Bosch III injectors are NOT interchangeable w/o tuning
09-22-2017, 01:27 PM
#51
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Thread Starter
09-22-2017, 01:29 PM
#52
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Thread Starter
Re: Bosch III injectors are NOT interchangeable w/o tuning
Just put this post on the other thread about the bosch lll's:
Want to say that I'm sorry that some of you are having difficulty with the bosch lll injectors. It's kind of upsetting to us as we've been selling these injectors for just about 10 years and we've sold well over 10,000 of them.. Our customers have been extremely happy with them. They never called to tell us that they needed a tune or that they're BLM's were too high after installing the injectors. We go by customer feedback. I hear your frustration however I do not have an answer for you....I wish I did. What's confusing to me is that after selling so many of these things throughout the years you would think that I would have heard something and that's why I'm at a loss, not to say that there may have been some issues however I was not aware of them. I spent hours on the phone yesterday trying to get some info for all of you. Spoke to a contact of ours from Ford who tried desperately to help me yet could not find any info. He told me to try calling Motorcraft which I did, they told me to call bosch which I did and spoke with someone in the Bosch technical support department. I asked them for the specs/voltage offsets for the injectors..they have them yet they told me that they couldn't release the info to me for proprietary reasons.
They told me to call Ford Again so I spoke with someone in Michigan who could not help me. I'm not sure what the big secret is. I purchased a couple of new ones yesterday in hopes that the info will be inside the box...but something tells me that we couldn't be so lucky. We have been a sponsor on this forum for many years and it's very important to us that you are happy with our service and products. As always we will be here to help in anyway we can. I'll continue to research this issue in hopes that I can come up with some info that will be helpful to you.
__________________
Want to say that I'm sorry that some of you are having difficulty with the bosch lll injectors. It's kind of upsetting to us as we've been selling these injectors for just about 10 years and we've sold well over 10,000 of them.. Our customers have been extremely happy with them. They never called to tell us that they needed a tune or that they're BLM's were too high after installing the injectors. We go by customer feedback. I hear your frustration however I do not have an answer for you....I wish I did. What's confusing to me is that after selling so many of these things throughout the years you would think that I would have heard something and that's why I'm at a loss, not to say that there may have been some issues however I was not aware of them. I spent hours on the phone yesterday trying to get some info for all of you. Spoke to a contact of ours from Ford who tried desperately to help me yet could not find any info. He told me to try calling Motorcraft which I did, they told me to call bosch which I did and spoke with someone in the Bosch technical support department. I asked them for the specs/voltage offsets for the injectors..they have them yet they told me that they couldn't release the info to me for proprietary reasons.
They told me to call Ford Again so I spoke with someone in Michigan who could not help me. I'm not sure what the big secret is. I purchased a couple of new ones yesterday in hopes that the info will be inside the box...but something tells me that we couldn't be so lucky. We have been a sponsor on this forum for many years and it's very important to us that you are happy with our service and products. As always we will be here to help in anyway we can. I'll continue to research this issue in hopes that I can come up with some info that will be helpful to you. __________________
Maybe I'm being too simplistic in my thinking, but if you have a flow bench and can simply vary the input voltage to the injector, wouldn't it be the case that you could generate an offset table for a given injector type?
If the flow rates are kept within a narrow tolerance range, then a one time characterization for a given injector p/n should be enough to support the entire product line of that injector.
Even if what you achieve is not the same as Bosch's rating down to the last micro second, the reality is that any residual difference will not be noticed by 90% of users if you get within 10-15% of Bosch's rating. And for those folks who are as **** as I am, they can go after that last 10-15% with some additional fine tuning.
Last edited by ULTM8Z; 09-22-2017 at 01:33 PM.
09-22-2017, 01:32 PM
#53
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Re: Bosch III injectors are NOT interchangeable w/o tuning
I have the 22lb Bosch IIIs on my otherwise stock 350 from Southbay and they also peg my BLMs at 160 at idle. Nothing indicates anything other than the injectors as the cause, so I do want to move away from them unless I can get it tuned properly.
09-22-2017, 01:42 PM
#54
Re: Bosch III injectors are NOT interchangeable w/o tuning
https://www.thirdgen.org/forums/diy-...or-sticky.html
It would be great to see the data on the 700 and 710 injectors.
They are having trouble getting any information from there supplier.
09-22-2017, 01:50 PM
#55
Re: Bosch III injectors are NOT interchangeable w/o tuning
Ack, you are right! So hard to keep this stuff straight sometimes. Thanks! I corrected my post. The mistake lives on though in the embedded quotes.
