ULTM8Z

Admins... I'm seeing a sufficient number of people running into issues after swapping out to Bosch-III injectors. People seem to be spending lots of money throwing parts at the car thinking they have ignition problems or fuel pressure problems, etc... before doing a search and realizing it could be related to the injector swap.

Thinking at this point we may want to have a sticky.

Let me know and I can start compiling links to the threads regarding this issue.

GTA1990

iTrader: (1)

As another thirdgenner with first hand experience of this, including the frustration and extra cash it cost (with thanks to the thirdgen community for the support in helping to resolve the issue), I'm a strong advocate for keeping this information in the forefront as much as possible.

I'm concerned about how these injectors are marketed across the internet, and frankly from a site sponsor (not to sound ungrateful for the otherwise great service that was provided). Save from challenging the sponsor to make it explicit that tuning will be required (which I'll correctly leave to the powers that be to consider), I'd hope to see our thirdgen community come together and do all we reasonable can to bring this known issue to the attention of people considering purchasing these injectors, to help them make a better informed purchase.

Its frustrating and an extra cost at the least, but even more worrying, and perhaps why I feel compelled to post, risks an unknowing user running their car quite lean

ULTM8Z

Yeah and I would advise putting the sticky in the DIY PROM, DFI ECM, TPI, and general tech sections for maximum visibility.

Tuned Performance

iTrader: (92)

It would be a real assist to have known Bosch 3 injector offsets listed.

ULTM8Z

Ok, here’s what I”d recommend for putting into the sticky. If the admins agree, I can simply copy this post out into a new thread and you guys can sticky it…

*********************************************

Thread title => Bosch-III injectors – Important Info Before Purchasing

Before I start, I know we have injector companies as site sponsors and they participate in and contribute to the message boards to advance the hobby.

So this thread is not intended to slam them or anyone else. It’s a merely a heads-up announcement to people considering purchasing Bosch-III injectors (or already purchased them) believing that they are “drop in replacements” for the factory Multec injectors. It may also be the case that in light of all of this new information, that the injector companies may want to post a caution note about this as well, but I’ll leave that up to them.

This is also not intended as a discouragement from buying Bosch-III’s either. Actually quite the contrary! In fact, I highly recommend buying them as they’ll give you a nice driveability improvement you’ll be able to feel/notice once they’re properly tuned for.

And that’s really the crux of the issue here… as It’s becoming increasingly apparent that these injectors are not really drop in replacements. Mechanically they do indeed fit just fine, but they do require some very minor re-tuning of the ECM to get them to work properly. It may cost you a little money for the chip, but we also have tuners on this site as well. Again though, it'll be worth it.

I first encountered this issue a couple of years ago when I bought some injectors third-hand from a particular injector company. They were known to be only a year or so old. But they were literally un-tuneable, while only trying to go after just the VE tables, AE, PE, etc… I chased my tail for a month or so trying to get them dialed in, but then discovered through this site about the voltage offset tables by doing some searching. The P/N’s had been scratched off the injector bodies so it was impossible to tell what I had.

After e-mailing the injector company, they sent over some generic offset table which I put in, but it still didn’t work. To their credit, they did offer to take them back and test them free of charge, but I was so frustrated, I abandoned those and got some factory OEM Ford injectors with the offset table corresponding to that exact p/n. Upon starting the car, I knew immediately that the problem was solved (before I even pulled out of the driveway!). It literally was that obvious. Tuning from there was a breeze as the injectors were very well behaved and responded to tuning changes in predictable ways…

Since that time, we (the thirdgen.org community) have been uncovering several other instances of folks tracing the source of their mysterious problems back to their injector swaps, sometimes after having spent significant sums of money needlessly replacing other things (fuel pumps, distributor caps, plugs, rotors, wires, fuel filters, you name it). It’s particularly bad for folks who do not have access to scanners or tuning equipment (trying to diagnose EFI issues by “feel” is a near impossible task).

Any rate, this thread is intended to save the hassle of a search for all the info relating Bosch-III injector swaps. I’ve compiled what I believe to be all the necessary info relating to the swap that users can read through it and know what to do.

