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Extreme Lean Running Engine, no get up and go in this motor!!!
VABURB
post May 26 2017, 01:02 PM
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2004 5.3 suburban 240,000 . I am experiencing severe lean running engine. I am having no codes pop up. once in awhile p0332 will come on. that is it.
symptoms is very limited power like the truck is pulling a chisel plow!
question is what kinds of things should I be looking for? coolant is spot on (no leaks) , changed oil no milky oil, brakes are not hanging. I am scratching my head.
I changed the max air sensor old one was bad . it did nothing to fix the lean.
had intake gasket changed in aug 16 , nothing out of the ordinary there. Is there anything else I should be looking at?

also truck has a pvc but I see that its non changeable, could that be a issue?
my next move is pull plugs and look for lean. I know what they are gunna tell me. very white on the plug.
I'm stumped please help. Thanks
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duntov
post May 26 2017, 02:02 PM
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If you are lean and your sensors are good, then you should have codes.


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Jonota
post May 26 2017, 08:37 PM
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QUOTE (VABURB @ May 26 2017, 02:02 PM) *
2004 5.3 suburban 240,000 . I am experiencing severe lean running engine. I am having no codes pop up. once in awhile p0332 will come on. that is it.
symptoms is very limited power like the truck is pulling a chisel plow!
question is what kinds of things should I be looking for? coolant is spot on (no leaks) , changed oil no milky oil, brakes are not hanging. I am scratching my head.
I changed the max air sensor old one was bad . it did nothing to fix the lean.
had intake gasket changed in aug 16 , nothing out of the ordinary there. Is there anything else I should be looking at?

also truck has a pvc but I see that its non changeable, could that be a issue?
my next move is pull plugs and look for lean. I know what they are gunna tell me. very white on the plug.
I'm stumped please help. Thanks


Have you looked for an air leak? If it were sensor only, I'd say look for an exhaust air leak. It being seen by poor plug performance and reduced engine power, I'd check for a leaky intake manifold, loose or broken vacuum connection, or a leak at the throttle body.

Jon


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VABURB
post May 29 2017, 03:53 PM
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QUOTE (Jonota @ May 26 2017, 09:37 PM) *
QUOTE (VABURB @ May 26 2017, 02:02 PM) *
2004 5.3 suburban 240,000 . I am experiencing severe lean running engine. I am having no codes pop up. once in awhile p0332 will come on. that is it.
symptoms is very limited power like the truck is pulling a chisel plow!
question is what kinds of things should I be looking for? coolant is spot on (no leaks) , changed oil no milky oil, brakes are not hanging. I am scratching my head.
I changed the max air sensor old one was bad . it did nothing to fix the lean.
had intake gasket changed in aug 16 , nothing out of the ordinary there. Is there anything else I should be looking at?

also truck has a pvc but I see that its non changeable, could that be a issue?
my next move is pull plugs and look for lean. I know what they are gunna tell me. very white on the plug.
I'm stumped please help. Thanks


Have you looked for an air leak? If it were sensor only, I'd say look for an exhaust air leak. It being seen by poor plug performance and reduced engine power, I'd check for a leaky intake manifold, loose or broken vacuum connection, or a leak at the throttle body.

Jon



I will start looking for leaks. Are we talking smoke test and ether to see if the engine jumps or has a leaky intake?
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kidphc
post May 31 2017, 11:56 AM
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If it was actually running lean the car would throw codes. The Air Fuel trims would be out of wack and the upstream O2 sensors would be showing lean wave forms. If the O2 sensors were screwed up the voltages or even the wave form response times would be out of spec, causing the ecu to throw codes.

****I DO NOT THINK YOU HAVE A LEAN ISSUE
In fact when the engine runs lean you get better fuel mileage and more power.

Start with the P0332.... its the fricking knock sensors.

The purpose of knock sensors are so the ecu can listen for pinging(pre-detonation) or knocking(detonation) of the fuel. This allows the ecu to advance the timing on most cars, to maximize power and fuel economy. If it detects pinging or knocking it will be retarding the timing..... If the pinging or knocking gets bad enough newer card go into limp home.

Stop throwing money at it and guessing. Diagnose the P0332. Probably, oil or coolant fouling the sensors, or just went bad. If you need to change one, change both, the harness and refresh the intake manifold gaskets. Diagnose it though, I have replaced ECU's because a shorted sensor back fed to ECU and fried part of the ECU. I bet you the knock sensors are most likely the problem. If you have the torque app and the a dongle. You can watch the timing from the ECU standpoint through the app.
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Jonota
post May 31 2017, 02:52 PM
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QUOTE (kidphc @ May 31 2017, 12:56 PM) *
If it was actually running lean the car would throw codes. The Air Fuel trims would be out of wack and the upstream O2 sensors would be showing lean wave forms. If the O2 sensors were screwed up the voltages or even the wave form response times would be out of spec, causing the ecu to throw codes.

