This is a professional tune?? If so I give up.Let me know whats wrong

[BrianC98Z28]

So for a little back ground info on the car first. 02 SS 6spd w 3.90s. Ls2 403. PRC 2.5 5.3 heads/TSP 248/254 611 613 113 camshaft. Pacesetter LTs tsp duals,42lb injectors. at the time of this tune the car still had the stock maf and slp lid but now has the fastoys 85mm lif and 85mm maf. Soon to go to a 90/90 setup also but for now still has the ls6 intake. The tuner we went to in DFW for one didnt really want us asking alot of questions and I specifically remember him telling me "it doesnt matter what you adjust as long as you get the right a/f ratio". Well I dont really agree with that method of thinking. Look at the IFR, they are 42lb injectors and hes got it all outta wack. The car bucks and hessitates HORRIBLY now. Im doing my best to get on here and read and learn so I can maybe retune it for him to get it going in the right direction. Any pointers are apprciated and any areas that need to be seriously adjusted please feel free to help me out here. Heres the tune.

[97K15004WD]

Do you have any logs?

[BrianC98Z28]

no i dont have any up to date logs of the car. anything specific youd like to see?? I could try to get a good log later tonight when he gets off work. The car wont barely idle anymore either.

[SSpdDmon]

Did you change anything or did you just read the tune? I ask because if his file in the car matches what the tuner last saved, I'd take it back to the tuner and have him fix it. He probably paid near $500 - the tuner should fix it.

Until you get some experience under your belt, that's a pretty heavily modded car to be 'learning' on IMO.

[BrianC98Z28]

Ive changed only the throttle folower to try and aliviate a hanging idle problem. Im not a total newb at this,I have a cam/nitrous setup myself along with my dads heads/cam setup just trying my best to help a friend out to get a good setup to run the way it should. He has no interest in going back to the tuner. Why would the IFR be so outta wack? Im guessing he was messing with the IFR to try and get the desired WOT a/f ratio or am i wrong in thinking that??

[Scoota]

I don't have a stock tune file to compare the tunes but from what i can see I think the injector rate is slightly out, I have 60lbs and the injector rate is pretty close to mine, your fuel pressure might be right up there for them to be where they are.
I'm not sure what he has done to the main spark table, I can see that being a problem with interpolation down low on low rpm.

A log file would be good.

Cheers Scotty.

[BrianC98Z28]

you have 60lb and he has 42lb and his ifr being close to yours and that doesnt seem to be a problem????

[JezzaB]

If the injectors flow 42lb/hour @ 43.5psi testing rate the flow rate WITHOUT a manifold referenced fuel reg should be around this @ 58psi fuel pressure:

LB/HR
48.498278
48.800534
49.100929
49.399498
49.696273
49.991286
50.284569
50.576150
50.866061
51.154328
51.440980
51.726044
52.009545
52.291509
52.571960
52.850924
53.128423

If it was manifold referenced it would be 48.498278 across the board

The reason the VE figures are so low is the IFR is out. Its compensating.
The desired airflow is VERY low for even a stock cam. Do a RAFIG
Timing table could use that huge grand canyon taken out of it but it should be functional as you wont hit those cells
Throttle cracker and follower are "interesting"


Jez

[dc_justin]

If the injectors flow 42lb/hour @ 43.5psi testing rate the flow rate WITHOUT a manifold referenced fuel reg should be around this @ 58psi fuel pressure:

LB/HR
48.498278
48.800534
49.100929
49.399498
49.696273
49.991286
50.284569
50.576150
50.866061
51.154328
51.440980
51.726044
52.009545
52.291509
52.571960
52.850924
53.128423

If it was manifold referenced it would be 48.498278 across the board

The reason the VE figures are so low is the IFR is out. Its compensating.
The desired airflow is VERY low for even a stock cam. Do a RAFIG
Timing table could use that huge grand canyon taken out of it but it should be functional as you wont hit those cells
Throttle cracker and follower are "interesting"


Jez


The VE table is out because of the change to the tune for the 402ci from 350. With no other changes, the VE table needs to be increased by ~15% to stay inline with the new cylinder volume.

[dfe1]

For reference, the approach taken by some "professional tuners" is beyond comprehension. I recently had a customer with a road race car who had purchased EFILive so he could learn how to do his own tuning. We downloaded the "professionally tuned on a dyno" data from the PCM and I still can't believe what I saw. Commanded AFR in PW was between 15.5 and 16:1, the IFR wasn't even close and the idle air settings, if not from a different planet, were from at least from a different vehicle. And the car ran surprisingly well-- until it fried the engine. Rather than develop a proper VE table, this tuner had adjusted injector flow rate to get fuel flow where it needed to be. By using IFR numbers that were 3 to 4 lbs/hour less than actual injector flow, he got actual AFR in the ball park, but then had to whack the PE settings to prevent the engine from running too rich.

Considering the above-- take any claim of "professional tuning" with a very large grain of salt, until you actually see the tun file.