Bringing TBI and Multi Port Fuel Injection to a New Level.     EFI Conversions and Tuning! Seattle to Portland! E-mail Tuning Consultant!
Page 1 of 2 12 LastLast
Results 1 to 15 of 16

Thread: First stab at adjusting fueling '95 LT1

  1. #1
    Fuel Injected! Dirtybob's Avatar
    Join Date
    Aug 2016
    Location
    Quad Cities
    Age
    49
    Posts
    36

    First stab at adjusting fueling '95 LT1

    So I've finally swapped out my 2.56 open rear for 3.42/yukon posi and have begun to tune the car a little.
    It's a stock '95 roadmaster with the only mods being "home plate" delete and 3" pvc running from the stock airbox to the elbow @ the throttle body.
    Analysis of my first set of logs showed the car was running pretty lean and had a few knock events between 4300 and 4800 rpm at WOT.
    Attachment 11012

    Made some changes to the MAF tables and reset the target afr to 14.1 to reflect the el cheapo 10% ethanol gas I normally use. FWIW the knock events disappeared and the log anaysis looks like this.
    Attachment 11013
    Attachment 11014

    I'm currently researching PE fueling and timing changes but am in no hurry (prefer to do this at the dragstrip since my butt dyno isn't well calibrated). Just looking for a little feedback, areas I could work on etc....
    attaching the most recent log and bin file if anyone wants to have a look.
    Edit: seems my log file is "invalid" as an attachment...

  2. #2
    Fuel Injected! steveo's Avatar
    Join Date
    Aug 2013
    Posts
    2,438
    your fueling looks perfect

    stock pe is rediculously rich from the factory especially on the b-bodies. a lot to be gained there

  3. #3
    Fuel Injected! Dirtybob's Avatar
    Join Date
    Aug 2016
    Location
    Quad Cities
    Age
    49
    Posts
    36
    I recall reading somewhere that 880 mV is an appropriate (narrowband o2) value for WOT operation. Any truth to this?
    No plans for a WBO2 in the near future...

    Decided this morning to copy the timing tables from a stock 95 impala ss bin (a bit more total advance and comes in quite a bit faster than the roady bin) and am seeing knock/kr again. Primarily above 4k rpm and 85+ kpa. Filled it with premium and it made no difference so am currently lowering the timing and logging the difference(s) in between the grandbaby tearing down the house and the dog being sick.
    It definitely likes the more agressive advance curve, much more tirespin now.

  4. #4
    Fuel Injected!
    Join Date
    Oct 2013
    Posts
    900
    You really can't equate that voltage to the correct AFR for WOT. Every O2 is different and the same O2 even reads differently depending on it's element temperature.

  5. #5
    Fuel Injected! Dirtybob's Avatar
    Join Date
    Aug 2016
    Location
    Quad Cities
    Age
    49
    Posts
    36
    will just have to get it out to the dragstrip then.
    Last edited by Dirtybob; 10-21-2016 at 07:20 PM. Reason: scratch noob question.....

  6. #6
    Fuel Injected! steveo's Avatar
    Join Date
    Aug 2013
    Posts
    2,438
    wideband is ideal, dyno is better, but if your trims are near perfect even at high rpm/load (might have to disable pe to get enough data up there) you can dial an afr target for pe and probably get close. try to calculate about 12.5:1, should be safe. you'll usually hit peak power near 13:1 but the difference is small.

    as far as spark goes, bbody spark tables are for load hauling. but iron heads don't need a lot of spark advance to hit peak power either. eehack's spark skew will help a lot in finding ideal timing...

  7. #7
    Fuel Injected! Dirtybob's Avatar
    Join Date
    Aug 2016
    Location
    Quad Cities
    Age
    49
    Posts
    36
    interesting how the impala timing setup made my car knock (even on 92 octane) when the differences between the cars are so minimal.
    my current setup looks a lot like the stock table except a little more agressive between 1600 and 3600 rpm @ 90+ kpa.
    Attachment 11022

    Attachment 11023

    Attachment 11024

    not too worried about making the most power out of it, doesn't matter to me if it runs 14.8 or 15.0 (or whatever). more concerned that it is consistent (bracket racing) and won't prematurely self destruct.
    will definitely get fine tuned on the 1/4 mile track, seen too many "500 hp" dyno queens only running mid 13's to rely solely on dyno results.

    on a side note, the best bracket car I ever had was an old 87 iroc z28. basically just swapped the 305 for a 350 with rv cam and shorty headers (did this in '91), kept the tpi and added an adjustable fpr. car would run within .03 on the ET all day long (using bfg drag radials)...

  8. #8
    Fuel Injected! Dirtybob's Avatar
    Join Date
    Aug 2016
    Location
    Quad Cities
    Age
    49
    Posts
    36
    been racking up logs the last few days and have been seeing spots of KR here and there. after reviewing the data it seems that each event was in PE mode during a CCP duty cycle, with some other timing weirdness related to the CCP (screenshot below)...

