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I've got an ongoing random SES Light, the only code stored is Code 44/Lean Exhaust. Can anyone confirm my list of troubleshooting? Should I start w/ the O2 Sensor replacement? Lastly, can anyone post a Vacuum Line Diagram for the L03 and the Vacuum Line size? How much can a bad O2 Sensor really impact performance?
I've got an ongoing random SES Light, the only code stored is Code 44/Lean Exhaust. Can anyone confirm my list of troubleshooting? Should I start w/ the O2 Sensor replacement? Lastly, can anyone post a Vacuum Line Diagram for the L03 and the Vacuum Line size? How much can a bad O2 Sensor really impact performance?
Put the Haynes manual in the outhouse under the Sears Catalog.
Get a proper GM service manual.
The steps listed in your post are not a bad start. They're far from thorough or exhaustive.
Yes, it's entirely possible to have a defective O2 sensor that reads correctly--or not incorrectly enough to set a code--during some running conditions. I had a similar lean exhaust code only at highway speed. I could drive around for a month in-town and not set a code. Five minutes at 60 mph, and the SES light was on. Having checked all else, raised the fuel pressure, and tested the AIR system for operation, I put an O2 sensor in, and immediately solved the problem. The failed sensor was "about" 60--70 thousand miles old. (Not so old that it's guaranteed to be bad, but certainly old enough that I didn't cry about a $15 sensor.)
The false lean indication drove the fuel mix extra-rich. Mileage improved with the new sensor.
Thanks for the Vac Diagram, any clue on the line size. I'd like to replace all of them... And that flow chart lost me at ground the ADAL, and start the engine. Does that mean leave the OBD1 scanner connected and start the engine, doesn't it ground out the connections needed to display the codes? A flow chart for dummies LOL would be great.
* I also skipped straight to replacing the O2 Sensor but it wouldn't budge, any removal suggestions?
Put the Haynes manual in the outhouse under the Sears Catalog.
Get a proper GM service manual.
The steps listed in your post are not a bad start. They're far from thorough or exhaustive.
Yes, it's entirely possible to have a defective O2 sensor that reads correctly--or not incorrectly enough to set a code--during some running conditions. I had a similar lean exhaust code only at highway speed. I could drive around for a month in-town and not set a code. Five minutes at 60 mph, and the SES light was on. Having checked all else, raised the fuel pressure, and tested the AIR system for operation, I put an O2 sensor in, and immediately solved the problem. The failed sensor was "about" 60--70 thousand miles old. (Not so old that it's guaranteed to be bad, but certainly old enough that I didn't cry about a $15 sensor.)
The false lean indication drove the fuel mix extra-rich. Mileage improved with the new sensor.
Thanks, I had an offer out on eBay that was just accepted for the actual GM Service Manual for $22 + S&H.
BTW how'd you bump up fuel pressure? Is there an adjustment screw on my stock TB/Fuel Injector Pod or is that stored in the PROM?
Can you elaborate on "Lean Exhaust"? Does this mean there's more air being drawn in than acceptable in the AFR? OR a weak pump not providing the volume of fuel needed to create balance in the AFR... I'm lost.
Last edited by 92RS-HeritageEd; 08-06-2018 at 02:38 PM.
Thanks for the Vac Diagram, any clue on the line size. I'd like to replace all of them... And that flow chart lost me at ground the ADAL, and start the engine. Does that mean leave the OBD1 scanner connected and start the engine, doesn't it ground out the connections needed to display the codes? A flow chart for dummies LOL would be great.
* I also skipped straight to replacing the O2 Sensor but it wouldn't budge, any removal suggestions?
soak it down with pb blaster. Grounding the aldl is jumping pin a to pin b at the aldl. The connector that’s on the drivers side under the dash about knee leaves .
* I also skipped straight to replacing the O2 Sensor but it wouldn't budge, any removal suggestions?
I took one out of an 89 K1500 this morning. ENGINE AT AMBIENT TEMPERATURE.
7/8 box-end wrench. Unplug sensor, push wire through box wrench so wrench fits properly around sensor. Smack with BIGASS hammer to turn it counter-clockwise.
I'd give it a sixth of a turn, then tighten-loosen-tighten-loosen that same sixth of a turn until it spun easily. Then push it another sixth of a turn loose, and tighten-loosen-tighten-loosen. Repeat until it becomes easy to fully unscrew.
I have a thread cleaner for 18mm spark-plug threads (same as O2 sensor). Clean female threads in the manifold, put a touch of anti-seize on the female threads of the manifold, coat the male threads of the sensor, reinstall sensor and connect/secure wire.
