Mandic

I have an engine swapped 1983 Malibu here with a 1995 LT1 in it. The only modifications are an MSD ignition(opti, coil, wires, new AC Delco plugs), a simple intake that routes to a filter over at the fender(no screen on the MAF), and a full dual exhaust with dual cats, cross-over tube, and exiting out the back. Stock manifolds, both O2 sensors are brand new Bosch units, the wiring harness is a brand new Street and Performance unit, and the injetors are brand new Venom 24lbs injectors.

I was tweaking on the tune a little and have run into an issue. The Right side O2 seemed slow to respond so I replaced it, it picked up responsiveness but the BLMs on that bank still keep maxing out (160). The left bank is running lean (144) but not nearly as bad as bank 2. I did adjust fuel and got Bank 1 back down to about 128, but bank 2 only came down into the 140s. So I still have a darn near 20 BLM split between each banks.

I realize there is little to do with the tune but can anyone point me toward something to figure out this split? The intake hasn't been removed(ever it looks like) and checking with carb cleaner finds no vacuum leaks anywhere(watching trims). There is absolutely not an exhaust leak on that bank. The O2 is in the manifold and there are no manifold leaks.

I can add a Datamaster file to show the split if it helps. I backed out the tune to the factory tune(my tune had a tip in stumble I need to work out) so the Bank 2 is back to 160.

Attached is a Datamaster log file of the car(.uni). I renamed it .txt to upload it here. Just change it to .uni to view it in Datamaster.

Any input? Also any input on my tip in stumble? I realize that would be hard to say without a log file of that tune also.

Ed Wright

iTrader: (1)

If you have no exhaust leaks you might try swapping banks with the injectors to see if the lean side moves. Venom injectors are pretty much junk, and you may have (another) mis-matched set of injectors. I would have kept the original injectors. I have stopped trying to tune cars with Venom injectors. Life is too short.

jakemussman

iTrader: (1)

What color are the wires on the driver side O2 connector? Tan, purple, brown, and brown?
Or same colors with solid white lines?

Mandic

Both sides are Tan, Purple, Black, and Red. The O2s themselves are black and white with tracers. The harness is aftermarket like I said. They were clearly marked "Drivers side" and "Passenger Side" on the harness(doesn't mean they weren't tagged wrong). Like I said putting in a new O2 I saw a responsiveness difference with the Passenger O2 readings.

And yes I have learned how junky the Venom injectors are. The engine sat for upwards of 5+ years and the factory injectors were stuck shut. Customer opted to put in new injectors. Unfortunately we didn't research the terrible reputation of Venom injectors before ordering them.

jakemussman

iTrader: (1)

Sorry I missed the aftermarket harness part. I asked because I had a very similar issue when I had the O2 sensor wires crossed to the wrong banks. When I did my swap they were about the same length so I got them mixed up. The car would run ok in open loop but would run horribly in closed loop. One bank was maxed out on the rich side and the other was very lean. I also swapped out an O2 because one seemed lazy. O2 volts looked slightly better afterwords but didn't fix the issue. I figured it out while disconnecting injectors one at a time (thought I had a faulty one) I noticed whatever I did to bank 2 had no effect on the bank 2 O2 volts but instead was affecting the bank 1 O2 volts. I would watch live data while disconnecting injectors one at a time. I may be wrong about your harness being crossed but this will also isolate any non functioning injectors.

Mandic

It may well have been mislabeled also. I haven't try continuity testing and confirming the harness pinout at the ECM. I also don't think low of Street and Performance so pretty certain that isn't the issue.

My next step is going to be swapping injectors bank to bank and see what happens. As noted, I have done more research while trying to find exact specs for the Venom injectors(good luck with that by the way) and have seen the absolutely terrible reviews and data on Venom injectors. Never again for sure.

Mandic

Swapped Injectors Bank to Bank. Split didn't move. Smoking the intake in a moment.

Ed Wright

iTrader: (1)

I had a Vette in the shop once that the shop that installed headers had the O2 sensor connectors swapped. You might just unplug one and fire it up while watching the scanner. If you unplug the left side O2, verify the B1 O2 mili volts are stuck around 450, while B2 voltage switches. I'm guessing both sides do switch normally now?

