[ryans88gt]

Like the title says.

Engine is a 393w with 36 lb/hr injectors, 70mm throttle body, edelbrock vic jr heads. 11:1 compression with a 248/252 108 deg LSA 550 lift camp with fairly agressive ramp rate.

I built a tune where all I really did was raise the idle to ~900, changed injector slopes, and MAF transfer function.

Runs great cold. Once it gets hot, it still runs great, but when I lift off the throttle and put it in neutral it wants to die if I don't pump the throttle once or twice.

I have a quarterhorse and haven't gotten it to sync up correctly to datalog yet. I know I know, more data would be useful here.

Any help on some things to change that might be diagnostic of the problem?

I do have a wide band and the car idles around 15.5-16.0 when in CL, I checked and recalibrated wideband. New O2 sensors.

I have read a little bit about compensating for big cams, but haven't yet done anything.

Not necessarily looking for "the" answer, but at least, what are some levers I can pull to see if there is any improvement.

[cgrey8]

My guess is your Closed Throttle(CT) decel is truly lean and is conking the engine out because of over-lean condition at a vulnerable condition. But before I corrected for that, what I'd do instead is reduce the DASPOT rate to slow down just how fast the ISC closes off when you go CT. This should help.

However another scenario to test for is if this is a manual, even if this fixes the problem, it might not fix the scenario where you declutch after being at CT for a few seconds. The scenario is you are driving along, go down a long hill with the vehicle in gear but at CT. Then at the bottom of the hill, you declutch. Depending how the tune is setup, DASPOT might be depleted and thus any slowing that you did wouldn't help you in this scenario. The only fix for this scenario's conk condition is to either enrich the decel condition OR raise the minimum ISC position while moving (i.e. MPH > a scalar value). I know GUFx has this problem when DFSO is active, but I just don't know CBAZA well enough to know if this is an issue CBAZA users have to deal with.

[2Shaker]

Keep in mind that CBAZA shuts off the injectors completely on most decel conditions.

[decipha]

dial in idle air and poof.. issues resolved

[ryans88gt]

what should I be tuning with to adjust the idle air, just the low end of the MAF transfer, or is there something else I should be looking at?

[Paulie]

what should I be tuning with to adjust the idle air, just the low end of the MAF transfer, or is there something else I should be looking at?

http://info.efidynotuning.com/idleair101.htm

[ryans88gt]

OK, I read that and understand very little of it.

I was able to get my data acquisition working. I raised my idle to 1000 and got the idle air adjustment screw set so that the IAC can control the idle +- 300 rpms. Set TPS voltage.

MAF voltage was at 0.9v idling, which calls for 51 kg/hr air based on the MAF transfer I am using. It is idling in the 15.5:1 range. Lambse seems to be calling for about 13:1. When I raised the maf transfer function in this area around 15%, the idle richened to 14:1 and it idled like shit and I could smell the unburnt fuel. Also Load % was around 28% at idle and a quarter throttle blip made it instantly go to 100%.

Car runs pretty well other than wanting to die when warm and going to closed throttle clutch in. I haven't been able to data log and decent running time due to no vin#, license, registration, or insurance (factory five kit car). Also a bit rich at WOT (around 10:1), should be calling for around 12.5:1

I attached the current bin file I am using.

Open to suggestions.

[Stengun]

Howdy Ryan,

I've seen your post before on ffcars.

Where do you have your O2 sensors and WB sensors mounted in the exhaust? Also do you have your sidepipes installed?

My car is a Spyder with the Coupe's 2-1 headers and I've found that I cannot get any accurate readings off the O2 sensors or the WB without my sidepipes installed.

I understand your "OK, I read that and understand very little of it." statement because I feel the same way. I've had to reread and reread and reread the write ups to get any of it to soak in to my dense skull.

Paul

[ryans88gt]

Side note, I have PRLDSW set to 1, stock T4MO calibration has it set to 2. I see some people suggest setting it to 0.

I expect the engine to do a little better than 115% VE. I have scale the spark and fuel tables to 200 and 150...

I have not scaled load. I did correct the CID to reflect actual.

Should I be using the 0 setting for PRLDSW?

It has been a few years since I did any tuning that didn't involve a mechanical secondaries carb and mechanical advance distributor.... so bear with me and try to use terms that I might have a chance of understanding

[ryans88gt]

Howdy Ryan,

I've seen your post before on ffcars.

Where do you have your O2 sensors and WB sensors mounted in the exhaust? Also do you have your sidepipes installed?

My car is a Spyder with the Coupe's 2-1 headers and I've found that I cannot get any accurate readings off the O2 sensors or the WB without my sidepipes installed.

