TBIThrottle Body Injection discussion and questions. L03/CFI tech and other performance enhancements.
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The 383 is running. It fired up on the first crank. It turns out the TV cable I ordered from the GM dealer happens to be the right cable so it's going to get installed and adjusted. The starter bolts I found still weren't the proper length so the stock ones had to be cut and re-threaded. I haven't driven the car yet. I just got the fuel pressure set and adjusted the settings in the program using EBL and an Ostrich. Just a few more things need to get buttoned up and I can start driving and tuning.
I set the fuel pressure at 18psi to start. That gives me 83lbs. worth of injector on each side. I'm also using a slightly modified vortec timing table. I'll start with that and modify it from there. When I get a chance I'll post an EBL datalog of it idling.
I drove the car for the first time today. It feels much stronger than the Vortec 350. Also, even though I've got it set at only 18psi it still runs a little rich. The AFR was fluctuating from anywhere between 11:1 and 14:1 depending on how high I was revving the engine. Of course I knew I was going to work on the tune once I got it going. We start tuning this evening.
Okay, I know it's been a few days since I've posted. Since the last post I've run the car at 24psi and at 21psi which gave me 96lbs./hr. and 89.9lbs./hr. The engine overall seems to like it better at 18psi. I'll turn it down to 20psi which will give me 87lbs./hr. I'll see how the car runs there and do a little tweaking of the fuel curves. The modified Vortec spark curve seems to be working well so far.
Are you using a WB to get those AFR values? The fuel pressure really won't matter much as long as your PW isn't too short at idle and your PW at WOT isn't much past 85% or so.
I am using an LM-1 and logging it with the EBL. I'm pretty sure your right about the pulsewidth. When I had the fp at 24psi I set my BPC at 95. That's the number I got with my calculations and it kept wanting to go lean. When I had it set at 18psi I had the BPC at 105. Instead of turning down the fuel pressure I think I'll just bump my BPC back to 105 and see how it runs from there. I'll try it this evening and see how the engine likes it. Thanks.
Well, it's been a little more than a week since I've posted. Only because I'm kind of at a stand still right now. My recently rebuilt 700R is slipping and leaking fluid. So I haven't had the opportunity to do much tuning until I can get the car into a trans shop in order to see what's going on.
It's been three months since my last post. I haven't had the time to get the car into a trans shop so I've just been starting the car every now and then. No driving, just idling. Now the car has developed an exhaust leak. At least I hope that's all it is. It sounds like a whistling sound from under the car and it's loudest when I stick my head behind front driver's side tire. The whistling is loudest at startup yet progressively gets lower as the car warms up and is completely gone after about 6 to 7 minutes of idling. The engine idles smoothest with an A/F ratio between 13:1 and 14:1. It likes it a little richer. I will have a day off next Friday and I plan on getting the car in to a trans shop to see what's going on. The fluid doesn't smell burned and is very clean. Very few miles on the rebuild and only 122 miles on the engine. Hopefully the problem will get taken care of within the next two weeks so I can get this project back on track.
Okay, I took the car in to the trans shop 11 days ago and got it back today. The good news was I didn't need a complete rebuild since it already had one. Bad news, I still had to spend 800 to fix the problem. It had zero line pressure in overdrive and the guy that originally did the work did not set up the trans-go shift kit properly. They rebuilt the overdrive section and only replaced what was necessary in order to set up the shift kit properly. The trans is functioning much much better now. The 1-2 and 2-3 shifts are beautiful. Nice and firm but not violent. I am very pleased with the results and now I can get back to tuning the engine since I've got a functioning transmission. Also, the whistling noise seems to have gone away completely. I have no idea what it was but when I picked the car up from the shop the noise was gone. So, trans fixed and no more whistling noise. Now I will post some datalogs either this evening or tomorrow evening.
Well I've driven the car the last couple of days and performance has improved with each outing. I've pretty much got idle in park and drive dialed in. The EBL is still pulling fuel in the upper rpm ranges though. To get things to go quicker I might drop the entire VE table a few percentage points and see what happens from there. The last few runs of highway as well as stop and go driving the EBL has pulled fuel to the tune of -11 in the majority of the cells hit. I've taken a couple of short datalogs so I will see if I'm able to get them posted.
