggressive, and caused the idle to constantly overcompensate while trying to reach it's target. I'll try some new trim settings and see if I can fix this surging.

domyz

iTrader: (6)

Nice job, and I think you are right about correction too agressive. It's like a PID with too much gain. Process value chase setpoint and may or may not be able to stabilise, depending on gain strengh.

For ExVitermini, the mega rpm spike doesn't seem to be caused by steps. The rpm doesn't react to steps and then it overreacts all at once. Very odd. I'd clean IACV on this car, it can't harm.

ExViTermini

iTrader: (25)

Interesting note, and highly likely, I sadly hadnt thought of this:/. Does have 115 on the clock

Few notes, this car has a later model throttle body and both upper ports on it are welded shut. Has new seals as well. And yup, boost leak test is good as I just conpleted one after the turbo install.

It is another thing that my car out of the 3 locally Ive tuned recently is the only one that acts like this. I will check out the IACV tonite! Thanks!!

Raptord

iTrader: (10)

Update; I think I've found some values for the "ISCV Demand Target Idle Trim" table that work quite well. I've completely gotten rid of the problem where the ISCV would alternate between over and under compensating to bring the idle to the desired rpm.

The values I'm now using are as follows:

0	0.0
62	0.4
125	0.4
188	0.8
250	1.6
312	1.6
375	1.6
438	2.0
500	2.4

And the value I'm using for the "Target Idle ISCV Trim Adjust Frequency" table is 1000ms.

I'm now focusing on figuring out the high rpm spike right when the engine starts.

domyz

iTrader: (6)

Is this spike last about 3 seconds after startup? Jamie found that the ISCV demand startup adder is used from startup + 3 seconds.