Anyone have a listing on a 14 or 16 PSI spring?
CK5
Register an account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members.
Tuning a GMPP 383
- Thread starter cuervo
- Start date
After talking Brian at tbichips, BPW under 100 are no good and wont let the computer work correctly.
So a long time professinal tuner just varified what I told you?
Wish I had an extra spring to send you, just looked...
So a long time professinal tuner just varified what I told you?
Wish I had an extra spring to send you, just looked...
Yup, we've been over that a couple of times and like I said, I had to use what I had at the time and try and make it work.
The dyno for my engine says 340 hp so I should be good with a stock spring. But my question is will the duty cycle on those injectors be ok or should I really be chasing down some 65 lbs injectors and a 14 psi spring. I guess the stock spring wont be that hard to source but I'd rather not go through changing it twice if I do not have to.
I was thinking if a 14 psi spring and a set of 65 lb injectors would get me a BPW a little higher then 103 I might be better off.
Stock spring will be fine and go to 15 or 16 PSI, I forget. You;ll probably be good at 13.
Why waste time and money trying to find RARE injectors that people have been snatching up for years? They are only 4 pounds difference.
Why waste time and money trying to find RARE injectors that people have been snatching up for years? They are only 4 pounds difference.
dave w
1/2 ton status
But my question is will the duty cycle on those injectors be ok or should I really be chasing down some 65 lbs injectors and a 14 psi spring. I guess the stock spring wont be that hard to source but I'd rather not go through changing it twice if I do not have to.
I was thinking if a 14 psi spring and a set of 65 lb injectors would get me a BPW a little higher then 103 I might be better off.
I don't know the best answer. The tuning rule is simple, try stuff and figure out what works. What I know from experience ... 1987 GMC 1 ton dually 454 Turbo 400 I converted to a '427 PCM ... stock 454 injector and stock pressure regulator spring needed the injector flow programmed 71 lbs per hour. Using 0 ~ 100 psi fuel pressure gauge down by the fuel filter showed the stock spring was making about 11 or 12 psi. The injectors were serviced by Which Hunter http://www.witchhunter.com and the flows were measured at about 90 lbs hr. I don't have the data sheet from Which Hunter, so I don't know at what pressure the 454 injectors were tested at. Besides all that, the injector cleaning fluid is not gasoline and will affect flow rates anyway.
Maybe a stock spring and 454 injectors will work for you?
dave w
Well, if that 4 lbs takes my BPW from 103 to 115 and the computer likes it and the truck runs better I have no issues with spending the money on them.
I'm going to run by the dealer, cringe, and see if they happen to have the spring or can get one before the weekend.
Brian also told me the only true way to tune WOT is with a wide ban O2 sensor. Looks like more tools now. lol
Last edited:
I got another tip from Brian. Rather then push your VE table above 90 use the power enrichment Vs RPM table for tuning 3/4 to WOT AFR.
Ordered the new spring last week and still don't have it!
I was hoping to be able to post an update, but without the new spring I really can't do much.
I still very excited by what I have learned so far and really can't wait to make some real progress on this.
I can really see why you are so abscessed with efi technology and tuning.
What do you think of this system for wide ban WOT tuning?
http://www.moates.net/innovate-mtx-...l-ratio-gauge-kit-pn-3844-p-257.html?cPath=48
I have the Innovate lc1 with a Moates O-Meter and it's a pain in the ass. Was going to get a MTX gage but they said it was discontinued... if they get a gage to plug into lc1 and you can use the other wires for datalogging it may be better...
Was told this TT1 from Dynamic EFI is way better but still have to add a gage to it. Looks simpler to wire.
http://www.dynamicefi.com/TT-1.php
Was told this TT1 from Dynamic EFI is way better but still have to add a gage to it. Looks simpler to wire.
http://www.dynamicefi.com/TT-1.php
Put the new "15" spring in and guess what? The fuel pressure went up from 18 to 20 psi.
Needless to say, I ordered a stock 13 psi spring.
Needless to say, I ordered a stock 13 psi spring.
Did a 20 minute ride on the new spring; pressure is right at 13 psi now.
As you can see I have a lean condition that starts at 70 kpa. I could probably tune that better in the VE table but when you look at how big a change it will be from the 60 kpa the difference is pretty big.
I was under the impression that you wanted a smooth table.
While watching the histogram build the data I would say 90% of all the lean hits happen between 50 and 100% TPS. The lower TPS hits are when above 65 mph and on the highway.
