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Discussion Starter #1
Now that I have insurance for my beast I manage to do a little driving today, not getting too far from the house. Can someone look at the attached and see if they can give me a clue as to what's what. My O2 sensors look a little off and I know I have DTC 77 which I'm going to get disabled, as my fan is controlled by other means. Car bogged and stalled at a stop sign, so something needs tweaked.

http://www.brutusv8.com/misc/log1.uni

Cheers!

Paul
 

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Your left O2 signal is bad, very slow activating (took over 300 seconds to come ready) and then stuck at 740 Mv up to your stall at the end of the graph below. You can see the right O2 voltage switching (black line) and the left O2 comparison (red line). I would swap O2 left to right and see if the lazy/stuck around 740 Mv moves to right (says O2 is NG) if it stays on left it says heater circuit is not working or O2 sense lines are messed up. What is your setup. log looks basically stock. Nothing else pops up, when I saw the left O2 I did not look into any other AFR stuff as it's all invalid w/an O2 reading like that.. Have O2 lines been extended, if so hopefully no cuts or splices between sensor and it's connector..

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Discussion Starter #3
Your left O2 signal is bad, very slow activating (took over 300 seconds to come ready) and then stuck at 740 Mv up to your stall at the end of the graph below. You can see the right O2 voltage switching (black line) and the left O2 comparison (red line). I would swap O2 left to right and see if the lazy/stuck around 740 Mv moves to right (says O2 is NG) if it stays on left it says heater circuit is not working or O2 sense lines are messed up. What is your setup. log looks basically stock. Nothing else pops up, when I saw the left O2 I did not look into any other AFR stuff as it's all invalid w/an O2 reading like that.. Have O2 lines been extended, if so hopefully no cuts or splices between sensor and it's connector..
Saw the same thing. Damn can't find my socket adaptor. I believe mine are Bosch and from what I've read most say AC Delco is the only way to go. I'll swap them around to be sure it isn't bad wiring, the harness is custom, but I can't see a splice, but the swap will show that. Now where the heck is my O2 socket adaptor.

Thanks for the help. Just starting to log and sort out issues before I get the PCM tuned. Engine is a little ways from stock (355, custom intake, no emissions).

Paul
 
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Discussion Starter #4 (Edited)
Well it looks like Bobdec your suspicions were correct. I swapped the O2 sensors and sure enough the left is still slow. Crap. :eek:

Looking closer at the wire from the O2 sensor it looks like there might be a splice which as I've read before is bad. I assume the "proper" way to fix this is to run a new wire from the PCM to the all the way to the O2 sensor's connector? Any less pain in the ass ways to fix this?



http://www.brutusv8.com/misc/log2-4292013-o2swap.uni

Paul
 

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Hope what you said was a typo.. looked at your pic and at log (BTW link is bad has 2 HTTP's) LEFT is still failing, it's slower to come ready and not switching at correct voltages.. here is the schematic..ref shbox.com http://shbox.com/1/1995_pcm2.jpg . What I would do is let it cool off then pull the left (drivers) O2 out - connect it back to the harness - while it's hanging loose turn on the key Do NOT start the engine.. start datamaster ASAP and observe the O2 voltage it should be about 450 Mv when ice cold (not switching) after about 1-2 mins the heater should get the tip of the O2 too hot to touch. At that time the O2 should start switching and go to 100 Mv or below, indicating a lean (100% air, no HC) reading. Getting hot says your 2 heater circuit wires are OK, going to 100Mv says the 2 O2 sensor circuit wires are OK. I suspect it's the O2 sensor wires. I chased a bad heater circuit once ended up being an intermittent open at the +12 volt splice in that schematic. Headers make the heater much more critical as the O2's will cool at idle and go not ready , or in most cases switch incorrectly.

INFO.. the O2 works by comparing outside air to the exhaust mix. The outside air is provided by a very small gap in the sensor wire insulation between the sensor and it's connector. That's why there should never be a splice between the connector and sensor. Nor any tape, sealer or dirt around the connector. Also the sensor signals are low voltage and very low current, very sensitive to any problems in a twisted wire type of splice. Soldering or an extension cable are the recommended ways to add length to the harness.
 
