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Discussion Starter #1
Here is some backgroud.

5.7L Vortec, 1997 Burb, K1500

Engine sucks lotsa gas! But it's a Burb. :)

Idle is high.. About 1K.

Runs a little rough when cold.. (well idles rough, drives fine)

Cleaned the throttle body and iac.

New bosh platinum plugs. I rather AC Delco but were out of stock..

2 plugs were fouled! Plugs 3 and 5 I think. (2 middle cylinders on driver's side? )
With a weird white yellowish powder? When I looked on the net, the closest match claims I used too much additives?

PCM is throwing codes. P0134 (HO2S Circuit insufficient activity Bank 1 Sensor 1) Am I right to assume bank 1 sensor 1 is the upstream on the driver's side? (same side as fouled pluggs)

PCM Throwing code: P0507 Idle Speed high

When monitoring sensors with my scantool, O2 on bank one fluctuates slightly. but O2 on bank 2 is always erratic, (witch I assume erratic means working normally)


What should I be looking for? Fouled injector? Bad intake gasket? (*gasp*), EGR?

I can't notice any vaccuum leaks. Sprayed engine down, no idle fluctuations.


If you need additional data to diagnose, let me know, I can read most sensors.
 

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1000 rpm is not really all that high. typical RPM should be about 700-900rpm.
I'm pretty sure that you are correct on the sensor. I know it's the upstream, but I think it's the one on the driver's side. Maybe someone else can verify.

I'm thinking your secondary code is a result of the o2 sensor being bad.
start with replacing the O2 sensor, and see how the ecu reacts. I don't think you'll need to look for any other problems after the O2 sensor.
 

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I'm with Patrick O2 sensors will cause all of what you described. Lean fuel mixure and poor idle. Trust me my van is in shop for same reason right now...Your over analyzing Cable guy :lol:
 

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Discussion Starter #4
I'm with Patrick O2 sensors will cause all of what you described. Lean fuel mixure and poor idle. Trust me my van is in shop for same reason right now...Your over analyzing Cable guy :lol:

So what you are saying is my o2 sensor needs an equipment swap do to ingress and packet loss?? :)

What worries me is the truck idles rough at startup... Should it not be in closed loop ignoring o2 data?

I'm also blessed with more missfortune!! I bought an o2 for the truck. It has a square connector, my truck has a flat connector much like a trialer harness.
The parts guy thinks my harness has been basterdized.. all o2's on my truck use the same connectors... Weird..

Cheers!
Eric
 

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So what you are saying is my o2 sensor needs an equipment swap do to ingress and packet loss?? :)

What worries me is the truck idles rough at startup... Should it not be in closed loop ignoring o2 data?

I'm also blessed with more missfortune!! I bought an o2 for the truck. It has a square connector, my truck has a flat connector much like a trialer harness.
The parts guy thinks my harness has been basterdized.. all o2's on my truck use the same connectors... Weird..

Cheers!
Eric
You were given the wrong part.
Try a different parts store, and return the one you got.

 

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I hate it when Patrick is right :tongue: but I'm afraid he's right (Mr excessive packet loss, Due to upstream impairment) :he:
Beat that guy that sold you that over the head with that old o2 sensor. and yes it can affect idle curcuit too
 

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Discussion Starter #7
You were given the wrong part.
Try a different parts store, and return the one you got.



OMG!!!! That is the one! you sir are the man!!!! Do you have a part # for this? (prefferably a bosh #)

The one they gave me looked like a square connector and they checked with GM to confirm it was the right one.. then they told me someone hacked my harness....

THANKS AGAIN!!!!
 

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I hate it when Patrick is right :tongue: but I'm afraid he's right (Mr excessive packet loss, Due to upstream impairment) :he:
Beat that guy that sold you that over the head with that old o2 sensor. and yes it can affect idle curcuit too
*lol* Reffer to maint. on this one! *lol*

I'm so releived that the harness was not actually hacked.. they told me someone hacked the harness to save a few bucks on a generic o2. (I thought that was odd, sine all the connectors were the same on the truck...)
 