Last edited by Tootie Pang; 09-22-2017 at 02:13 PM.
09-22-2017, 02:21 PM
#56
Sponsor
Re: Bosch III injectors are NOT interchangeable w/o tuning
Thanks man.
With regards to the 771's being rated at 17lb, that is not accurate. There is a lot of info on the net that unfortunately is not correct. There are many variables. First you need to know who came up with this flow rate and how? What calibration fluid was used? What machine did they use? etc
I can tell you that they flow 19lb @ 43.5 psi on our benches. And once again we have been selling them forever as 19lb injectors.....go figure
With regards to the 771's being rated at 17lb, that is not accurate. There is a lot of info on the net that unfortunately is not correct. There are many variables. First you need to know who came up with this flow rate and how? What calibration fluid was used? What machine did they use? etc
I can tell you that they flow 19lb @ 43.5 psi on our benches. And once again we have been selling them forever as 19lb injectors.....go figure
09-22-2017, 02:28 PM
#57
Supreme Member
Thread Starter
Re: Bosch III injectors are NOT interchangeable w/o tuning
The 17 lb value being in the ECM does not indicate the injectors flow 17 lb/hr.
It only means that in the context of everything else that has been programmed into the ECM for fueling (VE tables, injector offsets, O2 sensor swing points, stoich constant, etc), that in order for the ECM to deliver the correct amount of fuel to maintain ~128 BLMs, it has to command the injectors as if they were flowing 17 lb/hr.
I'm running 31 lb/hr on my 30 lb/hr Bosch-III's. So it's not even the case that you always go smaller on the flow rate constant.
It only means that in the context of everything else that has been programmed into the ECM for fueling (VE tables, injector offsets, O2 sensor swing points, stoich constant, etc), that in order for the ECM to deliver the correct amount of fuel to maintain ~128 BLMs, it has to command the injectors as if they were flowing 17 lb/hr.
I'm running 31 lb/hr on my 30 lb/hr Bosch-III's. So it's not even the case that you always go smaller on the flow rate constant.
09-22-2017, 02:45 PM
#58
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Car: 1989 Pontiac Formula 350
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Re: Bosch III injectors are NOT interchangeable w/o tuning
Southbay is working on getting the offsets in another thread.
https://www.thirdgen.org/forums/diy-...or-sticky.html
It would be great to see the data on the 700 and 710 injectors.
They are having trouble getting any information from there supplier.
https://www.thirdgen.org/forums/diy-...or-sticky.html
It would be great to see the data on the 700 and 710 injectors.
They are having trouble getting any information from there supplier.
I'll just remain on standby on the subject for now. I don't think it's needed, but I can provide datalogging of my ride if needed.
09-22-2017, 02:55 PM
#59
Sponsor
Re: Bosch III injectors are NOT interchangeable w/o tuning
It almost seems like something you guys could characterize on your own?
Maybe I'm being too simplistic in my thinking, but if you have a flow bench and can simply vary the input voltage to the injector, wouldn't it be the case that you could generate an offset table for a given injector type?
If the flow rates are kept within a narrow tolerance range, then a one time characterization for a given injector p/n should be enough to support the entire product line of that injector.
Even if what you achieve is not the same as Bosch's rating down to the last micro second, the reality is that any residual difference will not be noticed by 90% of users if you get within 10-15% of Bosch's rating. And for those folks who are as **** as I am, they can go after that last 10-15% with some additional fine tuning.
Maybe I'm being too simplistic in my thinking, but if you have a flow bench and can simply vary the input voltage to the injector, wouldn't it be the case that you could generate an offset table for a given injector type?
If the flow rates are kept within a narrow tolerance range, then a one time characterization for a given injector p/n should be enough to support the entire product line of that injector.
Even if what you achieve is not the same as Bosch's rating down to the last micro second, the reality is that any residual difference will not be noticed by 90% of users if you get within 10-15% of Bosch's rating. And for those folks who are as **** as I am, they can go after that last 10-15% with some additional fine tuning.
believe me if it was that easy I would have the info on every single injector
09-22-2017, 03:13 PM
#62
Supreme Member
Thread Starter
Re: Bosch III injectors are NOT interchangeable w/o tuning
For a modified car, it would indicate your VE tables and everything contributing to closed loop fueling are ok. But unless you knew ahead of time that your Open Loop and Power Enrich AFR's were also good (using a WB O2), then there's no gaurantee you're good in non-closed-loop operation
09-22-2017, 03:27 PM
#63
Re: Bosch III injectors are NOT interchangeable w/o tuning
I think for every engine. If there are no leaks and the BLMs are good, then wouldn't it be setup right? Yes, closed loop only. For sure.