****I DO NOT THINK YOU HAVE A LEAN ISSUE
In fact when the engine runs lean you get better fuel mileage and more power.

Start with the P0332.... its the fricking knock sensors.

The purpose of knock sensors are so the ecu can listen for pinging(pre-detonation) or knocking(detonation) of the fuel. This allows the ecu to advance the timing on most cars, to maximize power and fuel economy. If it detects pinging or knocking it will be retarding the timing..... If the pinging or knocking gets bad enough newer card go into limp home.

Stop throwing money at it and guessing. Diagnose the P0332. Probably, oil or coolant fouling the sensors, or just went bad. If you need to change one, change both, the harness and refresh the intake manifold gaskets. Diagnose it though, I have replaced ECU's because a shorted sensor back fed to ECU and fried part of the ECU. I bet you the knock sensors are most likely the problem. If you have the torque app and the a dongle. You can watch the timing from the ECU standpoint through the app.

This is not a true statement on several fronts.
1. Lean conditions will not always set codes, although *usually* that is the case.
2. Lean conditions absolutely can cause poor power and fuel mileage. Further, while rich conditions can cause fouling, lean conditions can cause high cylinder temperature and engine failure.
3. Pinging is an indication of too lean a mixture. Reduction in the timing will also reduce engine power.

I do agree with diagnosing the P0332, which may require someone to scan for you. The easy way to address the O2 sensor questions is to scan the computer with the engine running and evaluate the O2 waveforms. If you don't have scanning software, an cheap OBD II scan plug w/bluetooth connectivity and the torque app for any smartphone can be had for super cheap.


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1996 2-dr Tahoe 5.7/4L60e w/14-bolt rear upgrade
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Jonota
post May 31 2017, 03:13 PM
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QUOTE (VABURB @ May 29 2017, 04:53 PM) *
I will start looking for leaks. Are we talking smoke test and ether to see if the engine jumps or has a leaky intake?

First I'd just do a visual, cracked boots, listen for sucking noises, crack manifolds, etc.
Next a smoke test is usually pretty good if you can keep the engine fan off. If they're electric just pull the fuse/relay.
I'm not a fan of either/wd40/carb cleaner spraying in the engine bay, but I've seen it work.

Scanning the 02 sensor behavior can tell you a lot, but might not catch a very small air leak pushing you towards lean.

Another weird one is fuel pressure regulator failure. If it is maintaining a lower fuel pressure, the computer thinks it's putting in more fuel than it actually is.


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kidphc
post May 31 2017, 03:23 PM
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QUOTE (Jonota @ May 31 2017, 04:52 PM) *
This is not a true statement on several fronts.
1. Lean conditions will not always set codes, although *usually* that is the case.
2. Lean conditions absolutely can cause poor power and fuel mileage. Further, while rich conditions can cause fouling, lean conditions can cause high cylinder temperature and engine failure.
3. Pinging is an indication of too lean a mixture. Reduction in the timing will also reduce engine power.


You are correct, some of what I wrote was based on opinion due to what I have seen. The computer should attempt to adjust for lean values, and will only throw codes for a lean bank when the threshold is surpassed. From what I can see it is normally the short and long term fuel trims.

Best bet investigate the knock sensors. If the truck is having the issue currently, get a shop to run spectral gas analyzing on the exhaust while it is having the issue. Low HC(hydro carbons) and high NOx (nitrogen dioxide and Nitric Oxide the chief two NOx gases) is a clear indicator that the car is running lean.

For lean codes to trigger these conditions must be met.
CONDITIONS FOR RUNNING THE DTC
- DTCs P0101, P0103, P0108, P0135, P0137, P0141, P0200, P0300, P0410, P0420, P0430, P0440, P0442, P0443, P0446, P0449, P0506, P0507 or P1441 are not set.
- The engine coolant temperature (ECT) is between 75-115C (167-239F).
- The intake air temperature (IAT) is between -20 to +90C (4-194F).
- The manifold absolute pressure (MAP) is between 26-90 kPa (3.7-13 psi).
- The vehicle speed is less than 137 km/h (85 mph).
- The engine speed is between 400-3,000 RPM.
- The barometric pressure (BARO) is more than 74 kPa (10.7 psi).
- The mass airflow (MAF) is between 5-90 g/s.
- The fuel level is more than 10 percent.
- The throttle position (TP) is less than 90 percent.

