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Cc503 issues, rpms sticking, high o2 volts, expertise needed

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Cc503 issues, rpms sticking, high o2 volts, expertise needed

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Old 07-16-2018, 03:21 AM
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Cc503 issues, rpms sticking, high o2 volts, expertise needed

Something just isn't right with my car that I'm trying to figure out. I'm going to try to explain some trends I've noticed.

96 lt1 m6, 140k miles. Just installed cc503 cam and 1.6 rrs. Has long tubes on it as well.

I have had issues with high voltage codes to my o2 sensors. I viewed them on torque pro and sure enough they were at some points glued to .9 or 1 volt.

So, I changed o2 sensors for brand new ac Delcos. Same intermittent problem.

I've also randomly been noticing my rpms get "stuck" and don't want to come down at times. Even if I push the clutch in or put it in neutral, they stick. Punching the gas real quick can sometimes get rid of it. There are no kinks or anything in the throttle cable. Measures 0 to 100 percent perfectly when I have engine off. I will mention, on torque pro, sometimes my throttle position doesn't come all the way down to 0 when I let off, sometimes it does. If it doesn't it will stick to .78 or something but I'm not sure if that's the computer trying to compensate?

Tonight, while logging, I noticed that any time the rpms stuck my o2 volts were both high. As soon as it would "snap out" of it and rpms would come down normally, my o2 readings would drop to 0. Every single time. So there has to be a correlation there.

My radio has also been turning on and off, and it acts up the most strangely when my rpms are sticking and my o2 volts are sticking.

Could all 3 of these issues be tracked down to 1 simple problem? I'm out of ideas.
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Old 07-16-2018, 10:25 AM
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Re: Cc503 issues, rpms sticking, high o2 volts, expertise needed

Outside what seems to be random electrical issues, did you retune the car for the different cam?
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Old 07-16-2018, 11:39 AM
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Re: Cc503 issues, rpms sticking, high o2 volts, expertise needed

Can you upload a data log in .csv format for review?

When the weird things happen, like the radio turning on and off, what is the voltage showing on the dash gauge?

The PCM can't change the TPS volts or throttle position to "compensate". The voltage is simply a reading of the TPS sensor. The idle is controlled by the PCM using the idle air control valve. It is normal for the PCM to increase air flow using the IAC valve as RPM increases, to keep the engine from stalling if the throttle blades are suddenly closed. That feature tends to keep the RPM high, even when the throttle is closed. The idle will not return to "normal" idle speed (800 RPM for an M6 with a stock tune), until the vehicle speed sensor shows 0 MPH. Until then you will see elevated idle.

Then there's the issue of decel fuel cut off (DFCO). When the throttle closes, the PCM shuts off the fuel injectors to prevent raw fuel from reaching the cat(s), and keeps them turned off until a specific programmed RPM is reached. I suspect you are seeing very high O2 readings because the injectors are staying on too long on decel, and then seeing the O2 readings drop to 0 when the PCM shuts off the injectors.

What is your normal throttle closed TPS voltage (engine off)? Have you checked for a weak return spring? If the TPS volts are staying higher than that, it's due to a blade problem, nothing the PCM is doing.

Does your car have traction control? That can affect the TPS volts, because if you have TCS the pedal cable and the speed control cable both connect to the servo mounted on the driver side valve cover, and the EBTCM control modulates the cable that runs to the throttle body, integrating the needs of accel pedal movement, TCS and speed control systems.

Most of this (except the radio shutting off, and TPS volts) seems to point to a poor tune.

Last edited by Injuneer; 07-16-2018 at 11:41 AM.
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Old 07-17-2018, 01:47 AM
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Re: Cc503 issues, rpms sticking, high o2 volts, expertise needed

Originally Posted by Injuneer View Post
Can you upload a data log in .csv format for review?

W

When the weird things happen, like the radio turning on and off, what is the voltage showing on the dash gauge?