I'll shut up now because I'm waaay out of comfort zone
I'll shut up now because I'm waaay out of comfort zone
09-22-2017, 03:49 PM
#64
Supreme Member
Thread Starter
Re: Bosch III injectors are NOT interchangeable w/o tuning
Not really... if you've modified your car and attempted to redo the fueling without a WB to look at actual AFRs, in a worst case scenario you can have perfect BLMs in closed loop but still have AFRs so lean in PE that you could damage the engine.
09-22-2017, 04:16 PM
#65
Re: Bosch III injectors are NOT interchangeable w/o tuning
True that, but I am purely talking about a car that is already running without leaks and the BLMs are 128, regardless of injector. If the BLMs are good, then stoic is achieved. If I understand correctly- BLMs are ECM adjustments to the open loop table values to achieve perfect stoic using feedback (rich-stoic-lean) from the narrowband sensor, i.e. closed loop. If the tables are wrong, then the BLMs will have to move way far, probably too far and hit the limit of their adjustment.
Last edited by Tootie Pang; 09-22-2017 at 04:32 PM.
09-22-2017, 06:02 PM
#66
Supreme Member
Thread Starter
Re: Bosch III injectors are NOT interchangeable w/o tuning
Actually BLM's are adjustments to the VE tables to try to achieve stoich.
ECM ignores the open loop tables when in closed loop operation.
When in PE operation (which doesn't actually doesn't go into open loop), the BLM Learn is disabled (and it also ignores the O2 sensor).
ECM ignores the open loop tables when in closed loop operation.
When in PE operation (which doesn't actually doesn't go into open loop), the BLM Learn is disabled (and it also ignores the O2 sensor).
09-22-2017, 09:18 PM
#67
Re: Bosch III injectors are NOT interchangeable w/o tuning
I made a post in here last year about me contacting Southbay about this. At that time, they had no idea what I was talking about and I even referred a thread from here to them. This issue has been going for too long now. I have them in my car and I know somethings not right. I had another vendor flow test my original Multecs just for peace of mind ( I had a ghost white bent valve) . I assumed it was from a failed injector. I bought B3 injectors anyway and then was told that my oem ones were the best flowing injectors they had ever seen. They were perfect. Sadly, I sold them and I wish I never did now.
My car has no cats and it stinks at idle. There is a stumble at part throttle acceleration too. I went from 224/301 stock to 236/300 with the addition of Dyno Don headers and ypipe (no cats, air pump or EGR), magnaflow catback, TPIS intake, SLP runners (both ported), ram air setup behind the fogs with baffle cut out, AFPR (3 psi above stock setting), and a tune from 1MeanZ here.
My car has no cats and it stinks at idle. There is a stumble at part throttle acceleration too. I went from 224/301 stock to 236/300 with the addition of Dyno Don headers and ypipe (no cats, air pump or EGR), magnaflow catback, TPIS intake, SLP runners (both ported), ram air setup behind the fogs with baffle cut out, AFPR (3 psi above stock setting), and a tune from 1MeanZ here.
09-22-2017, 09:33 PM
#70
Supreme Member
Thread Starter
Re: Bosch III injectors are NOT interchangeable w/o tuning
Interesting... do you have Tunerpro data? Ability to burn chips? I wouldn't mind taking a look at your calibration and running data if you're able to send them... maybe can get this injector thing straightened out for ya...
ultm8z@yahoo.com
ultm8z@yahoo.com
09-22-2017, 09:36 PM
#71
Re: Bosch III injectors are NOT interchangeable w/o tuning
Im a total newb when it comes to tuning. I had a local fbody friend/tuner do some live data logging with me last year just so he could see what was going on. I will have to see if there is anything saved in the TunerPro program on my other computer. I dont have a WB because I didnt want to mess with drilling holes in the car but I think I may buy one and just do a quick hook up of it to tune this car. let me get back to you on the tune. I hope I have something saved,
09-22-2017, 09:38 PM
#72
Supreme Member
Thread Starter
Re: Bosch III injectors are NOT interchangeable w/o tuning
yeah, with your setup you shouldn't be getting stumbling like that. My guess is we can get to the bottom of this without a WB... your factory PE and Open Loop tables should be just fine with your current setup, so WB not really needed.