Mandic

Always check the basics. Entirely stupid I didn't start from the beginning. 4 and 6 plug wires were swapped. Didn't seem to be idling rough but they were dead just pumping air. BLMs are still split at about a 6 point difference between banks, but that is a whole lot better than it was before.

I am a big enough person to admit my own stupidity. This was a clear case of it.

Of course now that I got it running better suddenly it developed a ridiculously long crank I can't narrow down.

Ed Wright

iTrader: (1)

Your not the first or last to find something like this.
Glad you found it.

jrwilliams95z28

6 points isent that bad there's a table to adjust one back by itself isent there? It's been a while since I tuned so I'd have to brush up on it

Mandic

Only way I am aware of to adjust it would be to adjust individual cylinder compensation via the "Individual Cylinder Fuel Trim Compensation" table. Am I incorrect in this thought? I haven't gotten around to it yet.
Been bouncing around a bunch of projects. Sadly 3 different engine management systems right now so my mind is going 10 different ways. Just fired another LT1 with a BigStuff3 system and trying to figure out what is missing from a customer supplied XFI LT1 project. LT1s coming out my ears.

Ed Wright

iTrader: (1)

That is correct. I believe I have posted before, the box labled 1 is cylinder #1the box labeld #2 is cylinder #8, etc. Follows the firing order top to bottom. the numbers are percent.

Mandic

Thanks. TunerCAT seems to have them in order of firing order (18436572)

After I figure out why the car suddenly the last two days doesn't want to start when cold, I will get those trims fixed up. Damn thing suddenly cranks and cranks and cranks, but doesn't want to start after it has sat for a few hours.

Ed Wright

iTrader: (1)

John must have changed that. Mine is a very old, severely hacked, version. Lots of parameters added. Easy for me to know if another tuner is reusing my stuff (find that all the time) when one shows up that was done by somebody else before. One of the first things that show up are gear ratio & tire size. Not in the commercial version.

Ed Wright

iTrader: (1)

Check your fuel pressure. If OK, try spraying something like starting fluid or carb cleaner at the air filter to see if it likes that. Check your coolant & IAT temps. May not be reading cold enough.

Mandic

Temps are reading fine in Datamaster, right around ambient after a cold soak. Fuel pressure is 40psi KOEO. So below spec(41-47) but it is good once it gets running(35psi).

Gear Ratio and Tire size have been added to the new version. I am sure you have a lot going on, just an FYI. I can plug in the metric tire sizing, current gear ratio, and the program calculates that all out and adjusts for it.

Ed Wright

iTrader: (1)

That is a good bit below normal of 45 to 47.

I'm not talking about the speedo calculator. First two constants that come up are gear ratio and tire diameter for a quick reference when I'm looking for a base file to start with. If you open the gear/tire calculator it doesn't tell you what it is already programmed for, but you do enter the new values. I don't think these "tuners" that keep reusing my work either don't realize the differences, or don't think the PCM will ever cross my desk. I never use anybody else's work, I always start over with either a virgin file or start with one of my proven base files for a similar combo.

Mandic

Played with it a bit again. When it is stone cold it just cranks and cranks. Has spark but the spark looks a little weak(bulb style tester, misplaced my kv/gap style tester). Installed a new adjustable regulator, now KOEO I have 45psi, cranking/running 40psi. Introducing external fuel(carb cleaner) didn't make a difference. IAT and ECT are reading right on as far as an infared thermometer says. No DTCs tripping. I am really perplexed.

Next step is checking out the ICM and power to the Opti. Seems like maybe during cranking I am getting weak power to them? Doesn't really make sense as to why after the initial hard start it starts up easily.

Ed Wright

iTrader: (1)

What voltage does Datamaster show when cranking it over? I see a lot of street rods with poor battery cable configurations. So many batteries in the back of the car with the battery grounded right there. You can often get by with a carb, but not with EFI. Voltage drop may be your problem. If your battery is in the other end of the car the proper way to do it is running the ground cable full length of the car. Voltage could be lower with the battery cold from sitting overnight.