Originally Posted by 92RS-HeritageEd
I had an offer out on eBay that was just accepted for the actual GM Service Manual for $22 + S&H.
Excellent. That's about what I paid for mine. I ended up with an early-edition service manual set for my '88 K1500, copyright 1986. Has lots of errors, and an entire service manual supplement book with corrections. Wiring diagram book, Unit Repair Manual, etc.
Originally Posted by 92RS-HeritageEd
BTW how'd you bump up fuel pressure? Is there an adjustment screw on my stock TB/Fuel Injector Pod or is that stored in the PROM?
There is a screw on the regulator, it's spot-welded in place. Regulator has to be removed from the TBI unit. You can break the spot weld and adjust. I just stretched the spring a little. Took me from ~10 psi to 11.5 psi. Some guys suggest putting a nickel under the spring as a spacer. Either way, it's a total pain in the ***.
Originally Posted by 92RS-HeritageEd
Can you elaborate on "Lean Exhaust"? Does this mean there's more air being drawn in than acceptable in the AFR? OR a weak pump not providing the volume of fuel needed to create balance in the AFR... I'm lost.
The computer adjusts the duty cycle of the injectors to vary the fuel mixture based on input from the various sensors, and the computer programming. Fine-tuning the mixture is done when the computer pays attention to the O2 sensor.
If the O2 sensor shows too much oxygen in the exhaust (lean mixture) the computer keeps the injectors spraying a little more to compensate. When the O2 sensor shows too little oxygen in the exhaust, the computer shuts off the injectors a little sooner. The computer bounces back and forth between too rich and too lean, but on average it holds the mixture exactly where it should be. A faulty O2 sensor provides bad data to the computer which can screw-up the mixture too rich, or too lean.
If the fuel pump is weak, the computer may not be able to keep the injectors on long enough to retain a proper fuel mixture.
If the AIR system has failed, it may push air into the exhaust system "upstream" which would add oxygen to the exhaust where the O2 sensor would notice it and provide a false reading. Normally, the AIR system adds oxygen "downstream" of the O2 sensor, for use by the catalytic converter.
Originally Posted by Tuned Performance
soak it down with pb blaster.
Total waste of time and penetrating oil.
The threads of the O2 sensor are sealed gas-tight with a metal gasket. The penetrating oil cannot get past the gasket to wet the threads, therefore it does NOTHING useful. It will make an oil-spot on the driveway as it drips off uselessly, though.
I can imagine heating the sensor body with an oxy-acetylene torch until it glows orange or red, letting it cool, and then unscrewing it. So far, I've never had to do that. An O2 sensor socket and LONG ratchet handle--or a long 7/8 box-end wrench and a hammer--is all I've needed.
DO NOT FAIL to install anti-seize on the threads of the new sensor, and a little on the female threads of the manifold.
soak it down with pb blaster. Grounding the aldl is jumping pin a to pin b at the aldl. The connector that’s on the drivers side under the dash about knee leaves .
Sadly I couldn't even find a good angle to hit it w/ the PB Blaster without soaking everything around it.
Originally Posted by Schurkey
The computer adjusts the duty cycle of the injectors to vary the fuel mixture based on input from the various sensors, and the computer programming. Fine-tuning the mixture is done when the computer pays attention to the O2 sensor.
If the O2 sensor shows too much oxygen in the exhaust (lean mixture) the computer keeps the injectors spraying a little more to compensate. When the O2 sensor shows too little oxygen in the exhaust, the computer shuts off the injectors a little sooner. The computer bounces back and forth between too rich and too lean, but on average it holds the mixture exactly where it should be. A faulty O2 sensor provides bad data to the computer which can screw-up the mixture too rich, or too lean.
If the fuel pump is weak, the computer may not be able to keep the injectors on long enough to retain a proper fuel mixture.
If the AIR system has failed, it may push air into the exhaust system "upstream" which would add oxygen to the exhaust where the O2 sensor would notice it and provide a false reading. Normally, the AIR system adds oxygen "downstream" of the O2 sensor, for use by the catalytic converter.
So with the arrival of my official GM Service Manual... I've found a step by step Diagnostic Aid for the Code 44 and I hadn't even scratched the surface. Inside I'm cursing Haynes however Haynes helped me a million times over before the discovery of this gem. I didn't even know these manuals were available to the general public. Any insight on checking for poor sensor ground or intermittent ground in wire between connector and sensor? Where's this ground cable located? How do I test my MAP Sensor? I can't just hop out the car and disconnect it when the SES lamp comes on, i'm likely in motion trying to accelerate when the code pops. Also, wth is a injector balance test? Sounds like something only the dealership can do... Exhaust leaks above the O2 sensor? I did JB Weld a hole found in the driver side manifold... Finally the AIR System, and making sure air isn't being directed to the exhaust ports while in closed loop??? What is closed loop, and how can this happen?
