First start, 7060 to 7427 Conversion - Crazy rich at idle

[Daveo91]

I've spent the last few weeks checking my re-pinning instructions and the re-pinning itself. I'm pretty sure I have everything right. All sensors seem to be providing appropriate data streams, including WBO2. Engine starts fine and idle speed does not seem too out of whack. But in about 10 minutes of total run time (idle and light revs only) the highest I've seen WB02 is in the 12s. Mostly it's been in the 11s and has even pegged down in the low 10s. And the smell of raw gas out the exhaust is pretty intense. The other symptom is the slightest crack of the throttle causes a significant bog, almost to the point of killing the engine, but not quite. Once past the bog, it does seem able to rev.

The only other tuning I've done so far is on the previous 7060. On that computer I would suspect a wrong BPW, but the 7427 doesn't use BPW? Should I adjust injector flow rate? The TBI scalar value is set at 70lbs/hr but I think I'm actually running 74 lbs/hr injectors. I'll have to look up what I have to be sure. Would this difference be enough to cause my problems?

I can provide .xdf, .bin, and a short TP log file if it would help. But I'm hoping someone would give me some ideas of easy stuff to check first.

Thanks.

[dave w]

The '7427 has a parameter for Injector Flow Rate. What is the injector part #?

Gearhead-efi link for TBI injector flow rates: http://www.gearhead-efi.com/Fuel-Injection/showthread.php?81-GM-TBI-Injector-size-color-and-part-numbers

dave w

[Daveo91]

The '7427 has a parameter for Injector Flow Rate. What is the injector part #?

Gearhead-efi link for TBI injector flow rates: http://www.gearhead-efi.com/Fuel-Injection/showthread.php?81-GM-TBI-Injector-size-color-and-part-numbers

dave w

Thanks, Dave. They are 17084304 injectors, 74 lbs/hour. I'm assuming I should change the injector flow rate in my BIN to that number? The .xdf has entries for TBI lbs/hour and grams/sec. Do the conversion and enter both? It also has entries for other fuel injection systems - ok to ignore those?

[tayto]

what pressure

[Daveo91]

what pressure

Good question. I should have checked since I have a gauge at the TB. I will check next time I run it, but it usually runs around 13 psi. Too much?

Thank you.

[stew86MCSS396]

13 psi should be fine. That xdf regarding lbs/hr gms/sec, you change 1 and they all change respectively based on "fuel injection system." :thumbsup:

[Daveo91]

13 psi should be fine. That xdf regarding lbs/hr gms/sec, you change 1 and they all change respectively based on "fuel injection system." :thumbsup:

Thanks!

I changed the 70 lbs/sec to 74. Ran it again after that and it seems to have helped, but still very rich. Actually was able to drive it this time. After a long warm up it will rev and accelerate without bogging, at least enough to drive. I got it to go into closed loop and much more driveable in that scenario, but most BLMs are 110 or below, some pegging low at 90. It seems rich across the range.

My question is what to adjust? Should I adjust VE table as I know how to do? (Dave W's averaging spreadsheet) Or should I adjust more globally, since it's rich everywhere? If globally, how do I do that? Change the injector flow rate?

One other thing: the mask I'm using shows manifold air temp as -40 deg C. I noticed there is a flag for MAT that is NOT check marked so I think it shouldn't matter? But I just want to ensure that there's not a problem with the computer thinking the air coming in is freezing cold. Engine Temp and coolant temp values appear to be correct.

[dave w]

I would try injector flow of 78, with the expatiation that all BLM averages will increase from rich (less than 128) to a number much closer to 128. An injector flow rate that has some VE cells with BLM averages rich and some VE cells with BLM averages lean is a good setting.

The Manifold Air Temperature settings are correct, and -40 temperature is correct too.

dave w

[Daveo91]

I would try injector flow of 78, with the expatiation that all BLM averages will increase from rich (less than 128) to a number much closer to 128. An injector flow rate that has some VE cells with BLM averages rich and some VE cells with BLM averages lean is a good setting.

The Manifold Air Temperature settings are correct, and -40 temperature is correct too.

dave w

Thank you, Dave. I've gone up to 78 on injector flow rate - it improved things, but still very rich. No BLMs are above 128, most are in 110s or lower. Should I just keep increasing flow rate in 4 lbs/hr increments until I see some BLM values over 128?

One other thing: at warmed up idle, closed loop, spark advance is jumping around a ton, all between 15 and 25, mostly between 15 and 20. Something to be concerned about?

[dave w]

Verify the O2 sensor is working correctly by looking at the voltage swings in the "Monitors" screen of TunerPro RT. If the O2 sensor is working correctly, then increase the injector flow another 4 lbs. It seems unlikely the injector flow would be greater than 86 lbs.

