Ok so i am new to this and i decided i wanted to try tuning my 383 myself. Got a burner, using tunerpro, 165 ecm and using the 32b mask. Now i started slow, like the faq stated, and started with changing the injector size and fan on and off temps. I also messed with the idle rpm adder constant and upped it alittle bit because of the cam i figured i would need alittle more rpm. So i put the chip in and it actually ran alot better (im working with a stock 305 tune on the stock prom). However the only real issue i am having is it running lean up top and detonating. Now i figured this meant i needed to start working into the "tables" part of tunerpro, but i dont know where to begin. Ive read alot but its still kind of gibberish to me. I managed to talk to the guys over at tpiparts.net for about an hour and he was extremely helpful but i am still alittle lost. THanks guys

 

Does it still have the stock MAF? If so, then you may be maxing out the MAF. The two ways to deal with it are mess with the PE parameters in the ECM to get more fuel, or use a larger MAF and fudge the gms/sec airflow tables and injector constant (if applicable). The latter is a better solution, but requres you to use another MAF. FWIW, a properly sized mass airflow system wont need much tuning.

 

ok that makes sense. Ok another issue i noticed, i set the injector size smaller...from 30 to 28 to 26 and then i think i have it at 24 right now. It will detonate for a good second or two under like a decent throttle with no down shift. It seems like it stopped detonating up top but still does it in the mid range alittle bit. I believe if i run to stock 305 tune set to 19-20lb injectors it doesnt denoate at all. But i feel thats only because im running it rich as hell right? (the same concept as if i were telling the computer that even though i have 30lb injectors i want it to believe it has 24 and what not...its basically just running rich)

and yes i ahve the stock 305 maf and the engine is a 383 with edelbrcok heads, comp cam, edelbrock full tpi intake...am i maxing it out?

 

Its very likely you could be maxing out the MAF. What tables are in use in the 32B? The pulsewidth vs airflow and RPM tables? I vaguely recall that being an option. Im not real familar with the early MAF masks, but if it does, then the $6E, which is a later mask, is the way to go. With a larger MAF, you can scale the injector constant so the ECM can see over 255 gms/sec.

 

ok so i can download that mask and tune using that?

 

anybody else have any suggestions?

 

In the "tables" section of Tuner Pro, you should see "WOT % change to Fuel / Air ratio vs coolant temp" and "WOT % change to Fuel / Air ratio vs RPM". Perhaps start with the RPM table. I know the stock bin for my '87 vette actually leans it out a bit from 3600 rpm and above.

Do you have a wideband? I found the LM1 meter to be EXTREMELY helpful in tuning A/E and WOT.

 

thank you sir...i actually changed all those tables after i posted that and it fixed it..so you said yours was leaning out at 3600 and above huh? My tach is screwy and i havent had the oportunity to get a datalogger on her ( i will be able too tn though) so i wasnt sure at what rpm it was leaning out. So i just upped all the tables that had 18% to something higher..like 40% lol. It stopped detonating and i worked my way down from there. It still sounds like it does it just for a split second when i mat the pedal all the way to the floor and it downshifts. Any ideas on that?' and one more question, i only changed the rpm tables...should i change the coolant temp 1 as well to match w/e i have done to the rpm table?

and no unfortunately i dont have a wideband though i am going to invest in one soon. I just shelled out the money for a granatelli maf for the car

 

If you are getting a "pop" when you first hit the pedal, that is most likely a lean spike. You can tune that out using "LV8 (Load) Accel Enrich Factor vs Delta LV8" and/or "LV8 Accel Enrich Coolant Factor vs Coolant Temp" tables. By increasing the multipliers, you will add more fuel when you first hit the throttle (acceleration enrichment, or A/E).

If you had success just changing the RPM tables, I would leave it at that.

Before I got a wideband, I spent a lot of time reading the plugs - they can tell you much of what you need to know, its just a pita to always pull a plug (or several) after each run / driving session.

Good luck!

 

ah you rock dude thanks! all the help is much appreciated

 

Glad I could help!

-Dan

 

o and one more thing acutally. The only real issue with the car now is startup. It seems like im getting too much fuel at start up and i gotta rev it a couple of times so the car stops running rough and idles nice. Its not THAT big of a deal but i would like to fix it. I was looking at the start up air fuel ratio table...mess with that a bit?

