white01ss

iTrader: (37)

Damn, you guys have been busy!

Again, injector offsets, injector offsets, injector offsets. In Banish's latest tuning book, he has an entire chapter on injectors that talks about this. Can you get a car to run without changing it, sure. But you'll be compensating for this error in all the other fueling tables.

When the injector offsets are smaller than they are supposed to be, you will get lean spikes which can cause misfires. I would expect, once you get this taken care of, you will stop getting the misfires.

Frost - I commend you on taking on this task. It is a difficult one to do remotely, and now it's under a microscope. I would, however, disagree with you on the fuel. Trims should only be looked at after the O2 switch points are setup to target 14.7. Without those being calibrated you have no idea what a/f ratio the pcm is trimming toward.

Tuning a car, especially a sc'd car, without ample wideband logging is a dangerous thing to do. I wouldn't go into boost until it gets dyno'd with a wideband. Also, there is a big difference between tuning to get a car to run and getting it to run well. You'd have to have incredible luck and expertise to nail it in the first couple tries.

Frost

iTrader: (45)

The values are correct, in fact, they are better than than what is supplied with his DVD because they allow a lower minimum pulse width. If you look at the screen shot I posted already, it shows total trims within 5% at idle and an IPW of 1.6mS. If you use his (well not HIS, but what he interpolated from the OEM data) short pulse tables, you won't EVER get under 1.8-1.9mS (could be 2.0 even, I forget). Reading is good, but reading and doing your own research is better. The manufacturer never needed to hit that type of minimum pulse for their original application and certification. I know though, through working with them for the last 5 or more years now that they are very stable down low and can be run much lower without ever even coming close to the injector misfire point. I have seen them stable at 1.3mS. 1.6mS will make a 60#er idle on a stock engine in stride though.

-Q-

iTrader: (10)

Just a small update here...I got my HP Tuners last night and got everything hooked up and took another log. Steve @ Frost had asked me to take a log of the engine running with closed loop turned off to get a better idea of where the misfires are coming from, so even though I'm a super-newb at HPT, I managed to do it. Interesting thing, though...car runs perfect in open loop. My log showed zero misfires, engine idled perfectly, no hesitation on any level throttle application, and absolutely no surging. Waiting to hear back from Steve on his ideas from this...anyone have any thoughts? O2 sensors are brand new Bosch 13111 (long Corvette O2s), so I doubt there's an issue there...

flame

iTrader: (13)

What did you end up finding on this?? I hate when you follow a post and read 14 pages and there is no answer.........

-Q-

iTrader: (10)

Wow, where to begin. It's going to sound really anti-climactic, but it turned out there really wasn't a physical issue with the car...other than the fact that my engine is a mutant alien that acted unlike any other Steve@Frost had ever seen before. And that's not an exaggeration...he'll back me up on that if he sees this.

The 60lb injectors ended up coming out. We worked with them for the better part of a week, and got close, but were still having issues. We got WOT perfect with them, and I was even able to drive it around fairly well, but I had issues with the car stalling coming to a stop, and also surging/bucking at low rpm/part-throttle. Steve has tuned literally hundreds of LS1s with 60lb injectors before, but for whatever reason, mine just didn't like them. I can't really blame it on the injectors either, as they were new.

Put the OEM injectors back in with a boost safe tune (just so I wouldn't have to unhook the system), and things got a lot better fast. We finally decided to go with a set of 42lb injectors.

I bought a set of Bosch SVO 42lb injectors, installed them, and we started over. It still took 6-8 adjustments to get it perfect, but we finally got there yesterday. Car runs/drives perfectly now, and pulls hard at WOT. Making about 8psi now, and I'm happy with it. Getting ready to buy a SDCE 8-rib spring tensioner setup to get rid of this god-awful rattling, but other than that, it's squared away now.

Frost

iTrader: (45)

On Brad's car for whatever reason, the 60s just flowed too much.

There is a 100% stock F-body in my drive way right now that will run 60's and idle at stoich at 1.5-1.6mS of IDC. On Brad's car, we ran the injectors down to the ragged edge of having them misfire (1.2-1.3mS IDC) and idle was still fat. Asking for shorter opening times past that means that here and there, they won't open at all. When that happens in CL, trims move negative to fight the rich mixture. Tip-in of the throttle takes you out of that area and on application of throttle, there is a lean spot. That lean spot though is in a bad place and causes an off-idle hard stumble when moving through it.

