Anarchy71

Hey all,
Need someone with a little more experience than I. I have a 94 z28 Lt1. SLP CAI, LT headers,ORY, 3 inch magnaflow exhaust, no cat, no egr and no air pump. I thought we had a date set for the end of April for the dyno but the guy he wants working on it will not be here until June.
Here's my problem,,,I had planned on driving to Virginia next weekend to spend time with family. I'll probably put about 2000 miles on her while I'm away. I'm worried about it though,,I know she's running rich and I've played around with tunercat and seem to have gotten the LT BLM's a little closer to 128. I guess what I need to say is,,,,Can one of you look at the datamaster file and either tell me it'll be ok to drive her or some advice on what to do to get her able to drive. It sure would help my mind a little. Posted a link to the uni file on google drive

https://drive.google.com/file/d/0B5n...ew?usp=sharing

GaryDoug

Looks OK to me but then I am no expert on this. Some repliers may want a csv version of your scan. If so, here it is:

Anarchy71

WoW! Thanks man!! I was worrying about that .uni file and figured I'd tackle it again in the morning with your program. Never expected that,,,,,Can't thank you enough.

Injuneer

I'll try and look at the file Monday.

Anarchy71

Thank you Fred!

Injuneer

What did you do to pull the BLM's back to 128? If you see BLM's departing more than 5% from 128, you have to look for the cause. There is nothing in your mods list that would cause problems with split BLM's. It's a fairly basic list.

To me, its a mistake to start tweaking the MAF calibration (for example) to pull the BLM's back toward 128, until you know all other possible causes have been eliminated. Are you sure both your O2 sensors, and their wiring are healthy? Are the injectors clean, balanced and not leaking?

It's still pulling out more than 5% in the low load/low RPM cells on the driver side in particular. Can't tell you what the cause is. The high load cells like 14 and 15 are right at 128. Is that because you altered something in the program, or simply that you have not driven it a lot at high load/high RPM? I only saw a couple minor events using those cells.

You had one minor knock retard event, but that appeared to be a response to knock count, which may have been the result of the ignition advance reaching 43-degrees at that particular point. Have you been adding advance?

The absolute best thing you could have done, with the limited mods was to leave the tune alone, and look for the cause of the imbalance between left and right side. With a big cam, that's a problem you may have to solve in the tune, but not with a stock setup. Lots of people drive with those mods and no tune, and have no problems. They may not be making max power like they would with a tune, but most of the gains seem to come from leaning out the overly rich target A/F ratio in Power Enrichment mode. You can get decent gains there with a totally stock engine.

You're OK to drive it as far as I can see.

Anarchy71

Hey Fred,
I decreased the Maf tables by .30 throughout the range. I need to put the stock tune back in and log it now. I was going over some things last night and found the block off plate for the egr wasn't as snug as I like them to be. I don't know if that was causing my trouble but I doubt it was helping it. I picked up 2 Bosch O2 sensors this evening. It was due for them even if they aren't my trouble. I do agree with you in the fact I should have left it alone. I kinda freaked out when I saw those low BLM's. Thanks again Fred. Is there any way an OPTI could be causing this?

Anarchy71

Hey, just to follow up. I don't have the spots around here to really get the rpm's up without raising too many eyebrows that don't need raising lol. I've never had luck with advancing the timing and this car, I would get retard with the slightest raise. You mentioned the Drivers side still pulling fuel,,,It should be the original O2 sensor on that side and a replacement Bosch on the passenger side. I knew one had been replaced but figured I'd get two new ones to rule out all possibilities there. I went ahead and ordered a MSD opti, some Percy header gaskets and a new coil. I have seen a DTC 16 Low res fault pop up once in a blue moon. Most of what I've seen points to the Opti for that code. I'm trying to get everything worked out so she can get the best tune when it's time. I don't really know what's been done to the car Fred,,,It sat in a barn for 3 years before the mans son sold it to me. 120k on it right now and I've put 7k of those in the past 8 months,,I'm a firm believer in enjoying it while I'm here. It ran really rough when I got it. Changed Wires, plugs, air filter, fuel filter, seafoamed the gas to clean the injectors and she ran pretty good. I had an exhaust leak that was killing me so I did the headers and full exhaust, egr delete with the cold air and that's where I'm at today. I have an appt to put her on the dyno in June and supposedly the guy coming in to do it goes around the country specializing in LT1's. don't know his name but everyone around here recommends Ed, who is the guy bringing him in. it gives me high hopes.

I ran the car tonight with the original tune and although I didn't get it as pretty as Dougs, I did figure out how to export to .csv If you want, I guess it'll give you a comparison.

Injuneer

Any reason you aren't using AC Delco or Delphi O2 sensors? Based only on feedback on this site, people have had problems with Bosch.

Ditto on the MSD Opti? I am not aware of any advantages it offers over AC Delco or Delphi units. I have traced several difficult problems with surging, erratic tach and engine roughness to the optical sensor in the MSD. In one case, the Opti had just been returned to the owner after being "rebuilt" by MSD, and was causing those problems. Owner went with Delco and solved his problems.

There is no question DTC 16 is for the Opti. Just check the description in the factory manual for that code. However, if you have the code and the engine is running, it is a stored code, not an active code. Active code shuts down the fuel system = no start/no run. It isn't unusual to see it as a stored code. I suspect it's just a slight delay in the PCM receiving the code during startup.

I'll try and look at the data log tomorrow.

Anarchy71

No reason really for not going with AcDelco. The MSD Opti has a +/-5 timing adjustment on it and it's vented. I read a lot of good reviews and knew the name was good. O2 sensors I wasn't sure about, I just knew to stay away from Denso because they gave problems.

That code is definitely a stored code then. It's never cut the car off nor has she ever failed to start. She did get wet in one of those car washes that sprays up from the bottom and cut off. A little hesitant to start back up but hasn't seemed to effect it since.