The idle SA is somewhat concerning, swings of a few degrees is normal. Idle SA swings of 10 or more degrees is concerning.

dave w

[Daveo91]

Verify the O2 sensor is working correctly by looking at the voltage swings in the "Monitors" screen of TunerPro RT. If the O2 sensor is working correctly, then increase the injector flow another 4 lbs. It seems unlikely the injector flow would be greater than 86 lbs.

The idle SA is somewhat concerning, swings of a few degrees is normal. Idle SA swings of 10 or more degrees is concerning.

dave w

Thank you, Dave. From what I know about the NBO2, it looks like it's working normally by watching the monitor. Pretty regular swings from 100 to 900 mV. It does plateau low or high for a few seconds at times, but then starts swinging again. I'm going to bump up flow rate to 82 lbs and see what happens.

As for SA, I also plotted that on the monitor and it looks more normal there. Previously I was just watching it on the analog gauge in TP dashboard. At the end of the drive I let it idle for several minutes in closed loop and the SA stayed pretty close to 17-18, with swings of a degree or two either way, but very consistent. It did bounce around quite a bit more if I rev'd it, but I think that's expected. I also noticed that SA was very large (40-41) on cold start up and linearly decreased as engine warmed. Weird?

[Daveo91]

The idle SA is somewhat concerning, swings of a few degrees is normal. Idle SA swings of 10 or more degrees is concerning.

dave w

Finally got back to tuning today and noticed that today's log and the most recent one before that Code 43, Knock Sensor Circuit is being set. I haven't had a chance to look underneath yet, but I'm wondering if my knock sensor circuit is open or broken. I've had problems with wiring down there by the exhaust before - maybe it melted. Could an open on that wire cause fluctuating advance at idle?

Haven't ruled out traditional ignition problems, either, e.g. plug wires, distributor, coil, etc. At hot idle I can hear slight fluctuations in the exhaust note that seem to correspond to fluctuations in spark advance.

[Daveo91]

Checked the wire from PCM to knock sensor: not melted and there's continuity between the PCM connector (B15) and the connector at the KS. So now I guess it's time to do the full diagnostics on the KS circuit? Some more data:

- KS is brand new Delphi, AS10016.
- First data logs after '7427 install did NOT flag code 43, or any other code.
- SES lights intermittently, but rarely and for a short time. Has lit after both accel and decel as well as at cold idle.

Maybe the connection at the KS is just loose? Thoughts on what to check next? It seems like there are some voltage checks one can do on the KS circuit, but I've read some conflicting data on the 'net.

[dave w]

Maybe if the KNK was temporarily disabled in the chip will help with the diagnostics troubleshooting.

dave w

[Daveo91]

Maybe if the KNK was temporarily disabled in the chip will help with the diagnostics troubleshooting.

dave w

Thank you, Dave. I can do that. But sorry for my ignorance, what will that tell me? Should I expect to see a more stable spark advance if I disable?

[dave w]

Thank you, Dave. I can do that. But sorry for my ignorance, what will that tell me? Should I expect to see a more stable spark advance if I disable?

Yes, disabling the KNK might provide a more stable spark advance. Possibly indicating the Memcal knock filter circuit is faulty, or PCM is faulty / PCM not faulty.

dave w

[Daveo91]

OK, I have knock retard disabled in the .bin. At least I think I do. I have min temp, RPM, and MPH for knock retard all set at maximum values, and I unchecked the "Set" check box for Code 43. But as soon as start the data stream, engine running or not, the flag sets? Not sure why, I must be doing something wrong in TunerPro? Assuming I actually do have it disabled, I'm still not seeing any change. Lots of fluctuation on spark advance at idle, more than 5 degree swings. But not seeing SES light, not hearing any knock on driving, and advance settles down with any load/throttle.

I'm going to start checking the obvious stuff. Timing, dist cap, rotor, plug wires.

[dave w]

Setting the KNK enable parameters to maximum will normally disable the KNK. Disabling code 43 will normally disable the SES from illuminating if code is set.

It appears from the post above, disabling KNK had no effect on timing swings, so re-enabling KNK is a good plan.

It's normal to see some timing fluctuations of a few degrees at idle with a timing light. More than 5 degrees is outside of the normal range.

Perhaps the Ignition Module is degraded?

dave w

16888

[Daveo91]

Setting the KNK enable parameters to maximum will normally disable the KNK. Disabling code 43 will normally disable the SES from illuminating if code is set.

It appears from the post above, disabling KNK had no effect on timing swings, so re-enabling KNK is a good plan.

It's normal to see some timing fluctuations of a few degrees at idle with a timing light. More than 5 degrees is outside of the normal range.

Perhaps the Ignition Module is degraded?

dave w



Thank you, Dave. I haven't actually checked with a timing light, but I will do that next. It's been quite a while since I've checked timing. I figure while I'm doing that I'll take a look at each plug wire with the light, just to make sure nothing odd going on with a given cylinder.

I am trying to remember when the last time was I replaced the ignition module. I may have a working one still around. If I find it I will put it in to see if that changes anything. Thanks for the tip.