adding 50% fuel at WOT

[Billett]

I called around 4 and the rep I've been talking to said he told the tuner and the tuner was supposed to send it to me, but I haven't gotten it yet. Said he would send it tonight. We'll see.... Also mentioned the fpr thing to him and he's under the impression that since the fuel pressure itself stays constant then the regulator shouldn't be causing any problems. Wonder where he's reading it from though...

[Hart_Rod]

The very first thing you need to do is to make sure that the fuel injector data is correct for the injectors that you have (flow rates, pulse corrections, min injector pulse and offsets). If these aren't correct, everything else you do is a waste of time. Once that is done, verify that the fuel pressure at the fuel rail is correct. I believe you have a Gen III which should be 3 bar or approximately 43 psi. The corvette FPR should give you this (assuming it is the from a corvette LS1). To tune the MAF, you've got to adjust the VE table. This is done by logging the data with the engine running and then comparing commanded AFR to actual AFR (you really need a wideband to do this correctly). Based on what the errors to AFR you see, you would then make corrections to the VE table. Now this is way more complicated than I just wrote, but you kinda get the picture. I would like to see the tune also if you don't mine. My email is robhartley@aol.com.

PS. Make sure you have your exhaust connected!!!!!!!!

[BR3W CITY]

Damn you got comfortable walking around in HPT didn't ya Rob? haha

[Hart_Rod]

Originally Posted by BR3W CITY

Damn you got comfortable walking around in HPT didn't ya Rob? haha

, yeah man, I jumped in deep.....I spent so much time on looking at this stuff when I first started, I was dreaming about it at night......I finally had to take a couple weeks off to clear my head, . As soon as I get my cold air box done, I'm jumping back on it.

[Super73]

In theory I don't for see a problem with a vette regulator inline prior the deadheaded factory rail with regulator. Reason being, the vette regulator should be holding the 58psi. Pressure should not creep nor drop through throttle changes. The factory regulator on the rail can't increase pressure beyond what the vette regulator is supplying. Could there be a further pressure drop, I suppose, but with the return blocked, it can't put the fuel anywhere except the injectors. So again, in theory, I don't see it dropping pressure either. You would need a guage on it through throttle transitions to confirm.

Have any of you ever put even an SVO 30lb injector in place of a stock 28lber? The SVO 30's are rated at 43psi (Ford rail pressure) and on an LS rail at 58psi, they act like 36lber's. They will not idle with out injector flow being plaid with or your foot holding throttle and rpm. My point, if the injectors have been changed with out the flow rate being adjusted, it wouldn't even want to run well idle or part throttle. If they are off by 2-3lbs, it might not be that noticable as the Ltrims are doing there job in closed loop, enter PE, go in to open loop and that might change. But simply adjusting PE EQ Ratio should get it in line.

If the truck is running decent part throttle, it is because the vehicle is in closed loop relying on the narrow bands to keep stoich using Ltrims. Enter Power Enrichment and it goes in to open loop. If the VE table does not match the MAF table, or if PE EQ Ratio is way off, guess what, it could be going way rich.

Things like Cat over temp settings will also cause an over rich deal.

Just curious, does this tuner have a track record with GM gen3/4?

[Billett]

The tuner is Race Proven Motorsports over here in DE. They are very well known in the corvette and Camaro community, but I have a feeling they don't do budget swaps like this very often. Fran the owner did go to a pretty respectable school for engine building out in Texas, and they pretty much tune LS's exclusively, but I don't know how high my truck is on the priority list. Biggest problem I'm having right now is communication. Fran, the owner, knows what he's doing but I can't seem to have a good conversation with these guys. Every time I call its just sort of "still doing the same stuff, we have a couple more things to try" but its already been a solid month with no progress.

I know the problem is odd but I'm frustrated to say the least. The majority of the cars they seem to get in are toys shipped in from Cali and Florida, but I use mine every day and really need it back... just stuck between a rock and a hard place because I don't want to piss them off while they still have my truck and even if I go get it from them I still won't have a tuned truck and there aren't any other shops near here that do work like this.

[BR3W CITY]

Originally Posted by Super73

Have any of you ever put even an SVO 30lb injector in place of a stock 28lber? The SVO 30's are rated at 43psi (Ford rail pressure) and on an LS rail at 58psi, they act like 36lber's. They will not idle with out injector flow being plaid with or your foot holding throttle and rpm.

My truck runs the SVO blue injectors which I think are the ones you refer to . They are close to 40lbs at rail presssure, and do a nice job fueling my cam only lq4. Iirc the tuner said duty cycle didn't breach 75% to do so.

[Billett]

I imagine that means the 26 #ers are about tapped out with a stock engine then.

[BR3W CITY]

YES

My guy often laughs because he gets that question a lot. The stock injectors can BARELY support the engine as it is.

