Extreme rich condition - Page 8 - ZR-1 Net Registry Forums

Perry Mitchell · 07-12-2020

Time for an update. Because the consensus is that I have tied the injectors to the ECM in pairs since I do not have the secondary relay modules, Marc has provided me with another re-calibrated prom that reduces the fuel flow by 50% at idle. I cleaned the AIT sensor and the IAC sensor. I adjusted the TPS to .55 volts. The engine started and idled as before but this time I had no obvious rich condition at idle. But when the engine ran for 2 minutes, the rich condition seemed to re-appear. I am getting close but not there yet. I purchased an ALDL to USB cable and am trying to figure out the Tuner Pro application. I will let you know what I find out. Thanks Marc.

-=Jeff=- · 07-12-2020

Alright.. so the theory was right on the fuel. I have to wonder if the paired injectors are causing more load on the ECM. Based on you description, I wonder if it is going to closed loop after 2 minutes and the fuel tables might be off due to the way you have the injectors.

If you need help with TunerPro, I use it all the time and I helped create some of the ADX files

Perry Mitchell · 07-12-2020

My brother and I were trying to download the application on my laptop but were having trouble with it. He took the CD and cable with him to work on it this week. He is much more tech savvy than me so I know we will have a working solution next week when he returns. I also wondered if the computer went in to closed loop as well.

-=Jeff=- · 07-12-2020

Cool..

I have a nice ADX setup with a dash board for TunerPro.

XfireZ51 · 07-12-2020

Quote:

Originally Posted by Perry Mitchell

My brother and I were trying to download the application on my laptop but were having trouble with it. He took the CD and cable with him to work on it this week. He is much more tech savvy than me so I know we will have a working solution next week when he returns. I also wondered if the computer went in to closed loop as well.

Depend on what coolant temp was when engine was started. If CTS is >20C and <70C, C/L happens in 150seconds.
I agree w Jeff that the ?paired? injectors very likely would put a load on the ECM that I wouldn?t be comfortable w for the long term. Its the reason why the secondaries use the secondary relays to drive the injectors, altho they get their pulse width command from the primary.
One possible reason ur still getting rich condition even after cutting the idle fuel by 50% is because as the secondary injector gets it PW command from the primary, the ECM is still calculating the PW based in part on the Injector Bias. The IB the amount of time the ECM calcs in the PW for the injector to open. In a stock calibration that IB will be 579usec for the stock injectors. Plus there?s an additional 45-76usec for small PW (as in idle operation) since the stock injectors were not linear. This is assuming that the ECM is seeing 14.4 Batt voltage. If its less the IB is larger. Your use of FIC injectors also adds to the error in PW calc.
In your case, the ECM adds that IB to the calc?d PW, but it is doubled by the fact that the secondary injector is also firing. And the calibration doesn?t allow for you to modify the IB just for idle conditions. You could scale the IB back, but then it would be incorrect for all other engine operating conditions aside from idle.
Idle won?t be the only area affected. It will be rich also on decel w TPS at 0% and DFCO disabled.

Marc Haibeck · 07-12-2020

Perry,

Based on your observations, we may need to remove more fuel. We need to proceed carefully because if we remove too much it could lead to stalling which is a worse problem. A cold engine will tolerate a rich mixture because it needs more fuel. As the engine warms it needs less fuel so a rich condition can get worse as the engine warms. Since you are close to having scan data we should wait until you can observe the BLM and Integrator fuel trim values. Also report the TPS%. And the Port Throttle status, Open verses Closed.

In the meantime take a look at the oxygen sensor wiring. Make sure that there is a connector a few inches away from the sensor. The wires should not be hardwired and taped. The connectors should not have tape on them either. The sensor gets reference oxygen through the wires.

Perry Mitchell · 07-13-2020

You guys are talking way over my head now. What do BLM, IB and DFCO stand for. I hope my brother can understand your lingo. I know, with the help from you guys, we will get this figured out. Marc, the O2 sensors have a pigtail with a connector that is about 8'' long. They have a covering on some of it that is loose but then so did the original sensors.

XfireZ51 · 07-13-2020

IB Injector Bias. Injectors have an opening and closing lag which must be accounted for when calculating Pulse width. Think of it the same way you think of Spark Advance. If the the Pulse Width is calculated as X, then the ECM must take into account how long it takes the injector to open in order to meter the fuel properly. The amount of time that it takes for the injector opening is dependent on the voltage available at the injector. The higher the voltage, the faster it opens. Its also a static number. Therefore, it is a significant fraction of the calculated PW when the PW is small, ie as in idle and decel operation.
Different injectors have different Injector Bias depending on their electrical properties.

DFCO- Decel Fuel CutOff - during deceleration w closed throttle, fuel is cutoff for emissions purposes. If this is disabled, then fuel will continue albeit at very small PW. In your case both injectors will continue firing.

BLM Block Learn Multiple. Used by ECM to adjust fueling when in Closed Loop.

Perry Mitchell · 07-13-2020

Thank you Dominic. I never would have figured those abbreviations out . I asked Siri what BLM stood for and all she said was Black Lives Matter which is fine but not what I was looking for.

Marc Haibeck · 07-14-2020

Perry,

The data items that I requested will be easy to find once you get the scanner working. The names will be on a list that is filled in with data from the engine.

You can you can write the numbers down and report them here. Or if you have the time you can learn how to record them on a graph and post the graph here.

From your description it seems like your oxygen sensor cables are okay.