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Discussion Starter #6
Hope what you said was a typo.. looked at your pic and at log (BTW link is bad has 2 HTTP's) LEFT is still failing, it's slower to come ready and not switching at correct voltages.. here is the schematic..ref shbox.com http://shbox.com/1/1995_pcm2.jpg . What I would do is let it cool off then pull the left (drivers) O2 out - connect it back to the harness - while it's hanging loose turn on the key Do NOT start the engine.. start datamaster ASAP and observe the O2 voltage it should be about 450 Mv when ice cold (not switching) after about 1-2 mins the heater should get the tip of the O2 too hot to touch. At that time the O2 should start switching and go to 100 Mv or below, indicating a lean (100% air) reading. Getting hot says your 2 heater circuit wires are OK, going to 100Mv says the 2 O2 sensor circuit wires are OK. I suspect it's the O2 sensor wires.

INFO.. the O2 works by comparing outside air to the exhaust mix. The outside air is provided by a very small gap in the sensor wire insulation between the sensor and it's connector. That's why there should never be a splice between the connector and sensor. Nor any tape, sealer or dirt around the connector. Also the sensor signals are low voltage and very low current, very sensitive to any problems in a twisted wire type of splice. Soldering or an extension cable are the recommended ways to add length to the harness.
Yes, typo, I meant Left is still slow even after switching. There is no splice between the O2 and Connector but there may be between the connector and the PCM. The left O2 cabling is rather tight too, I'll loosen it up. I've decided, since these are older Bosch units anyway to replace both of them and trace the cable on the left side back to the PCM. Doing that this weekend. Will change to AC Delco units and try those first to see if they are less sensitive than the Bosch unit to whatever is causing this.

I also noticed in my log that my voltage is low, low 12's even into high 11's at one point. I'm sure that could cause various issues. :craz28: always something.

Paul
 
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Discussion Starter #7
Grabbed an AC Delco O2 Sensor at lunch and slapped it in, in the hopes it wouldn't be as "electrically sensitive" as my apparently junk Bosch unit, no go. Same exact reading, but since after this I'm getting the engine tuned better to put a couple of AC Delco in their anyway and not worry about it. Granted I got the AC Delco Denso units and not the actual Delco unit.

So this weekend I get to trace wire, clip cable ties and generally look for a needle in a haystack. At least it's not as bad as tracing wires in a Camaro.

Paul
 

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That voltage displayed is +12 ignition from the key, I've noticed it's usually about 1 to .75V lower than actual battery voltage. Voltage probably drops as it feeds other circuits and some loss thru the ignition switch. Still it s/b up around 12.5 as battery's usually at 13-14 when running normal loads. They say PCM should run at 8+ volts, but I would not trust that... If you look at that voltage on DataMaster log when cranking the starter it will be down near 9 volts and the PCM is still doing it's thing OK to start the car. FYI.. DTC 50 (low system voltage) sets at 8 volts...
 
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Discussion Starter #9
That voltage displayed is +12 ignition from the key, I've noticed it's usually about 1 to .75V lower than actual battery voltage. Voltage probably drops as it feeds other circuits and some loss thru the ignition switch. Still it s/b up around 12.5 as battery's usually at 13-14 when running normal loads. They say PCM should run at 8+ volts, but I would not trust that... If you look at that voltage on DataMaster log when cranking the starter it will be down near 9 volts and the PCM is still doing it's thing OK to start the car. FYI.. DTC 50 (low system voltage) sets at 8 volts...
I just tested the alternator and it's fine, 14.3 volts. I can't add any load because it's going to rain and don't want to run the engine too much in my garage (door open) as with no cats it gets pretty bad pretty quickly. The water pump is electric so the best way to tell would be to get it to kick on and see if the alternator is still reading correctly.