09-24-2017, 12:24 PM
#73
Re: Bosch III injectors are NOT interchangeable w/o tuning
Follow up. Replaced the Multecs with -710's from SouthBay and an adjustable regulator. According to Witchhunter, the -710s are rated at 210cc or 20 lbs. At slightly above stock fuel pressure my INT's are right around 124 at idle, BLM's are around 110. Higher RPM/Loads, BLMs aright near 128. Fantastic! Engine is buttery smooth at idle and up. Still misfires above 4000 at WOT but I'll figure that out later.
Last edited by Tootie Pang; 09-24-2017 at 01:22 PM.
09-24-2017, 01:21 PM
#77
Re: Bosch III injectors are NOT interchangeable w/o tuning
Not sure. I set it to 50 psi initially (no vacuum) and the INTs were running low (108-110). When I had put in the regulator, I took the screw down to touching the spring and then another full turn, this gave me 50 psi. I backed it off 1/4 turn to try to bring the INTs up and that did the trick. I have not checked what the actual pressure is but it has to be lower than 50.
Last edited by Tootie Pang; 09-24-2017 at 01:28 PM.
09-25-2017, 04:22 PM
#78
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Re: Bosch III injectors are NOT interchangeable w/o tuning
Follow up. Replaced the Multecs with -710's from SouthBay and an adjustable regulator. According to Witchhunter, the -710s are rated at 210cc or 20 lbs. At slightly above stock fuel pressure my INT's are right around 124 at idle, BLM's are around 110. Higher RPM/Loads, BLMs aright near 128. Fantastic! Engine is buttery smooth at idle and up. Still misfires above 4000 at WOT but I'll figure that out later.
well this is good news!
Just to add my two cents, the 710's are rate at 20lb on the net...however once again, it depends on what calibration fluid they use. . The 710's flow closer to 21.7lb at 43.5psi but in all honesty the engine will not know the difference between 20 and 21.7lb. I'm sure you know that they actually flow 19lb but it's important to know that it's at Ford pressure which is around 39psi
09-25-2017, 05:25 PM
#79
Re: Bosch III injectors are NOT interchangeable w/o tuning
Agreed. There are lot of elements to flowrates. Fluid, temperature, pressure. When testing injectors the fluid must have the same flow characteristics as gasoline at that temperature and pressure or a conversion function to give a flowrate in gasoline. The flowrate in gasoline is the language these ECMs speak. Flowrates of water, fore example, or honey, without a conversion function, would be completely useless. I would imaging flow testing with gasoline at ambient temperature is the best way to determine the actual flowrate of an injector at a given pressure. Using any other fluids could result in very wrong ratings.
Last edited by Tootie Pang; 09-25-2017 at 05:28 PM.
09-25-2017, 05:39 PM
#80
Re: Bosch III injectors are NOT interchangeable w/o tuning
Check out this engineering discussion on injector flow bench fluids:
http://www.eng-tips.com/viewthread.cfm?qid=117108
And if the engineers can't agree then maybe that helps explain the confusion on the user end.
http://www.eng-tips.com/viewthread.cfm?qid=117108
And if the engineers can't agree then maybe that helps explain the confusion on the user end.
09-25-2017, 06:36 PM
#81
Sponsor
Re: Bosch III injectors are NOT interchangeable w/o tuning
Agreed. There are lot of elements to flowrates. Fluid, temperature, pressure. When testing injectors the fluid must have the same flow characteristics as gasoline at that temperature and pressure or a conversion function to give a flowrate in gasoline. The flowrate in gasoline is the language these ECMs speak. Flowrates of water, fore example, or honey, without a conversion function, would be completely useless. I would imaging flow testing with gasoline at ambient temperature is the best way to determine the actual flowrate of an injector at a given pressure. Using any other fluids could result in very wrong ratings.
don't get me wrong,, I'm not saying that all info on the net is inaccurate...but for the layperson it's difficult to decifer what's correct and what's not. For instance...we have a particular 24lb injector that we sell...it's rated at 17lb on the net..that's a huge difference.
09-25-2017, 07:08 PM
#82
Re: Bosch III injectors are NOT interchangeable w/o tuning
What fluid do you use?
Also, I wonder if the pulsing rate of different injector technologies affects the flow rating (eg. pintle vs disc). So for static flow,thats one thing, but pulsing may be another. Again, I'm just thinking out loud. I have no idea.