    Attachment 11026

    just putting this out there in case it helps somebody else....

  9. #9
    Fuel Injected! steveo's Avatar
    Join Date
    Aug 2013
    Posts
    2,438
    CCP is definitely unrelated.

    KR in $EE isn't always actual knock. it throws other timing retard events in there. it can be generated by things other than actual knock events, such as BURST KNOCK RETARD (a normal event that retards a little bit timing based on airflow to avoid knock during the transitional lean condition when you stab the throttle).

    i'd trust your eehack knock analyzer map rather than knock retard. that uses knock sensor counts.

    EDIT: ccp is active a lot at high throttle, since that's a good time to purge, when that tiny bit of tank fume activity won't affect how the engine runs

    EDIT2: your timing retard is in the ~1 deg range which is zero concern

  10. #10
    Fuel Injected! Dirtybob's Avatar
    Join Date
    Aug 2016
    Location
    Quad Cities
    Age
    49
    Posts
    36
    the screenshot is just of the "weirdness", nothing else. low throttle position cruising in traffic with slight kr...

    took another look at the logs and CCP is active almost anytime the trottle is open more than x amount so I definitely need to rethink this. was looking for some kind of correlation (O2 reads, target afr, etc...) and CCP was the only thing I noticed.

    the actual knock events were all at 90+ kpa and over 4k rpm in first gear only. can run wot to the 2-3 shift with no kr happening in 2nd gear.

    been busy at work lately and the car has been sitting, maybe get a chance this weekend to try and figure out what is acually happening.
    thanks for the feedback.

    edit: burst knock is easy to spot in the logs, short kr spike related to quick throttle opening. I just ignore those...
    Last edited by Dirtybob; 10-28-2016 at 05:42 AM.

  11. #11
    Fuel Injected! Dirtybob's Avatar
    Join Date
    Aug 2016
    Location
    Quad Cities
    Age
    49
    Posts
    36
    another question about the above mentioned "weirdness".
    the logger shows no (increase in) knock counts when this happens. I am assuming that knock counts = knock sensor(s) registering noise, correct?

    on a side note, it looks like my belt tensioner is getting sloppy. gonna install a new one and see if the 'real' knock events are mitigated...

  12. #12
    Fuel Injected! steveo's Avatar
    Join Date
    Aug 2013
    Posts
    2,438
    if the knock counter isn't going up, then it's calculated pre-emptive knock retard like burst knock, low octane compensation, or god knows what other stuff. if it's only a degree or two it's definitely nothing to worry about.

    in other words EE uses that 'knock retard' field as general output of additive 'timing retard'

  13. #13
    Fuel Injected! Dirtybob's Avatar
    Join Date
    Aug 2016
    Location
    Quad Cities
    Age
    49
    Posts
    36
    well, it appears that the tensioner was rattling enough to register on the knock sensor(s). took over an hours worth of logs with the last one on 10% ethanol 87 octane (took me that long to burn thru a tank of fuel) and have no knock events (other than burst knock) or "weirdness" showing.
    only other thing that may be in play is the weather, went from mid 40s to mid 60s and I haven't been keeping track of density altitude as of yet.

    edit: DA went from less than 100' to 2200'+ fwiw. will have to grab more logs when it drops down again...
    Last edited by Dirtybob; 11-01-2016 at 01:00 PM.

  14. #14

  15. #15
    Fuel Injected! Dirtybob's Avatar
    Join Date
    Aug 2016
    Location
    Quad Cities
    Age
    49
    Posts
    36
    well maybe. it wasn't a bad bearing but the spring, you could see it bounce if you revved the engine high enough with the hood up. the pulley/bearing was still smooth as silk.
    you would also think it would've shown something at the top of 2nd gear.
    will have to see

Similar Threads

  1. Adjusting VE Fueling tables with BLM data Tutorial!
    By EagleMark in forum Fuel Injection Writeups Articles and How to New and Old
    Replies: 41
    Last Post: 11-22-2017, 10:19 PM
  2. $EE LT1 - Fueling tables & AE
    By Terminal_Crazy in forum GM EFI Systems
    Replies: 11
    Last Post: 06-13-2016, 05:39 PM
  3. Adjusting VE Fueling tables with BLM data Tutorial
    By rsicard in forum GM EFI Systems
    Replies: 18
    Last Post: 01-16-2015, 08:15 PM
  4. 7747 to 7427 Fueling
    By TheApocalyptican in forum GM EFI Systems
    Replies: 7
    Last Post: 06-21-2013, 11:12 PM
  5. Synch vs Asynch fueling
    By 1project2many in forum GM EFI Systems
    Replies: 122
    Last Post: 06-11-2013, 07:22 AM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •