Im back again with a few questions.First Ill describe that my car just doesnt seem to be making much power and I just got a pcmforless tune hoping it would correct the car feeling so sluggish.The car doesnt seem to really break loose on me and on my a/f guage I see it bouncing from stoich to lean as I start climbing up in rpm so I always let off in fear of blowing my motor.I think my holley regulator is too low on pressure..but I always seem to have to bump it up every few days.The car take for ever to start and kinda stumbles to life but once its warm and start with half a crank..never sounds like its hard to start..just not enough fuel.

The car idles around 850-950 rpm and Im getting around 54kpa on the map sensor..which is around 12-14of vacuum.I cant tell if I have a vacuum leak since under the hood noise is fairly loud.Another problem is that the car doesnt downshift if I stomp on it right away before I had the motor built.

My previous tune had a base timing of 10*btc and the pcmforless requires 6* for base and its totall advance is 43*...sounds a lil too high.Would it be worth bumping my timing down as suggested with my current afr 195 65cc heads? I need to get a data logger and let you guys see what the car is going so I can make this thing scream like its meant to do..Im itching to show a few of my honda buddies what torque really means

 

43 degrees total advance is way to much. With my new motor on the engine dyno and AFR 195 heads it did not like anything over 32 degrees total timing. Any more timing and it lost power. We settled on 30 degrees total as there was no power loss at that setting compared to any more advancing. A custom tune would do wonders for your car. You need to find someone who can do one for you even if you have to drive 100's of miles. You can also have Pcmforless drop the timing back as an intermediate step.

 

I can change the totall advance on the pcmforless bin file since Im using a ostrich 2 and tunerpro.Im not good at tuning yet so Im using this as a base line to tune from.Ill set the totall to 30 degrees and see how she reacts to that.I thought 43* was way too high aswell.

What is your base timing set to?I need a fuel pressure gauge again to see what its running with vacuum..I think the holley regulator is defective.Im hoping this is where my loss of power is from.

 

That combo should make about 450 flywheel horse power. The injectors are a little on the small side.

Can you paste the spark advance table, and your PE spark adder?

-- Joe

 

If you can direct me on how to copy it or an email.I can show my bin file to you.Pm me

 

easy. In tunercat or tunerpro, just goto file and save as - call it something like mybin.jun19, then just email me at anesthes@cisdi.com and attach it as a file.

-- Joe

 

Awesome..its in the mail,and thanks for any help and advice guys.Hoping I can find my missing power in this setup.

 

So attached is your spark tables.

No PE spark, which might be why it feels a little slower, but that's actually how I do it too. I'd rather not have the tires break loose when it enters PE mode.

I would however ramp up the advance.

I'd have brought the advance in to 34 degrees by 3,000 RPM, then after 4500 I'd bring it out to 36 degrees. (after torque fell off).

I'd also run 10 degrees initial, which would allow you to bring the rotor closer to the terminal, so you'll end up having less voltage loss at the plug.

Remember, at 45* you are dead center between the cyl it just fired and the cyl it's about to fire. Which terminal gets the charge is a crap shoot

I'm heading out for the night, but if you'd like I'd be happy to alter some of the tables for you and you can give it a try. However, without seeing any logs I have zero idea what your fuel situation is like. If you can get a log snip in datamaster of maybe a 2000-6000 rpm pull in 3rd gear that would be helpful. Don't break any speeding laws.


-- Joe

 

I dont have anything to data logg with yet to really see whats going on when the car is underload.But if you can modify those tables and send the bin back to me I will try it out asap.Ill leave my base timing at 10* then and see how she likes that tune.

 

My base timing is set at 6 degrees.

 

my 385 with a super ram 280xfi made 467HP and 517TQ at the crank... with 8* base timing and 36* total timing

 

My only thought is with the new AFR heads he may not need that much total timing. The design is pretty good with the double quench pads for fast burning of the fuel.

 

ought to be making more than that. i say anywhere near 500hp

 

With a slightly bigger cam, and a good intake.

-- Joe

 

That's a thought, however all of the dyno combos they advertise, and all of the tunes I've seen with AFR run 34-36 degrees.

http://www.airflowresearch.com/chevy_dyno.php

Every combo is a little different though, plus it depends what his final AFR is.

-- Joe

 

Interesting. My compression is 11.1:1. I wonder if that has anything to do with it? My motor did not like 34 degrees of timing and lost power. No power difference between 30 and 32 degrees so we left it 30. I guess it is like you said and depends on the combination.

 

What is the DCR ? Quench distance?