Fundamentally, here’s what needs to change in the calibration… and it could require a couple of iterations…

1.) Injector flow rate. Your factory calibration has the “advertised” flow rate of the stock injector. Stock injector rated for 19lb/hr? You’ll have 19 in your calibration. Rated for 22 lb/hr? You’ll have 22 in the calibration. However, with the Bosch-III’s, even though you’re buying say, a 19 lb/hr, you may end up with 17 or 18 (or even 20 or 21) depending on the flow characteristics and your fuel pressure. Or if you buy 24’s, you may end up with 22 or 23 (or maybe even 25 or 26) depending on flow characteristics and fuel pressure. You may end up iterating this value after getting done with 2 and 3 below. Ultimately, you want to end up where the fuel trimming being done by the ECM (mainly the BLM long term fuel trim) is the same as before the swap. And to do that, the ECM needs to “know” exactly what injectors you’re running. For a bone-stock car (or a modified car that was tuned properly prior to the injector swap) if your BLMs are off (but not pegged at 160 or 108 where the ECM is beyond correcting any further), you may not notice it on part throttle unless it’s so bad that even your AE (accelerator enrichment) is so far off that you’re getting stumbling. But it would be an indication that your power enrichment (PE) and open loop (OL) fueling is off since the ECM will not correct the fueling in PE or open loop.

In other words, during part throttle the ECM will monitor the O2 sensor and correct the fueling to compensate for incorrect injector offsets (you’ll see that in BLM’s that are either very high or very low). But during PE or OL, the ECM will command fueling but ignore the O2, so if (for instance) your new Bosch-III injectors flow a lot more than your old Multecs, you’ll get a lot more fuel for the same pulse width… hence clouds of black smoke, stumbling, loss of power, etc… (and vise versa on the lean side, possible engine damage).

2.) Injector voltage offset table – Each injector has a different flow vs voltage characteristic for a given pulse-width. This should be characterized into a table, from which you can simply copy the numbers over into your table. The voltage values may not line up exactly (injector tables provided by the manufacturer may test at voltages that do not correspond exactly to the voltages in the table in the calibration). But, some linear interpolation should be fine to get really close.

3.) Low pulse width correction table (not sure if this is $8D/7730 only or not) – Bosch-III’s flow much better at low PW’s than the factory injectors. This table was designed to “help” the factory injectors at low PW’s by adding “on-time”, but it’s not necessary with Bosch-III’s. As a result we typically zero out this table.

For more detail on these things, I’ve compiled some links below where these things are explored in greater detail. Some of these have offset tables for certain injector p/n’s.

https://www.thirdgen.org/forums/diy-...ctors-not.html

https://www.thirdgen.org/forums/diy-...r-offsets.html

https://www.thirdgen.org/forums/diy-...r-offsets.html

https://www.thirdgen.org/forums/diy-...nnot-dial.html

https://www.thirdgen.org/forums/diy-...tors-take.html

https://www.thirdgen.org/forums/diy-...gn-iii-pw.html

https://www.thirdgen.org/forums/tpi/...-injector.html

https://www.thirdgen.org/forums/diy-...155-710-a.html

https://www.thirdgen.org/forums/tpi/...4lb-south.html

https://www.thirdgen.org/forums/tpi/...injectors.html

https://www.thirdgen.org/forums/diy-...pw-offset.html

https://www.thirdgen.org/forums/diy-...bosch-3-a.html

someone972

iTrader: (2)

Interesting thread. I'm curious about #1 in your proposed sticky: Does this mean that you may have to tune fueling under conditions like WOT? For example, I've been having knock counts occur under WOT conditions; could this be potentially be attributed to the Bosch IIIs leaning out too much? I'm sure I'll have to get a wideband on there to know for sure but might be worth mentioning if this is a common issue.

ULTM8Z

Tune for WOT? You can, but in some cases it may not be necessary if you're happy with how the car already drives.

Let's say you have bone-stock factory car and can scan the ECM to know what your BLMs are, but don't have a wide band to measure the actual AFR during PE and OL.

Frankly I wouldn't even do a swap like this unless you can at least scan the car. Even if you have your chip re-calibrated by a professional, there's really no way to know if the new calibration is really correct unless you can see what the ECM is actually doing.