If I could acquire a scanner tool that allows freeze frame where I could capture some data and post it would said data help anyone here in helping me with diagnosis?
Sadly I couldn't even find a good angle to hit it w/ the PB Blaster without soaking everything around it. Use the "straw" that it hopefully came with...bend it as needed to aim the stream at the threaded base of the sensor. If the surroundings get a little on them, no harm. Wipe excess off the pipe, floor pan, etc.
So with the arrival of my official GM Service Manual... I've found a step by step Diagnostic Aid for the Code 44 and I hadn't even scratched the surface. Inside I'm cursing Haynes however Haynes helped me a million times over before the discovery of this gem. I didn't even know these manuals were available to the general public.Any insight on checking for poor sensor ground or intermittent ground in wire between connector and sensor?
I think you have a single wire oxygen sensor. Intermittent would be that the insulation on that wire has chafed off somewhere, or is pinched in between a couple of items, and is occasionally touching a bare piece of metal, allowing the signal voltage in the wire to be lost. It's just a visual inspection, though I like to physically run my hand over as much of the wire as possible, looking for breaks in the insulation, or spots where it's pinched or grounded.
Where's this ground cable located? How do I test my MAP Sensor? I can't just hop out the car and disconnect it when the SES lamp comes on, i'm likely in motion trying to accelerate when the code pops. Also, wth is a injector balance test? Sounds like something only the dealership can do...
Exhaust leaks above the O2 sensor? I did JB Weld a hole found in the driver side manifold...Go back and check this spot carefully. The smallest leak above the O2 can cause havoc. I have no experience with JB Weld (which I like in the right applications) on an exhaust system. I would think there would be too much thermal expansion of the cast iron that the JBW could not keep up with.
Finally the AIR System, and making sure air isn't being directed to the exhaust ports while in closed loop??? What is closed loop, and how can this happen? Open and closed loop refer to the points at which the ECU actively takes control of the mixture, timing, etc. Vs. a fixed program. When the engine is cold, particularly the O2 sensor (which only operates properly when fully warmed up [hot]), it runs in open loop. A fixed program of timing and fuel run the vehicle. Once the engine and O2 warm up, and the O2 can provide accurate information, then the system switches to closed loop, where the ECU takes active control of timing and mixture, and some other functions.
If I could acquire a scanner tool that allows freeze frame where I could capture some data and post it would said data help anyone here in helping me with diagnosis? Yes. And allow you to see what some of those sensors you asked about (ie: MAP) are doing.
My best attempts to answer some of your questions in bold above. More knowledgeable folks will be along to fill in the blanks.
Last edited by DynoDave43; 08-10-2018 at 09:20 AM.
My best attempts to answer some of your questions in bold above. More knowledgeable folks will be along to fill in the blanks.
Thanks,
*UPDATE*
Went to a local mechanic today with then intention of grabbing an Innova OBD1/2 Scanner w/ Live Data however while in test-before-purchase run... wouldn't load live data. He also tried some heavy duty large tablet it also wouldn't load live feed data. Not sure what's up with that.
Connected a smoke machine to it and found a few leaks I'd say you call them. Smoke came from the under side of the EGR valve, the base of the tbi unit and from where the throttle cable assembly goes into the tbi. He suggested a TBI Rebuild kit before continuing.
TBI base gasket is notorious for leaking, so absolutely zero surprise to find that bad. EGR gasket, and TBI throttle shaft bushings...sure. Cleaning those up will help the way it runs for sure.
No clue on why it won't talk to you. If you try to flash the codes, are you at least getting the code 12?
I get the code 12, and the stored Code 44 on all scanning equipment, but no live data communication.
I'll be grabbing a TBI Rebuild Kit, but related to the EGR, I'm not sure it was the gaskets. Smoke was actually coming out of the physical EGR valve, not from it's base/mounting surface.
Also, are TBI throttle shaft bushings included in traditional rebuild kits?
Last edited by 92RS-HeritageEd; 08-17-2018 at 01:50 PM.
I get the code 12, and the stored Code 44 on all scanning equipment, but no live data communication.
Failed ECM, failed wire harness, or failed connection at the ALDL.