-- Joe

 

DCR is right around 8.5 and the quench is at .036". Headgasket was .038" and the pistons were at +.002.

 

You can't get any more perfect than that, in my opinion.

Did you measure the DCR at .050+ 15 degrees, or did you use the .006" advertised IVC ??

I usually shoot for 8.5 using the advertised (pat kelly), and 9.0 using the .050 + 15.

-- Joe

 

I used the .006" advertised IVC. I also used Pat Kelly.

 

Well a lil update.I tried the bin you supplied me with the modified tables Anesthes and I did notice more power out of it..however I still have to change the injector flow rate to around 10lbs per hour for it to keep a consistent afr.

The car idles around 900rpm and on my vacuum gauge Im getting around 15-18in..when I rev it up a little..the vacuum increases..and then starts to fall down..is this normal?

I seem to always be increasing the holley regulator and trying to adjust the bin back to 24lbs but the motor does not respond well to that change and runs lean according to my autometer afr gauge.

Start up is still rough aswell when the motor is cold. I have to prime atleast 2-3 times and then crank for 10 seconds before she fires up..after that I have to feather the throttle slightly for a minute or 2 before it will idle on its own.This bin still shows that max spark advance under tables is set to 43* and im wondering should I change this down to 36*.The car doesnt feel sluggish while reving it in park..but under load it no longer surges but once second gear hits..the motor bogs..It barely peels first gear from a brake stand and I think it shifts too early.

Still on the quest of making this thing perform half decently..but she sure does sound mean.I got high hopes from this combo seeing as its a proven package ..though the xfi280 seems rather tame so far bottom end wise..im hoping my topend hp will be fantastic

 

I have noticed every so often that my idle/o2 readings/afr readings would drop as if something either knocked or a misfire withing every 30seconds or so..if i hold a steady throttle position..this will still occur.I really need to learn how to data log and understand all the things Im reading/adjusting.....Im afraid to make major adjustments in tunerpro and only adjust things like totall spark advance...fan enable/disable temps...injector flow rate and spark distributor initial timing base.

 

uhhhh, no, burnout91 is making 399rwhp with a 355 hsr and 195 eliminators, with the xfi 280, si he should be over the 500hp mark given a 20% drivetrain loss 400 rwhp like burnout.

 

Correction, It's a stock 350 G92 short block. Not a 355.

 

500hp should be around 425 rwhp. Unless he's running a TH400 with a very loose converter, like a 5500 stall, 20% drive train loss is wicked high.

Most cars I've seen built, from engine dyno, to rear wheel dyno lost at most 15%.

AFR did a dyno test of the xfi 280 on a 383 at 9.5:1, 34 degrees total timing, 1 3/4" headers, etc. It made 460 flywheel hp.

460 * .85 = 391 rwhp.

Seems to be damn near close.

-- Joe

 

We need to disable closed loop on that bin. Unplug your battery for a few minutes to clear the NVRAM, then fire it back up. we need to set your injector constant to 24, set your fuel to something reasonable like 50psi with vac line disconnected, then start modding your VE tables til we get around 14.5 AFR at idle.

Then dial in AE, then dial in PE. Then once all that is dialed in, you can re-enable 'screw up my tune mode'. (close loop) and spend 6 months playing with 02 offsets to try and get it to work properly

-- Joe

 

MY 383 has Dart heads, KB100 pistons, 10:1 CR, Super Ram, and 280XFI. My combo wants LESS than 30 degrees. It fights itself with more. Strange, but true ;-)

 

Just another example of every motor being different. The tune needs to be spot on.

I'm breaking my 412 in with an RPM air gap intake, 750 carb, and vac advance. I have a harness, couple of ecms, small cap dizzy, etc just not sure what I'd like to use for an intake. I'm really tempted to try a 4 or 8 injector 4bbl throttle body.

I guess I'm kinda waiting for a good deal to spring up on a complete used intake

-- Joe

 

Yea I know its a long process to get it tuned decent enough ..but Im still chasing down what causes the ecm to really start running lean even when I bum the fuel pressure and and set it to 24lbs injectors..this happens maybe 30 mins after the car is running and upto tempt things get strange.

I have a tech 1 gm scan tool and its showing im getting 55kpa at idle for map,my o2 fluctuates like crazy from rich to lean..hovers for a seconds at stoic but very close to rich..and then drops lean..then super rich and keeps repeating that cycle.When i set the injector constant to something crazy like 12lb injectors..the car runs strong and at wot I get a code for rich exhaust.

Needles to say..without anything to datalog and have some of you more experienced tuners point out to me whats going on and how to adjust things to be better..I have to live with what I got for now.

