Tuning a Classic FAST

[Chevman2448]

The "Gross Correct" only comes on when the fan kicks on. I did get the INJ DC down to "1.0 ms" with this program and all the other things seem to be in spec. A 12.6 A/F ratio seems to be best with little added fuel by the CPU with the fan on (1.6%) with it going back down to "0" when the fan turns off. The cars idle doesnt change so much when the fan kicks on. I tried going back to the 13.1 AFR but the engine almost dies when the fan kicks on and the idle is erratic. I replaced the rubber gasket for the PCV valve before I let it idle for a while. Now that I got ALL the vacuum leaks fixed I should be good to go for sure on accurate tuning. Of course winter is on its way here so this might be all that I accomplish this year.

 

[Reggie West]

I would not concentrate too much on the actual AF ratio of the car at idle. My first concern with any car I have ever had is that the damn things needs to start AND run with the turn of the key. No holding the pedal down or anything else.

I have observed that these cars run much smoother at 12 to 1 or so. I give it what it wants at idle.

If the fan kicks on and the idle is dropping I would be looking at the alternator and voltage supply. If there are 2 things the FAST units are finnicky about its the voltage supply to the ECM especially and smooth transitions between cells on the VE table all other things being equal.

 

[Chevman2448]

The engine starts and runs right away with target AFR of 12.6 that I put in there. It didnt want start and run smoothly with the 13.1 Alternator is showing 13-14 amps at idle. Did the in dash volt meter conversion before I even got the rest of the parts to get it running. It just surges when the fan kicks on and that is it. My TBI 305 Camaro that was all stock did that. 30 year old wiring and not the greatest grounding will do that. I didnt plan on doing wiring and all that untill the tuning is in order.
I did have to modify the VE table once I changed the tune. In the idle area they are in the 40-44 range because of my undersized injectors and I havent smoothed out the VE table yet. I know this is a tough question and one that requires actually being there to be able to do it, but how smooth should the VE table be? I can post a picture (if I havent already) of what I have for the VE table. Or take a look at the file I posted. That is the tune im using.

 

[Chevman2448]

Got the tune adjusted. Dropped the AFR to 12.3 and it idles even smoother. Had to adjust the fueling vs TPS position and all that to get rid of the hesitation. The exhaust even smells better. Of course winter is almost here so......next year Ill actually get to 'drive' it.

 

[Chevman2448]

What injectors would any of you actually have recommended for this engine? Of course Camshaft and head specs need to be accounted for but in a typical build like this (4.1 .060 over, cam specs unknown, i didnt install most of what was on the car when I bought it). what would you recommend?

 

[Chevman2448]

Now I can work on the fine tuning!!! So I FINALLY figured out the last issue I was having. The car has two wastegates. One is near the turbo and the other on the crossover. Why? I dont know! So I pulled both of them off and checked them. Well the upper gate was good. I took the lower one apart and the valve wasnt sealing in the housing. I could see a lot of daylight through it even when it had pressure on it. I picked up a Tial 38 mm and put that on the upper spot and the delta 2 on the crossover, for now. I got a set of OEM headers that im going to install when I get them. My boost gauge also works now too.

 

[pacecarta]

2 gates was common (old school) because the deltagates were so small one just couldnt control the boost on a larger turbo

 

[Chevman2448]

Thanks

 

[Chevman2448]

So now the engine starts and runs right away. The idle AFR is set at 12.5, everything is set and looks good as far as the dashboard is concerned. All but the RPM, Map numbers are green. I am assuming if they are green and not yellow or red the tuning is within parameter. Trouble is now off idle it backfires out the intake. I understand that as lean. I have adjusted most of the TPS, MAP vs Fuel rate of change to no avail. Is there something I am missing on this? Ive adjusted fuel pressure, voltage is good (I installed Caspers ground kit and that has helped keep voltage at normal levels no matter what RPMs)

As stated previously getting larger injectors, if it will make this entire process easier, is something I will install. 80#'s? 120#. I dont intend on racing the car very much. It will be mostly a street driven occasional driven to car shows car.

 

[Chevman2448]

Finally have gotten to drive the car. I cant believe how fast it is when the turbo spools. One thing of concern is that it seems to have an acceleration issue. Off idle its fine. But once it gets to a certain RPM (dont know which RPM was too busy trying to watch what was ahead of me ) it falls on it face, then picks back up. Basically it just seems to have a bit of a dead spot at a certain RPM. It also has a tip in issue when cold (doesnt want to rev).

 

[UR50SLO]

Post or send me the current tune file... That one you started with Oh my GOD some one needds to be shot!

There wasn't one number in there in any perameter I was happy about... 9.3's at WOT WHAT!

Your getting the hang of it... Just had some numbskulls in it before you.
~Scott

 

[Chevman2448]

Did you look at the combo of parts that I am working with? With my injectors every number in the VE table needs to be higher than normal. The 93 you saw in the VE table was the table I am working with. Those are that high because that is how far the tune was off. The original tune is saved but was way worse than what it is now. The help ive been getting here has helped immensely with drive-ability.

 

[UR50SLO]

You can delete that original Tune Lol

I made some edits to your file..... Since this is a newer computer and I downloaded the old Classic FAST software it's in Demo mode till I can go hook it up to a system... I'll try to get that done this week if possible.