However my main concern right now is the O2 sensors. Bobdec, want to help trace wires this weekend? :roflmao:
 
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Discussion Starter #10 (Edited)
Okay, good news and bad news.

Good news, it looks like the O2 sensor is fixed. No continuity on ground, so I gave the O2 sensor wire temp ground and logged and sure enough it comes online like the passenger side bank. The actual wire was cut, in half, so I need to find the other half and splice it. I just attached it to the block temporarily which seems to work good enough.

Now the bad news, the car took FOREVER to start, it would turn over but it just wouldn't fire. Once I got it started it wasn't drivable No power, just wouldn't pull away at all. Got a few pops out of the exhaust too. It wouldn't move an inch very strong smell of fuel too.

Here's my datalog if anyone can make sense of this, don't know what I'm looking for. Could grounding the O2 sensor directly to the block temporarily cause this, seems odd to me, but thought I'd ask.

http://www.brutusv8.com/misc/log3fixo2ground2.uni

 

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grounding the o2 to the block is fine. there are some sensors that you aren't allowed to ground to anything but the PCM (because they're filtered), but not the o2 sensor.

by the look of your MAP and trims, i'd be looking at fuel pressure and checking out your injectors, etc. the way it drops in vacuum so dramatically when you're barely touching the throttle isn't good, and neither are those trims.
 
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Discussion Starter #12
grounding the o2 to the block is fine. there are some sensors that you aren't allowed to ground to anything but the PCM (because they're filtered), but not the o2 sensor.

by the look of your MAP and trims, i'd be looking at fuel pressure and checking out your injectors, etc. the way it drops in vacuum so dramatically when you're barely touching the throttle isn't good, and neither are those trims.
I was thinking possible vacuum leak, *sigh* always something. Double checked my intake manifold bolts, will double check the intake post MAF. Hope I haven't broken the seal on the intake manifold, not a problem I'd relish fixing.
 
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Discussion Starter #13 (Edited)
I was thinking possible vacuum leak, *sigh* always something. Double checked my intake manifold bolts, will double check the intake post MAF. Hope I haven't broken the seal on the intake manifold, not a problem I'd relish fixing.
Intake looks good, made sure the seals were tight. Weird. *sigh* another needle in the proverbial hay stack. :craz28::mad:

Here's a datalog of trying to start the car.

The voltage is low but that's likely from me trying to crank the car too much.

http://www.brutusv8.com/misc/starttrouble.uni
 

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well.. there are points in that log where you're at idle, giving it 30% throttle, and your vacuum is gone, damn near atmospheric, with no rpm increase.. which shouldn't really happen unless you're lugging the engine or flooring it.

it's behaving like you left your ebrake on, or you dumped the clutch too hard.

the ecm is responding appropriately.. as the engine is loading up heavy because of the map reading, and it's giving it only 7 degrees of advance, and fueling appropriately

could your exhaust be plugged up or something?
 
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Discussion Starter #16
well.. there are points in that log where you're at idle, giving it 30% throttle, and your vacuum is gone, damn near atmospheric, with no rpm increase.. which shouldn't really happen unless you're lugging the engine or flooring it.

it's behaving like you left your ebrake on, or you dumped the clutch too hard.

the ecm is responding appropriately.. as the engine is loading up heavy because of the map reading, and it's giving it only 7 degrees of advance, and fueling appropriately

could your exhaust be plugged up or something?
Unless a small woodland creature climbed into the exhaust not likely, it's a straight pipe for each bank with no cat and a very simple magnaflow muffler.. What are you looking at in the logs that shows no vacuum? MAP?
 
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Discussion Starter #19
Damn, yeah, meant to do that earlier.
LOL, fuel pressure is 2psi at ignition ON position. Er, yeah, that's a problem. Fuel filter is likely plugged, or the pump is toast. I can hear it come on though. I think I'll also take out my fuel cell and clean the snot out of it. Hope the foam in the cell isn't degrading and causing it to get eaten, that would not be ideal.
 
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