 

If it is just at start up, then yes - you would modify that table, though I'm not sure how long that table affects the A/F ratio once the car is running. It is probably somewhat brief (a few seconds maybe?).

If you are having more of an issue while the car is warming up (in open loop), then you would change the "Open Loop Fuel/Air Ratio % Change vs. Coolant Temp" table. I had to lean this table out a bit since my engine was a bit rich during open loop warm up, but I didn't change anything on the "Start Up" table.

I wish I could be out there tuning too!!!!

 

lol thanks man

and yea its just for a few seconds. I have a 160 degree thermostat and i dialed in the fans to turn on at 200 and off at 190...thats not gunna screw up open loop to closed loop right? The engine feels it is fully warmed up at what? 185?

 

You'll be fine. I've got a 160 stat - fan on at 175, off at 170. Car runs nice and cool and goes into closed loop as commanded. (Had to install a heated O2 with the headers though).

(8-15" of snow expected tonight/tomorrow!!)

 

sweet..and since i see you have a 383 as well...can you list your specs. The company suggested i set the base timing to 10 degrees base..what are you running as far as your setup goes...bc its pretty wierd how i am having the exact same issues as you..seems like whatever works for you will probably work for me as well.. but i am just curious as to what your setup is

 

I am running the following:

TPIS Mini Ram, 58 mm Holley TB, Accel 30 lbs. inj., AFR 195 heads, 1.6 Howards Cams roller rockers, 306/306 adv duration, 240/240 @ .050, .580 lift, 112 lsa (+4) Howards hyd roller custom grind, Eagle forged rotating assembly, JE forged pistons (approx. 10.0:1 comp), Walbro 255 fuel pump / Racetronix wiring kit, 1 3/4" TPIS ceramic coated headers, Borla mufflers.

Based on the custom grind, the tech at Howards Cams recommended base timing be set at anywhere from 14-18 degrees. I found best results at 17 degrees, as it got real choppy / rough when I tried to go lower. He also recommended total timing to be around 38-42 degrees, in by about 3000 rpm. I set my target idle to 1050 rpm.

I am still trying to get my BLMs / INTs in line, but that will have to wait until this ice melts!!!

 

i see..well tn from a dead cold start i got on it and it detonated pretty bad for a bit and then went away..so i guess i do need to mess with the WOT% v.s coolant right?

and you said dialed in full advance at 3000rpm..what table are you using for that..Spark advance in WOT v.s rpm? b/c my table is showing 5 degrees at 4800?...shouldnt it read more like 40?

also battling a high idle in park...i cant find any vac leaks, tb blades dont even look like they are open, i back the screw off completely, unplugged iac, unplugged tps...idle stays the same...i cant figure it out..

sorry for all the questions, i really appreciate the help

 

If it's the initial blip of the throttle, that would be Acceleration Enrichment vs coolant temp. It it's while you've got your foot in it, then yes - that would be WOT % vs coolant temp. WOT is tougher to dial in without a wideband, so pay attention to the plugs.

Spark advance vs RPM vs Load is the main table used for timing. The spark advance in WOT throttle vs RPM (what you were looking at) is the additional degrees of timing advance added to the total timing table at WOT. That's why you are only seeing 5 degrees.

When you are in park and the car is idling high, what are the IAC steps reading? What is the target idle set to? Is there something preventing the butterflies from closing all the way? If I remember correctly, min idle is set first, then TPS, then timing.

 

its weird..its more if i gradually lay into it...it pings for a second and then goes away as the rpm's raise..

and yea i wish i could tell you the answers to your last questions, but for some reason now datamaster wont sync up to my ecm.....im batting a thousand here...no sense in asking you questions if i cant even get you any info..

when the car went into limp mode when the ecm died i thought THAT was why it wouldnt sync up...now everything is working properly and the bitch still wont read.. If i test it it recognizes that GM 160 ecm is present but then if i click start or monitor it wont read..

 

after some tinkering i got it to datalog..anyway, i think ill send you the files, i use datamaster..which doesnt have the blms that i need does it..but anyway, you can tell me what you think? What datalogging software do you use?

and the park position for the iac was reading 136...thats way to high isnt it? it idles at 1300..and i think my desired idle (at least in the desired idle v.s coolant temp) is 1000 when cold and works it way down to 850 when warm..but i figured that was for in gear idle...b/c thats right on the money..she idles at 800-875 in gear..

