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Discussion Starter #1
So I finally managed to get Datamaster to talk to my car and recorded a little run, short cruise at about 40 or so, then a stop and WOT to about 65ish.

I dont know what Im looking at here (first time ever logging a car) but m wondering about my Knock Count (shoots up to over 6000) and wondering whats going on with my EGR. or is anything going on with it?

I saved the .uni file and then just zipped it... should I do something else with it? I have heard mention of CSV files... Should I have converted it to one somehow? If so let me know how I can help you help me... :)

Thanks guys.

Tip of the old Stetson...
 

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Your long term and short term fuel trims are off, but what really jumped out at me was your iac counts. They remained way high at all rpm, even when you were at around 4000 rpm briefly. You still had high iac counts which should fall as rpm rises.

But for a better appraisal of your info, I'd pm bobdec and ask him to take a look.

If you would pm me with your e-mail address, I'll send you the pdf file of sensor readings and what they mean.

Your file you uploaded runs fine on my datamaster.
 

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coco, IAC is tied to speed, it is increased the faster car is going so when the throttle is released the engine speed is slowly decreased instead of a sudden drop that may cause stalling. The 69 is not abnornal, it's running about 39 at idle which is OK.

Up front I really like to see a log start with an few mins of idle in a trace as in the sequence of tuning you start at idle, go to cruising and then to WOT. This log started while cruising with no idle info.

What I see is the fueling is off on left and right sides. Just prior to entering PE mode in the pic below the LT BLM's were at 156 saying the PCM was adding 20% fuel to both banks to obtain correct fueling as shown by the ST BLM's at 131/129. It looks as you entered PE this 20% lean could not be compensated enough by the PCM and possibly the WOT fueling went lean, knock and subsequent spark retard (up to 10*) occurred (blue line). Just my guess, you really need a wideband that can measure WOT AFR to prove that.

Not in the pic, but just before your 1>2 shift, (RPM peak, churp of tires indicated in speed line hitting 2nd) the Injector duty cycles were at 85% (considered max reliable operation) that's to high if you car is stock. . So you may have fuel delivery problems under load also. Lean cruising and high DC under load MAY be tied together if fuel pressure is low during cruising, FP s/b high 30's to low 40's. But they also could be separate problems.

I would verify fuel pressure, check for any air entering intake that is bypassing the MAF. Snorkel leak after MAF, open hose, etc. Let it idle in closed loop and see what LT and ST BLM's are at. Remember in closed loop LT is used to calculate fueling, ST is actual O2 AFR. If LT is high PCM is adding fuel (lean detected) and the ST readings tell the results of the addition.

Do you have any mods to intake, MAF, de-screening, stock TB, ect ??


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Yea, the PO de-screened the MAF... One other thing I was going to mention is the car has 150xxx on it and I have no clue as to the condition of the O2 sensors. I am planning on ordering new ones from rock auto soon. as well as trying to find a stock MAF with the screen still in it.

No air leaks that I have seen, no hoses unplugged or anything like that. the OPTI's hose wasnt hooked up when I got it, so i had to splice vac hose onto that to get it to hook back into the intake snorkel.

as to an idle log... tonight I will do that. Cold startup and will idle for a few mins, then slow cruise off the facility I work on (3 miles at 20mph) then once I get on the highway it is a few more miles before I can go over 40. I was basically just playing around and had finally figured out how to use datamaster when I made this log.

I believe the car is basically stock... The guy I bought it from said he had bought it to "Make a racekar out of" but never got past the new gears in the back end and the K&N FIPK on it. Not sure that makes it a racekar but oh well. I dont think anything to serious has been tampered with on it but you never know.

So it seems that I will be looking for a new MAF, O2's, fuel filter, and checking fuel pressure... Would an LT4 knock module be beneficial for me? I have heard they do better at filtering out false knock. Also what octane should I be running? I have read that these require 91 or better, and I have read that anything over 87 on a stock motor is a waste. I have been running 91 (that's as high as they sell around here), but my wife had borrowed my car Saturday while I was changing brakes on her Saturn and was kind enough to fill it up with 87 for me while she was out. She means well at least...

Thanks for looking at this for me. it is all greek to me, but Im learning.

Tip of the old Stetson...
 

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I would do one thing at a time, log after each to verify results and insure you don't haven't added a new problem.
Get a baseline idle log first, that way if PCM is correcting a lean condition at idle (LT BLM's above 128, in BLM cell 16, closed loop), you can test it after changes w/o having to drive it... IMPORTANT since LT BLM's are remembered by PCM, and correct slowly after changes, a good technique after doing work is to reset the PCM (pull +12 power fuse to PCM, or battery negative cable) for a min or so. This resets LT BLM's to 128 and you will see results more quickly after the PCM enters closed loop.

- Verify Fuel Pressure, probably lowest cost thing to do, plus it's a good tool to have around w/modern FI cars. I use one of these Fuel Pressure Tester & Fuel Injection Pump Tester
- 20% rich on a stock car w/150K and unknown history I would replace the O2's, get Delco, or Densco stay clear of Bosh. Our PCM's do not like their switch pattern.
- Some disagree with this, but you can unplug the MAS connector, start it up , car will revert to Speed Density Mode, calculating fueling with RPM/MAP and O2's. Ignore the SES indicator . Check log and see if LT BLM's are closer to 128. If so MAs is bad, If not reconnect it and move on. Descreened MAF alters the air flow past the actual sensor, thus reporting incorrect air flow to the PCM. PCM should correct this, and it's never 20% out, usually a few percent at the most. I would fix it eventually, don't forget about it, not urgent compared to the real problem, but it may effect AFR readings..
- The 'hose system' to the opti has a check valve/flow regulator in the line from opti to intake manifold fitting. Make sure it's there. Other opti hose is fresh air from intake snorkel. Make sure it's 'after' the MAS so the air flow is metered (reported to PCM) . ALL air to intake s/b through MAS, otherwise it's a vac leak.
- Lt4 knock module is for false knock, it was used in LT4 roller rockers to filter out the valve train noise being falsely reported as knock. Your knock may be real, but at this time I'd wait till fueling is corrected to make that decision.
- On a stock setup "If" low octane fuel caused repetitive knock, the PCM will activate the 'low octane' routines and start lowering timing advance, not to be confused with spark retard. It will lower timing till the knock disappears and hold it there. Engine will run fine no damage will occur, but it will have less power, maybe lower mileage as drivers will make up for it w/more throttle. If no knock occurs w/87 then nothing happens. Higher octane usually gives better performance and/or mileage. Individual decision if it's worth the extra $$. If you ever get a performance tune then it's a requirement as more timing is required.. 17-19 year old LT1's are not what I would call a cheap, reliable DD's, you got to pay for the fun.. My mods require 91 or better, however I've run 91 since I owned the car prior to any mods.
 
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