Any rate, let's say before your swap, you have all of your BLMs hovering around 128 and your OL and PE are good (to the extent that you're happy with the power output even though you don't have a wide band to actually measure anything). Fuel pressure is good, ignition is solid, etc... overall the car is running really well.

You buy 19 lb/hr Bosch-III injectors to replace your 19 lb/hr Multecs. Then after the swap your BLMs go haywire. What I would do is put in the correct voltage offsets and zero out the PW correction table. Then, I would modify the injector constant. If you're running rich (low BLM's), then raise the injector constant by a point or two and see what happens. Repeat until you're back to your original BLMs. Basically, if the ECM thinks you have a bigger injector, it'll command a lower pulse width to get the same amount of fuel it thinks you need. It'll have the effect of raising your BLMs over time. If you're lean (high BLM's), then do the opposite... ECM will think your injectors are smaller and command longer pulse widths to get the same amount of fuel, thereby lowering your BLMs (which is what I had to do with my friends car in the first link).

The above is also true for modified cars where the tune was well established and everything functioning properly before the swap.

So in this case, the most basic thing to do is get your BLMs back to the way they were. If the ECM is back to trimming your fuel the same way as before, that means it's compensating properly for the different injectors and I would expect that your OL and PE fueling would also be back to the way it was before the swap as well. Which would mean you're done.

Now, if you're having malfunctions before the swap, it'll be difficult to isolate your tuning mods to the injectors because you'll be tuning around the malfunctions as well. Most likely chasing your tail.

In the end, if you want to dial in your PE and OL, then by all means get a WB and start doing that (I'd actually recommend it). GM went notoriously rich on these third gens especially in PE (to guard against potentially engine-damaging lean conditions). But AFR's in the 11:1 range is not optimal for power. I can definitely feel a difference between 11:1 and say 12.5:1. So, there's a little power to be had in getting the AFR's correct, even if your car is stock.

To answer your other question, yes, it could be due to a lean condition. What are your BLMs saying at the moment?

GTA1990

iTrader: (1)

is there a formal 'sticky' submission process or otherwise a way we can bring this to the attention of admin to opine on?

someone972

iTrader: (2)

I'll have to relog to see what they are floating around now. I'll make a new thread if needed to continue with this train of thought so that this one can stay focused on the sticky content. Thanks for the pointers!

ULTM8Z

I guess one other thing to watch out for with this voltage offset thing is the switch in the calibration options where you can tell the ECM to look at the battery voltage or the fuel pump voltage (essentially the keyed igniton voltage) for the injector voltage/PW compensation.

You should have the switch unchecked (for looking at ignition voltage). Reason being is the injectors are running off of keyed ignition voltage. If there is a significant voltage drop from the battery to the ignition voltage, and the ECM is looking at battery voltage, it’ll be using the wrong voltage for PW compensation which will somewhat defeat the purpose of using the right offset tables.

In the $8D code, I believe it comes from the factory with the switch unchecked.

ULTM8Z

I guess no dice on making this a sticky...

Oh well, I suppose it'll show up when people search on Bosch-III's then....

RBob

iTrader: (1)

Have you PM'd an Admin?

RBob.

ULTM8Z

I don't know who they are... I was hoping they'd read the thread and either reply to it or PM me...

southbay08

Just 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.

southbay08

So here is some info on the bosch 280155700's. Hope this helps. They are rated
19lb at Ford pressure and 22lb at GM pressure:


Bosch EV6 19 lb/hr @ 39.15psi
0-280-155-700 / 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

Fred SS

iTrader: (3)

Southbay, is the Bosch 280155700 the yellow injectors that you sell? That is what I have. Bought them from you several years ago.

southbay08

yes they are and they're rated 22lb at 43.5psi

Fred SS

iTrader: (3)

Thank You.

1tpi

Thanks for some good info

ULTM8Z

Folks,

I was clear that this thread was not intended to bash injector companies. There’s probably a host of reasons why this becoming more noticeable now, as opposed to the many other customers who are using Bosch-III’s with apparently no noticeable issues.

