Obviously something is wrong but I'm having trouble figuring out what.

Installed new PRC LS6 and TR224, also LS6 intake, Pacesetters LT's with TSP off road Y, SLP UD, new TR55's, wires, and Racetronix 42lbs (plenty of breathing room). I calculated the new flow rate rate for my injectors and the car started on the first shot.

It kind of runs like ***, backfires every now and then. It lugs and when I hit the throttle it has a steady hesitation at part throttle and falls on it's face at full. It was running pig rich but while I've been waiting for my LC1 (just got it yesterday, haven't had time to install) I've been tuning my car using LTFT's and STFT's to get me in the ballpark and it's helped some.

The problem is that I keep logging negative LTFT's that have sunk some VE cells to 0. This can't be right. It's only occuring in some cells in the lower rpm and lower MAP regions of the LTFT map in EFILive, where the computer looks when coasting, off throttle. I'm sure that something is up that is affecting the entire range though, that would explain the drivability problems.

I have replaced my bank 1 O2 with a Bosch 13111 and the LC1 is going in bank 2 this weekend.

What could be making my LTFT's keep trying to dive down like this? Leaky header or vacuum leak? Lazy O2? I would expect to see it trying to fuel a vacuum leak, not cut fuel. Could I have a bad injector dumping fuel? All the header tubes seem to be about the same temperature, I ran for a little bit and felt each tube, and then later sprayed a little water on each after driving around for a bit. The water boiled off about the same for each so it seems like all 8 cylinders are lighting off ok but who knows.

I have included my current tune showing the 0 VE cells and a log I took on my way in to work. If anyone has time to take a look at these I would appreciate it.

Oh, and I am remembering to update the secondary VE when I'm updating the primary, so that's not the problem.

http://www.unf.edu/~n00193816/tune_and_log.zip

I have also posted on the EFILive forum.

 

If you've got the LC1, I'd hold off on doing much of anything until you get it installed.

Without that, it's just guess work. Why guess, when you're so close to having the "correct way" to know what's going on?

How negative are the LTFTs?

 

You have similar mods to me (except the injectors).

From first glance, I'd say that's where the problem is. How did you calculate the flow rate?

 

VE cells at zero, a good tune no make.

I'd say your tuning technique isn't quite accurate. Get that LC-1 installed. Find the correct IFR values for those injectors. Then do the auto VE tuning in open loop speed density. Then enable closed loop with or without the MAF, your preference, and then see what you've got.

 

Yeah, the VE cells at 0 definitely indicate something wrong, no doubt that the tune is off. This is my first h/c install on a computer controlled engine so I didn't know what to expect. Even with the VE cell at 0 the car is still pulling -10 to -15LTFT and then showing some more - STFT for the zero cells, so it wasn't happy.

Whatever it is I think it's a large enough problem that the LC1 wouldn't make a difference, don't need a microscope to see something is wrong here, but it should make tuning VE's a snap once I get the problem tracked down and will definitely be going in very soon.

The injector flow was calculated using a spreadsheet I found in posts on the board here. I think it's from redhardsupra. Checked my idle fuel pressure as well, 58 psi.

On EFILive it was suggested that it is probably a header or vacuum leak since one bank is so much different from the other, "bank one is flatlined, Bank 2 keeps reading leaner and leaner."

I switched to the LS6 instake manifold during my h/c install and I bet it isn't seating properly on one side, if I had to guess I'd say the passenger side since that is the side that the knock sensor wires run down. I removed some little plastic clips from them when I was doing the install, but maybe i need to flatten them out a little more. I also have new Comp intake manifold seals in a box in the garage so I guess I could try them too. (The manifold was new so I didn't see the point in changing the seals.) This seems the most likely culprit because I don't hear any ticking like I would expect to hear from a header leak (but I'll be going over that as well).

Thanks for the replies everyone. If you think of anything else or have any advice I'd appreciate it.

 

If u r a 99 make sure u r modifying the secondary VE table if u have the MAF disconnected.

 

Your log looks ok. I see you are only talking a couple of cells at zero.
Issue is the way trims work in blocks, wideband will read infinately variable. trims are based on rpm and map boundaries. Hence why wideband is recommended.
If you select your whole ve and bang the smooth function like 2x (looks like a sine wave), you get something that looks a whole lot better.

But as already mentioned wait till you get your LC1 in before messing too much with the VE table. It can be done, but you are making it hard for yourself.
Looks like you are getting a good chunk of BKR in a couple of places too.

 

I looked for about an hour and I can't see there being an intake leak or header leak. I propaned the intake and tb, nothing. On the exhaust side the headers are making zero ticking noise and no soot marks. I have a hissing noise but if I put a piece of card board over the air filter (K&N FIPK) it goes away, so I think that is just the air going through the ported tb. I may have a leak that I can't find, but I can pull the PCV hose and it doesn't run much worse. (Engine races then settles back in.)

Ringram - are the differences in Bank 1 and 2 LTFTs normal? One is rich <5 and one is lean <5 so is that reasonably dialed in? They are both rich in the 800 to 2400 rpm by 20 to 35 kpa matrix. Oh, one O2 is brand new (bank 1) and the other (bank 2) has 90k miles on it.

I'll get the LC1 on there as soon as possible but something is still bothering me about the way it is running, lots of missing, shaking and the occasional backfire. It seems like I'm pretty close, I'd expect it would be running much better than it is at this point. I hope the LC1 will make that big of a difference but if it does it will be like magic, it really seems like I'm a way off right now.

 

Might want to check plugs and leads etc.

O2's dont always switch at the same time, as long as they do switch then you are steping over stoich so should be ok. Main thing it they both go high under PE mode (WOT/Throttle) to around the same extent.

 

Ok got the LC1 in and have been tuning for a week now but I'm still having the same problem.

In the 1200 to 2400 rpm, 20 to 35 kPa range (off and very light throttle), I keep getting BEN factors that are taking my VE's to 0 in those cells.

Here's a log and tune to illustrate what I'm talking about. It includes injector pulse width and duty cycle info. I'm concerned it may have something to do with my injector tuning. I've got 42# from Racetronix. I changed my injector flow rate table to match the new injectors and checked my pressure at idle (58 psi).

Plugs are good, can't find any vacuum or exhaust leaks.

log and tune