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Driving Power Open Loop vs. Closed Loop N/A
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2001Ls
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PostPosted: Sat Oct 27, 2012 12:37 am    Post subject:  Driving Power Open Loop vs. Closed Loop N/A Reply with quote

I've noticed for quite some time that when I first get driving in the morning my car has very rapid throttle response while I drive down my street. The reason I notice this is because once my car warms up the throttle response is dead and it doesnt want to go. Sometimes when I stomp the gas in closed loop (operating temperature) ,most the times actually, my car bogs. Sometimes however when the car is warmed up I will stomp the gas and get all 200hp that the 3800 has to offer. I just noticed the throttle response difference between open loop (first thing in the morning) and closed loop, I'm wondering if my 180 thermostat could be the problem. I believe that the pcm in my car goes into closed loop when the coolant temperature sensor reaches a specific degree (which I don't know exactly). I have a 180 thermostat , but I do not have a tuned pcm. I think that this is also kind of a notorious symptom of a MAF but I have a relatively new one (aftermarket from advance autoparts) and also I used a scanner to read MAF flow and I was at around 128 gps at WOT in park (was about 48 I believe at idle). *Don't quote me on these MAF readings because I deleted the screen shots I had, I can do it again and get MAF readings but only while parked bc my laptop battery dies and I have a ELM327. Anyways... I don't exactly know what to do, I can get all the basic diagnostic numbers because I do have a basic scanner program if that would help understand my lack of performance. Oh also as a side not I have a small exhaust leak post cat, not very big. Any help or ideas?

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grimsin
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PostPosted: Sat Oct 27, 2012 7:37 am    Post subject:   Reply with quote

knock sensors dont kick in tell 160 degrees so almost your full operating temp, you have any kr showing at operating temp?

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2001Ls
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PostPosted: Sat Oct 27, 2012 9:09 am    Post subject:   Reply with quote

To be honest i've never checked it. I have no serious mods either.

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grimsin
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PostPosted: Sat Oct 27, 2012 9:14 am    Post subject:   Reply with quote

these car come out of factory with kr...not much but its there.
if you lose power at operating temp i would be checking your kr(knock ratio).
and dont be flooring it when your engine is cold cause you have no knock sensors to tell your engine that your getting kr untill your reach 160 degrees or more. so you could kaboom your engine.
if your are getting alot of kr that will retard your timing which results in no power.

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PostPosted: Sat Oct 27, 2012 10:37 pm    Post subject:   Reply with quote

Idle and Closed Loop Data

4.10 g/s maf

Intake Manifold Press
40 kPaA 5.8 PsiA

Rpm Fluctuates
700-750

Ign Timing Adv Cyl#1
20 Degrees

Short Term FT Bank 1
00-.78%

Long Term Bank 1
2.34%

Cooolant 206

Air Intake 75

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PostPosted: Sun Oct 28, 2012 8:34 am    Post subject:   Reply with quote

I have no idea what the stuff means lol, I just know how kr can kill your power..
if no one answers here knows anything about those #'s try grandprixforums.net , I know how most people here hate gp owners but there alot of knowledgeable people their that know everything to know about 3800's

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PostPosted: Sun Oct 28, 2012 8:11 pm    Post subject:   Reply with quote

Get a log of your KR* under WOT throttle. Preferably when it's warmed up so you don't run the risk of blowing your motor. Beating on a cold motor is never good for it.

If you can read all that information you should definitely be able to read the KR.

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PostPosted: Sun Oct 28, 2012 8:32 pm    Post subject:   Reply with quote

billy101 wrote:
Get a log of your KR* under WOT throttle. Preferably when it's warmed up so you don't run the risk of blowing your motor. Beating on a cold motor is never good for it.

If you can read all that information you should definitely be able to read the KR.

this.

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PostPosted: Sun Oct 28, 2012 10:39 pm    Post subject:   Reply with quote

Under WOT conditions, you also need to monitor the bank1 sensor1 o2 reading. During performance enrichment (PE), the STFTs and LTFTs aren't going to tell you anything about the car's fueling.

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PostPosted: Sun Oct 28, 2012 11:36 pm    Post subject:   Reply with quote

Thanks. I don't exactly understand what PE is, but I assume at WOT the computer dumps a set amount of fuel, so wouldn't WOT Bank 1 sensor not affect fuel delivery? And a question, is bank 1 the only 02 sensor that affects fuel delivery and bank 2 is only to check catalyst? I need to learn this stuff. Oh yeah also, what is KR and what will it be listed under on a cheap ob2 scanner>

My problem with reading at WOT and any time the car is in motion is my laptop batttery dies quickly so i need an extension cord. ...

