no power when first started
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Loop status has to do with how the PCM controls fuel mixture. In open loop the PCM ignores oxygen sensor data, and uses data from other sensors to control fuel mixture. In closed loop, the PCM uses oxygen sensor data to control fuel mixture which is far more accurate.
On each start up, the PCM operates in open loop. Several things must happen before the it switches to closed loop. The colder the engine is, the longer it takes to switch to closed loop. What we're looking for on yours is: Does the problem occur precisely when it switches to closed loop.
On each start up, the PCM operates in open loop. Several things must happen before the it switches to closed loop. The colder the engine is, the longer it takes to switch to closed loop. What we're looking for on yours is: Does the problem occur precisely when it switches to closed loop.
Thread Starter
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Senior Member
Joined: May 2013
Posts: 629
Loop status has to do with how the PCM controls fuel mixture. In open loop the PCM ignores oxygen sensor data, and uses data from other sensors to control fuel mixture. In closed loop, the PCM uses oxygen sensor data to control fuel mixture which is far more accurate.
On each start up, the PCM operates in open loop. Several things must happen before the it switches to closed loop. The colder the engine is, the longer it takes to switch to closed loop. What we're looking for on yours is: Does the problem occur precisely when it switches to closed loop.
On each start up, the PCM operates in open loop. Several things must happen before the it switches to closed loop. The colder the engine is, the longer it takes to switch to closed loop. What we're looking for on yours is: Does the problem occur precisely when it switches to closed loop.
. so i wanted to see how long it took to change from open to closed. it was a little over a minute, is that normal? gonna email innova and see what refresh rate is on it
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i will let it sit overnight and try it again around noon tmr, since i have the day off, will post results tmr
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ok, so i let the truck sit for a good 20 hours, started it up and with no hesitation started going. loop stayed open for a good 2 minutes before closing. slight power issue but not as bad as usual but hardly a difference when opened and closed
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so i did it again today, sat less than 8 hours. started it up and quickly went, ran very hesitant for a good 30 seconds, then went back to acting normal. was still open when went back to normal
not sure what that means
not sure what that means
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Joined: Mar 2009
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From: Belleville, Michigan
If it acted up in open loop, the oxygen sensors are NOT the issue. There could be a problem with MAF, MAP, TPS, ECT, IAT, (although you checked the last two already). Could even be a problem with fuel pressure dropping out momentarily. Driving with a tester connected you could watch pressure when it acts up. That might give a clue.
Jerry had a good point in post #4. A dirty MAF can cause issues without setting a DTC in memory. Have you tried installing a "known good" sensor or cleaning the one you have?
Jerry had a good point in post #4. A dirty MAF can cause issues without setting a DTC in memory. Have you tried installing a "known good" sensor or cleaning the one you have?
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have not tried swapping maf only because my mpg has been amazing lately and from what i read on here it really affects mpg if dirty. i heard cleaning them is very risky of damaging it.
as soon as i get my fp gauge ill give that a try. how would i test map and tps
as soon as i get my fp gauge ill give that a try. how would i test map and tps
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Joined: Mar 2009
Posts: 8,453
From: Belleville, Michigan
You need to be very careful with the elements in the MAF. If you look in the bore, you can see them, but DON'T touch them. There are 3 of them: one heater, and 2 sensor wires.
TPS is best tested in graph mode while cycling the throttle, (engine off). Needs to be a smooth pattern up and down, with no spikes, and no dropouts.
TPS is best tested in graph mode while cycling the throttle, (engine off). Needs to be a smooth pattern up and down, with no spikes, and no dropouts.
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