1SWT95Z

Hey guys I wanted to see if I could get some help on this site since no one really answered my question on ls1tech. I have a 1995 LT1 camaro with the following mods:
comp xfi-466 cam: 218/224 .565 lift on 113lsa
1.6 aluminum roller rockers(ebay-don't cringe)
ported stock heads 2.000/1.550 valves 180cc/67cc runners
#32 lb. bosch injectors
52mm Edelbrock tb
stock intake but port matched
355 ci bottom end 10.2 to 1 static compression
Mid length headers with no cats and borlamouth exhaust
Auto trans with stock converter and 3.73 gears

I had ordered a mail order tune from pcmforless about 7 years ago when I rebuilt my engine with these same mods. I have always thought the car felt like it was pulling timing out. I data logged earlier this week with DataMaster and found it was pulling up to 9 degrees at anywhere from 2500-3600. I would like to know if when I post my data log and TunerCat bin file if someone can look at them both and see if the tune has a lot of timing or not enough fuel or something else completely. I think it might be getting false knock but I want to make sure its not the tune first. Also how do I post the DataMaster file and TunerCat files? Thanks for any help.

bobdec

Unfortunately this forum does not allow posting files, you have to find a file sharing site, put the log out there and then post the link in this forum. When you say pulling timing is it knock retard, or do you just think the tuner left some room on the table for a more aggressive timing setup. We have members that could look at your files, if you can get them up on a sharing site. Since your tune is over 7 years old the vendor may have updated things since then, have you contacted them.

1SWT95Z

Thanks for the reply. I think it is picking up knock and retarding the timing. I don't know what the timing tables should be for a setup like mine. I can look at them in TunerCat but I'm not sure what is too high. I remember running a tank of mid grade (89) about 3 years ago and I could hear it knocking a bit because my exhaust was quieter then. Since then I only run 93 octane. Anyone have any ideas on what the timing tables are usually set at for a similar setup to mine? I did contact the vendor and they suggested getting an LT4 knock module since it is less sensitive to knock. I can do that but I wanted to get some opinions on if the tune could be adjusted a bit first. What are some of the external web sites to post the data files and bin files?

1SWT95Z

Here is the scanned data from DataMaster from last week Tuesday:
https://dl.dropboxusercontent.com/u/...%207.30.13.uni
It is a uni file.
Here is a link to the TunerCat setup currently in the car:
https://dl.dropboxusercontent.com/u/...%207.30.13.bin
It is a bin file.
Please let me know if these links work and if anyone can look at them to help me out. Thank you.

bobdec

Your knock is horrible..pulls timing at every acceleration . Key is look at when the knock count increments, timing retard is a by-product and the PCM pulls timing as a precaution even when KC does not occur. So the actual KC incrementing (goes pink on display) is what you want to look at. You are getting actual knock at high acceleration, low load acceleration and at deceleration and even at DFCO (decell fuel cut off) record 2642 in the log where TPS=0 and fuel is cut off (BPW=0). Bottom line it's not pre-detonation caused knock if throttle is closed and there is no fuel going to the cylinders. A LT4 KM may help, as you knock is called false. The LT4 KM, designed for the LT4 Corvette roller rocker valve train filters out excessive valve train noise that is being read as knock. However I would also look around for something vibrating. header or exhaust hitting the chassis, excessive noise from the engine, rod bearing or similar. Your's is probably the worst I have seen. If it were mine after visually checking for vibration, I would consider replacing the knock sensor as it could be overly sensitive. You timing when knock count increments is in range, heck your getting knock at deceleration with timing at 23* and DFCO when PCM sets timing to 10*, so it's not a timing problem..

1SWT95Z

Thanks for looking at that for me. I try to go through everything mechanical that I'm able to this weekend. I'll also do another scan. Could it be possible for the lifters and rocker arms to be causing the excessive noise?

bobdec

I have LT1 Hot Cam w/Kit 1.6 RR's and had a knock at specific RPM ranges during acceleration. AFR was good (not lean), was running 93 octane and I dropped timing 10* for testing. Nothing changed. So I decided knock was false, installed a LT4 KM and the knock went away. There are others on the forums that have cams and RR's that never see knock, so it's hard to say if it's your valve train or something else. Remember a knock SENSOR is a microphone that feeds the knock MODULE. The knock module has filters that filter out what the engineers decide are not pre-detonation knock frequencies. If you knock is a header hitting the chassis, or similar, a LT4 KM may not help. But if your noise is caused by the valve train then it may help. Sorry I can't be more definite, but there is some guess work involved..