The PCM can't change the TPS volts or throttle position to "compensate". The voltage is simply a reading of the TPS sensor. The idle is controlled by the PCM using the idle air control valve. It is normal for the PCM to increase air flow using the IAC valve as RPM increases, to keep the engine from stalling if the throttle blades are suddenly closed. That feature tends to keep the RPM high, even when the throttle is closed. The idle will not return to "normal" idle speed (800 RPM for an M6 with a stock tune), until the vehicle speed sensor shows 0 MPH. Until then you will see elevated idle.

Then there's the issue of decel fuel cut off (DFCO). When the throttle closes, the PCM shuts off the fuel injectors to prevent raw fuel from reaching the cat(s), and keeps them turned off until a specific programmed RPM is reached. I suspect you are seeing very high O2 readings because the injectors are staying on too long on decel, and then seeing the O2 readings drop to 0 when the PCM shuts off the injectors.

What is your normal throttle closed TPS voltage (engine off)? Have you checked for a weak return spring? If the TPS volts are staying higher than that, it's due to a blade problem, nothing the PCM is doing.

Does your car have traction control? That can affect the TPS volts, because if you have TCS the pedal cable and the speed control cable both connect to the servo mounted on the driver side valve cover, and the EBTCM control modulates the cable that runs to the throttle body, integrating the needs of accel pedal movement, TCS and speed control systems.

Most of this (except the radio shutting off, and TPS volts) seems to point to a poor tune.
Thanks for the reply.

I had the car tuned by Solomon.

With the radio issue, i've never noticed voltage drops or anything else stop working. Alot of people point to the BCM, but i've also never had a problem with my windows or anything else. It's just the radio, and this all started after I installed the cam.

My TPS volts last time I checked were around .5v at idle and 4.5 (ish) at WOT so everything seemed normal to me there.

No traction control. What's weird to me is I had none of these problems before the cam, literally none. Maybe the tune is just ****ty?

I uploaded a couple recent logs, your eyes are going to be better than mine when diagnosing them.
Attached Files
File Type: xlsx
July 14th 1st.xlsx (188.9 KB, 7 views)
File Type: xlsx
July 14th 2nd.xlsx (419.0 KB, 5 views)

Last edited by slikrider20; 07-17-2018 at 01:57 AM.
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Old 07-17-2018, 12:50 PM
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Re: Cc503 issues, rpms sticking, high o2 volts, expertise needed

Downloaded. Try to spend some time on them today.
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Old 07-17-2018, 07:34 PM
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Re: Cc503 issues, rpms sticking, high o2 volts, expertise needed

Appreciate it!
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Old 07-18-2018, 05:23 PM
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Re: Cc503 issues, rpms sticking, high o2 volts, expertise needed

Always a bit harder seeing a scanning system that I am not familiar with. There are columns missing in the download....

"1st" file - missing col's A, C, E, G, H, I

"2nd" file missing col's A, B, C, D, E, H. U

Is this something you can control when recording and printing the reports?

The "1st" file is the most useful, because the "2nd" file is missing MPH, for example.

Does the report offer the ability to record flags like "Closed Loop" and "PE Mode" enabled". Can you include a "time stamp" so we can tell how frequently the system is logging the data? Can it show the "Cell #"? Your long term fuel trims are 0 and both O2's are in the high 0.900s. then suddenly it shifts to a different cell with the LTFT's at -6.25% and it drops the O2s to 0.790 - 0.830.

Comments on "1st" file:

You have knock retard. With Col I missing, can't tell if this might be the result of high coolant temp. In "2nd" file, which does have Col I, coolant temp is 212 - 221degF. Lower temps might reduce knock (detonation). Running lean can cause knock retard, but the knock retard is shown when the target A/F ratio is 12.2:1, which is on the rich side. This is born out by the fact the O2 sensors are in the range of 0.950 volts, when the knock is occurring.