For anyone who has a customer service problem with Southbay or any other injector house, I would respectfully ask that you take it offline, or start a new thread, or PM them, or something.

This thread was intended to be a technical resource, and as a matter of fact I want Southbay to be a part of that discussion. So again, please do not derail this thread.

GTA1990

iTrader: (1)

Agreed

Can we also talk about longer cranking times as, in my experience, that seems to be a symptom of these injectors on stock tune. By longer I mean around 5 seconds of continuous cranking which can't be good for anyone (lol)

I searched TGO and there is a thread about changing the 'Crank PW Multiplier vs. Ref Pulse' table which I've followed and had some success with but requires more tweaking on my part

Post 20 of the below linked thread:
https://www.thirdgen.org/forums/diy-...ml#post6151103

EDIT: ULTM8Z has got this covered in his links in Post 5 above

Tuned Performance

iTrader: (92)

Has anyone tried these setting yet ?
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

ULTM8Z

That's pretty close to my settings...

I'm running M-9593-BB302 (0280155759) 30# injectors...

Dartht33bagger

Rather than another sticky thread that will get lost in the tens of threads listed in the current stickies, I think a wiki for DIY PROM information would be more appropriate. Standard forums are not great at organizing and grouping the amount of information contained in the current stickies. Furthermore, the important information posted in a thread may be embedded in a 50 post long thread, forcing the reader to read every single post in case they miss something. If implemented correctly, a wiki would collapse this information and organize it into easy to find and digest articles.

I realize this would be a massive undertaking but in the long run it would preserve the information found by members on this board for years to come in a more readable manner.

Tuned Performance

iTrader: (92)

Thanks, I plugged in the values South Bay put up Post 15. I am going to send them off to a member to give a try.

IROCZ1989

iTrader: (1)

Why buy these when you can get the stock replacements with no issues and correct offset times.

ULTM8Z

Because once properly tuned for (which isn' at all difficult to do) they run better.

and it's often the case with heavily modified cars that you need higher flowing injectors.

MrWillys

When this claim is run through the calculator it comes up with 20.02 lbs.
http://www.csgnetwork.com/fiflowcalc.html
Not trying to be rude but rather factual.

ULTM8Z

my recent experience with those settings and 20 lb/hr injector constant setting yielded remarkably good results on another members car. Mild mods mostly on intake and exhaust. He ability to send tunerpro data to verify. Thosr Mods required some minor adjustment to VE tables, but was pretty good overall.

if this other member is close to that or bone stock I would expect similar results.

Tuned Performance

iTrader: (92)

Bone stock, he doesn’t have a way to datalog
It will take awhile to get the results if it’s even a butt dyno.
It’s going to Canada tomorrow.

ULTM8Z

This other member's car was running slightly high BLM's (mostly in the high MAP areas) after the calibration changes for the injectors.

I'm surmising that was due at least partially to the higher flowing intake and the improved exhaust scavenging with Dyno Don's headers. His car was in good working order prior to the swap.

And when I retuned my friends bone stock 305 TPI last year, it was just the injector changes in the calibration and got it back to perfect BLM's.

So my guess If your customer's car is bone stock, it may be the case that his BLM's end up right on the money if everything is in good working order currently.

Tuned Performance

iTrader: (92)

Just found out he has a auto X-ray 6000, so it will be interesting to hear the before and after.

ULTM8Z

Advise him to baseline his BLMs before installing the chip!

Tuned Performance

iTrader: (92)

Done and done lol

brett89

Once I get the car out in the spring I'll do a before and after check of the blm's.. I don't have a data logger but I can watch the blm's in real time on my auto xray 6000.. looking forward to it .. Thanks guys for the help and I'll be sure to report back

ULTM8Z

If they're hovering between 124 and 134 I'd say you're golden.

If they're significantly out of that range and staying there, probably will need to adjust the injector constant one way or the other.

This other member I worked with was able to collect WB O2 data on his car and send to me. As usual, the WOT AFR's are pig rich as programmed by GM (even after we whipped the BLM's back in shape). Down in the 10.5 to 11:1 range... ridiculous...

