Hey guys,
Wondering if you guys couple help me out with a few issues i am having with tuning this Tuned Port. I have read the tech articles and its still a little unclear how i am to tweak the fueling sections.

I bought this IROC and the previous owner decided to slap a hotter cam in it and its throwing me off. It doesn't develop power below 2000RPM and revs easily to about 5500RPM. What i need to do is pull timing out below 2200RPM and add fueling up top where its leaning out.

I would like to get a wideband O2 sensor but i have to pay off some big credit cards so my girlfriend can get her house, so i am going to be doing this on a budget. I bought this one as transportation because the tranny went out on my other TPI, and so this car probably wont be getting dyno tuned anytime soon. It seems the guy i bought it from didn't really know what he had and after fixing the interior, suspension, and replacing the hood its got a nice running powertrain in there.

Anyway, back to the tuning:

I am getting lots of spark knocks down below 2200RPM at 32 LV8 at part throttle cruise and its running really rich at those RPM's.

Specs:
305 TPI with 19# injectors
Automatic with governor that shifts at 5500RPM

Tweaks:
Modified $6E ARAP bin - (SA maxed out at 40*BTDC)
Injector constant set to 18lb/hr
Disabled AIR injection - (looks like he gutted the CAT)
13*BTDC base timing
ARAP long crank fix

I have heard to fix fueling issues you are to modify the MAF tables, but which ones? It looks like there is a MAF Table 1-6 and a MAF Scalar Table 1-6.

The MAF tables look like its Grams/second versus Volts, is that MAF raw data volts or TPS volts?

I also noticed that the stock PE enrichment goes negative after a certain RPM, i think i am needing to add enrichment there to prevent a lean burn on one of my pistons.

BTW i am attaching this knock table from tunerpro, are those real knocks?

 

13* initial timing is too much, unless you have the setting at 13* in the bin, that can cause all kinds of knocking on the low-end.

The PE enleanment you speak of is normal as the engine reaches for peak HP. I typically expect to see 12.5:1 near peak torque and lean for 12.7-12.8:1 for peak HP. Stock tunes tend to run high 10s to mid 11s at peak torque and lean out to low-high 11s for peak HP. Overly rich to choke out the cat near peak torque is the norm.

 

I have 13*BTDC set as base timing in the ARAP BIN.

Maybe that just is too much for this particular engine. I ran a test bin with taking timing out where i was showing a lot of knock counts and the car fell flat on its face. Its like all the free revving that it was doing earlier just disappeared.

The thing is, i am just guessing where the peak TQ and peak HP are. The powerband has definitely moved up because it wont spin the tires much if you mash the throttle from a stop, even though its got 3.23's in the rear.

The main concern i have is getting more fuel up top, i dont mind a running a little rich down low because it will just foul the plugs.

 

How does it idle?? Lumpy? Or somewhat normal?

If the idle is decent, then he might have just put a higher stall converer in? A 2000 or higher one?

If he did put a bigger cam in with a real lumpy idle then it's probably leaning out up top because the fuel pump or injectors can't push enough fuel for the added HP/TQ.

 

the idle is pretty good and is not like a carb thats really bumpy. you may have a point, i have never been in a car with a higher stall converter. we got the vss working and it hates the stock tcc settings. anything below 60 mph and it begins to bog and feels saggy.

 

hard to say without knowing what cam is in there.

you'll probly need to modify the TCC settings and get a converter to help out the low end driveability.

13 degrees base timing and 13 in the bin will act just like stock, there is no difference. i would have figured you want more spark in the low end in that case, but if its knocking, check to see if you have enough fuel. check the plugs and BLMs

you may need more injector but probly just need to tweek the MAF tables. tables 5 and 6 is what you want to mess with, mostly in table 5 as you may not ever see MAF values that table 6 has. increase the values in that table by a percentage change to increase fuel.

work on the idle settings and o2 sensor values to help tame idle and light part throttle acceleration.

Also may need to play with acceleration enrichment.

 

Why is your injector constant set at 18, it needs to reflect your injectors at your installed fuel pressure. My 1986 fuel rail had the fuel pressure regulator, set at 46 psi. That would make the 19# injectors flow 19.5#/hr. That means that you would get an AFR approximately one full point richer with the constant set at 18 than you will at 19.5. Set the constant correctly for the pressure you are running.

I would copy MAF and Timing tables from the 305 over to the 350 ARAP bin. Changing the TCC settings to a higher speed would also help. I have an ARAP bin hanging around somewhere that I modified for a Hotcammed 305.