I understand your "OK, I read that and understand very little of it." statement because I feel the same way. I've had to reread and reread and reread the write ups to get any of it to soak in to my dense skull.

Paul

I have both my wideband 02 and narrowbands mounted in the side pipes just past the merge of the collector. I think they get plenty hot there, basis the golden color of the high temp paint.

I think a lot of the not understanding this comes from using tunerpro with completely different names for a lot of the inputs.

[Stengun]

Howdy Ryan,

I think your sensors are way too far away from the engine. It's worse that long tube headers.

I would move them closer to the engine.

Paul

[ryans88gt]

IDK, they are closer to the engine than long tubes in a mustang for sure.

There is no closer location to mount them that wouldn't result in tuning a single cylinder with the 4 into 4 headers.

[ryans88gt]

Anyone?

Side note, I have PRLDSW set to 1, stock T4MO calibration has it set to 2. I see some people suggest setting it to 0.

I expect the engine to do a little better than 115% VE. I have scale the spark and fuel tables to 200 and 150...

I have not scaled load. I did correct the CID to reflect actual.

Should I be using the 0 setting for PRLDSW?

[Stengun]

Howdy Ryan,

Yeah, it's not a perfect setup but most people just use one cylinder per side.

With my dual 2 into 1 headers I can at lest sample two cylinders per side.

Paul

[ryans88gt]

Don't seem to be having a problem with the HEGOs, and relocating them isn't an option. So moving on... :)

I decreased Dashpot rate and played around with increasing the low load low rpm timing

Doesn't die any more, but still has a bit of stumble when declutching throttle closed.

continuing to play around with things... open to recommended changes to the tune

[cgrey8]

When it stumbles on declutch, is the engine going lean or rich?

[ryans88gt]

Doesn't really seem to be either, but if anything it seems to be idling a bit on the lean side, especially prior to being all the way up to operating temp. But the stumble seems to get worse when it is up to operating temp.

Once it is titled/insured/plated I will be able to drive it more and do some datalogging.

sec of state police come for the inspection on next tuesday.

http://i249.photobucket.com/albums/gg20 ... uuxvjq.jpg

[cgrey8]

If the problem isn't fuel related, then perhaps the DASPOT is simply decaying too fast or your minimum clip for airflow is too low.

[ryans88gt]

what function controls "minimum clip for airflow" in CBAZA strategy?

[cgrey8]

I don't know what CBAZA calls it, but in GUFx, it's DASMIN (Idle - ISC Minimum Daspot Clip For Declutch).

And the daspot decay rate function is FN879 (Idle - ISC Dashpot Decay Rate).

CBAZA may or may not call them the same thing. Although I would expect it to have them in some form. But I could be wrong...

[85GT]

Closest thing I find:

Dashpot Min Clip Low Gears - FN894 - Used to prevent declutch stalls in 1st, 2nd and 3rd gears in manual transmission vehicles. Input value is the difference in between actual and lowest rpm recorded during closed throttle.

also:
Dashpot Pre Position - FN830 - A dashpot (pre position air flow) offset determined by the difference in rpm and the desired idle rpm.

[decipha]

read the dashpot write up

[ryans88gt]

read the dashpot write up

I did, doesn't seem to discuss at all CBAZA strategy and how it works. A lot of the Dashpot functions are at least labeled differently if not different functions.

Here are the functions I can find... see attached.

[ryans88gt]

recommended changes?

And did I mention this has a large cam? It's 248 deg @ 0.050 with 110 overlap, not a ton of vacuum, maybe 8" at idle.

[ryans88gt]

anyone suggest what dashpot values are equivalent to GufB strategy changes?

[ryans88gt]

anyone

[ryans88gt]

Can anyone explain what the preposition/preposition max clip/dashpot max clip vs. mph/dashpot min clip in low gears... are and how they work together?

Currently the tune is pretty good, but I still have a declutch issue where the engine dips to about 700 rpms with a little stumble and then returns to normal idle at 900 rpms.

I want to increase the cruising ISC duty cycle and slow down the transition to get rid of the stumble.


idle is good around 14.5:1, everything else seems to be working correctly.

[decipha]

read the dashpot write up

read it again, cbaza is covered

[ryans88gt]

So... anyway...

Got my wideband reading about the same as LAMDSE... but for some reason the computer is calling for around 16:1 at light cruise which is causing the car some lean surge and missing. But I have no idea why LAMBDSE is requesting that lean. Engine up to temp, ECT reading 174, ACT reading 102. Some multiplier I missed?? Am I drunk??

[ryans88gt]

And I am getting a lean stumble on throttle closing. What functions can be changed to smooth out the lean spot on closing throttle.