LT5

I noticed when i floored it and looked out the back i have alot of smoke coming out of my tail pipes, the car runs good, hauls ***, i put the code reader on it and one of the banks for 02s is spiking alot up and down as the other one is more consistant, could this cause a rich condition?

Injuneer

What color is the smoke.... white, blue, or black? Does it have a sweet odor, or a fuel or?

Both O2 sensors should e swinging rapidly up and down in closed loop, over a range as low as 0.100 volts and as high as 0.900 volts. If “the other” is not doing that, is may be defective. What kind of readings are you seeing?

When you put the pedal on the floor the PCM enters power enrichment mode. It uses a richer target A/F ratio. While it ignores the O2 sensor readings, is uses the LTFT's (BLM’s) if the were adding fuel in closed loop. A faulty O2 sensor, exhaust leaks before the O2 sensors, wiring problems, misfires, etc. can cause the LTFT's to (false) elevate, causing rich condition, which becomes more visible at WOT. Are you running a cat?

LT5

smoke looked black smell of gas. ill do video of logs later when off work.

Injuneer

I can look at a .csv file for you. Videos are seldom useful.

LT5

I forgot to say no cats, i worked alot of hours today, so i will try to get the video of my scanner on her. Thank you very much!

LT5

Ok i put my bosch scanner on her today, sorry for the delay ive been super busy and tired. Anyways i tried to take a video or do a recording of the data but not sure how to get that to you or on my phone. I checked all reading and the only ones that seem to concern me that are acting up is the Right bank o2. It will go below .100 mv, after about 5 more minutes (13.5 minute run time) the left one did do the same thing. Also it is to note that i do have an exaust leak at the END of the exaust, the tailpipe came off the muffler. Although i was told this will not effect the 2 o2s that i do have. The right bank one though will go to 700s or 900s, then go to .55 or so while the left one rarely went this low. Also i noticed at WOT the car due to the exaust leak in the back is VERY loud and the knock module went from 0 to 40 at wot!! Which im guessing is just the fact that the car is so damn loud lol. This is about all the info i can give you, but three is a strong smell of gas, and it does let out black smoke, also while driving the motor shakes like it does not want to go. I replaced fuel filter (had new one lieing around) and checked all plugs, wires, opti, (which are all new even the module and coil are brand new as of 11 months ago) I fixed all wiring issues, checked all fuses, im guessing this is just a bad 02, but im trying to do as much diagnostics i can before throwing parts at it that i don't need. Hope this helped and thank you for the support. Also if there is a link where i can donate to this site (since ive been getting help here for over 10 years) i will gladly donate.

:Chris

Injuneer

A video is generally not very useful. Best thing to do is a Scan9495 data log. That provides a continuous array of 50 different sensor readings and PCM parameters, enabling looking at a dozen sensors at the same time if necessary.

Not clear what the 0.100 volts (or 100 mV) means. How long was the engine running, was the AIR pump running, was it in closed loop/fuel trims enabled? Did it drop to 0.100 volts and stay there, or did is rebound quickly? Or, was it moving back and forth between rich and lean previously, but not going quite as low as 0.100 volts? Really need a data log to do a meaningful analysis.

No donations.... Jason and Chris p sold this site to a large company the owns numerous similar sites, and collects the advertising $$$$. They don’t need it. Everybody here works for free. And there aren’t many of us left - maybe a half-dozen or so. Lot of newbies who ask a question, get an answer and never come back, or don’t even come back to see if they got an answer.

LT5

The scanner says i can record data, this was closed loop 189 temp, the 02s or the right one mostly would drop below 100 which i assume is millivolts, then would go back to 400 or 300 then 700 ext, then way back down, as the left bank never hit a under 100 number for quite some time. Ill run another log and see if i can transfer it to my phone then upload it on here. I will note that when this number went to low on the 02s the motor started to act up at idle, then would try to fix itself.

LT5

Ok replaced oxygen sensors with new ac delco ones, (mine were old af anyways) and the car is running better, and not backfiring as much, but is still having same symptoms just less backfiring. Also i put the fuel pressure guage on it and it pulls 40 psi with key on not started......then after about 10 minutes goes down to 10 psi or less. I checked power to all injectors= good and then tested the injectors themselves for ohms, they all are within spec. Next i figure ill pull them and test for leaks, but at this point im wondering if the fuel pump is just not keeping up? Also i checked the fuel pressure regulator and it does not have gas coming out of it, and when i pull the line off while engine is idling it does have a hissing sound (meaning its working?). Sorry if there is lack of info, im just trying to test as best i can before throwing parts at it, also i need a new fp anyways because the sending unit is bused, and id rather just replace the whole assembly then the sending unit since its got over 113k miles on the original pump. Thoughts?

Injuneer

Large pressure loss after pump shutdown can be:

1) check valve in the pump

2) leaking injector(s)

3) leaking fuel pressure regulator. Can be failure of the valve seat that shuts off fuel flow through through the return line, not just the diaphragm leaking into the vacuum line. A fuel pressure regulator valve that doesn't seat is the hardest of these failures to detect.

