running very rich

[Blizzard242]

Re: running very rich

Those set tables in open loop are based off of sensor input. If a map sensor sees so much vacuum it puts that much fuel in. The o2 sensors correct the imperfections in these tables after they've been heated to get a proper read.

I'm just curious as to what sensors a 3.4 has to use to determine fueling so we could hopefully determine what is telling his pcm to dump so much fuel into the engine if it's not a faulty fpr.

[tkoforpresident]

Re: running very rich

Those set tables in open loop are based off of sensor input. If a map sensor sees so much vacuum it puts that much fuel in. The o2 sensors correct the imperfections in these tables after they've been heated to get a proper read.

I'm just curious as to what sensors a 3.4 has to use to determine fueling so we could hopefully determine what is telling his pcm to dump so much fuel into the engine if it's not a faulty fpr.

OK... your kind of right. The 3.4 when in open loop runs off set maps based off of the readings of TWO sensors while the o2's are still too cold to give a signal. These two sensors are the IAT (intake air temperature) and ECT (Engine coolant temperature). As far as i can tell no other sensors are being used while in open loop to determine fueling (besides rpms obviously)

so if you think it's worth a shot replace your ECT and IAT sensors while your at it, but i doubt those are bad.

[Blizzard242]

Re: running very rich

tko, where are you getting this information? I mean, where did you learn to tune a 3.4 because I'd like to read it too. And.. I was under the impression that there was a map sensor on the 3.4's.

[tkoforpresident]

Re: running very rich

tko, where are you getting this information? I mean, where did you learn to tune a 3.4 because I'd like to read it too. And.. I was under the impression that there was a map sensor on the 3.4's.

I'm not trying to sound offended but are you questioning my information?

quoted from the FACTORY SERVICE MANUAL...

"The run mode has two conditions called open-loop and closed-loop. When the engine speed is above 400 rpm, the system goes into open-loop operation. The PCM ignores the signal from the O2S and calculates the air/fuel ratio based on the inputs from the engine cooland temp(ECT) and intake air temp(IAT) sensors.
The system stays in open-loop until the following conditions are met:
1. The O2S has varying voltage output, showing that it is hot enough to operate properly(This depends on temperature.)
2. The ECT sensor is above a specified temperature.
3. A specific amount of time has elapsed after starting the engine.
When these values are met, the system goes into closed loop operation."

[atomicvirus]

Re: running very rich

thanks guys, i had to wait for the fpr rebuild kit. its suposed to be in today. ill let you know if that fixes the problem. i hope it does.

[Blizzard242]

Re: running very rich

calm down, he was just saying he wants to read wherever you got your info from so he can learn about the 3.4's OBD/closed/open loop

Exactly. I'm gettin beat up over a couple different threads from people who run the world.

kthx.

[atomicvirus]

Re: running very rich

i just checked the fuel pressure with key on engine off like the book said and it was 38 psi, the book says it should be at 40 psi is that close enough? now im gonna head back outside and change the oil and plugs so i can check it while it is running.

[thedetailman]

Re: running very rich

hey blizzard. are your from the perrysburg Ohio area. correct?
i was wanting to inquire a question to you, regarding hp tuners. can you tune?

[Blizzard242]

Re: running very rich

lmao, it's funny you ask in this thread since tko would say different. But yeah, I've got my car running pretty good. We should probably take this to PM