Also, I wonder if the pulsing rate of different injector technologies affects the flow rating (eg. pintle vs disc). So for static flow,thats one thing, but pulsing may be another. Again, I'm just thinking out loud. I have no idea.
09-25-2017, 10:54 PM
#83
Re: Bosch III injectors are NOT interchangeable w/o tuning
This is a more complex subject than can be described by a single max flow rate scalar. The problem is that max flow rate is calculated at 100% duty cycle and injectors do not exhibit linearity with respect to duty cycle between 95-100%, or between 0-5% and the rest of the (basically linear) area between 5 and 95% duty cycle..... These high and low flow rates are known as the "non linear upper flow rate area" and "non linear lower flow rate area".
So measuring an injectors max flow rate can be deceptive because two injectors that have the same max flow numbers may have completely different linear flow areas. And guess what - the injectors are virtually never used at max flow rate in practice. They are used at some lower flow rate - especially in circumstances where BLM is in play. At cruise you will be somewhere in the linear flow area - no where near the upper or lower non linear area.
So all this talk of max flow rate is misleading. Max flow rate is not at all important or relevant (except as a rough estimate to tell if they will be "big enough" for the application) unless the injectors being compared have exactly the same non linear upper flow rate area.
I have no data on the linear flow rates of Multecs compared to D3's. I do have an injector flow bench and could generate this data but I don't have injectors to do it with.
GD
So measuring an injectors max flow rate can be deceptive because two injectors that have the same max flow numbers may have completely different linear flow areas. And guess what - the injectors are virtually never used at max flow rate in practice. They are used at some lower flow rate - especially in circumstances where BLM is in play. At cruise you will be somewhere in the linear flow area - no where near the upper or lower non linear area.
So all this talk of max flow rate is misleading. Max flow rate is not at all important or relevant (except as a rough estimate to tell if they will be "big enough" for the application) unless the injectors being compared have exactly the same non linear upper flow rate area.
I have no data on the linear flow rates of Multecs compared to D3's. I do have an injector flow bench and could generate this data but I don't have injectors to do it with.
GD
Last edited by GeneralDisorder; 09-25-2017 at 10:57 PM.
09-26-2017, 08:31 AM
#84
Re: Bosch III injectors are NOT interchangeable w/o tuning
I believe it. It's like I was mentioning, it's their behavior when pulsing (which is always), not stuck open, (max flowrate). And their behavior when pulsing is not linear and its not the same. Sounds like these things have to be thoroughly characterized and the functions of their output characteristics determined and then the tables setup.
09-29-2017, 11:36 AM
#85
Sponsor
Re: Bosch III injectors are NOT interchangeable w/o tuning
Hi guys found some info on the 280155700's...they are the same as the 280155710's
19lb at Ford pressure 22lb at GM pressure. Hope this helps
Bosch EV6 19 lb/hr @ 39.15psi
0-280-155-700 / 0-280-155-710
Low Slope
23.76
High Slope
19.26
Breakpoint
0.00001
VOLTAGE OFFSET
voltage
ms
16.00
0.78
15.00
0.78
14.00
0.78
13.00
0.936
12.00
1.093
11.00
1.25
10.00
1.47
8.00
3.19
6.00
4.19
0.00
4.19
0.00
4.19
0.00
4.19
19lb at Ford pressure 22lb at GM pressure. Hope this helps
Bosch EV6 19 lb/hr @ 39.15psi
0-280-155-700 / 0-280-155-710
Low Slope
23.76
High Slope
19.26
Breakpoint
0.00001
VOLTAGE OFFSET
voltage
ms
16.00
0.78
15.00
0.78
14.00
0.78
13.00
0.936
12.00
1.093
11.00
1.25
10.00
1.47
8.00
3.19
6.00
4.19
0.00
4.19
0.00
4.19
0.00
4.19
Last edited by southbay08; 09-29-2017 at 11:43 AM.
