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Removing the filter and covering, or removing the entire CAI and covering the TB does the exact thing. Can limit the air flow until car dies down to idle lower.
I'm not sure if I understand your answer. If you take off the air filter and block the intake opening running to the throttle body, the engine should die completely and nearly immediately. This is because the air filter should be the only place air is entering the engine.

If the idle drops down to a normal idle level after blocking the intake then you have an air leak somewhere. If you take off the intake, cover up the throttle body, and it stays running, then the leak is after the throttle body and probably in the intake manifold or possibly the injector seals.
 

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Discussion Starter #22
I'm not sure if I understand your answer. If you take off the air filter and block the intake opening running to the throttle body, the engine should die completely and nearly immediately. This is because the air filter should be the only place air is entering the engine.

If the idle drops down to a normal idle level after blocking the intake then you have an air leak somewhere. If you take off the intake, cover up the throttle body, and it stays running, then the leak is after the throttle body and probably in the intake manifold or possibly the injector seals.
Sorry, I worded that poorly.
Yes, if I cover the TB completely the car dies. VERY quickly. same thing happens when I cover it at the end of the CAI(Removed filter)
Doesn't seem to be an air leak. and yes, we did the spray test too, no bubbles/hissing.

Nothing is blocking or stuck on or preventing the TB from moving.
It was doing this when I reinstalled it the first time, and its doing the exact same thing now that I put a brand new TB on.
The one on the car now is new.

Ill have to check on the numbers for you when I get home later, but im not understanding what youre saying about the TB position on your 2.4 being at 25%?
By specs that I could find it should be around 6% at idle. Mine is at the 25% mark and idling at the 3000rpm.
Something im misunderstanding?

As far as bad MAF...I can always change it just to see, but car isn't running rough or acting like its trying to die. It runs strong. Just a very high idle.
 

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Sorry, I worded that poorly.
Yes, if I cover the TB completely the car dies. VERY quickly. same thing happens when I cover it at the end of the CAI(Removed filter)
Doesn't seem to be an air leak. and yes, we did the spray test too, no bubbles/hissing.
That does make more sense, thanks for clarifying.
The spray test with starting fluid will not cause bubbles or hissing since the system is under vacuum.
The reason starting fluid is used is that the engine speed will increase if you spray it on a vacuum leak.

Nothing is blocking or stuck on or preventing the TB from moving.
It was doing this when I reinstalled it the first time, and its doing the exact same thing now that I put a brand new TB on.
The one on the car now is new.

Ill have to check on the numbers for you when I get home later, but im not understanding what youre saying about the TB position on your 2.4 being at 25%?
By specs that I could find it should be around 6% at idle. Mine is at the 25% mark and idling at the 3000rpm.
Something im misunderstanding?
When I read actual throttle position from the OBD data I saw 25% at normal idle. When I loaded the engine the throttle opening increased to keep the idle at 900 RPM.
IMG_20200202_124335554.jpg
The thing that bothered me about your throttle position is that you said it decreased to 6% when you loaded the engine by dragging the clutch. That makes no sense to me.

As far as bad MAF...I can always change it just to see, but car isn't running rough or acting like its trying to die. It runs strong. Just a very high idle.
I do not see any way that a MAF sensor problem can cause this, but out of curiosity, what is your MAF reading and at what RPM?

Also, intake air temperature was suggested as a problem, so what is that reading?
 

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Keep in mind on the 2.4 the MAF and IAT sensor is one in the same.
I want to clarify the previous statement. The Mass Airflow sensor and the Intake Air Temperature are not the same. They just happen to be contained in the same sensor module in this instance.
 

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I want to clarify the previous statement. The Mass Airflow sensor and the Intake Air Temperature are not the same. They just happen to be contained in the same sensor module in this instance.
Yea I should have made that clearer. Thanks for the follow-up sahein...
 

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Discussion Starter #28
Ok, so here are screenshots of the actual numbers. Also let me explain how these are coming up.

When i start the car it is idling at the 2300ish rpm.
After forcing a lower idle(e-brake on, clutch slowly let out while in first gear till car lowers idle to about 800. Then clutch back in, car stays are 900ish, in neutral, clutch out) idling around 900

I have no idea still what is going on. My next step just because...well, its affordable, is to replace the intake gasket, hope to stop an air leak? Then im left with buy new already programmed ECU.