1SWT95Z

Well thank you for taking the time to help out. I am going to try to go over everything mechanical this coming weekend. Any thoughts on whether ethanol in the gas could play a part in this? Also just a side note were you able to tell if the car on average was running rich or lean overall in closed loop? Does it seem like it could be leaned out more at idle and low rpm? Thanks.

bobdec

Using E10 should not be a factor .. PCM will adjust to using E-10, getting technical the O2 sensor reads Lamba and the PCM always adjusts AFR for the best burn or lamba=1. Using gasoline lamba 1 ends up at AFR of 14.7 parts air to 1 part fuel. E10 ends up at 14.1 parts air to fuel. So saying AFR = 14.7 is perfect only applies to 100% gasoline.

Your PCM is pulling a bit of fuel across the board at all ranges. I use histogram function of Datamaster to view that. Open log move the record slider to the first record of closed loop. Click View, then Histogram and then click Start button under the record slider. Remember the LT readings are what the PCM is using to correct the burn, and the ST readings are the actual result. A red Lt reading, but a white ST for that block means the PCM corrected. Your LT's are red across the board and ST are better but not the best. With all that knock I hate to say it, but you should start leaning out things.. Try a small increase in injector flow to fix all ranges, then individual cylinder trim multipliers to get idle and low end and then MAF tables for other ranges, then PE tables for WOT (you need a wideband for that) . Save old .bins in case you have to go back.. NOTE AFR tuning assumes your O2's and other sensors are working correctly..

1SWT95Z

Thanks again Bob. I'll try a few things and maybe post another datamaster file sometime this weekend.

1SWT95Z

Bob I need to lean it out? So increasing the injector flow rate will help that? Maybe I'm not thinking about that correctly but won't increasing flow rate make it richer? Also, do you think I need to increase the individual cylinder trim or decrease it? Would it help if I told you what those values currently are set at?

bobdec

Not sure what 32# Bosch injectors s/b set at. Can you look up the model and see what they deliver at 43 lbs fuel pressure (stock LT1 at WOT). I know GM uses 24.91 lbs for stock 24 Lb injectors. If you enter a higher flow setting then the PCM will shorten the injector pulse. As an example if setting is 32 lbs/min and you raise that up to 32.5 the PCM will think injector is delivering more fuel per min and it will reduce the injector pulse width 1.5% to deliver what it thinks is the correct amount of fuel. (0.5/32 = 0.0156) or 1.5% . So that will drop your fueling (LT BLM's) 1.5% across the board (128 X 0.0156 = 1.996) or about 2 BLM counts. Using histogram data see what percentage you want to lean out fueling and then adjust flow setting that percentage. Note it will also lean out WOT and w/o a wideband you really don't know where WOT AFR is at. For safety you may want to add a couple percent in PE tables till you can get a WOT AFR dyno reading or get a wideband.

1SWT95Z

bob, right now the tune shows anywhere from 39 to 45 degrees of main spark advance from 30 Kpa to 60 kpa at 1600 all the way to 6500-7000rpm. Isn't that a lot?

bobdec

Stock is 41-35 in that range, but cam tunes bring the low MAP (high vac) timing up. Mine are 50*-43* in that 30-36 Kpa range.. In that RPM/MAP range you s/b cruising about 50 MPH at 8-15% throttle. Very low engine load, torque demands and should not see any pre-denotation at that time. If you plot MAP against TPS you will see every time you hit the throttle MAP goes into the 50 Kpa and up cells and the timing drops to the the low/mid 40's as load increases. Usually MAP only goes below below 40Kpa when decelerating as the throttle is let off a bit when cruising. EG: As you look at main table draw a mental vertical line of where you idle MAP is at. Say with your cam MAP at idle is in the mid/high 40"s so when you are driving vacuum will never go below that unless you are decelerating.