I just changed the cam and put on some LT headers. The cam I just took out 230/236 114ｰ, I tuned myself. With my new cam 236/248 110ｰ I'm really having problems. I've read quite a bit on this forum on how to solve some problems but I don稚 have that much knowledge to solve this problem myself.

The problem is, the engine starts great but dies on me if I don't give some gas, a typical problem with so much overlap. It gets better when in closed loop but still idle goes from 850-1000 rpm. As soon as the fans kick in, the idle will drop down until the engine dies.

I have Datamaster (ECM $DA2) and a Romulator. I can send files if needed. Haven't driven my car yet because I've taken it off the road and it will still take 3 weeks until I can drive it on the road.
Hopefully someone will chime in and get my engine running.

In my sig. you can see most of my data.

 

Hi, Arnold - long time no hear. How's life??

There were some thoughts gathered here on LT1s and overlap last year:
http://forums.corvetteforum.com/show....php?t=1771567

One idea that seemed to show promise was running in open loop full time. Have you tried that yet?
Send me an email if you want to talk about it.

Regards,
Dave

 

Hi Dave,
You won't believe it, but I was thinking of you when I wrote this thread!!
I'll email you as soon as I can. Sorry no one else is chiming in on this.

Arnold

 

Why not run open loop only at idle or idle-5 MPH? When I ran OL continuously my fuel mileage dropped considerably.

 

Tell me how this can be done with my ECM DA2.

Arnold

 

I am at office now so dont have Tunerpro available but I believe under "idle" there may be a bit to uncheck or check to allow OL idle. Also a qualifyer of MPH I think allows OL to go beyond say 1 MPH to keep OL to what ever you set it too. Mine I believe is 3 MPH.

 

Just looked at my CATS Tuner tables and I can't find anything that allows me to go OL just for idle or a qualifier of MPH.

 

I searched and found this: "set the forced idle open loop bit in the option word". Again I am using Tuner Pro.

 

Setting the closed loop enable temp to something real high like 250 deg F will prevent CL from occurring period.

I recall TunerCat not having as many parameters as TP but they will add them if you request. At least they did for me.

 

Ronny,
I know how to set OL, thanks.
If I knew which tables I would need, I would then write TC and ask him to add them.

 

...create a rock solid 28* of timing at idle. This means no timing fluctuations AT ALL. This needs to be verified through the aldl. Searching through the forum will help you achieve that.

Run it about 15.5 AFR with little to no fluctuations. Just as you'll do in the timing table, make sure the surrounding cells in your ve are closely matched at idle. Running a little leaner than 15.5 might help too.

The minimum air rate needs to be adressed for that cam. This means you'll need to open the throttle blade set screw. I usually open the blades until the idle raises past the target, lower em back to the target and then 1/8 turn (closed) on the set screw.

Make sure the below items are up to par....
fuel pressure (aprox 45psi)
TPS (.54-.74)
IAC (75 counts or less)
injector pulse width (less than 2.4ms on sequential fuel injection can create idle problems)
sparkplug gap (.35-.45 depending on use)


......Turn off closed loop. I think that is all you'll need to make your engine run great at idle. Hopefully you'll post up the results!

 

..and add just a bit of iac counts @ idle. You'll also want the same value in the iac vs cts table from 70*c and higher.