I assume this indicates a need to adjust the WOT to AFR table. Is a higher or lower number more fuel? IE 14.7 is leaner then 13.5 or is it the other way around?
As you can see I have a lean condition that starts at 70 kpa. I could probably tune that better in the VE table but when you look at how big a change it will be from the 60 kpa the difference is pretty big.
I was under the impression that you wanted a smooth table.
While watching the histogram build the data I would say 90% of all the lean hits happen between 50 and 100% TPS. The lower TPS hits are when above 65 mph and on the highway.
I assume this indicates a need to adjust the WOT to AFR table. Is a higher or lower number more fuel? IE 14.7 is leaner then 13.5 or is it the other way around?
Last edited:
Remember there is more than one way to skin a cat. I am giving you my take on tuning that has worked for me.
During Wide Band O2 tuning I have kept a motor AFR to 12.5ish to 1 throughout RPM range. But felt a huge increase in power at like 2800 rpm up, VE showed the same. If I smoothed it AFR was way off! By huge increase in power I mean the car started to flex frame and I had to steer 1/4 to 1/2 turn steering wheel to right, to go straight.
I had to re read this thread, may be do to insomnia, 2-4 hours sleep a night for a year... but in re reading I am not getting the full picture! I'm seeing the data your posting in a picture, that's only a certain cell. I thought it was overall BLMs. Earlier you said your BLMs were 122 to 133. That's pretty close! So you would have to take out 5 or add 5 to VE to be closer to perfect. But I think you were BPW 96 and running out of preferred 40 to 90 VE. I have broken this rule and not had issues. Issues are usually at idle, surging when lower than 40, but does not always happen and happens less with more fuel pressure. I have run 18 VE at idle at 17PSI and had rock steady idle. Jumps to 40 VE off idle and drove smooth.
Another thing popped in my foggy head when re reading this thread is your always rich low RPM and always go lean high RPM. Can you run a fuel pressure gage up through cowl to like on windshield wiper so you can see fuel pressure while WOT? It may be dropping! When is the last time you changed a fuel filter?
Your changing springs but have no adjustable regulator? You ordered a 15 pound spring and got 20psi? And you had a what spring and got 18psi? Now you have a 13psi spring and have 13psi? Have you ever checked pressure on return side? Should be 0psi. Or run a line from return into a fuel can to see what pressure is at idle? Does it change? These are all things I have to know when I tune. If your fuel pressure is changing? Something is wrong. Should be within 1/2 pound from idle to WOT.
And where is your BPW with new pressure and this data?
Sometimes dave w does not say anything when I post but I always encourage him and others to respond. I am not a one man show and always have room to learn more.
I have looked at a lot of stock fueling tables and they are not smooth. You should smooth transitions some but NON stock motors have way different power bands than a stock engine which has a smooth power band and GM still did not have smooth fuel tables.
During Wide Band O2 tuning I have kept a motor AFR to 12.5ish to 1 throughout RPM range. But felt a huge increase in power at like 2800 rpm up, VE showed the same. If I smoothed it AFR was way off! By huge increase in power I mean the car started to flex frame and I had to steer 1/4 to 1/2 turn steering wheel to right, to go straight.
No. You need to get all cruise data, like under 70% TPS correct first. I am not familiar with $85 so you will have to look and see where WOT is? Or when PE comes in? Stay away from there until fuel is correct, then work up. WOT is an adjustment based off these numbers.
Lower number = richer.
I had to re read this thread, may be do to insomnia, 2-4 hours sleep a night for a year... but in re reading I am not getting the full picture! I'm seeing the data your posting in a picture, that's only a certain cell. I thought it was overall BLMs. Earlier you said your BLMs were 122 to 133. That's pretty close! So you would have to take out 5 or add 5 to VE to be closer to perfect. But I think you were BPW 96 and running out of preferred 40 to 90 VE. I have broken this rule and not had issues. Issues are usually at idle, surging when lower than 40, but does not always happen and happens less with more fuel pressure. I have run 18 VE at idle at 17PSI and had rock steady idle. Jumps to 40 VE off idle and drove smooth.
Another thing popped in my foggy head when re reading this thread is your always rich low RPM and always go lean high RPM. Can you run a fuel pressure gage up through cowl to like on windshield wiper so you can see fuel pressure while WOT? It may be dropping! When is the last time you changed a fuel filter?