In the data log, the O2's are mostly in the 0.900+ range, or in the 0.010- range. What appears to you to be a problem is not. It is doing exactly what I told you it would do.

While the data log does not have the "flag" for power enrichment (PE) mode, I can tell from the target A/F ratio that the PCM is in PE mode. When you push the throttle toward WOT, (actually a table of throttle % vs. RPM) the PCM knows you want increased power, and richens the A/F ratio.

When you see the target A/F ratio at 14.7:1, it's telling you the PCM is not in PE mode, and is operating in normal closed loop, trying to maintain the stoichiometric A/F ratio of 14.7:!, which is the AF ratio that minimizes total emissions (HS+CO+NOx), and provides decent fuel mileage.

So.... in PE mode, the PCM is providing a rich A/F ratio to make max power and torque, and the programmer has set the tables in the program up to produce an A/F ratio of 12.2:1. Seems a bit overly rich, because traditional thought is you will maximize power/torque generally in the range of 12.8 to 13.2:1. But, your tune is set to achieve 12.2:1. That is what is causing the O2 sensors to go into the 0.900+ volt range.

The output voltage of the O2 sensor is not linear. If the engine is running at 14.7:1, the voltage will be ~0.450 volts. Go very slightly rich (which the PCM does in closed loop to make the cats work) and voltage will rise rapidly. Go slightly lean (again, PCM toggles back and forth between slightly rich and lean to make the cats work), and voltage drops rapidly.

Air Fuel A/F Ratio Basics | Wideband vs Narrow O2 sensor

Point is, in PE mode, it is normal for the stock narrow band O2 sensors to read 0.900+ volts. Exactly what yours are doing.

Then when you let off the throttle, the PCM turns off the fuel injectors. The O2 sensors are only seeing the small amount of air passing through the idle air control valve..., the sensors read as close to 0.000 as possible.

The O2 readings of 0.950 are directly correlated to high throttle position %, and the readings of 0.010 are directly correlated to closed throttle. System is working fine. Can't tell if there is some delay in the PCM switching from fueling via PE mode to DFCO, because there is no time stamp in the data logs. But it appears you might be getting 1 frame of data per second, and that is not enough to show in detail what s going on in a device that is operating almost 10 times as fast as that.Don;t think there is any problem with the tune, other than maybe a bit rich in PE mode.

I'll add another few comments in the next post. I don't want to lose this one.

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Old 07-18-2018, 05:53 PM
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Re: Cc503 issues, rpms sticking, high o2 volts, expertise needed

The problem comes when you are not in PE mode (target A/F ratio 14.7:1). But the interval between lines of data appears to be excessive, so it's hard to figure out what is going on. As a minimum, also need the log to show time of each line, and columns for IAC counts, closed loop flag, fuel trim enabled flag, and fuel trim Cell #.

The O2's always seems to drop rapidly to 0.0xx volts as soon as the throttle closed. That indicates the sensors are reading OK. But it's the high readings when the throttle % is not 0 that is troublesome. I'ts like it's not in closed loop, and it's running extremely rich. Hence the 0.800 - 0.900 volt O2 readings for extended periods of time. I'm assuming the O2 sensor high volt codes you got were P0132 and P0152. Those code diagnostics run when:

- PCM is in closed loop
- Fuel trims are enabled
- Throttle % in the range 0f 3% - 20%
- target A/F ratio in the range of 14.6 - 14.8:1

And the code(s) set when the O2 readings stay above 0.774 volts for 30 seconds.

Need a better data log to try and sort this part out. GaryDoug's OBD-2 data logging software seems superior, and it's free. Plus Gary is generally here to answer questions on setup, etc.

https://www.firebirdnation.com/forum...nner-software/

Site for download:

http://www.mediafire.../?0elo4c935uc5s
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Old 07-19-2018, 12:22 AM
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Re: Cc503 issues, rpms sticking, high o2 volts, expertise needed

Apologize about the missing data, dug this one up and it appears to have all of the columns, hopefully will make it easier to evaluate.

