idle problems/ idle decay
Advanced
Joined: Jan 2005
Posts: 51
Likes: 0
From: Charleston SC
That's a hack way of doing things and I would never recommend altering the IFR table to try and cure a stalling problem. The IFR table is one of the 2 basis' that the entire calibration is based on. Changing it will change everything fuel related in the corresponding vacuum areas. The IFR should be properly set, along with the displacement, and everything else should work off that.
If a stalling problem cannot be cured using conventional methods, I would sooner recommend altering the base airflow table to help.
If a stalling problem cannot be cured using conventional methods, I would sooner recommend altering the base airflow table to help.
Instructor
Joined: Oct 2005
Posts: 188
Likes: 23
From: Victoria Texas
So for example if you are idlieng at 60 KPA instead of 25--it may help to adjust the IFR table in the 60 KPA range somewhat larger (will make the pulse shorter) Larger injectors always seem to make the idle/stalling problems occur-- Remember that in the IFR table the scale is shown as the recipricol of 100 KPA-(60 KPA is 40 on the IFR table)
Clearly his problems are airflow and timing related. You cannot afford to have big variances in timing at these lower airflow/load cells. If timing goes up and down, your hp will go up and down and the light weight of the flywheel will accentuate the surging. Also, you'll want to slow the throttle cracker and follower WAY down to soften airflow corrections when clutching in.
Ed gave the best advice. Once you have all your timing and fueling leveled out, crank up the airflow until you start to have a hanging idle when clutching in. The slowly start pulling airflow away until you're happy. Don't forget the timing though. If your timing is still going up and down when you clutch in, you're screwed.
Le Mans Master
Joined: Aug 2005
Posts: 5,375
Likes: 328
From: CA.
St. Jude Donor '13-'14-'15
you guys are really nit picking my suggestions just for the sake of argueing---no one said anything about disabling the STFT's--I guess you just picked that up out of the air-huttler was talking about his LTFT's being a minus 10---and i responded to that---I don't know where you implanted STFT's into the conversation--other than you didn't read carefully enough---AND as to the Idle MAP being low at idle and higher when under load--but with a cam the idle MAF spikes up--IF you can read i said ABOUT---and again you nit pick on numbers when i was just making an example--You guys really make me laugh-it's like you nothing better to do but stroke your egos by bad mouthing people on silly meaningless points--- And about HIS hanging idle--IF you read his post he has TRIED ALL THE USUAL TABLES to fix it but has been UNSUCCESSFUL--The only table he hasn't addressed is the IFR table or the higher MAP at idle--here too you make it sound like it's wrong but that's because you didn't read the entire post--And finally you make it sound like i suggested raping the IFR table--When agian all i said was to make a small adjustment to it in the idle area beacuse more than likely the IFR tabled is incorrect to start with--I would never suggest messing with the IFR table unless someione has installEd new injectors--More than likely the entire IFR table is off--Sometimes i think people forget that the 02's rule in closed loop--Most any fuel table you adjust--the 02's will always try to vary the fuel settings to get 14.68-1--AND when going to PE the MAP is always beyond the lower MAP scale and at 90-100 KPA- If you have a small spike to correct the idle at 70 KPA ---with or without a load the ECM will adjust the fuel to get 14.68-1
- I have tuned over 700 GM cars and trucks--at least 200 of those cammed--100 duramax diesels--
50 blown or turboed LS's---I have yet to have a ligetimate dis-satisfied customer--
This is a forum to help those with problems--not to critisize-After reading his entire post and asking for his engine mods I came to the conclusion he MIGHT have an IFR issue-This over zealous attack is exactly why LS1TECH went south and has the reputation for being A**H***S---I hope this kind of behavior doesn't infiltrate the corvetteforum as I still think it is the best one going
PS I'm done with this issue--
- I have tuned over 700 GM cars and trucks--at least 200 of those cammed--100 duramax diesels--
50 blown or turboed LS's---I have yet to have a ligetimate dis-satisfied customer--
This is a forum to help those with problems--not to critisize-After reading his entire post and asking for his engine mods I came to the conclusion he MIGHT have an IFR issue-This over zealous attack is exactly why LS1TECH went south and has the reputation for being A**H***S---I hope this kind of behavior doesn't infiltrate the corvetteforum as I still think it is the best one going
PS I'm done with this issue--
Le Mans Master
Joined: Mar 2004
Posts: 5,562
Likes: 5
From: South East coast Florida
I've had an idle problem ever since I put in this stinking LUK aluminum flywheel (regret). Lets just say the cam and the flywheel don't mix, I installed the cam first and then I put the flywheel in about 5k miles later. I've had problems with my idle for 4 years now...
Anyway I'm trying to make my idle not drop like a rock when I push in the clutch, this seems to be one of the main problems because it drops so fast that it falls all the way to ~500rpm and then the dreadful surging starts (quick & cyclic between 500-1300 rpms). VERY important piece: Idle problems are ONLY when I'm coasting, as SOON as the car comes to a stop the idle fixes itself within a few seconds at most, sometimes instantly. My car has been professionally tuned twice, the second time most of my idle problems went away because I voiced this as one of my main concerns. The second tuner also fixed another horrific problem, stalling and worse surging with the a/c turned on. Even with the second tune once in a while my idle problems randomly re-surface and that is what I'm trying to eradicate.
I've modified the throttle follower, throttle cracker, idle airflow tables, etc. countless times and nothing seems to work or even have much of an effect, unless I change it a ridiculous amount.
If a setting doesn't work I change it back to how it was and start from scratch. I also have tried changing settings under "torque management" because I was told those settings are where I need to compensate for the reduced weight of my flywheel (10lbs vs 24lbs stock), I didn't notice any changes in the engine's behavior when I modified this settings, no matter how extreme.
If all else fails I'm going back to a standard flywheel because my idle was fine even with the first tune before it I installed it.
Anyway I'm trying to make my idle not drop like a rock when I push in the clutch, this seems to be one of the main problems because it drops so fast that it falls all the way to ~500rpm and then the dreadful surging starts (quick & cyclic between 500-1300 rpms). VERY important piece: Idle problems are ONLY when I'm coasting, as SOON as the car comes to a stop the idle fixes itself within a few seconds at most, sometimes instantly. My car has been professionally tuned twice, the second time most of my idle problems went away because I voiced this as one of my main concerns. The second tuner also fixed another horrific problem, stalling and worse surging with the a/c turned on. Even with the second tune once in a while my idle problems randomly re-surface and that is what I'm trying to eradicate.
I've modified the throttle follower, throttle cracker, idle airflow tables, etc. countless times and nothing seems to work or even have much of an effect, unless I change it a ridiculous amount.
If a setting doesn't work I change it back to how it was and start from scratch. I also have tried changing settings under "torque management" because I was told those settings are where I need to compensate for the reduced weight of my flywheel (10lbs vs 24lbs stock), I didn't notice any changes in the engine's behavior when I modified this settings, no matter how extreme.If all else fails I'm going back to a standard flywheel because my idle was fine even with the first tune before it I installed it.