 

The MAF bins have a max airflow vs rpm or something like that.
You'll need to up those numbers for a 383.

Base timing- what ever it starts easy with and will run with the dist byp disconnected.
Once you go above ~ 300 rpm the ecm is in control of the timing as long as the system works and the byp is connected.
So then you can go to 18 degrees or whatever you like with the tables.
There is a coolant vs SA table too. Do some research on how that works up in the stickies.

IAC park position- that's for start up, not idle.

165 and data logging- do some searching on that too.

 

I use TunerPro RT to datalog (via AutoProm), so I'm not at all familiar with Datamaster. Can you dump the Datamaster info into Excel and send that to me? Although, it looks like I could download Datamaster from TTS and fumble through it if I had to

Regarding the idle, since I have a manual, I'm not as familiar with the different elements used to manipulate idle speed for an automatic. But, if your target idle speed has increased, then you would need to increase the idle speed you are setting as well. This thread over at CF describes it pretty well: http://forums.corvetteforum.com/show....php?t=1606209

Z69 is correct re: the Max Airflow vs RPM table. I entered "255" for ALL RPM values. Not sure that will solve your problem (without seeing a datalog), but if you are maxing out the tables, then the engine will be taking in more air than the ECM thinks, causing it to go lean and ping.

 

yea i really got to invest in tuner pro RT. I am using a friends laptop hence why i havent done it already. Im not gunna buy it and put it on HIS laptop heh. I think i may start looking into scan tools though, might be alittle easier to handle inside the car.

Anywho, yea i think you might wanna watch it play out in datamaster, its a pretty long cruise...its a nice tool to have anyway and is real easy to use. when you download it, just d/l the 86-89 version..its the 2nd one down from the top..for the 5.0 f bodys. Then when it opens go to play datamaster file and upload mine then click play. Real simple to read too. I noticed, by briefly looking at it, that at around 1,100 rpm my o2 volts plummit to around 113 ..but other than that i believe i am rich as hell everywhere since they say in the 900's a majority of the time.

whats your email?

 

PM with e-mail sent

Sounds like it is going pretty lean at that point. I definitely battled similar issues - for me it was pig rich at cold start / open loop, way lean on A/E, then pig rich at WOT again. The vacuum leak and false knock issues weren't helping my cause . Once I found the vacuum leak and took care of the false knock, data logging and tuning became much easier and I could actually see and feel the changes I made.

Anyway, if you truly are pig rich everywhere else, you may need to raise the injector constant, but that will amplify any lean spikes.

 

Hey i sent you files. No need to download datamaster, i put data i got from moates software and plotted them on an excel graph.

I see the BLM and INT columns but have some questions to help clarify. I read the article on tuning 32B and am still alittle confused.

For example, i got a blm of 117 and an INT of 128 do i take the difference of those 2 and make percent changes based on that?

2. I see blm cell ranging from 1 to 16 being the highest on my graph...does that represnt the BPW v.s. load tables columns? 1-17

like blm cell 1 = column 0 in the tables, blm cell 2 = column 16 in the tables, etc etc..

 

Cool - I'll take a look at it when I get home tonight.

INT is more of a "short term" correction number (second or two), where BLM is longer (a few seconds). So in your case, the ECM has decided, for that particular BLM cell, the engine needs about 8.6% less fuel ((117/128)-1=-8.6%). Once it settles in on a BLM of 117, and no further correction is needed for that cell, INT would go to 128. If this were the case across all BLM cells, you could increase your injector constant by about 8.6% and that should get your BLM numbers close to 128. If it is only in a particular cell or two, you would need to modify the MAF tables for that particular area.

No - the BLM cells are primarily determined by engine load (LV8). I don't think that table tells you what BLM cell the ECM is using, though I'm not exactly sure what table you are looking at.

I'll take a look tonight and shoot you an e-mail. Heading home form work now...

 

yea i was looking at the BPW v.s. load table...the table every says that needs adjusting for driveability, i just noticed it had 17 columns and saw that possibly that could relate to BLM cells.

so in order to decrease fuel i UP my injector constant?

 

Yes, but based on the data scans you sent, I don't believe that is the fix. CTS (and MAT) readings are pegged at -40* c, so this is likely the reason it is running pig rich. (See e-mail I sent).

Dan

 

sent you an email back...i think those readings were false...but see for yourself..