Im still thinking the holley fuel regulator is not working upto par.Its bottomed out for max fuel pressure and when I set my injectors back to 24lbs..the car was barely running and it was extremely lean which is very scary so I stopped trying that lol.

 

86W-
Is the A/F reading at idle reading reliable?
Can you get a fuel pressure gauge on your car while it is at idle?
Might be a way to check your fuel pump theory.
Otherwise, from what you say, you might want to check out your ECU.
I have to say, I don't think that spark table posted by Joe, with all the advance at low loads, would fly with my setup. Then again my ECU and program are stone age Accel. Good luck. When you get it worked out, the Torque just keeps you smiling.
89GTA-
What do you have for pistons? My thinking on my less than 30 advance is the KB100 pistons are part of the story.

 

if thats the case the xe line of comp is better than the xfi. didn't they test the new eliminator heads on the comp xe282hr10 cam and make like 535hp?

 

I had problems w/ my Holley fuel pressure regulator, the Holley diaphragms are leaky. I solved it by cutting the stock diaphragm free of its spring and using that stock diaphragm inside the Holley regulator with the Holley-supplied spring, etc. All problems cleared up, it now stays stable and reads the same pressure every time I put a fuel pressure gauge on it.

TA

 

They tested with the XR282 on a 355, and 383:

http://www.airflowresearch.com/chevy_dyno.php

The 350 made 450hp, the 383 made 480.

Look at what that 413 made.. dang. Cubes win.

-- Joe

 

The tech 1 scanner doesnt tell me a/f..only 02 readings in Mv and my a/f guage isnt a numeric display..just the bar graph.Ill have to write down what it fluctuates to next time I fire it up.My fuel integrator reading is around 110 for blm at idle aswell.

Ill record it on video aswell of how its running write anything down that could lead to my problem.Aside from that..Im hoping the regulator is at fault for most of it and the knock that still exists will be one for my engine builder to fix.

 

It should flip between lean/rich, thats your cross counts. It should flip fairly rapidly as the ECM balances the AFR. Your BLM (in closed loop) will be your indicator. 110 is pig rich.


Something is way goofy here. I wish you were local so I could play with it.
I didn't look at your VE tables, maybe they are just way out. I'd probably start by disable close loop, get your fuel pressure reasonable, and set the inj constant to 24. Then start knocking down the VE table until you can get the most vac on the gauge. Then you can re-enable closed loop and try to dial your BLM back in.

-- Joe

 

it does flip rapidly between rich/lean..i thought what was bad..shouldnt it be more steady/stable?.. also when i rev it.. my vacuum gauge would go to about 17-19in of vacuum and then start getting to under 10 closer to wot.is this normal?

I can readjust the inecjtor constant and get it to 128 blm.I can resend the bin if you like to take a quick glance at the ve?

 

*Bin sent Anesthes*

I agree something is really weird going on and I dont have anyone familar with this setup close by to help pick out the lil things that could be holding this motor back. I feel like a stock 350 would take me pretty badly right now..and Im afraid to drive the car too far. Cant tell if I have a fuel issue still..or if its just tuning.. or a mechanical error.

 

Well despite all the tuning efforts made I cant find a happy medium of getting this motor to be semi reliable.Im leaning towards the fuel regulator as one of the major culprits here from what Ive read about how much they fail out of the box.Im going to get the kirban unit and eliminate that concern and get a fuel pressure gauge mounted on the rail to be certain of consistent pressure.Once thats done hopefully the car will be more stable..and will start more than once a day without flooding.If I can iron out that tuning is decent and my fuel and spark are good I can be more confident about taking the motor out and having the block clearanced more to stop the slight knock and when its put back in I wont have any headaches and can move on to fine tuning tables.If not Ill be posting many parts for sale and searching for a lsx to swap for something more reliable..makes near the same power as my 383 should and even better mpg.

 

I built my 1st fuel map from a tuner one done by Accel, for a 383. It was so rich I fouled plugs every 15 miles. They swore the map was for 30 lb injectors, but even when I did a conversion factor, it was still rich. Eventually I leaned it out so it worked with mine. "Every engine is different" but maybe you are just "pig rich".
BTW- Just put my car up on stands to change over to an LS1
Good luck.

 

Hi ! I was just looking at your parts list and the first thing that struck me was the 24 lb injectors, they are way small for 383 ci. I have an xfi in my 88 5.7 GTA running 24 lb-ers on it,also have a 383 waiting to go in and run no less then 32 lbs. I think the 24 lb-ers are way small. just a thought,good luck.
Chris.