A datalog of the ECM in operation would certainly help.

Edit-I looked over ARAP and MANY settings are WAY wrong for a 305. ARAP is for an aluminum head 350 in a Vette, so the timing is WAY too high. Too much timing can make for a slow, sluggish, pinging engine as well.

I am going to attach the .bin for you that I modified with most of the 305 constants, you are more than welcome to try it, but don't blame me if its not right. It ran a LT4 hotcammed 305 with ported 305 vortecs great.

Open it with Mozilla Firefox as Internet Explorer seems to corrupt the bins we load on this web page.

 

Ok I think i know what to do now, got different answers on this one and i really dont want to mess with the scalars.

I was going to start messing with the PE Enrichment versus RPM and move a lot of those numbers up since the torque curve and horsepower curve seemed to be moved up.

I wanted the car to run richer across the board. The BLM's and INT values are much smoother now using an 18lb/hr setup. If i go back to 19# its going to run even leaner up top.

Yeah i set them to 45 for low gear and 50 for high gear, which helped but i am going to go back and move everything up about 5-10mph. If the TCC locks up before 60mph it lugs bad. I attached a copy of my formatted datalog on my first post in Excel format for easy reading.

Yeah i noticed that as well. The ARAP bin i have currently is a modified one that Vader helped me with so its not running the crazy advance the stock ARAP is. I have another 305 TPI with an L69 cam which is just slightly hotter than the stock cam and it runs fine without knock with the same setup.

Thank you for the BIN file, i am going to compare it with mine so i can fill in the blanks. I did add spark retard protection down low that the ARAP does not seem to have.

I am going to do some changes and see how it runs.

 

correct, but set that up and add more fuel via the PE WOT enrichment vs RPM table like you mentioned. thats the table for WOT tuning.

only touch the MAF tables to deal with part throttle fuel. low rpm cruise speeds may need adjustments to the MAF tables 1-2 and maybe the low end of 3.

I never did like the ARAPs aggressive spark tables. I'd use another bin designed for a 305 TPI setup and work with that. Or tweek a 350 L98 bin like the AUJL bin to fit your needs

but it sounds like you have too much cam for the gears and will need to swap them out to get rid of the chugging. keeping the TC unlocked will help overheat the trans. i'd rather get rpms up with gears which will also give you better performance

 

I went into the PE enrichment versus RPM tables and i just decided to guesstimate. I cut all the cells 0-1200 rpm in half and changed 2800-4400rpm to positive 6.25 and 4800rpm to .78 and the rest to zero. It looked something like this:
RPM Enrichment
6400 -0.00
6000 -0.00
5600 -0.00
5200 0.78
4800 0.78
4400 6.25
4000 6.25
3600 6.25
3200 6.25
2800 6.25
2400 6.25
2000 -0.00
1600 -0.00
1200 6.25
0800 6.25
0400 6.25
0000 6.25

I thought it would bog down low or up high but when i mash the throttle it free revvs nicely. Its much more aggressive and its making power where its supposed to. Although when i rev the engine to 4800 in 2nd it hits a wall and stops revving for a second and then starts revving again. I think i need to add more fuel up there.

The timing i have across the board is way milder than the one Fast355 posted up. Its still too aggressive i think i am going to lower the base timing.

I have 3.23's in the rear i am thinking, it hits 70mph doing about 2200RPM in overdrive. I will look for a set of 3.42's for it, or maybe we can find a better stall converter cheap.

 

Kind of seems like you might be getting false knock, or something. Maybe even real knock and it's yanking out timing too quickly and too much.
Can you hear any real knock? Try a bin with the knock retard limit set to 1 or 2 degrees and see if you can hear anything.

What is the "commanded" AFR during your PE blasts? There are 2 PE tables - one for coolant temperature, and one for RPM. They ADD together. Be aware of an old XDF that might be wrong (had one table showing double the actual enrichment that it would actually get). Stock, ARAP was something like 22.7% in the coolant table at warm engine, and +/- in the RPM table. 17% total will be what is needed for about 12.5:1. On my car, commanded matched actual without modifying the MAF tables (but it was relatively stock with just shorty headers).

Also, make sure your "Maximum Air Flow vs RPM" is set to 255 at higher RPMs, to avoid hitting that limit.

If the MAF is not modified, the tables shouldn't need much work, except maybe at idle and low flow or so.

ARAP PE spark advance is rediculous too. Make sure it's only adding ~2degrees, and not 9.

 

For PE AFR, I use AFRTuner from Moates.net on both the 6E and 8D setups. Makes changing the commanded PE AFRs quick and easy.

