I’m baaaack. Please excuse long post, don’t want to leave anything out.
Long read, I think I’m getting to where you guys are going to recommend…

‘94 Z M6 is at my mechanic’s.

Car was sitting for 14 years with drivability issues.

Mechanic approached this from “car hasn’t run in forever” point of view.
Replaced:
Fuel tank, fuel pump, some fuel lines.
Starter, alternator, A/C compressor & expansion valve.
2x O2 sensors & took my terrible splices out.
EGR valve (only).

Injectors (LS???) were serviced by Injector Connection (they verified appropriate for my tune).

Started - same horrible miss - same as what shut me down in the first place.
Pulled plugs and discovered #5 MSD Super Conductor wire burned to the conductor - plug looked un-fired.

Installed Accel P526S platinum shorty plugs and Summit “standard” wires. Now, I can fit a finger between the boot and the header.

After all of that started and idled fine. Blasted down the road and ran well (100+ degrees last 3 weeks…SES light on dash. Down on power and sub 500 rpm idle.
Shut off, restart - light out and ok again.
This went on repeatedly, with SES light coming on and slow idle/low power.
Note, that when running without the SES light, seems to run as I remember- smooth & strong.

Went down the ALDL to OBDI/II rabbit hole and bought an adapter plug. Realize that ALDL is not powered, however, Blue Point scanner has power and we finally were able to pull DTC 42. (ONLY code we pulled with Blue Point scanner)
Based on the symptoms (run down road, light comes on, etc), seemed like ICM could be it, as shut down for 15-30 seconds resulted in normal running. (Felt that, perhaps, ICM was bleeding off heat and “working”)

Replaced ICM with Delco Gold and it made 10 miles before SES. (Furthest yet)
ALSO, now had ABS INOP light.

New front hubs (sensors) were already installed, brake fluid changed (res full). Noticed “BRAKE” light not lit with parking brake engaged. Took console apart and debris blocking PB switch. Fixed that, ABS INOP gone.

Downloaded SCAN9495 & built cable last night.
looks to be communicating.
Only “permanent” DTC is 24 “VSS” vehicle speed sensor (BTW, speedometer is NOT working).

When in the DTC mode on the scanner, numerous codes appear for split second, but don’t stay. (Video them with iPhone and play back to read)

Also, after clearing the DTC 24, when in Engine mode, red flashes can be seen on the DTC field, but nothing sticking (yes, engine is running throughout).

Next, we went to the “Chart” screen and selected MAF, MAP, TPS & Spark Advance.

At idle, spikes can be seen on MAP & MAF -
there was even a spike on timing.

TPS seems to be OK, as with the engine off voltage climbs with no “dead” spots throughout accelerator pedal travel.

So, I’m ordering a new MAP (and plug), MAF , VSS, EGR Valve Control Solenoid (valve was already replaced, as was PCV valve).

I have door lock actuators coming (no action from them).
In addition to the speedometer not working, the radio won’t come or or display time.

I looking for some direction here. Never even had an SES light prior to trying to get this car back on the road.

If there is something else we should be charting, please let me know what it is.

BTW, if you search my previous posts (2009!!) it will tell you about the car and what had been going on.

Nitrous and Dealer added alarm system have been removed.

Thanks,
Chris
Fort Worth
214-762-2910








for llWe (he)

 

Find and verify all grounds. ALL.

 

Also, go through the wire harness and look for places where mice (or whatever) might have chewed some wires.

 

We did have rodent issues- replaced some connectors & wires (several grounds).
Unplugged and re-plugged lots of connectors.
Even removed PCM, opened it up, looking for smoked caps, corrosion, etc.

As far as the “flash” DTC’s that come up on the DTC screen, for just an instant.. is that a normal thing for this scan tool?
OR, can those be actual faults, that are not “severe” enough to log?

 

Has little to do with Scan9495. I can ask GaryDoug to comment, and advise whether the construction of a cable could contribute to the problem.

Typically it’s the result of interference on the data wire. Yours sounds excessive - both the false DTC’s and the spikes on some of the sensors. Some logs have none of those, some have a few that are easy to find and weed out so I can use various data analysis techniques. A few have many glitches, which makes it difficult if not impossible to analyze the data.

Was the verification of the injector sizing based on the LT1 43.5 psi operating pressure, or the LSx 58 psi (assuming “LS???” indicates you are unsure what the injectors are from?

Have you spaced the ICM/coil bracket away from the head?

4th Gen LT1 F-body Tech Articles

Was the fuel filter replaced? Have you checked fuel pressure?

Run a data log from a cold start, per my guidelines. Do as many steps as possible until it stalls or becomes undrivable. I have stopped reviewing logs, but in this case I'll make an exception.

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

 

Thank you for your reply and offer of assistance.

1. Injectors are 0280155931 Bosch, 24lbs/hr @43.5psi (sure you know that). Injector Connection did not supply these, only serviced them. He says these are the injectors he would spec for a stock LT1 with my tune/bolt-ons, as they have a superior spray pattern vs. stock injectors.

