Hot start problems hunting at idle
Thread Starter
TECH Addict
Joined: Aug 2005
Posts: 2,305
Likes: 126
From: Monroe,NY
Hot start problems hunting at idle I am new to tuning.I have a 1992 chevy pickup with a 2004 5.3 LT headers, CAI,no cats and a voodoo 212/218 cam with a 1999 pcm 5 speed manual.I also have a mail order tune but tuner will not answer my questions.Truck starts great cold but sometimes has trouble starting when hot.I did some searching and it looks like i should increase startup airflow initial but by how much.At temps 176 and higher setting is 0.0000.
I also have a little idle hunting problem on hot starts and if i rev motor sitting still and sometimes coming to a stop.It will hunt for 3 to 5 seconds.
Any help would be appreciated.
Thanks Joe
I also have a little idle hunting problem on hot starts and if i rev motor sitting still and sometimes coming to a stop.It will hunt for 3 to 5 seconds.
Any help would be appreciated.
Thanks Joe
Sounds more like you still have idle issue's, that is a small cam & should not require many changes to get it right. You don't want to start changing tables if the basics are wrong.
Post up the tune.
Post up the tune.
I don't have the software to look at the file posted, however, if I had a guess, I would say you need to add more air via idle airflow table at the temperature that you are having issues with
The START UP AIRFLOW is probably not to be needing a change, Just fix your base running airflow. In EFIlive it is table B4307. For the cam you are running, my values would be:
LABELS Desired Airflow (Lbs/Minute)
ECT °F {link: SAE.ECT} In Gear Park/Neutral
-40 2.820987 2.820987
-4 2.688710 2.688710
32 2.424156 2.424156
68 1.696632 1.795840
104 1.643669 1.564355
140 1.485040 1.392421
176 1.417520 1.371210
212 1.350000 1.350000
248 1.350000 1.350000
284 1.350000 1.350000
The START UP AIRFLOW is probably not to be needing a change, Just fix your base running airflow. In EFIlive it is table B4307. For the cam you are running, my values would be:
LABELS Desired Airflow (Lbs/Minute)
ECT °F {link: SAE.ECT} In Gear Park/Neutral
-40 2.820987 2.820987
-4 2.688710 2.688710
32 2.424156 2.424156
68 1.696632 1.795840
104 1.643669 1.564355
140 1.485040 1.392421
176 1.417520 1.371210
212 1.350000 1.350000
248 1.350000 1.350000
284 1.350000 1.350000
By chance do you have an idle log?
Yes, the BRAF looks very low to what wait4me posted.
You can look @ your MAF airflow @ idle, that will give you an idea if the BRAF is wrong. Also log Desired Idle Airflow in your scanner
Yes, the BRAF looks very low to what wait4me posted.
You can look @ your MAF airflow @ idle, that will give you an idea if the BRAF is wrong. Also log Desired Idle Airflow in your scanner
Last edited by ctd; Jan 14, 2013 at 09:48 AM.
After that, it if is fine when idling, then has a little hanging rpm while your truck is moving, and or coming to a stop, Go to a table that is THROTTLE CRACKER, or something to that nature of naming, In EFIlive the EXACT table name is B4309. This table adds airflow to that base table depending on mph and engine rpm to prevent stalling while moving. HOWEVER when you make a change to the BASE airflow table, all the adders get over sensitive, so you have to just pull a percentage from them to keep things in line.
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Before you get all excited about changing airflows
and such, try getting the IAT sensor out of the engine
bay (where it can heat-soak to indicate well above
real air temps).
and such, try getting the IAT sensor out of the engine
bay (where it can heat-soak to indicate well above
real air temps).
Thread Starter
TECH Addict
Joined: Aug 2005
Posts: 2,305
Likes: 126
From: Monroe,NY
Thanks
Thread Starter
TECH Addict
Joined: Aug 2005
Posts: 2,305
Likes: 126
From: Monroe,NY
I don't have the software to look at the file posted, however, if I had a guess, I would say you need to add more air via idle airflow table at the temperature that you are having issues with
The START UP AIRFLOW is probably not to be needing a change, Just fix your base running airflow. In EFIlive it is table B4307. For the cam you are running, my values would be:
LABELS Desired Airflow (Lbs/Minute)
ECT °F {link: SAE.ECT} In Gear Park/Neutral
-40 2.820987 2.820987
-4 2.688710 2.688710
32 2.424156 2.424156
68 1.696632 1.795840
104 1.643669 1.564355
140 1.485040 1.392421
176 1.417520 1.371210
212 1.350000 1.350000
248 1.350000 1.350000
284 1.350000 1.350000
The START UP AIRFLOW is probably not to be needing a change, Just fix your base running airflow. In EFIlive it is table B4307. For the cam you are running, my values would be:
LABELS Desired Airflow (Lbs/Minute)
ECT °F {link: SAE.ECT} In Gear Park/Neutral
-40 2.820987 2.820987
-4 2.688710 2.688710
32 2.424156 2.424156
68 1.696632 1.795840
104 1.643669 1.564355
140 1.485040 1.392421
176 1.417520 1.371210
212 1.350000 1.350000
248 1.350000 1.350000
284 1.350000 1.350000
Thanks Joe