"I" would grab the service manual, and see which pin carries the data. Make sure that pin is located in the correct slot of the ALDL, that it's fully seated, and that the wire to it isn't broken.
GM seems to move the wires around in the ALDL for no good reason I can think of. Different applications are wired differently. Make sure yours is correct.
Failed ECM, failed wire harness, or failed connection at the ALDL.
"I" would grab the service manual, and see which pin carries the data. Make sure that pin is located in the correct slot of the ALDL, that it's fully seated, and that the wire to it isn't broken.
GM seems to move the wires around in the ALDL for no good reason I can think of. Different applications are wired differently. Make sure yours is correct.
I'll pull out my GM Service Manual and see if I can locate the Data PIN. How can you test any of the wires on the ECM connectors to see if they're damaged/broken? They appear to be taped in a wire loom fashion. Also about the three possibilities mentioned...
Failed ECM - Although it's possible, it's kind of unlikely, It's a New/Reman'ed ECM w/ Stock PROM
Failed Wire Harness - Potentially, Sometimes only 1 of 2 injectors fire and if I move/relocate the ECM the issue goes away and both injectors fire as they should.
Failed connection at the ALDL - Not to sure, only tried the basic OBD1 Code Reader and it works
How can you test any of the wires on the ECM connectors to see if they're damaged/broken?
I'd disconnect the harness at the ECM, connect an ohmmeter between the ALDL pin and the harness connector that plugs into the ECM. Look for open circuits or high resistance. You'll need the service manual to tell you which cavity at the ECM connector relates to the wire(s) at the ALDL.
Originally Posted by 92RS-HeritageEd
Failed Wire Harness - Potentially, Sometimes only 1 of 2 injectors fire and if I move/relocate the ECM the issue goes away and both injectors fire as they should.
Trace the injector wires the same way you trace the ALDL wires. For both the injectors and the ALDL, be sure to wiggle the harness as you're testing resistance. Be sure you have continuity no matter how the harness is moved or wiggled.
Originally Posted by 92RS-HeritageEd
Failed connection at the ALDL - Not to sure, only tried the basic OBD1 Code Reader and it works
The "code reader" isn't using the data wire. If that one has a bad connection or broken wire or if the wire is plugged into the wrong cavity of the connector, the code reader wouldn't know the difference.
Resurrection is possible, just did it to this old thread of mine. On CAR # 2 now I have the same Code 44 however on this car when it happens the car dies like it literally ran out of gas. It starts as it should, idles great, no surging but as soon as you start driving... Code 44 and a stall shortly after, even though it starts right back up, and I can coast on to the destination. I've checked the following
- Fuel Level / Pressure: There's a 1/4 tank in it, Can't check pressure while driving but while in park or in park & giving it gas it's a solid 12psi.
- Recently Swapped in Stock 305 GM injectors VS the aftermarket unidentifiable injectors that dripped and had poor spray pattern.
- Swapped MAP sensors while doing some MAP/No-Start Troubleshooting, and the car starts and MAP Voltage is in line w/ TPS, idles like a champ.
I was looking over the datalog I was making at the time and noticed a whopping 0V for my O2 Sensor while driving @ 25MPH, and for a considerable amount of time it stayed below 250mV. Is that normal?
The o2 should toggle, showing lower than .450mv is lean especially if it’s staying there.
I have seen a dead o2 stay at .450mv but never at zero.
Originally Posted by Schurkey
Broken wire for O2 sensor? O2 signal never makes it back to the ECM?
Faulty O2 sensor?
Took the car out again, did the same thing backing into my driveway, but always starts right back up and as long as I remain in park it runs like no issue is present O2 voltage swings like it should. Per the GMSM "Oxygen sensor varies the voltage within a range of about 1000mV if exhaust is rich, down through about 10mV if the exhaust is lean", it sure didn't mention below 10mV OR a troubleshooting guide for an O2 sensor that functions as expected only in park.
However, given the pic I posted in my fuel filter situation thread, I may have to cut bait. If you check out that thread you'll see why...
While driving today I noticed the O2 sensor voltage was good for the first lap, as I drove the O2 voltage dropped and stayed below 250mv until I got the code 44 and of course the car died, waited 5 seconds, started right back up and limped home. Let engine cool a bit, tried removing the O2 Sensor... wouldn't budge. I despise the O2 sensor...
I had code 44 many years ago on my caprice and also had trouble passing emissions testing. i replaced egr with new and a known good cat off another caprice i had parted out. i eventually datalogged and saw the BLM were high. Ended up replacing the injectors with a used set from the wrecker and set my fuel pressure @ 13 psi. BLMs came down to where they were suppose to be. Car passed emissions with flying colors. infact in the 15 years i was able to look back in its history, it never had better test results. i had owned the car for 6 years and it had never ran this good, i sold it shortly afterwards.