CONDITIONS FOR SETTING THE DTC
- The average long term fuel trim cell value is above 23 percent.
- All of the above conditions are present for 6 seconds.
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VABURB
post May 31 2017, 06:11 PM
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So far I have been looking at intake. I have done the water test and came back solid. The lack of power really comes on when the outside temp heats up. Over 70 to 75 the lean (low power ) really becomes evident. I have. Scanner and will pull a freeze frame and have a look at what I am dealing with . The knock sensor code only has come up twice at random situations. Both highway speed though.
Truck when on cruise control has to really power up just to maintain speed and go up slight inclines. That is lean running I have been lead to believe. I have had mpg about 14.7 to 14.9. I drive very old lady because she is such an old gal!
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duntov
post Jun 1 2017, 06:03 AM
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Lot's of guessing going on. Have you taken out the plugs to see what it looks like? Post pictures of them.

There are numerous possibilities for your problem and may not relate to a 'lean' condition. Fuel pressure, mass air flow sensor, map, the list goes on. All these systems relate to one another. The knock sensor code may be just a symptom, not a cause of the problem. Given the mileage on your truck I suggest checking the most common problems. Fuel pump, any and all connectors on or near the engine and the MAF. Check the fuel pressure. The engine must be running to do this as just having the key on will not work.

Also, I think you have DBW. I am not positive, but the computer system may restrict it's opening based on many variables including fuel supply.

This post has been edited by duntov: Jun 1 2017, 06:55 AM


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kidphc
post Jun 1 2017, 09:53 AM
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Air density does come into play when it comes to the butt dyno and actual dyno. The hotter it is the less dense the air is. Generally, freeze frames are only recorded when a DTC is set to help recreate the problem.


I agree with duntov start with the basics. I would say if you are going to pull the plugs to have a looksie, then a compression test is only a few minutes more of your time.
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VABURB
post Jun 2 2017, 12:45 PM
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QUOTE (kidphc @ Jun 1 2017, 09:53 AM) *
Air density does come into play when it comes to the butt dyno and actual dyno. The hotter it is the less dense the air is. Generally, freeze frames are only recorded when a DTC is set to help recreate the problem.


I agree with duntov start with the basics. I would say if you are going to pull the plugs to have a looksie, then a compression test is only a few minutes more of your time.


ran down the source of the trouble. it turned out to be map sensor. I put one in and shes running strong again. $40 and 10min fix! I'm mad at myself for not looking for the source of the poor running sooner! Thank you all for the info.
p.s I never could get my scanner to do a freeze frame in the 3 days since this thread started. codes are still clean. reading no codes.
thanks
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duntov
post Jun 2 2017, 01:05 PM
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Glad you got it fixed. Something I have learned is that the actual problem can be something other than the first twenty or so guesses. Welcome to the world of a computer on wheels. I actually feel sorry for some of the really young guys that have never experienced the simplicity of a good ole carbed engine.

This post has been edited by duntov: Jun 2 2017, 01:15 PM


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VABURB
post Jun 2 2017, 01:55 PM
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QUOTE (duntov @ Jun 2 2017, 01:05 PM) *
Glad you got it fixed. Something I have learned is that the actual problem can be something other than the first twenty or so guesses. Welcome to the world of a computer on wheels. I actually feel sorry for some of the really young guys that have never experienced the simplicity of a good ole carbed engine.


amen to that.
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Gary P
post Jun 5 2017, 04:43 AM
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QUOTE (VABURB @ Jun 2 2017, 03:55 PM) *
QUOTE (duntov @ Jun 2 2017, 01:05 PM) *
Glad you got it fixed. Something I have learned is that the actual problem can be something other than the first twenty or so guesses. Welcome to the world of a computer on wheels. I actually feel sorry for some of the really young guys that have never experienced the simplicity of a good ole carbed engine.


amen to that.


DITTO! thumbsup.png Although the computer has brought us some fantastic improvements in our vehicles regarding performance and efficiency, sometimes simple is good! biggrin2.gif


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hdwrench99
post Jun 5 2017, 09:49 AM
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I still run points in all of my Harleys. ph34r.gif


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duntov
post Jun 5 2017, 05:12 PM
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QUOTE (Gary P @ Jun 5 2017, 06:43 AM) *
sometimes simple is good! biggrin2.gif


And way less expensive! thumbsup.png


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