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Argh!!! more complications!!!! Apperently there are 2 different o2 sensors for my truck. Depending on transmission??? With or without electronic transmission? How can I tell? it's a 97 K1500, with tow package, g80 rear locker.. 4x4.. Is there a way to id the tranny?

Thanks!
Eric
 

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Argh!!! more complications!!!! Apperently there are 2 different o2 sensors for my truck. Depending on transmission??? With or without electronic transmission? How can I tell? it's a 97 K1500, with tow package, g80 rear locker.. 4x4.. Is there a way to id the tranny?

Thanks!
Eric
Here's a link for the sensor you need from Parts America. You can order it online it you like. The part number listed is 15703, but that might be the stock number instead of Bosch's number.
http://www.partsamerica.com/ProductDetail.aspx?MfrCode=BOS&MfrPartNumber=15703&PartType=291&PTSet=A

Actually I see there is another model offered same plug but that male end instead of female.
http://www.partsamerica.com/ProductDetail.aspx?MfrCode=BOS&MfrPartNumber=13027&PartType=291&PTSet=A
Significant price difference.
 

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If it's a 97, its highly likely that you have an electronic tranny. you should be able to decode the vin if you can find a website with a decoder
 

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Open glove box, read list of equipment instaled at the factory.

it will have the trany listed.
 

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GM part # for O2 sensor appears to be 25166816
 

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Discussion Starter #14
Awwwwww CRAP!!!! Replaced the o2 sensor, same %$#@ Problem!

I had a feeling it wasn't the o2. :no:

Same weird yellowish powder stuff on the o2 sensor I removed as there was on the fouled plugs.

When at idle,on bank 1, my LONG TERM fuel trim is at +14-15% !!!! Yikes!!! Bank 2 sits between 0 and -3%.

When driving, both report normal fuel trims. -3 to +2% depending on load ect...

So what is causing bank one to run rich at idle but fine as soon as I touch the gas? Also runs rough when cold...

I also ran a can of GM's AC-Delco CLEENS through the engine before changing the o2.

oh.. one more thing! AHHHHHHH!!!!!!:shocked:
 

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Discussion Starter #15
ok, did somemore useless work on the truck. Replaced a ground wire to the engine hoping it was a ground problem. readings did not change.

I'm starting to focus bak on the 2 fouled plugs that were in the engine.

they looked alot like this:


according to my reasearch on the net... This is coused by heavy additives in the oil or gas.. But what worries me is that only 2 plugs were like this.. side by side. (#3 and #5) both on bank1.. the banks with the o2 problem. The same deposits were found on the old o2...

Any ideas??

Thanks!
Eric
 

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Wow now ya got me. I wonder if somethings up with valve guide seals or something crazy like that. Just seems odd to me. Antifreeze where it shouldn't be (careful not to say that to loud...thats expensive)5 & 3 eh. Let me do some research
 

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Is it that built up on plug? It could be DETONATION. Major causes include a faulty EGR valve, lean air/fuel mixtures, ignition timing advanced too far, and insufficient octane rating of the gasoline.
 

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Using A Scan Tool

What will a scan tool tell you about misfire? Not much unless the vehicle is a 1996 or newer import with OBD II. When the OBD II system detects a misfire that exceeds "normal" limits, it illuminates the Check Engine light and sets a P-code that corresponds to the misfiring cylinder. The last number in a P300 series misfire code tells you which cylinder is misfiring. A code P304, for example, says cylinder number four is misfiring. If you also find a P204 code (P200 series codes cover the injectors), you'd know the misfire was probably caused by a bad injector.

If you find a P300 code, it means the misfire is random and is moving around from cylinder to cylinder. The cause here would likely be something that upsets the engine's air/fuel mixture, such as a major vacuum leak, leaky EGR valve or unusually low fuel pressure (weak pump or faulty pressure regulator).