Before Brad's car, I have said that 60s can definitely run great on a stock bottom end and with stock internals. Cruising through my calibrations folder shows it to be the case for almost 40 other setups (not just with 60s, but with 60s on stock engines with power adders). His base pressure was a little higher than the rest, but not enough to have been the reason. I kind of wondered in the back of mind what those injectors actually flowed.

He yanked out the 60s and tossed in some 42s and we got it dialed in.

I'm pretty sure he's busy during the day but should be back to post this evening. -edit- OK I lied... and I was slow typing too.

XtremeDime

iTrader: (16)

I can vouch for this. Q lives 15 minutes from me and we were running exactly the same 60#ers. my car runs amazing with Frosts base tune! I ran some logs and it really is quite remarkable how good he got it from 4k miles away.

youngrigo

I had the same problem when trying to tune the 60lb on my car.... My tuner meesed with it for like 5hrs and im not lying either about the time he spent on it! For what ever reason we could not slow them down enough at idle.. So i went with the 42lb green top and no problem. c

Im only worried now because im going to build a forged block and im gonna need bigger injectors but hope we can get them to work at idle

youngrigo

I think we went as low as 1.1 but im not 100% sure if it was that low

-Q-

iTrader: (10)

That's really interesting. I know it's just two of us, but we're the first two I've seen with this problem...

My concern is that I'm planning on a cam this winter, and I'm pretty sure I'll be stretching the limits of the 42s then. Hope I can find something bigger that will work OK...

youngrigo

People were telling me to take it to another tunner.... I know my guy knows his ****! Hes done it plenty of times on stock cars! He was dumb founded why he couldnt get it to work... I even sent the injectors out to get cleaned flow matched and all that so i know the injectors were not messed up. and i know he knows his ****! Just like frost he was like ive never had this problem with 60lb...

Frost

iTrader: (45)

I'm glad I had it happen. I have read of it in the past and dismissed it as people misunderstanding how to work on minimum pulse width. I drove Brad's down until they did not reliably open (just south of 1.2mS) and the AFR would just not come into range. They (IDC's) were pushed 25-30% lower than the point in which they have worked on many stock setups and they were just too fat there still, even with the idle jacked up to 900.

I tried work-arounds; re defining LTFT boundaries to put it in a dedicated place at 0% TPS and immediately jump into the next region at any + TPS. For reasons I don't feel like typing out, that didn't work great. There were others that were equally unsuccessful. That off-idle spot was just the deal breaker. If the car was full time OL we'd just let it get fat at idle and not care.

flame

iTrader: (13)

Thanks for the follow up. I guess my 42# green tops should work when I put the P1SC on my car soon!!

-Q-

iTrader: (10)

No problem, man...you were right to begin with. I hate it when I'm searching for information on something and the thread I'm reading just dies.

Bob@BruteSpeed

iTrader: (16)

This is a first for me on problems tuning in with 60 pounds injectors, it is good to know that it can happen. Bob

d1ws6

Hi ,Ive been looking for someone who is having the same symptoms i have and this appears to be a carbon copy of my car except mine is an 02 SO TA. Mine ran perfect until we put a D1 with 60lb injectors . It has been a bear to tune ( its been tuned by a very experienced tuner who has never seen this ) and nothing but issues with light throttle response .It hesitates and starts to drive worse the the more you feather or drive in normal traffic. WO it runs great then low end clears .
Im curious ,do you think its the ECM ? if not would the problem have been resolved if you put a Speed Density Tune?

Thanks

Frost

iTrader: (45)

I think there was a batch of bad 60s... The shop I share space with is a Mustang shop. They had the EXACT same thing happen with an 06 this last week. I mean that every symptom was the same too. I got an email from a guy in FL that I tune remotely. He is currently experiencing the same thing. After a swap to smaller injectors, his issues vanished like Brad's. After using the same injector data without issue for YEARS, there HAS to be something physically going on with these "problem 60s".