sluggish open loop
Thread Starter
Teching In
Joined: Aug 2005
Posts: 8
Likes: 0
From: San Diego, CA
sluggish open loop well i just got efilive and i dont really know how to use it. when i drive and the engine is in closed loop everything works fine. but when i get on the gas and the engine comes into open loop it pulls back and it feels like something is suppressing the engine. beforehand, i had messed with a few small things like mil enablers, fans, speedo pulse, etc. i thought i might have messed up something by accident. so i reflashed the ecu with the stock tune but i still get the same problem. when i reflashed it, the first time i went into open loop everything was good for a few seconds but then it got sluggish again. does anyone have an idea what the problem is? engine is stock
Originally Posted by spanky192
well i just got efilive and i dont really know how to use it.
It could be a world of things, possibly tune related, possibly mechanically related, possibly all in your head. Do you have TCS? Thread Starter
Teching In
Joined: Aug 2005
Posts: 8
Likes: 0
From: San Diego, CA
let me rephrase that. i know how to use the program. i dont have a lot of experience with tuning an engine. i had completely returned the ecu tune to stock and still have the same problem. i did a few hours of research and think that the maf may be defective.
If it's defective that should be plain as day in the
scans. You can only really have four problems with
the engine; fuel, air, spark and compupsychosis.
Start with the big three and process of elimination.
For an example, you might have a built up motor
that has better breathing up top than the tunes
model, and a MAF that reads true and a lard-***
power enrichment table like coimes from factory.
So step on the pedal, near term you use a short
airflow model (speed density) and this makes the
over-rich PE settings not so bad (two wrongs
make a right, for a while) but then the MAF comes
back on line, tells the truth about airflow and you
roll on more fuel (as commanded by PE) and go
right back to your piggy ways (as well as pulling
out more spark).
All of this could be seen by what the Dynamic
Airflow and MAF airflow are doing about the point
of roll-on and after, the timeframe of the jump-
and-bog. Dynamic Cylinder Air (or whatever EFILive
might call it) is derived from this and is the spark
table index. If CylAir is low after tip-in and climbs
up, this is upside-down for most motors in the mid
to upper range; CylAir peaks at torque peak and
fades with intake / exhaust restrictions as you go up.
If Dynamic Airflow initially mismatches MAF airflow
but snaps to, this means your fueling is changing
in real time along with it.
Everybody wants to jump into changing stuff but
taking the time to scan it and understand what the
data tells, pays. Make sense of the symptoms and
the cure often steps forward (or, at least you can
ignore the irrelevant).
scans. You can only really have four problems with
the engine; fuel, air, spark and compupsychosis.
Start with the big three and process of elimination.
For an example, you might have a built up motor
that has better breathing up top than the tunes
model, and a MAF that reads true and a lard-***
power enrichment table like coimes from factory.
So step on the pedal, near term you use a short
airflow model (speed density) and this makes the
over-rich PE settings not so bad (two wrongs
make a right, for a while) but then the MAF comes
back on line, tells the truth about airflow and you
roll on more fuel (as commanded by PE) and go
right back to your piggy ways (as well as pulling
out more spark).
All of this could be seen by what the Dynamic
Airflow and MAF airflow are doing about the point
of roll-on and after, the timeframe of the jump-
and-bog. Dynamic Cylinder Air (or whatever EFILive
might call it) is derived from this and is the spark
table index. If CylAir is low after tip-in and climbs
up, this is upside-down for most motors in the mid
to upper range; CylAir peaks at torque peak and
fades with intake / exhaust restrictions as you go up.
If Dynamic Airflow initially mismatches MAF airflow
but snaps to, this means your fueling is changing
in real time along with it.
Everybody wants to jump into changing stuff but
taking the time to scan it and understand what the
data tells, pays. Make sense of the symptoms and
the cure often steps forward (or, at least you can
ignore the irrelevant).
Thread Starter
Teching In
Joined: Aug 2005
Posts: 8
Likes: 0
From: San Diego, CA
wow, that was a whole lot of stuff i didnt understand. other than the uninstalled air/egr this engine and its tune are stock. correct me if im wrong but i don't see any reason why there should be any problems with a stock engine running on a stock tune unless the information being fed to the pcm by the engine is incorrect via a malfunctioning sensor. the problem is i dont really know what i should be monitoring and what values i should be seeing to determine if the sensor is working correctly or to determine whats causing my problems
If there are no mods (no lid, headers, etc.), then the stock tune should be fine. But, it doesn't sound like it's truly stock because I got to thinking, "Why would you pull the AIR if you still have the cats?" So, let's assume you have headers and a lid. This alters the airflow characteristics of the car and you may need to increase the MAF by 7~10% in some areas to compensate. In essence, you could be running lean right now, which could be slowing you down. I don't know how true the "lean is mean until boom" theory is. Indy cars dial the AFR up to 14.5~15.0 to conserve fuel at times and you can see the cars slow down in their lap times. So, you could be running lean. If it is completely, 100% bone stock and you're running stock AFR's, you can improve on it by leaning the motor out and on some, increasing the timing slightly. Some things to think about:
When did you last change the plugs, change the fuel filter, or run some injector cleaner through it? (NGK TR55's, a new fuel filter and bottle of injector cleaner will run you $30)
Is it possible your MAF is dirty or damaged? K&N oil, clogged screen, etc.? (QD Electronics Cleaner from Autozone will help - $4)
Are you seeing any knock retard when you go WOT? Positive fuel trims?
