ascastil

Went down to the dyno to see what kinda power my car was making after an AI head, cam, and intake swap and PCMforless tune. I had no idea what I was in for, good thing I went.
Now, I didnt think the car was gonna be at 100%, but didnt think it was this bad. The BEST pull was a whopping 360hp. Definately disappointing. We decided to try and point us in the right direction on why power was so low to weld in a bung and get some a/f numbers. At IDLE, a/f was near 18. Once I put it in gear it would drop between 14-15, but during the pulls it never dipped below 13. The higher the rpms climbed, the leaner it would get, and Im not running a stock pump or injectors, 42# and Walbro 255. All the mods are in the tune also.
Since they dont have LT1 software, I think Im gonna buy the Jet software and take it back down there to have it tuned.
I would assume I got some knock going on. Lean+Knock+Timing Retard=Loss of power. Does that sound somewhat right? Do you think if I can get this fueling issue ironed out I could reach the 400whp mark? The car is parked till I can save the money to get the Jet software, dont worry.

96capricemgr

You might still be able to get OBD2 software direct from tunercat and I would look at that before JET. The JET is a version of Tunercats software.

Herter has blown up a lot of even milder engines with 14:1 and leaner AFR at WOT and some cases of over 40degrees of timing.

ascastil

Tunercats FAQ says you gotta buy it from Jet now, sucks.

Injuneer

I'd get data logging software before jumping into tuning software. Might help you figure out what is going wrong. Putting a tune on a faulty setup isn't the right way to go.

Did you check the fuel pressure under load? Do you have an AFPR, and if so, what brand?

ascastil

Does the Carputing software for the '97 datalog also, or strictly tuning?
CARPUTING.COM

MachinistOne

I've said it a hundred times, email tunes are a scam.

RamAir95TA

OTOH, my car put down 440whp with a mail-order tune from Bryan without a problem.

96capricemgr

Herter in particular is VERY hit or miss, he gets a few cars right to maintain a positive reputation but there are more stories of problems. I stopped working with him after I had a few tunes so bad that I would load them back out of the driveway and then the car was so lacking in power it couldn't climb the apron back into the driveway and I would have to reflash the old tune in the street just to get the car back in the driveway. I have shipped replacement stock pistons to MULTIPLE customers of his who cracked ring lands due to too little fuel and too much timing.

It is great that Joe had good results with his work but Joe's result is the exception.

Mailorder tuining is not always a bad thing, my car is mailorder tuned BUT I also have a wideband and Datamaster so I can give the tuner meaningful data to work off of.

ascastil

Ill check the fuel pressure sometime soon. If that checks out, I think Ill start looking into data logging and dyno tuning. I dont have a fuel pressure regulator. Is this something I should look into purchasing for the car? Whats a good brand to go with?

mrmint69

You should use the stock oem regulator with your mods. A lot of aftermarket brands have problems.

Guest47904

I believe you meant to say that you don't have an ADJUSTABLE FPR. Which indicates you have the original FPR as the system would not function without it.

Also correct if I'm wrong (like I had to ask). Seems to me the problem is more at idle and lower speeds than at the top end. Do you really want more fuel than 13:1?

18 to one then 14 to one and finally 13 to one is getting richer not leaner as you suggested it was.

I quote
It's parts air to fuel 18 parts air to 1 part fuel etc. Get it?

Incidentally stoichiometric air/fuel mixture is approximately 14.7

Dave89IROC

Powerwise I like to see 12:1 under load

ascastil

Speedy, sorry I wasnt clear enough. Yes I meant ADJUSTABLE.
Also, about the A/F, yes I get it, although when typing it may have been misleading. Here is an example of one pull. I dont like trying to get pics posted on here, I think its a PITA.

4000-5500 is 14
5500-6300 climbs to 16.45
6300-6700 drops straight back down to 14.00
The a/f looks like a rollercoaster.

96capricemgr

Stop running it hard before you break something.

you are going to want it say 12.7ish for a safe tune, some guys do go up into the 13s but that is a bit lean if you endup having some other complicating factor.

12:1 is richer than necessary for an NA LT1.


The AFR you have seen are bad enough to hurt things particularly if the timing was aggressive.

I never fine tuned the AFR on mine it is say 12.3-12.7 across the rpm range with max programmed timing of 29degrees. The computer adds a little so it reports about 31-32 in datamaster. I wont say it is perfect but it is good enough to run well.

ascastil

No more driving it until it is fixed for sure, its parked in the garage for now. What should I do about testing fuel pressure though? One more WOT pull with my fingers crossed, lol.