09-29-2017, 01:24 PM
#86
Re: Bosch III injectors are NOT interchangeable w/o tuning
ms to usec
16.00 Volts 780 usec
15.00 Volts 780 usec
14.00 Volts 780usec
13.00 Volts 936 usec
12.00 Volts 1093 usec
11.00 Volts 1250 usec
10.00 Volts 1470 usec
8.00 Volts 3190 usec
6.00 Volts 4190 usec
0.00 Volts 4190 usec
16.00 Volts 780 usec
15.00 Volts 780 usec
14.00 Volts 780usec
13.00 Volts 936 usec
12.00 Volts 1093 usec
11.00 Volts 1250 usec
10.00 Volts 1470 usec
8.00 Volts 3190 usec
6.00 Volts 4190 usec
0.00 Volts 4190 usec
09-29-2017, 01:38 PM
#87
Re: Bosch III injectors are NOT interchangeable w/o tuning
have adjusted* these in excel to the volt increments that I see in tuner pro if of help to anyone. Will try this on my car tomorrow and report back
*basic linear calc. E.g. for 6.4, found the rate of change for ms between the 6&8 volt values then multiplied this by 0.4/2 and took this away from the 6v value. Use the below at your own peril!!
v ms
6.4 3.99
8 3.19
9.6 1.558
11.2 1.2186
12.8 0.9674
14.4 0.78
15 0.78
16 0.78
*basic linear calc. E.g. for 6.4, found the rate of change for ms between the 6&8 volt values then multiplied this by 0.4/2 and took this away from the 6v value. Use the below at your own peril!!
v ms
6.4 3.99
8 3.19
9.6 1.558
11.2 1.2186
12.8 0.9674
14.4 0.78
15 0.78
16 0.78
10-02-2017, 04:13 PM
#88
Supreme Member
Thread Starter
Re: Bosch III injectors are NOT interchangeable w/o tuning
One thing to also keep in mind when setting your injector offsets...
Check your calibration flags/switches. At least on $8D, there's a switch/flag that determines whether the ECM looks at the battery voltage or the keyed ignition voltage (fuel pump voltage as it's sometimes referred to). The switch setting should be unchecked.
Sometimes there's a voltage drop from the battery to the keyed ignition voltage. If it's significant enough, and you're pointing the ECM to the battery voltage, it could be commanding the injectors based on a different voltage than what the injectors are seeing (injectors see keyed ignition voltage).
The voltage range in the offset table that most people operate in is the 14.4V to 12.8V. So if you're battery voltage and your ignition voltage are both in that range, then no problem since voltage offset value is the same for that entire range.
However, if your battery voltage is say, 13.5 and your ignition voltage is say 12.6, you may encounter driveability issues as the offset values will be different for each of those voltages. IOW, if your ECM is told to look at 13.5V battery voltage and the injectors are seeing only 12.6V, the injectors will be incorrectly commanded for the AFR ratio you want the ECM to hit (most likely to show up in PE or Open Loop when the ECM is ignoring the O2 sensor).
I believe the switch is not checked from the factory, but doesn't hurt to look.
In Tunerpro, it's a Flag, entitled "Voltage Source for Injector Voltage Offset". It should be unchecked.
In Tunercat, it's Calibration Option entitled "Inj. Offset Select (X=Battery)". Like in TP, it should be unchecked.
Check your calibration flags/switches. At least on $8D, there's a switch/flag that determines whether the ECM looks at the battery voltage or the keyed ignition voltage (fuel pump voltage as it's sometimes referred to). The switch setting should be unchecked.
Sometimes there's a voltage drop from the battery to the keyed ignition voltage. If it's significant enough, and you're pointing the ECM to the battery voltage, it could be commanding the injectors based on a different voltage than what the injectors are seeing (injectors see keyed ignition voltage).
The voltage range in the offset table that most people operate in is the 14.4V to 12.8V. So if you're battery voltage and your ignition voltage are both in that range, then no problem since voltage offset value is the same for that entire range.
However, if your battery voltage is say, 13.5 and your ignition voltage is say 12.6, you may encounter driveability issues as the offset values will be different for each of those voltages. IOW, if your ECM is told to look at 13.5V battery voltage and the injectors are seeing only 12.6V, the injectors will be incorrectly commanded for the AFR ratio you want the ECM to hit (most likely to show up in PE or Open Loop when the ECM is ignoring the O2 sensor).
I believe the switch is not checked from the factory, but doesn't hurt to look.
In Tunerpro, it's a Flag, entitled "Voltage Source for Injector Voltage Offset". It should be unchecked.
In Tunercat, it's Calibration Option entitled "Inj. Offset Select (X=Battery)". Like in TP, it should be unchecked.
10-09-2017, 11:33 AM
#89
Re: Bosch III injectors are NOT interchangeable w/o tuning
I do think that there must be some quantitative difference in the injectors. Here's the points that need to be considered:
1. The MAX flow rate is NEVER reached in operation. Most engines are setup to use no more than 80-90 percent (duty cycle) of the maximum flow rate.