I leaned out the commanded AFR across the board by 5% and that got him into the 12.5 to 12.7-ish range where I think most SBC's are happy. He said it felt a little better in the ol' butt dyno...

Lucid

iTrader: (4)

I'm kind of confused. Which table are you all referring to? I see the Injector Pulse Width Correction Vs Battery Voltage table ($6E mask). I finally found the Low Injector Pulse Width Offset vs Base Pulse Width using the expanded $6E XDF.

So for Low Inj Pulse Width Offset vs Base Pulse Width, just zero out all the values in that table. In the Correction vs Battery Voltage I need to convert from ms to usec and use Rbob's values and zero out the values under 6.4 volts?

ULTM8Z

Yep, you got it.

sweetmelissa

I have those bosch III's in my stock 350 ... that explains my longer cranking time and sometimes redline low battery voltage (brand new die hard).. If I hook up cables to the battery it just takes 10 seconds and it fires right up.. When it starts on it's own I get the excessive cranking ( I don't let it just keep cranking) I pull the key back and turn it again and it fires up immediately...... I have been looking for a ground wire and even blown fuse links.....

Lucid

iTrader: (4)

That might be a separate issue. Which BIN are you using? The ARAP bin from the Corvette is known to have a long crank issue when used on iron headed engines. Also, do you hear the fuel pump prime when you initially turn the key? It should hum for 2 seconds or so. You can measure your fuel pressure (set up your camera facing the pressure gauge and record it while you prime and while cranking).

Lucid

iTrader: (4)

This may sound like a really dumb question but I've been extra dumb this week. How do you convert ms to usec? Multiply by a factor of 1000 ?

RBob

iTrader: (1)

Yes, multiply by 1000 to convert from msec to usec.

For the entries under 6.4 volts, just use the 6.4 volt value, Then at 0 volts use the 12.8 volt value. This is done in case a wire breaks or the ADC channel goes bad or what-not.

RBob.

Lucid

iTrader: (4)

awesome, thank you sir

sweetmelissa

So,, you don't think this is an injector issue .. Yes the fuel pump primes !!

Lucid

iTrader: (4)

I'm not really sure. It sounds like these new injectors seem to run a bit rich. What you are describing is either way too lean or a mechanical/electrical issue. You may want to start your own thread and include:
-engine
-which BIN you are running (this is DIY prom section)
-the injectors you are running
-what you have done to troubleshoot the problem
(ie fuel pressure testing, is the SES light on, do you have any trouble codes)

sweetmelissa

Thanks for the reply Lucid !
At this point I wish it would just throw a code..... I am trying to find out why the battery keeps draining so low (at times) that it can't start the car,, completely dead except auxillaries...... aggravating !! I hope I am not having a problem with the injectors as I did notice the excessive crank after I put them in .....Thanks for replying ...

Tuned Performance

iTrader: (92)

Have you tried a Parasitic draw test and pull fuses to. narrow down the circuit of the draw. The ecm will draw about 50mv iirc. The injectors would not be a source of power draw with the engine off.

Z51bob

I too have been down the green injector trail with my 42 lb ebay specials. Only generic flow & offset data was available. I called the vendor about injector offset info - he replied “what's that?” The first set just would not tune BLMs were all over the map. So, I built a tester. The injectors did not match near 20% in steady state flow and performance at pulse widths below 2 msec was all over the map.
My second set - also from ebay was matched in steady state flow and remain linear down to about 1220 usec, below that the opening curve is very steep and in my expeience all but unusable. They start opening at around 900 usec at 12.8volts. While they don't match up with the test data for 280-155-968 injectors they were sold as (posted near the top of this thread), they all match closely and run well using my test data. I can post the data if anyone is interested.

Moral of the story - don’t buy injectors without test data.

IROCZ1989

iTrader: (1)

Just have the factory ones serviced and cleaned. Idk why the big push to put these bosch 3s in our cars as replacements. All of a sudden the factory stuff is subpar?

Tuned Performance

iTrader: (92)

If the injectors you have are 89-92 multecs yes they are subpar.
The coils short out and will shut down the injector driver or cause a misfire.
Noting wrong with the Bosch 3s they have better spray pattern with the four hole design for better atomization.