*and now just for kicks, I'll take a stab at anyone running a boost-a-pump. People think jamming an enriched FPR, a boost-a-pump, or jamming a massive pump behind stock injectors somehow helps. It doesn't so stop. You can throw 15v and 100% duty cycle at the stock fuel system but it still won't want to support anything past a hot cam. You see this in homemade tunes when using the PE and VE to get it to run, they wind up using almost full duty cycle to barely maintain fuel thru the range. *

[Super73]

SVO 30's are red top. Going from fords rail pressure of 43 to the ls rail pressure of 58 they become 36lb. When I first had the 347ci motor in the truck, at 449rwhp through an 80e and 11.4x @ 117mph these injectors were in the low-mid 90% duty cycle.

Stock 01 camaro fuel system (28lb) injectors, I made 405rwhp with bolt ons and a cam through a 6speed) injector duty was high 90%.

Same car before the cam swap but with bolt ons (335rwhp) plus a 125 dry n20 hit, I was > 100%.

I agree that I don't like the bandaid boost a pump deal. Can they get you out of a punch, sometimes. Build the fuel system right instead.

I now have 60lbers I put in the 347 almost 5 years ago. Now being 418" and on e85, I am in the low 90's again. Time for an upgrade which I will do when I hang the twin 67's on it.

[BR3W CITY]

Mine are like the navy blue.... is that 36lb Cobra injector? The ford guys can't keep it straight on their own forums.

[mcfarlnd]

A lot of these replies are good but, there is no way to trouble shoot this without seeing the tune and a log of when this vehicle starts to go "50% rich". We could tell you to try this and try that all day and would honestly be a shot in the dark. Part number of the injectors would be good to have as well. Way to many moving parts to the equation to pin it to one thing.

[vannatta20]

Sounds like they are tuning only the primary ve table with maf disabled. The secondary must be tuned first. When the maf is disabled the secondary table provides all fueling calculations.

[Billett]

So, I'm finally back on. Got the truck back Friday. From what he tells me the tune in the pcm was originally a bone stock van tune, and he hasn't worked with one before. The way it was explained to me is that the problem wasn't that it added extra fuel at the top end, but for some reason had been cutting it out at the bottom end. The o2's can't read that large of a range so they were going by the low end readings as normal. Whenever they would tune in the proper amount of fuel the o2s would go crazy. Once he adjusted the bottom end a little and things started getting better he realized what was going on, and now it runs great. I meant to get the tune on a USB when I picked it up but forgot to ask. I'll still try to get a copy anyway.

Not quite as high as I was hoping, but to be fair its not bad for a bone stock engine with just headers and a tune.


If someone else ends up having a similar problem feel free to PM me and I'll get you in touch with the tuner. I'm happy with their work, just wish it didn't take so long. Definitely missed my truck with all this snow.

[Super73]

Glad they got it fixed for you.

Did they ever pull it past 5,100? Looks like it was still making power.

Also, did they try leaning it out more? Looks like it is still a bit on the fat side in the high 11's for AFR. Kind of doubt that the motor made best power that that AFR. I bet there is a good 15-20rwhp right there.

Makes me wonder where they set timing, if they ever did.

IMO a 6.0 with headers and tune should make a solid 325rwhp+

[Billett]

Not really sure, but once I do finally get some upgrades on the engine I'll definitely just add HPT and a good wideband to the shopping list.

At this point, I'm just happy to have the truck back and the fans working so I don't overheat.

[BR3W CITY]

The "van" tune should be the same as a truck tune afaik, I'm not familiar with any inherent differences. All the trucks start with very little timing, and are extremely sensitive to changes related to torque management.
Its not uncommon to add a bunch of timing, do a pull...and find out that tq management tried to pull the timing again...so it has to be modified. I'm not sure if thats happening, but I don't know what else would be that "Different" about starting from a base tune (whether it be van, truck, whatever)

[Billett]

I'm not sure either. He said he pulled about half the torque management and the timing was around 20*

[Super73]

If you are going to buy HP tuners and a wide band anyway, my suggestion is to make those two items your next purchase. Learn it on your truck, you will be surprised how some little changes can make drastic changes to the tune. I once went from a 3" x-pipe with Warlock mufflers to a dual 3" cut out set up that necked down to 2.5" with turbo muffler. This skewed my perfect AFR and I had to retune the full VE table.

Funny as it sounds, the laptop goes with me and I data log just about every ride I take in the truck.

Start helping friends on their vehicles and you will learn more (Have them buy a single license for $100). Once you get a real good handle on it, you can even start making some of your money back on the side.

I have about 15 regular customers that come to me for little to big changes. I am always very fair with them. In one weekend I cleaned up 5 tunes (some on a dyno, which they paid for the dyno time) and I put $1,000 in my pocket.