Is cat overtemp protection enabled? (This commands a 11.7 AFR to keep the cats cool)
If the car is not completely stock, I'd tune it so the AFR in the exhaust equals the AFR commanded. Then, plug your PE numbers in, play with the timing a little and have fun!
When did you last change the plugs, change the fuel filter, or run some injector cleaner through it? (NGK TR55's, a new fuel filter and bottle of injector cleaner will run you $30)
Is it possible your MAF is dirty or damaged? K&N oil, clogged screen, etc.? (QD Electronics Cleaner from Autozone will help - $4)
Are you seeing any knock retard when you go WOT? Positive fuel trims?
Is cat overtemp protection enabled? (This commands a 11.7 AFR to keep the cats cool)
If the car is not completely stock, I'd tune it so the AFR in the exhaust equals the AFR commanded. Then, plug your PE numbers in, play with the timing a little and have fun!
Thread Starter
Teching In
Joined: Aug 2005
Posts: 8
Likes: 0
From: San Diego, CA
come to think of it, this problem came up after i sucked seafoam in through the intake. actually i actived the purge solenoid and sucked it in through the tube that supposed to attach to the charcoal canister (which i also dont have). thats after the maf so it couldnt have damaged that. could it have possibly damaged something else? when it goes into open loop its like something is forcing the engine to slow down. the engine isnt struggling at all, its a steady suppression. its almost like a rev limiter is kicking in and keeps the engine below/at 2000 rpm. this happens the very instant it goes into open loop and goes away the very instant it goes back to closed loop
Last edited by spanky192; May 30, 2006 at 12:31 PM.
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Verdad Gallardo I can take a look. I'd need to know mods (lid, headers, etc.) and a log with the following:
Absolute Throttle Position SAE.TP
Air Flow Grams/Cyl - Speed Density GM.DYNCYLAIR_DMA
Air Flow Rate From Mass Air Flow Sensor SAE.MAF
Air Mass Per Cylinder CALC.CYLAIR
Engine Coolant Temperature SAE.ECT
Engine RPM SAE.RPM
Fuel System SAE.FUELSYS
Fuel Trim Cell Number GM.FTC
Heated O2 Sensor Voltage Bank 1 - Sensor 1 GM.HO2S11
Heated O2 Sensor Voltage Bank 2 - Sensor 1 GM.HO2S21
Ignition Timing Advance for #1 Cylinder SAE.SPARKADV
Intake Air Temperature SAE.IAT
Intake Manifold Absolute Pressure SAE.MAP
Long Term Fuel Trim - Bank 1 SAE.LONGFT1
Long Term Fuel Trim - Bank 2 SAE.LONGFT2
Mass Air Flow Raw Frequency GM.MAFFREQ
Retard Due to Knock GM.KR
Short Term Fuel Trim - Bank 1 SAE.SHRTFT1
Short Term Fuel Trim - Bank 2 SAE.SHRTFT2
Vehicle Speed Sensor SAE.VSS
I think that's everything I log....should be enough. Try to repeat what you're talking about as well as gathering a decent amount of normal driving. Are you getting any DTC/SES codes?
Absolute Throttle Position SAE.TP
Air Flow Grams/Cyl - Speed Density GM.DYNCYLAIR_DMA
Air Flow Rate From Mass Air Flow Sensor SAE.MAF
Air Mass Per Cylinder CALC.CYLAIR
Engine Coolant Temperature SAE.ECT
Engine RPM SAE.RPM
Fuel System SAE.FUELSYS
Fuel Trim Cell Number GM.FTC
Heated O2 Sensor Voltage Bank 1 - Sensor 1 GM.HO2S11
Heated O2 Sensor Voltage Bank 2 - Sensor 1 GM.HO2S21
Ignition Timing Advance for #1 Cylinder SAE.SPARKADV
Intake Air Temperature SAE.IAT
Intake Manifold Absolute Pressure SAE.MAP
Long Term Fuel Trim - Bank 1 SAE.LONGFT1
Long Term Fuel Trim - Bank 2 SAE.LONGFT2
Mass Air Flow Raw Frequency GM.MAFFREQ
Retard Due to Knock GM.KR
Short Term Fuel Trim - Bank 1 SAE.SHRTFT1
Short Term Fuel Trim - Bank 2 SAE.SHRTFT2
Vehicle Speed Sensor SAE.VSS
I think that's everything I log....should be enough. Try to repeat what you're talking about as well as gathering a decent amount of normal driving. Are you getting any DTC/SES codes?
Last edited by SSpdDmon; May 30, 2006 at 12:59 PM.
