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bandit86 03-24-2011 05:55 PM

Loop question
 
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?

gone-ot 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?

gone-ot 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 (Post 229049)
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.


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