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PostPosted: Mon Oct 29, 2012 12:03 am    Post subject:   Reply with quote

2001Ls wrote:
Thanks. I don't exactly understand what PE is, but I assume at WOT the computer dumps a set amount of fuel, so wouldn't WOT Bank 1 sensor not affect fuel delivery? And a question, is bank 1 the only 02 sensor that affects fuel delivery and bank 2 is only to check catalyst? I need to learn this stuff. Oh yeah also, what is KR and what will it be listed under on a cheap ob2 scanner>

My problem with reading at WOT and any time the car is in motion is my laptop batttery dies quickly so i need an extension cord. ...


PE is known as Power Enrichment, and is just that. When power is needed, the car will use a LOT more fuel then when driving like normal. Not too sure about o2 sensor readings, but you are correct about bank 1 monitoring AFR (Air to fuel ratio). It reads whats coming out of the exhaust and sends it to the PCM to make corrections in fueling. Bank 2 checks to make sure the catalytic converter is doing its job according to bank 1's readings. Not sure how it works when in Power Enrichment, but thats what they do. KR is Knock Retard, and basically when you are driving there is a "false knock" also known as pre detonation. Basically, depending on different scenarios (engine temp, octane, intake temp, etc.) when under compression the fuel can combust without the need for a spark. This is known as false knock, or pinging. The computer "hears" this with Knock Sensors and in turn is known as KR or Knock Retard, which then the computer determines how much timing to pull from the motor to keep it from grenading itself.

Someone correct me if thats in anyway wrong, it's been a long day, I'm tired and I'm just trying to help a guy out.

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PostPosted: Mon Oct 29, 2012 9:27 am    Post subject:   Reply with quote

2001Ls wrote:
I don't exactly understand what PE is, but I assume at WOT the computer dumps a set amount of fuel, so wouldn't WOT Bank 1 sensor not affect fuel delivery?


Power Enrichment is a variation of Open loop fueling. There are a few different criteria for PE to enable (throttle position mainly in a stock car). The car doesn't use any data from the O2 sensor to determine fueling, it uses the MAF curve and modifies the AFR depending on the duration of time the car is in PE.

You scan O2's during WOT because the O2 will still collect data about the AFR, the PCM just won't use it. The downfall is that the sensor is a narrow band which will ONLY produce accurate data at 14.7 AFR, the data produced at other AFR's is not accurate enough for PE tuning purposes but can be a good indication of what AFR the car is running at WOT. To get truly accurate WOT AFR data you need a wideband O2.

Quote:
is bank 1 the only 02 sensor that affects fuel delivery


Directly, yes. Bank 2 has an indirect effect when the sensor itself is bad or if it reads that the CAT isn't working. If one of those two situations are present it will then put the PCM into cat protection mode which dumps fuel in an attempt to produce a response from the bank 2 sensor (checking to make sure it's still working). This causes your AFR to go all wonky, but won't generally cause driveability issues.

Quote:
bank 2 is only to check catalyst?


Yes.

billy101 wrote:
KR is Knock Retard, and basically when you are driving there is a "false knock" also known as pre detonation.


False knock is exactly that - false knock. It's knock that doesn't exist, like your exhaust hitting something that the knock sensor picks up as knock. Pre-detonation is knock.

Quote:
This is known as false knock, or pinging.


Again, two separate things. False knock is not real and won't hurt your motor. Knock (pinging/pre detonation) is real and will hurt your motor.

The PCM knows when it should be telling the ignition coil to ignite the fuel/air mixture through the timing table...which is a measurement of the crank angle in degrees. When knock happens the PCM knows the crank angle at the event (when knock occurs) so it subtracts that from the commanded timing and produces a value (measured in degrees) that represents the amount of timing it had to pull to avoid knock.


Back on topic...sounds like a clogging cat problem to me.

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PostPosted: Mon Oct 29, 2012 12:24 pm    Post subject:   Reply with quote

i believe he changed his cat a few months back

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PostPosted: Mon Oct 29, 2012 12:36 pm    Post subject:   Reply with quote

grimsin wrote:
i believe he changed his cat a few months back


Doesn't mean it can't be bad. (Depending on brand quality)

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PostPosted: Mon Oct 29, 2012 1:32 pm    Post subject:   Reply with quote

That would make me so mad if thats the case

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