I've spent the better part of this summer trying to get my car to do the following perfect:

1) Cold start
2) Warm/hot start
3) Idle
4) Low rpm driving
5) Coming to a stop

I have tried so many different combos of TB plate holes (I currently have 3 TB plates trying different sizes) that I am about to give up.

Any time I get my IACs low enough to have a decent warm start, I start getting the cruise control effect (CCE). But, to keep the CCE away, I have to use smaller holes thus keeping IACs higher and thus making warm starts a constant stalling/surging nightmare.

My idle is at 800rpm in both park & drive with a B1 cam (221/221//.558/.558//114). I have tried different idle rpms (as high as 950) and I still have the same issue.

I have an older version of LS1 Edit that does not allow me to adjust IAC or rpm decay tables. I really don't want to buy the updated version, because even then I don't really know if that's gonna fix this issue.

I guess my question is, can I try anything tuning wise with my older version of Edit to improve this issue? Timing maybe? A/F? Or, are we A4 guys with cams just forced to deal with some issues reguardless of how much tuning/messing with the car we do?

Right now I've got a TB hole/idle rpm combo that gives me pretty good driving manners, but on warm starts it still surges and sometimes dies.

What to try next?

 

TTT

 

You need to scale your VE to help with warm starts. Something in the range of 60% to 90% should be good, but remeber only 1200 rpm and below. You might even try a 60-70-80% combo. Oh the other thing, is drive around for a week inbetween changes to give the PCM time to adjust to the new values.

 

The throttle decay will definitely fix your "cruise control" issues. My buddy and I got his 228/236 cam to idle pretty well in his A4. Wouldn't have been possible without the VE stuff, IAC stuff, and the throttle follower section. We also did drill the TB to 5/16". It's worth the upgrade.

 

Tell me more about how this works. Are you saying I should take all the values in the 1200rpm and under section of the VE table and multiply them by 60%? When you say "60-70-80%" are you saying to progressivly change the percent with rpm (in that case, rising or falling with rpm?), or just start at a full 0-1200rpm 60% change and work up in increments of 10% till I find the right combo?

One last question, when you say 60%, are you saying (if rpm = A and the new value = B) A x .60 = B or A x 1.60 = B? Just wanna make sure I am moving the tables in the right direction. Not sure if you want me to increase or decrease the values (60% or 160%)...

 

In LS1edit when you specify a percent like 60%, it actually multiplies all the highlighted values by 0.60. Yes, you want to reduce all the values 1200 rpm and below, since with a cam your engine has a lower volumetric efficiency than it did before at the lower rpms. I got the best results with 400 rpm = 50%, 800 rpm = 60%, and 1200 rpm = 70%. Yes that's what I would call progressive, but your car may need slightly different values since you have a different cam, exhaust system, etc.

Oh BTW, don't worry about not being able to adjust your IAC tables. In my experiance, the PCM just sets them to what ever it sees as necessary anyway.

 

Ahh, that makes sense. Thanks.

One more question though. I was looking at my LS1 Edit manual and it says that the VE table is only used when the MAF isn't working and the car is in SD mode. So I'm not sure if this is the VE table that I should be messing with or not. I think in newer versions of Edit there is more than one VE table (something like a "crank VE" maybe?). So I just want to make sure that it is the regular VE table under the fuel tab that you are talking about here...

Thanks,

 

In my version it's called "Main VE." The Crank VE is what's used before the engine starts, while cranking it only. You want to modifiy the Main VE table. I believe the VE tables are used exclusively when the MAF fails, but they are also used the rest of the time as well. If you don't believe it, just try putting some rediculous numbers in this table and see how well your car runs! Open or closed loop, same story. I actually tried this once, and I almost didn't make it home.

 

Cal, thanks so much for you help so far! The results I've seen from my first test are very positive. I did a 60-70-80% adjustment in the 400-800-1200rpm ranges respectivly.

Now I need to enlist your well proven research once more, lets talk VE effect on Ltrims. My Ltrims used to sit at about +4 to +8% at idle. Since I have made this VE adjustments I have noted that my Ltrims are at +14 to +16 at idle. Is this due to a learning curve still in place? Did I not give the car enough run time? (did the idle relearn procedure already) Or will I need to adjust the Ltrims to compensate for the new VE table inputs? Did you note this change in your setup as well?

I hate to be such a bother, but I really haven't done much Edit tuning besides the absolute parameters since I bought it back in summer of '02 so I'm still learning. How exactly do I change my Ltrims (if you feel I should)?

Any help you can give would be great. And thanks a TON for the help you've already given

 

I believe the VE tables are used exclusively when the MAF fails, but they are also used the rest of the time as well.
The VE tables are used by the PCM in the Base Pulsewidth Equation. So they are extremely important in all fueling/tuning. VE tables are global. FWIW.
-Just trying to slay some internet myth.