I have a 383 with about the same specs as your motor. I have 68 lbs injectors and only run 12 to 13 psi. From idle to 5500 the motor never goes lean. I have a turbo city regulator with the stock spring in it. I also have the stock fuel pump. The motor has about 500 miles on it. I had a chip burnt for it by Turbo city and it had some driveability issues at first but after just going out and driving the thing, varying the speed, rpm, and driving style and motor is pretty smooth now. The motor lobes slightly but nothing major at all. I have a T-5 with a 3.30 first gear and 3.73 posi and the car will smoke the tires from a roll all the way through 1st and half way through 2nd. At 55mph drop the car into 3rd and it pulls nicely. Its not a rocket but its fun to drive (especially after putting 50,000 on the original LO3). I used this site through the whole build and found it useful. Have fun.
Thanks for chiming. I was hoping someone with a similar set up would so we could compare notes. When I first got the engine running I had the fp at about 18psi with the 68lb. injectors which gave me 83lbs. Of course I turned it up to around 21 which gave me 90lbs. I've driven the car and the EBL VE learn pulled quite bit of fuel out of the tables. So at this point whenever I drive the car and run a VE learn it either pulls 1 to 2 or adds 1 to 2. So I've got the fuel table pretty close but you're right. To me the car ran smoother with the lower fuel pressure but I didn't want it to go lean hence I increased the fuel pressure. I think my engine(and I'm pretty sure yours as well)likes less injector with a larger BPC. When I get home I think I'm going to turn it down to 16psi, increase the BPC and tune from there. What cam, heads and intake are you using?
Okay, my last post was a bit over two months ago. I haven't done much with the car since then because after having the trans repaired I had to turn my sights to the cooling system. I was using a 3 row copper brass radiator, 160 thermo and a fan switch that wouldn't trigger fans until the coolant temps reached 227F. Needless to say the car was always running hot and I was not comfortable with it. So I finally found the time to do some research, purchased a larger aluminum radiator, 180 thermostat and a 200/185 fan switch. The cooling system is functioning beautifully now. I also believe the car was running hot because of the timing. I'm using the EBL so the fuel tables are coming along well but I'm having trouble with the timing tables. I'm going to try to post my bin so if someone would like to take a look at it and let me know if they see anything unusual or just plain wrong with the bin I would greatly appreciate it. I've switched from a modified Vortec timing table to an LT1 timing table to timing table that came with the EBL. The engine seems to like the LT1 table so far but haven't tried it with the new cooling system. Next I want to try an arap timing table and go from there to see how it runs. Right now the engine runs well but I know it's still got a lot of power left on the table. Any help any of you guys can provide is greatly appreciated.
Okay. I finally got a couple of datalogs. So far they're just at idle in park. I didn't want to risk driving it because I just noticed that one of the plug wires was touching the header pipe and it's burned through the insulation. I'm going to get that repaired and some plug boots before I take it back on the street. Anyway, I also switched to a slightly modified LT4 timing table. The engine seems to like that one the best so far. It starts right up and idles real smoothe. I also zeroed out the initial SA. So here are a couple of datalogs and the bin file. I'm still learning so any advice, pointers or anything would be a big help and greatly appreciated. Hopefully I can get that wire fixed this week and I've got some plug boots on the way.
Here are a couple of datalogs with the latest bin which I posted in the previous post. The engine runs so much better and with much more power. There are some lean spots but it's nothing a few VE learns won't take care of and possibly a fuel pressure increase. The first log is some back roads driving and the second log is some freeway driving.
I can't believe it's been six months since the last post. I finally got some time to work on the car, a new laptop as well as an EBL Flash upgrade. Since the last post I increased the fuel pressure to 22psi. The car ran better with the fuel pressure increase but what really made the difference was the EBL Flash. I used the LG4 bin that came with the EBL flash and copied my fuel and spark curves over from the EBL classic bin I was using. And of course I changed the fuel injector constants as well as the displacement setting. I must say that I am thoroughly impressed. The engine runs much smoother and with much more power with the new bin. I should've taken a datalog but was so excited about how the engine was running I forgot to take one. I will take a datalog tomorrow evening and post it up.
The engine is running better but now I'm getting a lean surge at idle at cold start up. And it's also got a lean surge when coming to a stop light or a complete stop. I just need to figure that out and it should pretty much be done. But yes, it's running much better with the EBL Flash. Just a few more bugs left. I'm self employed and work almost every day so I don't get much time to work on it so it's taking me a while. I will post more and hopefully some datalogs once I get to work on it some more.