first time owning a cammed car - normal behavior?
05-03-2010, 08:35 AM
#1
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first time owning a cammed car - normal behavior? Not sure what forum topic to put this under...mods feel free to move if this fits under a different forum topic better...
Got my car back from the shop (needed it tuned a little better and some other little stuff taken care of), and it drives GREAT, been driving it around all weekend, but...
I noticed that when I start it up, I have to blip the accelerator just a tiny bit, and it will start up fine. But then if I immediately put it into gear, the engine wants to shut off. I also noticed that when it's colder outside, like at night, it takes a little longer before I can put it into gear after I start the car.
Is this normal on a car that has a cam in it? Mine is a 233/239 cam and my trans is a TH400. I mean does everyone that has a cammed LS1 have to do this when they start their car? Or is this normal from a fresh tune (the tune was done last Friday), does the computer take a while to learn how to start up nice and smooth?
Got my car back from the shop (needed it tuned a little better and some other little stuff taken care of), and it drives GREAT, been driving it around all weekend, but...
I noticed that when I start it up, I have to blip the accelerator just a tiny bit, and it will start up fine. But then if I immediately put it into gear, the engine wants to shut off. I also noticed that when it's colder outside, like at night, it takes a little longer before I can put it into gear after I start the car.
Is this normal on a car that has a cam in it? Mine is a 233/239 cam and my trans is a TH400. I mean does everyone that has a cammed LS1 have to do this when they start their car? Or is this normal from a fresh tune (the tune was done last Friday), does the computer take a while to learn how to start up nice and smooth?
05-03-2010, 08:58 AM
#2
You have a car with a 233/239 cam and a th400 and you are concerned about driveability??
haha
Sorry about that...
At any rate... part of the trouble with a th400 is that your PCM gets setup for a manual and the PCM can't know when you put the trans in gear. It trims back airflow for an unloaded idle and then you drop it into gear and there is not enough airflow to keep things idling under the sudden load. Maybe touch the gas pedal just a shade and as it comes back to idle, put it in gear. That will keep it from running idle air trims negative.
If you want a car that you start cold and just begin driving right away, I'm not sure that this is the most ideal.
haha
Sorry about that...
At any rate... part of the trouble with a th400 is that your PCM gets setup for a manual and the PCM can't know when you put the trans in gear. It trims back airflow for an unloaded idle and then you drop it into gear and there is not enough airflow to keep things idling under the sudden load. Maybe touch the gas pedal just a shade and as it comes back to idle, put it in gear. That will keep it from running idle air trims negative.
If you want a car that you start cold and just begin driving right away, I'm not sure that this is the most ideal.
05-03-2010, 10:12 AM
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That makes sense Frost, thanks man. Ok, so if there is something to let the engine know that a load has been put on it, then it should compensate, correct? Would vacuum change when you put it into gear?
Btw, not concerned with driveability, I love the way it drives. It's actually pretty smooth when cruising around and stomping on the throttle.
I was just concerned with startup. Didn't know if this was normal or not.
Sent you a pm too btw.
Btw, not concerned with driveability, I love the way it drives. It's actually pretty smooth when cruising around and stomping on the throttle.
I was just concerned with startup. Didn't know if this was normal or not.Sent you a pm too btw.
05-03-2010, 08:09 PM
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Found out some info on my wiring harness (Painless PN 60506):
Locate the Orn/Blk and Blk/Wht wires in the dash group. These two wires are for the GEAR
INDICATOR SWITCH, NOT the Neutral Safety Switch. If you have a GM column then you can use the
combination switch Delco P/N D2286A and wire it as described in paragraph 2 or 3 below. The
ORN/BLK wire needs to be grounded in "Park and Neutral" and ungrounded in "Drive". This can also
be done with a toggle switch or a switch on the parking brake.
You may want to install your own switch. This switch must connect the Orn/Blk wire to ground
only when the car is in PARK OR NEUTRAL. You may or may not want to use the Blk/Wht
wire. The other end of the Blk/Wht wire is already grounded throughout the harness.
Looks like that's what's needed to go to my neutral safety switch so that the PCM knows that it's in gear.
Locate the Orn/Blk and Blk/Wht wires in the dash group. These two wires are for the GEAR
INDICATOR SWITCH, NOT the Neutral Safety Switch. If you have a GM column then you can use the
combination switch Delco P/N D2286A and wire it as described in paragraph 2 or 3 below. The
ORN/BLK wire needs to be grounded in "Park and Neutral" and ungrounded in "Drive". This can also
be done with a toggle switch or a switch on the parking brake.
You may want to install your own switch. This switch must connect the Orn/Blk wire to ground
only when the car is in PARK OR NEUTRAL. You may or may not want to use the Blk/Wht
wire. The other end of the Blk/Wht wire is already grounded throughout the harness.
Looks like that's what's needed to go to my neutral safety switch so that the PCM knows that it's in gear.
05-03-2010, 08:47 PM
#5
It should be that easy...
The car will still need to have an automatic-based calibration. The norm is using a manual trans calibration for something like that though. Also, if you do have the auto-calibration, it will have to have the in-gear airflow tuning done already. That would be tricky since the switch wasn't there when the vehicle was tuned.
The car will still need to have an automatic-based calibration. The norm is using a manual trans calibration for something like that though. Also, if you do have the auto-calibration, it will have to have the in-gear airflow tuning done already. That would be tricky since the switch wasn't there when the vehicle was tuned.
Last edited by Frost; 05-04-2010 at 02:20 PM.
05-03-2010, 10:58 PM
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Ok I'm confused, sorry...it sounds like you are saying the best case scenario is to have an automatic tune, but the norm is that people tune TH400s as a manual...is that correct?
If I were to keep the tune as a manual, how would you let the engine know a load has been put on it?
If I were to keep the tune as a manual, how would you let the engine know a load has been put on it?
05-04-2010, 02:20 PM
#7
You really don't; manual setups don't have in/out of gear, they only use one set of idle and airflow tables (always considered IN gear).
It's always nice to know what's going on, but I think you'd be better served talking to your tuner about the issue. It's not like a post here will get you fixed unfortunately.
It's always nice to know what's going on, but I think you'd be better served talking to your tuner about the issue. It's not like a post here will get you fixed unfortunately.