If anyone has any ideas to help that would be amazing. Really dont want to drop the money on another part that isnt needed if this is something stupid im overlooking.

PS, outside air temp today when running the car was 45F Screenshot_20200211-145922.png Screenshot_20200211-145900.png
 

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Your throttle at 22.75% open is flowing more than twice as much air as mine is at 24% open.
Your throttle is flowing very nearly the same amount of air as mine is at normal idle (0.58 lb/min = 4.38 g/sec).

I think that you do not have an external air leak because the mass flow is reasonably equivalent to mine at normal idle, and you are indicating more air at higher RPM.
I think that you do have either a throttle butterfly/seat problem, an internal leak, a feedback wiring problem, or an ECM problem because your throttle at 16% is flowing as much as mine at 24%.
 

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Discussion Starter #30
Your throttle at 22.75% open is flowing more than twice as much air as mine is at 24% open.
Your throttle is flowing very nearly the same amount of air as mine is at normal idle (0.58 lb/min = 4.38 g/sec).

I think that you do not have an external air leak because the mass flow is reasonably equivalent to mine at normal idle, and you are indicating more air at higher RPM.
I think that you do have either a throttle butterfly/seat problem, an internal leak, a feedback wiring problem, or an ECM problem because your throttle at 16% is flowing as much as mine at 24%.
The TB is new. When this happened i replaced it with a brand new one.
0 change after doing that.
ECM problem is what i keep going back to. Ive read about the same sort of thing being caused by that. Which is why i had it flashed, which did nothing. Of course, i dont know exactly what they did...i have no decent place around here to take it to to have that done.

Could you elaborate on "feedback wiring problem" and "internal leak"?
If possible i would love to check on those things before going further.

Also, to the best of your knowledge. If it is a problem with the ecu(say its fried) and i buy a preprogramed ECU for this year of the car(I think the company i found said i would have to send them my vin to program it correctly) would that "Fix" the problem?

Like, no additional flashing or programming, that should handle it.
 

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An internal leak would be something that lets air bypass the throttle, but still routes it through the MAF sensor, since yours seems to be reading appropriately for the engine speed. It would not include a gasket or PCV hose, for example, because any air entering those would not go through the MAF sensor.

Feedback is the normal term for signals that return to a controller to let it know what is happening with a device like the throttle body. There should be some sort of sensor on or in the throttle body that measures the butterfly opening, and wiring that sends that signal to the ECM. I have not looked at the throttle body wiring, so I do not know exactly how it is controlled or how the ECM knows how open it is. I will look at it tonight though, if someone hasn't posted information about it before then.

It seems unlikely to me that a "fried" ECM would work correctly except for one function. Controllers generally do not work, or fail, that way.

An ECM has to be flashed with your VIN to work in the car. That has to be done by someone with access to GM's network, but can be a dealer or independent mechanic.
 

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Discussion Starter #32
An internal leak would be something that lets air bypass the throttle, but still routes it through the MAF sensor, since yours seems to be reading appropriately for the engine speed. It would not include a gasket or PCV hose, for example, because any air entering those would not go through the MAF sensor.

Feedback is the normal term for signals that return to a controller to let it know what is happening with a device like the throttle body. There should be some sort of sensor on or in the throttle body that measures the butterfly opening, and wiring that sends that signal to the ECM. I have not looked at the throttle body wiring, so I do not know exactly how it is controlled or how the ECM knows how open it is. I will look at it tonight though, if someone hasn't posted information about it before then.

It seems unlikely to me that a "fried" ECM would work correctly except for one function. Controllers generally do not work, or fail, that way.

An ECM has to be flashed with your VIN to work in the car. That has to be done by someone with access to GM's network, but can be a dealer or independent mechanic.
Ok, great information.
I took it to the local dealer to be flashed. So Its sounding to me like somewhere along there, there has to be a leak.
Which i took the whole thing apart, twice. its very possible. I just cant seem to find it.

TB is new
ECU has been flashed by the dealer
Relearn has been tried MANY times(In all ways that ive read about, unless im doing it wrong)
Tried finding air leak, but nothing on the CAI.

If i understood correctly, a hose past the TB, or possibly...intake manifold?
 

