Loop question - Fuel Economy, Hypermiling, EcoModding News and Forum

bandit86 · 03-24-2011, 05:55 PM

01 jeep grand Cherokee. I have been watching the scanGauge and for an entire hour it didn't move from closed loop When I restart it it goes into open loop for a few seconds and stays in closed loop again

is this normal? I thought it supposed to flicker back and forth or at least go I to open under light load

my tps is 16 at the lowest does that make a difference?

Old Tele man · 03-24-2011, 06:12 PM

..."Closed Loop" is when the computer (ECM) is controlling everything off the sensor inputs, the EPA way.

..."Open Loop" is when the computer is NOT controlling everything, but rather using "preset" lookup information (sensors not yet up to temperature or not working), not so EPA friendly way.

bandit86 · 03-24-2011, 06:30 PM

I thought it was backwards

Joenavy85 · 03-25-2011, 09:04 PM

as far as the TPS i have an 05 Jeep Liberty that sits at 14 at idle according to my old scangauge, and at 14.1 (sometimes 14.7) according to my ultragauge, so i would say 16 is relatively normal

Phantom · 03-31-2011, 02:13 PM

The vehicle should be in closed loop most of the time except when first starting and heavy acceleration.

TPS is at 16? 16 What? If it is 16% at idle then something is messes up it should be at 0% at idle.

bandit86 · 03-31-2011, 09:07 PM

What is the best map reading for the most efficiency on a scangauge?

Old Tele man · 03-31-2011, 10:16 PM

...depends upon the engine, loading and gearing.

vskid3 · 04-01-2011, 01:27 AM

Quote:

Originally Posted by Phantom

TPS is at 16? 16 What? If it is 16% at idle then something is messes up it should be at 0% at idle.

My car shows about 9.8 at idle. 16 seems kinda high, but it probably isn't a problem. Its just the raw sensor data, I'm sure the computer figures out that 16=0.

bandit86 · 04-01-2011, 11:31 AM

i was thinking of backing off the throttle stop screws to see if it makes a difference, the IAC should compensate

Phantom · 04-01-2011, 01:01 PM

The issue with the TPS% (Throttle Position Sensor) so high is shift tables, TCC, and fuel enrichment tables are in the wrong cell. Such as shift from 1-2 at 15mph if between 0-15% TPS but if TPS is 15-30% shift at 19mph, the PCM will shift at the higher value. Load and other things are calculated using TPS also.

It could be the way the scangauge reads but if it is polling the PCM then thats what it is using. To correct the issue a few things can be done.
1. Back the throttle stop screw out some and see if it fixes it. (backing out to much might cause the plate to stick some when cold.
2. Have a TPS learn procedure done so it will zero it at that value (not sure if the PCM allows it)
3. Measure the voltage at idle and adjust the sensor to spec by turning it. If the sensor is not adjustable the mounting holes might need to be made bigger.