Hat's off to Cal for his recent demo of VE and it's use by the PCM in Closed Loop. I guess that Guy (NoGo)on the right bank (Conn) really does know a little about this stuff.
joel(Bink)

 

Ok, now I have a new issue that has developed besides the higher Ltrims. It seems that while warm starts are great, I now get a constant 300-400rpm surge while coasting and stopping. Once I actually stop, the surge is gone. I'm guessing that I need to back off my adjustments a little. Maybe I should do a %70 all the way 400-1200rpm and split the differece?

 

I was having similar issues as discussed here:
https://ls1tech.com/threads/showflat...=7&fpart=1

I don't believe I ever got a clear answer as to what shoutl be monitored for the proper scaling of the VE table.

 

Someone correct me if I'm wrong, but don't believe LTRMs at idle mean anything at all. You have to be at part throttle for a while to get a good reading on them.

The way to tell if you have reduced the VE too far is you will start to get some hesitation when you try to accelerate at low speeds.

To address the surge while coasting to a stop, try scaling up the decay tables. If you add too much you could get the cruise control effect, so just play with small amounts, then drive around for a couple of days. If that doesn't work, go the other direction. I'm still learning on this one myself, but I'm pretty sure you need to make the values bigger to reduce surging; was just doing some tests with this today. I have a M6 though which is much more immune to surging than a A4.

 

Well, the problem is my car still smells rich at idle, but now after the VE tweak I'm getting MAP codes. Never got them before the VE tweak. Just wanna see what I need to monitor to tweak it right, rather than the SOTP meter since it isn't well calibrated

 

Ok, here's what I've done & learned so far tonight.

It appears that my surging issue was directly related to my changes to the VE table. Not sure if this is something anyone else has noticed, but that seems to be the case for me. When I was at 60-70-80 (400-800-1200rpm) I was getting PERFECT warm starts but tons of surging while coasting and low speed manuvering (braking/steering/etc.). I slowly tried higher percentages (starting back at stock VE table values each time) until I found a compromise between the low rpm rolling in gear surging and the dieing/surging on warm starts that started this whole mess. I ended up at 80-80-80% for the 400-800-1200rpm ranges. That seems to give me better yet not perfect hot/warm starts from where it used to be and has basically reduced the low rpm in gear surging to all but nothing.

I don't have access to the rpm decay tables in my version of edit.

My IACs are currently in the 6X range, but I think that will settle down as I put more miles on the latest TB hole revision (I was using the same size as now all last year and had lower IACs so I think all the messing with different hole sizes will take time to learn out).

Basically, at least in my case, lowering the VE tables too far resulted in a serious case of idle surge that I've never had before (no other changes made). Is that to be expected, or do I have an apperent "special" condition here?

Also, before I try to maybe work with really fine adjustments to the VE table, should I just leave it at 80% for a couple hundered miles and let it relearn? I know that many adjustments seem to take quite a while to really set in.

Cal and others, what do you think?

And sorry for this long post guys, but I've been living with these issues since April of '02 and I'm sick of it....

Thanks for all the help.

 

What sort of MAP codes were you getting? Just so I can keep a look out. Also, are these codes that Edit can turn off? Thanks.

 

It is possible that setting the VE too low could cause some surging or jerkyness, all that's happening is the fuel mixture is getting leaned out. VE changes are supposed to be imediate, for the reasons mentioned above by binksz06. But anytime you reflash your PCM, it has to go though an idle learn process, so I'd give it some time. I've made the mistake before of making changes too fast and ended up going in circles. I doubt 80% would be too extreme of a reduction, although everycar and cam is different so you just have to patiently experiment until you get it dialed in. Keep in mind though, if you smell raw gas it's a sure bet the VE is too high.

 

As of now, I've tried a few more warm starts and it's better than before. As for the smell of the exhaust, is still stinks (ORY) but it's not nearly as bad as before. I can stand 5 feet back and my eyes don't water anymore Used to have to stand 10+ feet away and it still smelled very raw even then.

Right now it smells pretty much like the stock cam did with an ORY. I think that if 80% doesn't do the trick in time, I'll bet somewhere in the 75-79% range will work. I'm gonna give the 80% a while to learn first though.

Thanks again for all your help.

 

Just to add to this however, you will always smell gas coming from a car that has no cats and a cam. You will never lean it out enough to eliminate that, it is the nature of an aftermarket cam (for many reasons).

 

That's why I wanna know which parameters need monitored for tuning the VE. I was told it was Injector Pulsewidth but later that was changed.

The MAP code I'm getting now is P0106