07-12-2020	#71
Perry Mitchell Join Date: Nov 2018 Location: Washington Posts: 98	Re: Extreme rich condition Time for an update. Because the consensus is that I have tied the injectors to the ECM in pairs since I do not have the secondary relay modules, Marc has provided me with another re-calibrated prom that reduces the fuel flow by 50% at idle. I cleaned the AIT sensor and the IAC sensor. I adjusted the TPS to .55 volts. The engine started and idled as before but this time I had no obvious rich condition at idle. But when the engine ran for 2 minutes, the rich condition seemed to re-appear. I am getting close but not there yet. I purchased an ALDL to USB cable and am trying to figure out the Tuner Pro application. I will let you know what I find out. Thanks Marc.

07-12-2020	#72
-=Jeff=- Join Date: Jul 2007 Location: Bartlett, IL Posts: 7,152	Re: Extreme rich condition Alright.. so the theory was right on the fuel. I have to wonder if the paired injectors are causing more load on the ECM. Based on you description, I wonder if it is going to closed loop after 2 minutes and the fuel tables might be off due to the way you have the injectors. If you need help with TunerPro, I use it all the time and I helped create some of the ADX files __________________ 1990 Corvette ZR-1 #1051 Watson Headers (2" Primary) - Flowmaster Cats - Borla Catback Late Model IH - Plenum Coilovers - 4.10s Custom Interior NCM Lifetime Member #978

07-12-2020	#73
Perry Mitchell Join Date: Nov 2018 Location: Washington Posts: 98	Re: Extreme rich condition My brother and I were trying to download the application on my laptop but were having trouble with it. He took the CD and cable with him to work on it this week. He is much more tech savvy than me so I know we will have a working solution next week when he returns. I also wondered if the computer went in to closed loop as well.

07-12-2020	#74
-=Jeff=- Join Date: Jul 2007 Location: Bartlett, IL Posts: 7,152	Re: Extreme rich condition Cool.. I have a nice ADX setup with a dash board for TunerPro. __________________ 1990 Corvette ZR-1 #1051 Watson Headers (2" Primary) - Flowmaster Cats - Borla Catback Late Model IH - Plenum Coilovers - 4.10s Custom Interior NCM Lifetime Member #978

07-12-2020	#76
Marc Haibeck Join Date: May 2007 Location: Addison IL Posts: 241	Re: Extreme rich condition Perry, Based on your observations, we may need to remove more fuel. We need to proceed carefully because if we remove too much it could lead to stalling which is a worse problem. A cold engine will tolerate a rich mixture because it needs more fuel. As the engine warms it needs less fuel so a rich condition can get worse as the engine warms. Since you are close to having scan data we should wait until you can observe the BLM and Integrator fuel trim values. Also report the TPS%. And the Port Throttle status, Open verses Closed. In the meantime take a look at the oxygen sensor wiring. Make sure that there is a connector a few inches away from the sensor. The wires should not be hardwired and taped. The connectors should not have tape on them either. The sensor gets reference oxygen through the wires. Last edited by Marc Haibeck; 07-12-2020 at 06:58 PM.

07-13-2020	#77
Perry Mitchell Join Date: Nov 2018 Location: Washington Posts: 98	Re: Extreme rich condition You guys are talking way over my head now. What do BLM, IB and DFCO stand for. I hope my brother can understand your lingo. I know, with the help from you guys, we will get this figured out. Marc, the O2 sensors have a pigtail with a connector that is about 8'' long. They have a covering on some of it that is loose but then so did the original sensors.

07-13-2020	#78
XfireZ51 Join Date: May 2007 Location: Chicagoland, IL Posts: 9,698	Re: Extreme rich condition IB Injector Bias. Injectors have an opening and closing lag which must be accounted for when calculating Pulse width. Think of it the same way you think of Spark Advance. If the the Pulse Width is calculated as X, then the ECM must take into account how long it takes the injector to open in order to meter the fuel properly. The amount of time that it takes for the injector opening is dependent on the voltage available at the injector. The higher the voltage, the faster it opens. Its also a static number. Therefore, it is a significant fraction of the calculated PW when the PW is small, ie as in idle and decel operation. Different injectors have different Injector Bias depending on their electrical properties. DFCO- Decel Fuel CutOff - during deceleration w closed throttle, fuel is cutoff for emissions purposes. If this is disabled, then fuel will continue albeit at very small PW. In your case both injectors will continue firing. BLM Block Learn Multiple. Used by ECM to adjust fueling when in Closed Loop. __________________ [SIGPIC][/SIGPIC]Former Membership Chairman Former ZR-1 Registry - BOD 1972 Corvette 4speed base Coupe SOLD long time ago 1984 Corvette Z-51/4+3 SOLD 1992 Corvette ZR-1 Aqua/Gray #474 SOLD 1992 Corvette ZR-1 Black Rose/Cognac #458 2014 Honda VFR Interceptor DX Last edited by XfireZ51; 07-13-2020 at 01:03 PM.

07-13-2020	#79
Perry Mitchell Join Date: Nov 2018 Location: Washington Posts: 98	Re: Extreme rich condition Thank you Dominic. I never would have figured those abbreviations out . I asked Siri what BLM stood for and all she said was Black Lives Matter which is fine but not what I was looking for.

07-14-2020	#80
Marc Haibeck Join Date: May 2007 Location: Addison IL Posts: 241	Re: Extreme rich condition Perry, The data items that I requested will be easy to find once you get the scanner working. The names will be on a list that is filled in with data from the engine. You can you can write the numbers down and report them here. Or if you have the time you can learn how to record them on a graph and post the graph here. From your description it seems like your oxygen sensor cables are okay.