I'll definitely check out that logging program, torque pro doesn't let me do IAC counts or PE/closed loop mode.

Logs are generated every half second, but I can change the frequency of that to something higher if you'd like.
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Old 07-19-2018, 09:38 AM
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Re: Cc503 issues, rpms sticking, high o2 volts, expertise needed

The PCM updates at least 9 times per second. Data logs scanning at least 5 frames per second are more useful. I'll give the new log a look.

Its surprising how much can change in a fraction of a second. I was able to find a major defect in the MSD Opti's that was causing idle speed to surge as high as 3,500 RPM. A single spurious reading from one of the cam position pulse signals, lasting a fraction of a second, was causing the PCM to elevate IAC counts rapidly, causing the surge. After the logs from multiple vehicles were provided to MSD, they claimed they revised the optical module and the cap to eliminate the problem.

It's possible to infer PE mode operation by seeing a target A/F ratio that is not 14.7:1. Fortunately your scanner provides target A/F ratio. With the fuel trim Cell #s you can sort out if it's in open or closed loop. And it's possible to infer fuel trim learning is enabled by looking at whether STFT's seem to be locked at 0. Just easier to sort it out when the log tells you with a simple 0 or 1 if closed loop is enabled, learning is enabled, or its running in power enrichment mode.
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Old 07-21-2018, 03:10 AM
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Re: Cc503 issues, rpms sticking, high o2 volts, expertise needed

I updated my logger to update every .2 seconds which would be 5frames/sec.

Right now, I have my car torn back apart trying to figure out these issues. I had a small oil leak in the manifold (therefore, vacuum leak also I presume) and traced the 02 wires all the way back and found no problems. There is a chance that one of them got pinched in my driver side valve cover when I tightened them down. When I get it all put back together, i'll take some new logs, and see what happens.

I appreciate you looking at the logs and giving me such good detailed responses.
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Old 07-24-2018, 03:02 AM
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Re: Cc503 issues, rpms sticking, high o2 volts, expertise needed

So just an update:

I believe I figured out why the RPM's are sticking.

It's because my tb blades are sticking. Who would have thunk it. Driving down the road today and she stuck at 4k rpms so I pulled over and shut it off. Open the hood, and sure enough it's stuck halfway open. Disconnected the throttle cable and it was still stuck. Got it unstuck and went home and readjusted the idle screw so it didn't go back so far. I think it got adjusted too much previously and the blades were sticking sometimes. "snaps" right back into place now. TPS volts are still around .75 at 0 percent throttle, so as far as I know as long as they are between .3 and .9 i'll be fine, no?
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Old 07-24-2018, 08:47 AM
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Re: Cc503 issues, rpms sticking, high o2 volts, expertise needed

I actually mentioned a blade problem as a possibility in post #3. Is it possible you have oil/carbon buildup in the throttle body bores? Common problem if you have a plugged PCV valve, or excessive piston ring blowby.
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Old 07-25-2018, 03:35 AM
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Re: Cc503 issues, rpms sticking, high o2 volts, expertise needed

Yeah, I saw that but for whatever reason hadn't gotten around to really checking it out.

I took the TB out, cleaned it really well, adjusted it to where it wasn't "sticking" anymore and adjusted the TPS to about .5xxx volts closed throttle.

Definitely seems better now, seems as though the high volts going to my o2's were simply because I wasn't ever getting down to 0 percent throttle.

I'm not having any luck with dougs scan tool, it will say connected but the program just freezes. I messed with it for about an hour using all the different ports and it just doesn't want to work. Right now my best bet is to continue just using Torque Pro it seems...

Or, possibly converting over to obd1 and utilizing much cheaper/available tuning software.
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Old 07-25-2018, 09:15 AM
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Re: Cc503 issues, rpms sticking, high o2 volts, expertise needed

Let me see if GaryDoug can help.
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