Tuning In Lope

[gpr]

This might seem like a crazy question, but i was wondering if you can actually tune an engine to make it lope. I love the sound and actually tuned my duramax to lope at an idle and it is kinda fun playing around with

I think it would be difficult on a gas engine as the only way i could see doing it was by varying the throttle position, so it would need ETC. Or you could have it idle rich and rev up then maybe somehow lean it out... I thought it would be kinda cool if i could make the engine lope with out changing the cam. Any ideas?

[SSpdDmon]

Lope really has to do with valve events. I don't know if you could really alter a car to "lope" harder with out changing it mechanically. You might be able to drop the idle RPMs down some to try and achieve this...but, it'll probably stall more often.

[LS1_Dragster]

I want just the opposite! I converted my 97 to a 0411 computer with custom OS and I cant stop it from loping! When I changed the cam several years ago I was sad it didn't lope but for some reason now it does.

So I guess the answer is yes, but I just don't know how...

Lee

[WeathermanShawn]

I do not know if you can do this on your setup, but I experimented on 2002 LS1. I did the following:

1. Lowered idle to 650 Rpm's.
2. Lowered base spark to ~17-22 degrees.
3. Increased Desired airflow by 1-2 g/s (total 9 g/s).

Granted I have a cam with ~10 degrees of overlap, but, it did sound like a pro stock car. Personally, it was way too much for me. But, that is the only thing I can think of. I went back to a 800 Rpm, with ~22-24 degrees of base spark.

Would that work in your situation? It loped hard, but just did not sound right.

[gpr]

I'm messing around with a 2002 5.3L engine with an auto so i don't think I should have problems with it stalling. I will try the stuff you recommended. the engine is basically stock so i'm not sure if you can make a stock cam lope, but it would be fun if i could.

what does lowering the desired air flow do? i've never really understood what that table does as it seems if you have a set rpm idle point it should change whatever is needed to stay at that rpm.

[LS1_Dragster]

I found your answer, by mistake. Turn on your EGR valve at idle! Your tune will go to crap and you'll need to adjust for it but it will make it lope! If your vehicle has an EGR, it seems newer ones may not.

Lee

[WeathermanShawn]

GPR, go with whatever interests you. I can tell you from experience there is good lope, vs bad lope. What I mean by that is if you pick a reasonable idle, a lot of the 'chop' is from spark advance. Lower sounds choppy, higher sounds smoother. If a car sounds like it is dying..is that really lope?

As far as desired air, ironically raising it will make your idle sound louder. That is one of the best ways to get a cammed car to idle at a decent RPM. Lowering desired air (too much) it can make it sound very quiet. IMO raising desired air, a little less spark, and a slightly leaner AFR idle will get you to lope in a somewhat reasonable fashion. Granted having a decent cam with overlap is the best way!

[limited cv8r]

A big lope really comes from old school carby, dissy tuning where you could only adjust so much and have to come to a compromise on idle speed, fueling and timing. With these newer injected, computer controlled motors, you have a lot more control of all of these parameters for fuel,spark ,airflow etc. Unless it is a really big cam, then a lopey idle is probably due to poor tuning. You "can" make these engines lope, but only because they are strugling to run properly on the tune in them.

[Black02SS]

Quick way. Adjust the idle overspeed and underspeed timing tables. Take the overspeed and subtract another 10* and add 10* to the underspeed.

[gpr]

Quick way. Adjust the idle overspeed and underspeed timing tables. Take the overspeed and subtract another 10* and add 10* to the underspeed.

This method worked very well and is very simple. Thanks for the help. I was just messing around to see if i could do it. I love the sound of old school big blocks with huge cams, and this makes the pickup sound a lot meaner, not that i really need it but when my camaro gets here i would like to do something like this.

I wouldn't think the constant spark timing changes would hurt anything if i left it this way, would you?

thanks again!