Won't idle after hot start.
Thread Starter
On The Tree
Joined: Feb 2004
Posts: 156
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From: Fayetteville, NC
Won't idle after hot start. I posted this over on the HPT board as well. Well, I just got my VE dialed in, & have moved on to tuning the MAF, but have run into a problem that wasn't there before. After the car is fully up to temp. (oil temp @ 200), & I turn it off, if I go to restart it, it will fire up but not stay on. It idles for about 1.5 secs, then dies. I have heads, & a rather large cam, mods in my signature below.
Please help,
Tucker
Please help,
Tucker
I would up the desired airflow (RAF) a little for that operating temp range in order to keep the car running. Then log the STIT's and LTIT's from a cold start to dial it in. That's the most likely source of your problem.
Thread Starter
On The Tree
Joined: Feb 2004
Posts: 156
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From: Fayetteville, NC
Originally Posted by SSpdDmon
I would up the desired airflow (RAF) a little for that operating temp range in order to keep the car running. Then log the STIT's and LTIT's from a cold start to dial it in. That's the most likely source of your problem.
Sorry, no wideband.
Originally Posted by TSDuke
Well, I just got my VE dialed in, & have moved on to tuning the MAF,
Could you also post up your OL coolant-temp correction table, and the start-up enrichment vs coolant table?
Try increasing and decreasing the MAF values by a point or two in the range where the car normally idles. Mine seems to have a harder time on start up with the MAF on as well, but other's cars that I've tuned didn't seem to share that problem. I'm wondering if bigger cams just don't play well with the MAF at idle?
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Originally Posted by TSDuke
Here is a screenshot of my Base Running Airflow
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TECH Addict
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Originally Posted by SSpdDmon
I would up the desired airflow (RAF) a little for that operating temp range in order to keep the car running. Then log the STIT's and LTIT's from a cold start to dial it in. That's the most likely source of your problem.
Sounds like as soon as the start up airflow decays out she dies.
LTITs and STITs will become active above 176*F (80*C). Look for these Idle PIDS -> Engine-> Airflow-> Idle > LTIT in Gear and P/N and Idle Adapt (STIT).
From HP Tuners:
Idle airflow: Log the STIT and LTIT and add the 2 together. With a manual you will use LTIT in gear all the time, autos will use the respective LTIT depedning on the gear selector position. Add the 2 values together (or make a custom histogram) and make chagnes based on ECT. Say 30*C STIT is -0.30 g/sec and LTIT is 0.10 g/sec, you want to subract 0.20 g/sec from the 30*C cell in the idle airflow table. It is important to make these changes only from a cold start as they will give the most accurate data. Make sure it is logging and you make corrections in metric as it adds better resolution. For starters, adding 2 g/sec to the table before initial start up after a cam can help idle.
Here's a link ->http://www.hptuners.com/forum/showthread.php?t=3833
"Idle Relearn" is a big help with stabilizing your Idle with ETC. Basically, let it Idle above 176*F for 5 minutes and then turn the key to Off position for 15 - 20 Seconds. Then restart and let idle for a few minutes - until the Idle stabilizes. Do not use the Accel pedal on startup or during the Learn period (few minutes).
Good Luck.
Thread Starter
On The Tree
Joined: Feb 2004
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From: Fayetteville, NC
I made a few changes to the RAF using RHS's spreadsheet. I guess it helped a little, but it still wants to die. I'm pretty sure it has to do with an accessories load being put on the engine. The reason is it only does is when my high fan is on, or I'm parralel parking, & turning the steering wheel back a forth fast. Idle drops down really low, & almost does, or does die.
Hell, when the a/c is on I have no chance of the car staying on. As long as I'm sitting there idleing I'm fine, but the second I give it gas, & the idle comes back down, DEAD. I've doubled my AC Offset Min - In Gear, & Max - In Gear #'ers, but it changed nothing.
Hell, when the a/c is on I have no chance of the car staying on. As long as I'm sitting there idleing I'm fine, but the second I give it gas, & the idle comes back down, DEAD. I've doubled my AC Offset Min - In Gear, & Max - In Gear #'ers, but it changed nothing.
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Originally Posted by TSDuke
I made a few changes to the RAF using RHS's spreadsheet. I guess it helped a little, but it still wants to die. I'm pretty sure it has to do with an accessories load being put on the engine. The reason is it only does is when my high fan is on, or I'm parralel parking, & turning the steering wheel back a forth fast. Idle drops down really low, & almost does, or does die.
Hell, when the a/c is on I have no chance of the car staying on. As long as I'm sitting there idleing I'm fine, but the second I give it gas, & the idle comes back down, DEAD. I've doubled my AC Offset Min - In Gear, & Max - In Gear #'ers, but it changed nothing.
Hell, when the a/c is on I have no chance of the car staying on. As long as I'm sitting there idleing I'm fine, but the second I give it gas, & the idle comes back down, DEAD. I've doubled my AC Offset Min - In Gear, & Max - In Gear #'ers, but it changed nothing.
AC Offset Max in Gear:
bump it to -> 4.00 g/sec
Adaptive Idle Airflow Limits:
Max in Gear AC Off -> 3.00 g/sec
Min in Gear AC Off -> -3.00 g/sec
ST Adapt Airflow Max:
Bump it to 2.00 g/sec at all temps 60*C and above.
......................This should be a big help....expands your adapt idle air - LTITs and STITs.
Let it idle learn above 80*C for several minutes. Then turn on the AC and it will add in the neccessary airflow. After idle settles down the PCM will pull the added AC/On air from the STITs and offset (learn) the air into the "AC Offset Max in Gear" cell. You can scan and watch it happen. FWIW.
Good Luck,
joel
Last edited by Bink; Apr 20, 2006 at 05:04 PM.