2. Have NOT spaced ICM & MSD Blaster Coil, but I will.

3. Yes, new fuel filter. Unsure about pressure check, but will perform at next repair “session”.

My learning curve is straight up using this scan product. I believe that I will have no trouble following your directions for a useable scan.
However, I just need a little help with the logging part:

If I reset the Scan9495, do I just hit “SCAN” and run it through “stall” or “undrivable” situation?

Will this be with only the “Engine” Scan Selection OR should I also scan for “Elect Faults” and/or “ABS” (or others)?

I have reviewed some of the logs from yesterday and it looks like, according to the Excel sheet that it’s generating lines of data 3-7 times per second. Does this need to be adjusted or is this what you are looking for?

Also, is there anything I should “Chart”, for the 4 parameters available?

Thanks!
Chris

 

I'll have to get Gary to answer your questions on Scan9495. I have looked at hundreds of data logs, but have never used Scan9495. My Formula was running a MoTeC aftermarket ECU, with built in data display and logging capabilities.

@GaryDoug

 

You may have a problem with the alternator causing voltage spikes. Try disconnecting it while running another scan. The alternator does have brushes for the rotor current and they may be very worn.
You should not have to change any options in Scan9495 for almost all situations.

Follow the 4 steps shown on the panel.

For datalogging, you can do that either or both of two ways.
1. Run the scan and click on "Save scan to log file" afterwards before resetting. This makes for the fastest scan but you have to remember to do it at the end. Sometimes I click on that many times during the scan just to be safe. Each click will make a new file.
2. Before starting a scan, check the box labeled "Auto-save scan file". The file will be saved but the scan will slow down as the file grows in size.

 

Thanks for the information.
I built my own cable, per your instructions.
As stated previously, I have at least 1 log.

Alternator is AC Delco from RockAuto. Also have new battery.

Shall I hold off on new MAP, MAF & EGR Solenoid? We are getting those based solely on the spikes on the Charting Screen.
Or, at least scan “Before” & “After”?
Might not be able to scan again until Sunday

Chris

 

I wouldn’t rush out and buy parts based on the oddball readings. The log needs to be looked at.

 

Thanks

 

Like Right Said Fred ... the spikes have nothing to do with your sensors. Might be just a flaky ground path.
I have recently revised my recommendations about making your own cable. Much of the parts are not very reliable to do that anymore. I would buy one from these guys: https://obd2allinone.com/aldl.asp
But not the "river" guy.

 

UPDATE.

Well, after several data logging sessions, the only DTC that stuck is the VSS (vehicle speed sensor). After all, the speedometer has not worked since the resurrection process began.
So, after replacing the MAF, MAP & EGR Solenoid, the car runs really well, although it throws that VSS code.
Car was hot, with no access to lift, last Saturday.
So, I’m driving it with my laptop connected (ala Fast n Furious 12 minute drag race). Whenever the SES light comes on, it runs poorly and doesn’t want to idle. I found that I can reset the code, with the scan tool and it goes back to normal.
My mechanic replaced the VSS last week and discovered that the lock on the plug was broken and it had backed off! This, after my original concern was all about that sensor, when the speedo didn’t work.
Anyway, drove it about 25 miles on Sunday, ran great and no hard DTC’s.
I would argue that it has never run better (and this, with 97-104 degree temps)
It still “flashes” numerous, random DTC’s, but none are sticking in the DTC window. Is this normal?
How about the 1000’s of knock counts? I do have the LT4 knock module.

Thanks for all the help.

Chris

 

The random, spurious codes are common in some cars. Often accompanied by similar one-off impossible sensor and PCM parameter readings. As I understand it this is caused by interference on the data wire. Way back in the day (20 years ago) when TTS DataMaster was the primary OBD-1 scanning software, their instructions included a caution about spurious data generated by such interference. Only happens with a minor % of users. I'd say 75%-85% of the hundreds of Scan9495 logs I've reviewed over the years are free of these glitches. The remainder range anywhere from a “few” to “many”, sometimes rendering the data difficult to impossible to process with my preferred manipulations of data in Excel.

Knock count is a vague, cumulative field. When the PCM is reset, knock count starts at “0”. It then increments upwards with use. Not unusual to see it ramp up a couple thousand counts on startup. Keeps increasing, until it reaches 65,535 (2^16). The absolute number is not important, what is important is how fast it is increasing. I have never been able to correlate changes in knock count to actual knock. I've seen knock retard with no change in knock count. I've seen a big jump in knock counts, with no knock retard. I honestly don’t understand it. Focus first on indicated knock retard. When I see a sudden jump in knock count, but no knock retard, I look at the immediately preceding O2 sensor readings for a lean condition, look at throttle position % to see if knock count is generated by some algorithm that considers things that might cause knock. Again, focus on “knock retard”.

 

Thanks.
To clarify, by data wire, do you mean the one already in the car, or the ALDL-to-USB that I assembled?
GaryDoug told me to buy one from the “PCM” guy, but with $18 shipping on a 1/4lb item (matter of principle), I decided to go with mine, assuming ALL of those codes could not be correct.

Again, I’d argue that it is running better than it was prior to my NOS Experiment:

New Accel Platinum Plugs
Reman Delco MAF
Delco MAP

BTW, I swapped the SLP Loudmouth “resonator” for their same-sized “muffler”. 51% less obnoxious.