2. Different injectors can exhibit differences in the "upper non-linear flow rate area" and the "lower non-linear flow rate area". Thus two injectors that flow 20 lbs at 100% duty cycle, may not have the same "linear flow rate area" between say 5% and 95% duty cycle.
3. In the last few years, more and cheaper products have come to market for reading live data from these old ECM's. Also younger and more tech savvy owners are acquiring these cars and the tools to be able to watch BLM's, etc. Resulting in MANY more DIY'ers doing these modifications and seeing the results first hand.
4. In the cases where the BLM's are off, this may not actually be a problem in practice. First of all the BLM can adjust to compensate and will NOT throw a code - if it can adequately add or subtract fuel then it will seem to run normal. And these TPI systems ran CRAZY rich at WOT (like 10:1 in some cases - I've seen it), and so a reduction in Power Enrichment fuel flow would most likely lean it out just about the right amount to get into the 11 or 12:1 range where power may actually increase and feel better than it was before the injector change.
I do have a flow bench and would be happy to add my results to the effort. I don't have any injectors to test though other than the 24lb injectors in my car. Which I'm not going to remove from service at this time. So if someone wants to send me injectors I would be happy to post my results and send them back.
GD
1. The MAX flow rate is NEVER reached in operation. Most engines are setup to use no more than 80-90 percent (duty cycle) of the maximum flow rate.
2. Different injectors can exhibit differences in the "upper non-linear flow rate area" and the "lower non-linear flow rate area". Thus two injectors that flow 20 lbs at 100% duty cycle, may not have the same "linear flow rate area" between say 5% and 95% duty cycle.
3. In the last few years, more and cheaper products have come to market for reading live data from these old ECM's. Also younger and more tech savvy owners are acquiring these cars and the tools to be able to watch BLM's, etc. Resulting in MANY more DIY'ers doing these modifications and seeing the results first hand.
4. In the cases where the BLM's are off, this may not actually be a problem in practice. First of all the BLM can adjust to compensate and will NOT throw a code - if it can adequately add or subtract fuel then it will seem to run normal. And these TPI systems ran CRAZY rich at WOT (like 10:1 in some cases - I've seen it), and so a reduction in Power Enrichment fuel flow would most likely lean it out just about the right amount to get into the 11 or 12:1 range where power may actually increase and feel better than it was before the injector change.
I do have a flow bench and would be happy to add my results to the effort. I don't have any injectors to test though other than the 24lb injectors in my car. Which I'm not going to remove from service at this time. So if someone wants to send me injectors I would be happy to post my results and send them back.
GD
10-09-2017, 11:42 AM
#90
Sponsor
Re: Bosch III injectors are NOT interchangeable w/o tuning
That's exactly what I was going to do tomorrow. Unfortunately i'm not in the shop today.
I was going to video the 700's/710's and the 771's at both ford and gm pressure.
I'll be sure to post them tomorrow. I'll do my best to give you the info that you need.
What kind of bench do you have? What calibration fluid do you use?
I was going to video the 700's/710's and the 771's at both ford and gm pressure.
I'll be sure to post them tomorrow. I'll do my best to give you the info that you need.
What kind of bench do you have? What calibration fluid do you use?
10-09-2017, 12:03 PM
#91
Re: Bosch III injectors are NOT interchangeable w/o tuning
I have a Launch:
https://launchtechusa.com/x-sonic-clean-bt/
I just use odorless mineral spirits. I know that's not really a "calibration fluid" but for real world testing it gets very close and it is what Launch recommends. I test a lot of unknown injectors for Subaru applications and in testing many stock injectors of known flow rates it's rarely off by more than 5-10cc's on 500cc to 1000cc injectors. Mostly I am using it to see the difference between injectors in a "set" or to pick the closest injectors to make a set. But it's surprisingly accurate for checking flow rates in my experience.
Specific gravity:
Gasoline: 0.739
Mineral Spirits: 0.758
GD
https://launchtechusa.com/x-sonic-clean-bt/
I just use odorless mineral spirits. I know that's not really a "calibration fluid" but for real world testing it gets very close and it is what Launch recommends. I test a lot of unknown injectors for Subaru applications and in testing many stock injectors of known flow rates it's rarely off by more than 5-10cc's on 500cc to 1000cc injectors. Mostly I am using it to see the difference between injectors in a "set" or to pick the closest injectors to make a set. But it's surprisingly accurate for checking flow rates in my experience.