There's really no magic bullet for finding misfires. It takes a certain amount of detective work to isolate the fault and determine the underlying cause. So, the next time you face a misfire, don't miss the mark
 

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Do you have access to this tool?

A leakdown or cylinder leakage test is similar to a compression test in that it tells you how well your engine's cylinders are sealing. But instead of measuring pressure, it measures pressure loss.

A leak down test requires the removal of all the spark plugs. The crankshaft is then turned so that each piston is at top dead center (both valves closed) when each cylinder is tested. Most people start with cylinder number one and follow the engine's firing order.

A threaded coupling attached to a leakage gauge is screwed into a spark plug hole. Compressed air (80 to 90 psi) is then fed into the cylinder.

An engine is great condition should generally show only 5 to 10% leakage. An engine that's still in pretty good condition may show up to 20% leakage. But more than 30% leakage indicates trouble.

The neat thing about a leakage test (as opposed to a compression test) is that it's faster and easier to figure out where the pressure is going. If you hear air coming out of the tailpipe, it indicates a leaky exhaust valve. Air coming out of the throttle body or carburetor would point to a leaky intake valve. Air coming out of the breather vent or PCV valve fitting would tell you the rings and/or cylinders are worn.

A leakage test can also be used in conjunction with a compression test to diagnose other kinds of problems.

A cylinder that has poor compression but minimal leakage usually has a valvetrain problem such as a worn cam lobe, broken valve spring, collapsed lifter, bent push rod, etc.

If all the cylinders have low compression but show minimal leakage, the most likely cause is incorrect valve timing. The timing belt or chain may be off a notch or two.

If compression is good and leakage is minimal, but a cylinder is misfiring or shows up weak in a power balance test, it indicates a fuel delivery (bad injector) or ignition problem (fouled spark plug or bad plug wire).
 

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Or this tool?

A compression test will tell you if your engine has good compression. An engine is essentially a self-powered air pump, so it needs good compression to run efficiently, cleanly and to start easily.

As a rule, most engines should have 140 to 160 lbs. Of cranking compression with no more than 10% difference between any of the cylinders.

Low compression in one cylinder usually indicates a bad exhaust valve. Low compression in two adjacent cylinders typically means you have a bad head gasket. Low compression in all cylinders would tell you the rings and cylinders are worn and the engine needs to be overhauled.

HOW TO CHECK COMPRESSION

Compression can be checked two ways: manually with a compression gauge, or electronically with an engine analyzer the measures cranking compression. With electronic testing, a computer analyzer estimates compression in each of the engine's cylinders by measuring slight variations in engine cranking speed.

The results correlate well with actual gauge readings, and can be completed in a matter of minutes without having to remove any spark plugs. What's more, the analyzer prints out the results of the compression test making it easy to see and compare the actual numbers.




To check compression manually with a gauge, all the spark plugs must be removed. The ignition coil must then disabled or the high tension lead grounded. If the engine has a distributorless ignition, the ignition coils must be disabled to prevent them from firing. The throttle must also be held open.

The engine is then cranked for a few seconds using a remote starter switch or a helper while a compression gauge is held in a spark plug hole.

The maximum compression reading is noted, then the process is repeated for each of the remaining cylinders.

The individual cylinder readings are then compared to see if the results are within specifications (always refer to a manual for the exact compression figures for your engine because they do vary from

the ballpark figures quoted earlier).

IS IT THE RINGS OR THE VALVES?

If compression is low in one or more cylinders, you can isolate the problem to the valves or rings by squirting a little 30 weight motor oil into the cylinder through the spark plug hole and repeating the compression test. The oil temporarily seals the rings.

If the compression readings are higher the second time around, it means the rings and/or cylinder is worn. No change in the compression readings would tell you the cylinder has a bad valve.
 
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