Tuning a 89 IROC, 355, T5, 4/7 swap cam, 218/224, over 500 lift, 112 lsa, L98 AL heads, shorty headers, 3.08 gear, no cat, Vic E intake with 90* elbow, LS1 throttle body, stock MAF, 30lb accell injectors, 43.5psi fuel pressure, ituning with 6E and the base bin was a aypy.

Apparently no matter what I do, add a lot of fuel, AE, bring in PE way early, there is no way that I can get rid of a lean stumble from about 1700-2050 rpm. Happens in every gear except 5th. Once I get past that stumble it runs great. Makes decent power till about 6k

On the datalogs you can see it go from 800-900 mv to 0, 4.4, 8.8, 0, then bam right back to 800-900 mv.

Happens in open loop and without the MAF connected.

In this datalog from 7 sec till about 11 sec into it you can see what I mean.

Yes Im starting to lose my mind on this. lol Been at it for the past 4 days trying to edit whatever I can to see if it will make it go away and it doesnt.

Thanks guys

 

would it have anything to do with a ccp routine???

I'm just stabbing in the dark honestly..... just thinking it happens in every gear but 5th. Gotta be a correlation there

 

What AE options does your def file offer?

 

I'll have to look to see what exacty is in the xdf when I get home. Am using the 6e expanded version.

 

Here ya go.

 

Alright after more driving, swapping parts, and eliminating potential bad stuff, it is in the tune somewhere. It does just go dead lean right at 2k no matter what gear it is in. Cruising right at 70mph is about 2k on the tach. I can get the O2 to just go dead lean even if the pulse width is at 5 ish msec..

I have a feeling that Im missing something obvious here. Any ideas? Thanks!

 

Take a look at the "$8d major AE tuning tip" that keeps getting bumped lately. IIRC, $6E has a similar bit. I haven't gotten a chance to look at any datalogs or even my bin lately, since my transmission trouble started.

I'm seeing the same sort of thing I think. As AE dies out, and before PE takes over, it leans way out.

Also bear in mind, our throttle bodies take some BIG changes to some areas of AE. Seeing values of .5 or 1 in some of the stock tables makes you think that you should be making small changes, but actually you may want values of like 3 or 4 in there.

 

Taking a look at your datalog, I see that your Mass Air Flow values stick right at about 75 gms/sec throughout your problem area... Maybe this has something to do with it?

 

I saw that flag in there. I didn't have a chance to try it out. Will do when I get to the car next time around.

Cool will try the bigger values also. I did have them on one bin up there and it seemed to drown out the engine with fuel (pw's were like 15 msec. lol)

As for the g/sec it doesn't matter what g/msec it is at. It leans out right around 2k or so. Like in the attached file to this post.. From 4.03-4.07 the g/sec is at 32.

Next time I get back to tuning the car it should have a WB in it and see what is exactly going on..

Thanks for some of the ideas so far