Specific gravity:
Gasoline: 0.739
Mineral Spirits: 0.758
GD
Last edited by GeneralDisorder; 10-09-2017 at 12:08 PM.
10-09-2017, 12:19 PM
#92
Supreme Member
Thread Starter
Re: Bosch III injectors are NOT interchangeable w/o tuning
Folks,
As I alluded to in my “Bosch-III sticky” thread…
I want these threads to be purely technical discussions. If you have a problem with Southbay or other injector house, please take it offline and contact them directly. These threads are not the place for insults, snide remarks or arguments regarding customer service issues.
My read on Southbay is they’re genuinely concerned about the issue and are willing to work with the technical community here on determining the best solutions. As such, I want them to continue to be a part of the discussion. So again, as I said in the sticky thread, I respectfully ask that no one tries to derail the conversation.
Thank you.
As I alluded to in my “Bosch-III sticky” thread…
I want these threads to be purely technical discussions. If you have a problem with Southbay or other injector house, please take it offline and contact them directly. These threads are not the place for insults, snide remarks or arguments regarding customer service issues.
My read on Southbay is they’re genuinely concerned about the issue and are willing to work with the technical community here on determining the best solutions. As such, I want them to continue to be a part of the discussion. So again, as I said in the sticky thread, I respectfully ask that no one tries to derail the conversation.
Thank you.
10-09-2017, 12:27 PM
#93
Re: Bosch III injectors are NOT interchangeable w/o tuning
If you want to send me some injectors to flow I would be happy to do that and send them back. No problem. Maybe send me one of each size commonly sold for the TPI?
My equipment isn't the highest tech, but I do have knowledge of TPI and some tuning experience on my own TPI plus lots of tuning experience on other FI systems. So I'm not an injector guy without tuning experience or a tuner without injector testing experience. I have at least a working knowledge of both sides to the equation.
GD
My equipment isn't the highest tech, but I do have knowledge of TPI and some tuning experience on my own TPI plus lots of tuning experience on other FI systems. So I'm not an injector guy without tuning experience or a tuner without injector testing experience. I have at least a working knowledge of both sides to the equation.
GD
Last edited by GeneralDisorder; 10-09-2017 at 12:30 PM.
10-09-2017, 12:49 PM
#94
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Car: 87 Firebird, 89 Trans Am
Engine: 406, LB9
Transmission: T56, 700R4
Axle/Gears: 3.23 Torsen, 2.73 Posi
Re: Bosch III injectors are NOT interchangeable w/o tuning
Just as another data point. I'm not a tuning expert. I'm currently tuning my 305 TA using $6E in a 165 ECM.
My Multecs began crapping out one by one so I swapped in a set of South Bay D3 19lb 305 injectors and also observed that I had to lower my injection constant to 17lb because my car was running lean after the swap.
My Multecs began crapping out one by one so I swapped in a set of South Bay D3 19lb 305 injectors and also observed that I had to lower my injection constant to 17lb because my car was running lean after the swap.
Last edited by 87v6Bird; 10-09-2017 at 01:32 PM. Reason: Can't think and type at the same time
10-09-2017, 01:18 PM
#95
Re: Bosch III injectors are NOT interchangeable w/o tuning
Just as another data point. I'm not a tuning expert. I'm currently tuning my 305 TA using $6E in a 165 ECM.
My Multecs began crapping out one by one so I swapped in a set of South Bay D3 19lb 305 injectors and also observed that I had to lower my injection constant to 17lb because my car was running rich after the swap.
My Multecs began crapping out one by one so I swapped in a set of South Bay D3 19lb 305 injectors and also observed that I had to lower my injection constant to 17lb because my car was running rich after the swap.
10-09-2017, 01:31 PM
#96
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Car: 87 Firebird, 89 Trans Am
Engine: 406, LB9
Transmission: T56, 700R4
Axle/Gears: 3.23 Torsen, 2.73 Posi
Re: Bosch III injectors are NOT interchangeable w/o tuning
interesting. I have a 91 LB9 TPI and on changing the injectors to South Bay D3's my BLM's were at around 148-50 on idle and pegged in 160 at a few points in the rev range - in other words LEAN. I changed the injector constant to 17lb and used the offset values posted above and made some tweaks to the crank multiplier values to get fuelling in a somewhat decent state
Reduced injector constant results in the ECU holding the injector open longer to compensate for "smaller" injectors.
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