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I looked at a spare throttle body, then pulled the intake off of the one on the car, and I do not see any way for air to get into the engine except going through the butterfly if it is going through the MAF sensor. Your airflow reading tell me that all of the air is going through the MAF sensor.so that pretty much means that your butterfly is more open than it should be, and the question is why.

Did you check your throttle pedal position while this is happening? One option is that the throttle body is doing exactly what it is supposed to be doing based on a bad throttle position sensor..

Where is your throttle plate with the ignition on but the engine not running (obviously) and what does the position read?

This is mine at 26%.

IMG_20200213_184834881.jpg

If I push the accelerator pedal to the floor it opens to just about straight open, and indicates 88%.
 

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Discussion Starter #34
I looked at a spare throttle body, then pulled the intake off of the one on the car, and I do not see any way for air to get into the engine except going through the butterfly if it is going through the MAF sensor. Your airflow reading tell me that all of the air is going through the MAF sensor.so that pretty much means that your butterfly is more open than it should be, and the question is why.

Did you check your throttle pedal position while this is happening? One option is that the throttle body is doing exactly what it is supposed to be doing based on a bad throttle position sensor..

Where is your throttle plate with the ignition on but the engine not running (obviously) and what does the position read?

This is mine at 26%.

View attachment 111965

If I push the accelerator pedal to the floor it opens to just about straight open, and indicates 88%.
How have i not thought of this at all. wow.
I will find out when i get home and let you know.
 

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Discussion Starter #35
I looked at a spare throttle body, then pulled the intake off of the one on the car, and I do not see any way for air to get into the engine except going through the butterfly if it is going through the MAF sensor. Your airflow reading tell me that all of the air is going through the MAF sensor.so that pretty much means that your butterfly is more open than it should be, and the question is why.

Did you check your throttle pedal position while this is happening? One option is that the throttle body is doing exactly what it is supposed to be doing based on a bad throttle position sensor..

Where is your throttle plate with the ignition on but the engine not running (obviously) and what does the position read?

This is mine at 26%.

View attachment 111965

If I push the accelerator pedal to the floor it opens to just about straight open, and indicates 88%.
Ok, stupid question...but where is the TPS on the car?
Ive been looking it up in my free time for a few days. I keep finding where i can buy the sensor, or "kits", but 0 information on where its located. When talking to some people they keep saying that its integrated into the TB. I have to assume this is wrong given your idea of that possibly being my issue...
Any help to location would be greatly appreciated.

Thanks again.
 

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I am not looking at a service manual, so i am not certain about the exact names or alphabetizations used.

There is a sensor (two actually) integral to the throttle body that reads the position of the throttle butterfly to provide feedback to the ECM.

There is also a sensor on the throttle pedal that reads its position to provide an input to the ECM to tell it how fast you want to go.

Both (or all three) readings are available in the ECM data that you should be able to read through the OBD port.

Have you looked at the actual position of the throttle butterfly to see how it compares to mine, and what the indicated position is?
 

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Discussion Starter #37
I am not looking at a service manual, so i am not certain about the exact names or alphabetizations used.

There is a sensor (two actually) integral to the throttle body that reads the position of the throttle butterfly to provide feedback to the ECM.

There is also a sensor on the throttle pedal that reads its position to provide an input to the ECM to tell it how fast you want to go.

Both (or all three) readings are available in the ECM data that you should be able to read through the OBD port.

Have you looked at the actual position of the throttle butterfly to see how it compares to mine, and what the indicated position is?
I looked before and to memory, it looks like mine is in just about the same place.
And ok. Ill see if i can grab some more numbers from the OBD scanner later and report back. Im looking for pedal position basically? ill see what options i have and what i can find.
 

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Discussion Starter #39
So I checked the peddle position, at idle it seems to be reading around 15%
I think it was 14.51% to be exact. So just on a "I had access to the part", I replaced it with a new one. Now's it reading 14.90%. same result. Though it does seem much more steady and my response might be a little better now. Seems to be working as intended, just idles at nearly 15. When I force low idle, it actually increases slightly for a bit...then drops out when the low idle takes and holds. Staying around 7%.
I'm once more at a loss.
Is it just the entire ecm needing replaced? Did something incredibly odd happen here? Doesn't seem like this should be such a mystery fix...

Any suggestions are appreciated. I'll be checking the position of the tb tomorrow and taking pics when it's daylight.
Screenshot_20200220-191359.png
Screenshot_20200220-222302.png
 

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