Have you checked for exhaust leaks? Cracked exhaust manifold or Y pipe? This will cause the o2 to read lean. I would get injectors flow tested. at the very least confirm they are the CORRECT injectors for your engine. when i bought my caprice it had 4.3l injectors, was suppose to be 350 injectors.
I had code 44 many years ago on my caprice and also had trouble passing emissions testing. i replaced egr with new and a known good cat off another caprice i had parted out. i eventually datalogged and saw the BLM were high. Ended up replacing the injectors with a used set from the wrecker and set my fuel pressure @ 13 psi. BLMs came down to where they were suppose to be. Car passed emissions with flying colors. infact in the 15 years i was able to look back in its history, it never had better test results. i had owned the car for 6 years and it had never ran this good, i sold it shortly afterwards.
Have you checked for exhaust leaks? Cracked exhaust manifold or Y pipe? This will cause the o2 to read lean. I would get injectors flow tested. at the very least confirm they are the CORRECT injectors for your engine. when i bought my caprice it had 4.3l injectors, was suppose to be 350 injectors.
This car came w/ Cat Delete. Idk about a cracked exhaust manifold or Y pipe. When I got the car it also had aftermarket unidentified TBI Injectors w/ RIN-1000 on top, swapped in a set from a 305 TBI L03 Caprice and that helped get me where I am. I also have a few sets of 350 injectors, I guess I could try a set BUT the car is supposed to be a 305 L03 TBI although it's a 880 block while my other 92 is like 638 or something, I mentioned it in another post I did. It's just strange the Lean Condition only happens after the first or second lap around the block. If I were to leave the car in park and at idle it'd never pop a Code 44 O2 voltage swings like it should...
Last edited by 92RS-HeritageEd; 06-03-2019 at 07:47 PM.
- Can the Cat Delete & Pinched hose that used to go to the Cat have anything to do with a Lean Condition?
- When that hose is pinched off what happens to the air that would have been diverted there, and out to atmosphere? Is it forced back into the exhaust causing a Too Lean condition under load?
Out of options, I grew a set, tried something I'd consider dangerous. With over 1/4 tank I started the car, 12psi from cold start, put the car in drive after rpm's settled and tried coasting 100ft with my big toe on the gas and glanced down, didn't see 12psi anymore on my rigged FPG, it was more like 10psi, IMMEDIATELY backed right back up into the drive way, parked and by the time I opened the door it had dropped to what looks like about 5psi, and that was at idle.
- Can the Cat Delete & Pinched hose that used to go to the Cat have anything to do with a Lean Condition?
- When that hose is pinched off what happens to the air that would have been diverted there, and out to atmosphere? Is it forced back into the exhaust causing a Too Lean condition under load?
I would hope that whoever pinched the hose had enough sense to disable the diverter valve so the air blows uselessly into the air cleaner, or that they removed the belt from the AIR pump.
The AIR pump would be unhappy dead-heading into a plugged pipe or hose.
Originally Posted by 92RS-HeritageEd
UPDATE:
Out of options, I grew a set, tried something I'd consider dangerous. With over 1/4 tank I started the car, 12psi from cold start, put the car in drive after rpm's settled and tried coasting 100ft with my big toe on the gas and glanced down, didn't see 12psi anymore on my rigged FPG, it was more like 10psi, IMMEDIATELY backed right back up into the drive way, parked and by the time I opened the door it had dropped to what looks like about 5psi, and that was at idle.
Well, you certainly know what's next:
1. Figure out how much voltage is getting to the pump, by testing voltage as close to the pump as practical.
2. Figure out how much amperage the pump is drawing, by testing amperage most anywhere in the fuel pump circuit.
3. If the voltage or amperage is goofy, figure out if the problem is a failed fuel pump relay, corroded wiring, or some other electrical fault.
If none of the above indicates external problems, drop the tank, replace the pump, the in-tank wire harness, and the filter sock after completely cleaning out the fuel tank and verifying that the sending unit works OK and the pulse-dampener (if used) is leak-free.
If the pump is connected to the sending unit "hanger" by a piece of hose, assure that the new hose is suitable for immersion in gasoline (SAE 30R10) AND that you are NOT using those crappy worm-gear hose clamps. https://frsport.com/gates-27097-3-8-...ines-sae-30r10
08-05-2018, 08:24 PM