 

I just wanted to ask where in Ont. you are, I'm in Hamilton. Reason being, I ran into some trouble getting my xfi set-up right and finally had Brian Macy fly up here for a few days, last month ( he teaches the tuning classes for FAST) come out here to set mine up and he also gave me a rundown on tuning, if you're not to far maybe we could get together and get you sorted out. I to know how hard it is to find anyone around who knows much about fuel injection never mind tuning.

 

I know its small on the injector size but I was told 24's would be the minimum to start with.I had these injectors on my old 355 so I re-used them for now.I do plan on getting bigger injectors later but without having stable pressure and barely able to drive the car underload is my biggest concern.

I can get it running strong when I have the afpr maxed out and set my injector flow rate to 10lbs .At this point the car will run very rich uptop and gives a code for rich exhaust but its driveable from the low-midrange rpm.Once you shut the motor off no matter what temp or settings I have in the tune or on the afpr...the car will not start backup..it seems as if its floods itself when I shut it down.It will start up the next day and I have to feather the throttle untill it reaches closed loop or it will stall.

If there was a contest on here of who has the worst luck with their 383 hsr build..I might be a top contender so far lol.I really had my sights set on spanking a few hondas around here and surprising a few stock ls1 guys with this motor..so Im hoping I might get a string of good luck soon..or Ill have to bite the bullet on the lsx swap.

 

Im in Scarborough...and I know how hard it is to find support for these older cars here.Im just getting into tuning and still need to get equipment to datalog,but I built my carputer in my dash for this purpose of being able to tune as much as I could in the car while its running with the moates ostrich2..but not fully knowing what im adjusting can have very ill affects on the motor very quickly..leaving me very hesistant.

 

Ya! I bet you'd be concerned.. I have to ask the xfi 280 ? I'm not sure about the model, mine has internal and external data logging,are we not talking about the same ecu ?

 

im running the compcams xfi280 cam,as for the ecu its still the stock gm 730 ecu but instead of burning endless chips to get my tune..there is a real time emulator that plugs in where my chip used to be.This allows me to tune the car directly from my laptop without having to pull the ecu down.change chips and see how it runs.

I took this one step further and built my laptop into my car and put a 7 inch screen where my radio used to be.Its a pretty trick setup.Its good to know that even though the car may not run right or leave me stranded..I got full internet,dvd,bluetooth,gps to keep me occupied while I wait for a tow lol.

 

Sounds neat, I thought about it my self but chickened out, worried the hard drive in the lap-top might not like the vibration. I'll send you my e-mail address, if I gave you a call I could find out a lot more in less time, I'm really curious about your set-up, both mechanically and tables you're working with. My e-mail is ccalinesco@cogeco.ca, lets talk,always good to know someone else who's mod-ing the same car.

 

Just free revving yes, the vacuum may drop alittle with quick punch of the gas. But from what I've seen on my motor, the higher rpms I pull at free rev, the more vacuum it makes. Now while driving under load, the more load and rpms you pull the less vacuum you get. at WOT while driving you should have no vacuum. If you do you have a restriction in the intake path.

It sounds like this motor needs a good tune and thats about it. Theres a huge difference in a tuned motor and a not so tuned motor It will wake up, just needs tuning time.

 

I think once I get the kirban regulator on there..alot of my issues will go away and this tune will be a decent baseline.Id love to have someone local that have experience with tuning my 730ecm would really be able to dial it in and Id really appreciate the motor.For now I can only follow my butt dyno as I make my own very small adjustments trying to see what tables do what.. but not ruin the motor.I really need to get datalogging equipment and just dive in there.

 

If you can start datalogging with a WB02 hooked up it will change everything, makes things so simple.

 

Had to bring this thread up to give an update and hope I can get pointed in the right direction with my car.

I have narrowed down my 383 not performing because of fuel flow.I have no installed a kirban fuel regulator,new 255lhp fuel pump,new fuel pump relay,new fuel filter,will be installing bosch 3 injectors next week,and have a autometer fuel pressure guage mounted under the hood.

The fuel pump primes fine and all I get is maybe 10psi when it primes and then it drops right back to 0,it wont hold pressure and there are no physically leaks anywhere of fuel.I have tried putting the regulator to max pressure and still no change.It takes about 10 seconds of cranking to start the car when cold and then when it does start I have about 15psi of fuel pressure.

What else can cause the fuel pressure to drop off so fast without leaking fuel,only thing i can think of is the check valve in the tank or i have a bad fuel pump..but this pump is a few months old and ran my tpi just fine and no fuel pressure issues.

Need advice..my brain is fried trying to figure out what else to try aside from new injectors