 

wow that is a very nice option!! Is that downloadable from his site?

 

Its really hard to tell, once and awhile when i am cruising i can definitely feel it knock and a power loss. I found a broken line to the EGR valve, that may be why its knocking at cruise but its not always commanded to be on during low RPM. The car seems to have a gutted cat, stock manifolds and also has a loud flowmaster muffler, so theres some exhaust noise there.

Ok i will check, i reformatted the hardrive and i am not sure which version of the XDF i have. I dont understand what you mean by they ADD together. The stock ARAP is showing 22.66% at a warm engine, and if i add a positive 6.25% from the PE RPM table ... now i am lost for sure. It sounds like i am making it extremely rich?????

I just ran it right now and it will spin the tires now when you mash it.

PE Spark Mode advance is mostly zeroed out, upper RPM's show 1*. The main places i am showing knock is below 2400RPM on low load, below the 32 LV8 on WinALDL. There isnt even a table for below 32 LV8 on tunerpro!

I will change the max airflow values, right now only 6000RPM+ has 255gms/sec. My MAF is unmodified, only running K&N airfilters.

This cam, whatever it is, is a pain in the ****. I ran this setup on my buddies 350 TPI swap and all we had to do is change the injector constant and tweak some of the settings.

Sweet, that looks like it will come in handy once i figure out what i am doing!

BTW, thanks to all of you, you guys are awesome.

 

I decided to retime the car and i realized that i did something wrong the first time. I set the static base timing to 13* and then i plugged the EST wire in and adjusted the dynamic timing at idle just until it started to make valve noise. I got so used to doing that with the stock $32 BIN that i just did it automatically.

Ooops.

I went back and set the base timing at 13* and left the dynamic timing alone. I need to go back and reinsert some of the the timing i took out and test it, but i had to replace a water pump so i didnt data log it yet. It is much smoother now and feels much better.

 

What I have noticed using this modified ARAP bin is a high idle in Park and Neutral when the car has been driven for awhile and allowed to warm up.

I was tuning my friends car, and the only thing I couldnt iron out was the cold and warm idle speed. It will ramp up on startup to 1500 RPM and stay there.

Same thing with my cars, and the TPS voltage is spot on.

Any suggestions?

 

any vacuum leaks? whats your rpm vs temperature tables/values like? there should be open loop and closed loop tables dealing with idle rpm

is the TB closing all teh way? IAC counts?

 

Temp V RPM
306 575
284 575
262 575
241 575
219 600
198 600
176 600
154 600
133 637.5
111 700
90 850
68 900
46 950
24 950
03 950
-18 950
-40 950

Closed loop and open loop idle tables??

IAC startup position 160 steps

Warm IAC Park steps vs coolant
306 5
262 5
219 5
176 10
133 25
90 50
46 75
3 100
-40 125

To be honest, I dont know really what this would all do. The spark advance tables are modified from the ARAP tune so they are more aggressive than stock.

 

from that it looks like it shouldnt be shooting up over 950 rpms when cold and in open loop on first startup

i have to look thru tunerpro and the arap bin again to refresh my memory on the tables but basically in open loop the idle is higher until the coolant is hot enough for the motor to enter closed loop and idle should drop.

Temp vs rpm shows the motor should idle high when cold and drop as it warms.

if your still idling way high, then something is not correct. What is the IAC counts/steps at idle? if they are high then the motor needs more air at idle so give it more air by adjusting the TB blades alittle more open at idle and reset the IAC. I think you want like 40-50 steps at idle

 

Ok i will do a datalog tomorrow and check it out

Thanks for the help

 

Update:
I removed the idle stop screw cap and adjusted the idle speed with the stop screw until it idles at about 800 rpm in park. It seems to be behaving much better now.

Now I have a new question, which jumps right into the meat of tuning the maf tables for the cam I have. I am pretty sure there is a little bit of overlap and I am thinking that some of the intake charge is going into the exhaust.

The datalog looks like its oscillating between really rich and really lean for the BLM's and the INT shows rich most of the time. I have a rich flag on under WINALDL showing up and it looks like at idle this thing is running way too rich. In the raw data I see an overall trend of the thing running way too rich at low RPM's.

I am trying to figure out how to adjust the MAF tables so that I can lean her out at low RPM's to get it close to 128.

I have this thing in WINALDL called MAFB under RAW data ... is that the corresponding MAF volts that I see in Tunerpro? Am I supposed to make those look like the actual grams/second airflow that I am showing in the datalog?