Your changing springs but have no adjustable regulator? You ordered a 15 pound spring and got 20psi? And you had a what spring and got 18psi? Now you have a 13psi spring and have 13psi? Have you ever checked pressure on return side? Should be 0psi. Or run a line from return into a fuel can to see what pressure is at idle? Does it change? These are all things I have to know when I tune. If your fuel pressure is changing? Something is wrong. Should be within 1/2 pound from idle to WOT.
And where is your BPW with new pressure and this data?
Sometimes dave w does not say anything when I post but I always encourage him and others to respond. I am not a one man show and always have room to learn more.
It was extremely rich at BPW with the first Harris chip @126 BPW.
I kept lowering that until it was at 94 BPW and started to tune it.
Brian told me to change the spring, the motor wasn't making enough HP to keep the 18 psi in and that I would want at BPW over 100.
I change the spring to 13 and used a BPW 105 and that is what is show in the last post. I just thought you wanted a smooth VE table but if that is not the case I will start to tune the less then 70% TPS range.
The histogram you see is a combination off all the hits for those cells over a 20 minute drive.
I kept lowering that until it was at 94 BPW and started to tune it.
Brian told me to change the spring, the motor wasn't making enough HP to keep the 18 psi in and that I would want at BPW over 100.
I change the spring to 13 and used a BPW 105 and that is what is show in the last post. I just thought you wanted a smooth VE table but if that is not the case I will start to tune the less then 70% TPS range.
The histogram you see is a combination off all the hits for those cells over a 20 minute drive.
Well if they are 90lb injectors, which I have never seen? Then injector sizing chart says 103.7 BPW. So 105 seems like a good start.
But if they are 80lb, the biggest made by GM, then at 13 PSI and 95% duty cycle you would need BPW of 116.6 to supply 338HP.
I would go 120 BPW to keep WOT under 95% duty cycle, then tune VE.
HTH!
But if they are 80lb, the biggest made by GM, then at 13 PSI and 95% duty cycle you would need BPW of 116.6 to supply 338HP.
I would go 120 BPW to keep WOT under 95% duty cycle, then tune VE.
HTH!
dave w
1/2 ton status
I think the BPW is OK. If I was tuning a histogram like the ones pictured, I fix the VE tables that were red first. After fixing the red cells, I'd fix the green cells. Some tuner say VE cells interpolate with the corners of of a VE cell, depending if the engine is accelerating or decelerating.
VE Tables are not smooth. Depending on the data in the data log, I might "Smooth" the timing tables. A couple more degrees advance in the red cells is worth trying. A couple less degrees in the green cells is worth trying.
dave w
Well if they are 90lb injectors, which I have never seen? Then injector sizing chart says 103.7 BPW. So 105 seems like a good start.
But if they are 80lb, the biggest made by GM, then at 13 PSI and 95% duty cycle you would need BPW of 116.6 to supply 338HP.
I would go 120 BPW to keep WOT under 95% duty cycle, then tune VE.
HTH!
Well, I don't remember where I read the 90lbs but I think it was on thirdgen.
If I go with 80 lbs and the excel injector sizing spread sheet then 13 psi isn't enough pressure as it says it will only support upto 320 hp.
Is the BSFC rate on these TBIs .45 or .50? I just read where this is based off of engine and heads? I'm guessing my GMPP vortec 383 is a .45 motor.
Using that spread sheet, BSFC .45 - 80lb inj - 15 psi will support 348hp with a recommended BPW or 107. (wish I would have found this spread sheet sooner)
I did some logging last night with no more then 50% TPS. The log is very bright green in a bunch of cells over 60 kpa. Some of the BLMs are in the 150 range.
I ordered a Jet adjustable regulator so I'll get that installed and set the pressure to 15 psi and go from there.
dave w
1/2 ton status
Usually when BPW is close to being correct the data log will show some cells lean and some cell rich. Ideally it is best to begin tuning with steady smooth driving, with a slow rate of accelerate and slow rate of decelerate.
I usually do city driving logs first, then highway, then WOT last.
The adjustable FPR will help find the best setting for BPW vs Fuel Pressure. Ideally the VE Table will have number ranging between 45 - 95. If need be, it's better to keep the low VE numers above 40 with the high VE numbers no higher than 98.
dave w
I usually do city driving logs first, then highway, then WOT last.
The adjustable FPR will help find the best setting for BPW vs Fuel Pressure. Ideally the VE Table will have number ranging between 45 - 95. If need be, it's better to keep the low VE numers above 40 with the high VE numbers no higher than 98.
dave w