4) leaking fuel line, including the flex line in the tank.

Once the pump shuts off, its flow capability is a non-issue. Whether the pump can “keep up” is measured up on the road with the engine under max load - at least 5,000 RPM at WOT. If it can’t hold at least 40 PSI under that condition, it needs to be replaced.

LT5

You the man! Ill do more testing soon as im working alot and only have 1 day off a week. But i noticed on the scanner the knock sensor read 40 at wot. Will check all things you have listed....thank you so much!

Injuneer

There is no direct measure of the knock sensor. There is a reading for knock retard and that shows by how many degrees the PCM has retarded the ignition timing in response to the knock sensor or an increasing knock count. The stock programming limits spark retard the 15-degrees. And many custom tunes reduce the limit, meaning it is highly unlike knock retard can be 40-degrees. Engine wouldn’t run well with that much retard.

Then there is the “knock count”. That is a field that starts at 0 ind increases when knock is detected, or if the engine is operated under conditions that are likely to produce knock. It is a number that just keep increasing until it approaches ~64,000 then resets to 0. The exact number in that field is not important. What is important is how often it increases, and how fast in increases. It isn’t unusual for the number to increase during startup, and that does not indicate a problem.

You need to clarify what units the number 40 uses, and how it is labeled on the scanner. Some scanners report ignition timing (spark advance) as a negative number, so you may see -40, but that's a feasible number for spark advance at high RPM. Other scanners report advance as a positive number.

LT5

Replaced the 02 sensors, and got the exhaust welded back up, car runs a bit better but still stumbles and runs very rich. I did replace the fuel pressure regulator with a Delphi unit from jegs today as well. I have an entire fuel pump and assembly on the way with sending unit (mine was busted) so for 125 bucks that will be nice. I started the car up today and had a ses light finally! It went away after the rpm dropped to about 900 or so. Then i put the scanner on it and it threw a code 22. Low voltage tps. I also noticed on the scanner it said i only have 10 hg? Which before when i used my vaccume pump it was 20 solid. Which is good vaccume for any motor. I did notice it said the voltage on the map sensor was 9 volts? I believe this sensor only goes to 5v or less....so thats concerning....also as i slowly and fastly revved the tps voltage bairly changed....this thing may have more then one problem, all wiring checks out as i have fixed it all. Car is nearing 120k miles so i know things start going wrong. But im beating every problem one at a time. Cars opti, plugs, wires, coil, icm, are all new within 1 year, icm is actually 3 years old. Ill do what i can but with work and limited hours, im taking it one day at a time. I hope to get it running perfectly this year so i can finally take it to the dyno and track. Computer is pcm for less tuned, i have a spare....maybe i can swap out and see a diff? Ive heard of cpus going bad but usually they just crap out? Anyways, one day at a time hopefully i get this thing soon, shes to fun not to have at full power

Injuneer

The scanner reads the MAP sensor. That measures manifold ABSOLUTE pressure. 10”Hg at idle is normal with a stock or mild cam. That is not the same as “vacuum”. Your vacuum gauge measure “gauge pressure”. The is the pressure in the intake manifold referenced to a system that sets standard atmospheric pressure as “0”. When not connected to a vacuum, your vacuum gauge reads “0”. So vacuum is a negative pressure. -20”Hg is entirely normal at idle with a stockish cam.

But standard atmospheric pressure is actually about 30”Hg. That reflects the weight of the air pushing down on everything, at sea level. The PCM also measures and records the MAP sensor reading before the engine stars, and if you look at the MAP sensor reading without starting the engine, it should read 30”Hg (or about 101kPa if the reading is set to metric units). To use the scanner readings to calculate vacuum, subtract the barometric pressure from the engine running MAP reading. Example:

(10”Hg MAP) - (30”Hg Barometer) = -20”Hg vacuum.

If you understand all that, a 10”Hg scanner MAP reading at idle is exactly the same as -20”Hg on your vacuum gauge.

There is no way the MAP sensor voltage can read 9 volts. I suspect it actually read closer to 0.9 volts, although that would be closer to 8.5”Hg. The PCM starts with the voltage reading, (yes, ranging from 0 - 5 volts), and converts the voltage to “Hg or kPa (kiloPascals). If the voltage reading was 9 volts, you would have DTC 33 for “high voltage/low vacuum”.

My scanning guide explains a lot of this:

https://www.camaroz28.com/forums/com...-guide-886891/

Injuneer

You can't check the TPS voltage by playing with the throttle at idle. It takes very little throttle movement to raise the engine RPM with no load on the engine. Turn the key to run, do NOT start the engine, and watch the voltage as you slowly move the throttle from fully closed to wide open. The closed throttle voltage should be in the range of about 0.30 - 0.90 volts. The WOT reading should be about 4.0 volts higher than the closed throttle readings. The voltage should increase smoothly with no spikes or dropouts.

I doubt the PCM is faulty. You just need a clearer understanding of how the system works.