Engine Too Cold For Too Long?
#12
10-13-2009, 06:33 PM
Yeah mine does that also..I think a 180 stat also hurts your gas mpg.Its called a cold start loop.
http://vehicle.me.berkeley.edu/Publi...bshaw_ASME.pdf
http://vehicle.me.berkeley.edu/Publi...bshaw_ASME.pdf
When you change that, you also have to reflash the PCM as well in order to set the temp limit twenty degrees lower for a 180 and, 40 degrees for a 160 degree T-stat.
If the PCM is stock and has not been programmed / flashed to accommodate for those changes, the temp sensor voltage reads low and, the PCM runs the engine rich. This can be a real problem as it's in basically, choke mode the entire time it's running. They call this open loop mode. In OL mode, the O2 sensors don't supply feedback to the PCM thus not helping to balance out the rich A/F mixture.
I found this out and, after seeing all the talk about doing this- it's more of a problem that what it's worth. The fact is the engine actually runs better hotter than it does cold for one and secondly, you can get more HP by running hotter and lean as possible than running rich. It also saves on fuel by a lot.
Running rich fouls plugs, ruins CATS, and damages the internal engine components if left in that condition for long periods of time.
Hypertech sells the tuner to flash the PCM over to make it 50 state legal. It's just that all the third party places that sell the damn T-stats themselves fail to inform the buyer of the flash bit.
I have a 180 Hyper- T-stat and I have a SCT tuner but, the SCT tuner does not compensate for this nor lots of other things as I am now just finding out. Wish I would have known this before buying it.
Anyway, there's two options:
-reprogram the PCM to compensate or
-remove and replace that T-stat with a OEM rated 196-200 degree model and you'll be fine.
CM
#13
10-13-2009, 08:18 PM
Join Date: Feb 2009
Location: Amarillo, Texas
Posts: 1,145
Likes: 0
Received 0 Likes
on
0 Posts
It sure does. What people don't realize is that the PCM is programmed to use the 200 degree temp as the parameter for normal operation.
When you change that, you also have to reflash the PCM as well in order to set the temp limit twenty degrees lower for a 180 and, 40 degrees for a 160 degree T-stat.
If the PCM is stock and has not been programmed / flashed to accommodate for those changes, the temp sensor voltage reads low and, the PCM runs the engine rich. This can be a real problem as it's in basically, choke mode the entire time it's running. They call this open loop mode. In OL mode, the O2 sensors don't supply feedback to the PCM thus not helping to balance out the rich A/F mixture.
I found this out and, after seeing all the talk about doing this- it's more of a problem that what it's worth. The fact is the engine actually runs better hotter than it does cold for one and secondly, you can get more HP by running hotter and lean as possible than running rich. It also saves on fuel by a lot.
Running rich fouls plugs, ruins CATS, and damages the internal engine components if left in that condition for long periods of time.
Hypertech sells the tuner to flash the PCM over to make it 50 state legal. It's just that all the third party places that sell the damn T-stats themselves fail to inform the buyer of the flash bit.
I have a 180 Hyper- T-stat and I have a SCT tuner but, the SCT tuner does not compensate for this nor lots of other things as I am now just finding out. Wish I would have known this before buying it.
Anyway, there's two options:
-reprogram the PCM to compensate or
-remove and replace that T-stat with a OEM rated 196-200 degree model and you'll be fine.
CM
When you change that, you also have to reflash the PCM as well in order to set the temp limit twenty degrees lower for a 180 and, 40 degrees for a 160 degree T-stat.
If the PCM is stock and has not been programmed / flashed to accommodate for those changes, the temp sensor voltage reads low and, the PCM runs the engine rich. This can be a real problem as it's in basically, choke mode the entire time it's running. They call this open loop mode. In OL mode, the O2 sensors don't supply feedback to the PCM thus not helping to balance out the rich A/F mixture.
I found this out and, after seeing all the talk about doing this- it's more of a problem that what it's worth. The fact is the engine actually runs better hotter than it does cold for one and secondly, you can get more HP by running hotter and lean as possible than running rich. It also saves on fuel by a lot.
Running rich fouls plugs, ruins CATS, and damages the internal engine components if left in that condition for long periods of time.
Hypertech sells the tuner to flash the PCM over to make it 50 state legal. It's just that all the third party places that sell the damn T-stats themselves fail to inform the buyer of the flash bit.
I have a 180 Hyper- T-stat and I have a SCT tuner but, the SCT tuner does not compensate for this nor lots of other things as I am now just finding out. Wish I would have known this before buying it.
Anyway, there's two options:
-reprogram the PCM to compensate or
-remove and replace that T-stat with a OEM rated 196-200 degree model and you'll be fine.
CM
Goin' back to stock lol. Good thing it was only $5. Thanks for the help everybody who contributed. I'll post back if I notice any improvements.
#14
10-13-2009, 10:47 PM
nope, just take the belt off, and unbolt the ac compressor, and move it to the side, and use an extension to get to the housing bolts. its not a hard job, it only took me like 30 mins, and i think all data calls for 1.0hr.
#17
10-14-2009, 09:51 AM
Captain
#18
10-14-2009, 10:17 AM
Record Breaker
#19
10-14-2009, 01:35 PM
you know as many therms. as ive replaced here at the dealership, ive never had one give me troubhle with that tab. but then again, i always unbolt the a/c compressor and move it out of the way.
#20
10-14-2009, 03:58 PM