7a injector options

[RTurner992]

Hi all,

In my quest to solve my hot start issue and generally improve my setup, I've decided to upgrade the injectors. I'm having trouble importing the 034 kit from the US, so I'm taking the alternative (and cheaper) option of purchasing the fuel rail adapters from Epytec, making my own bypass loom for the resistor and sourcing injectors. I know it's been widely discussed on here and over the internet in general that the injector choices are typically

- Bosch 0280155931 (matches Hitatici spec)
- Bosch 0280150945 (Red)
- Bosch 0280156095 (Black)

As these are pretty old now, I can only find clones or refurbished units. There's one company that can supply me with a set of refurbished 095 injectors and a test certificate, which has given me some confidence and is likely my backup plan. However, ideally, I'd like to find something more current that's readily available new. The only Bosch injector I can see that seems to be the closest match is the 0280158116. Through all the info I can find, I can't see anything that's drastically different to the 945 or 095, other than the impedance being 12ohms, which I'm led to believe isn't going to be an issue. Some sources claim them to be 61mm, while the others are apparently 60mm. Even if that is the case, a set of washers under the fuel rail at the mounting holes should shim it to offset any minimal height difference (I hope).

Honestly, I'm not that clued up with anything else to look for apart from the obvious of comparing data sheets. I'm wondering if there's anyone else here with more knowledge than I have who wouldn't mind having a quick look at these and letting me know if they spot anything I might be missing.

Thanks

[RTurner992]

Here's some additional info I've found for comparison.

Injector	Bosch 945/095 (EV6)	Bosch 116 (EV14)
Length	60mm	60mm (maybe 61mm)
Connector	EV1	EV1
Flow @ 3 bar	~330 cc/min	~347 cc/min
Impedance	~14.5 ohm	12 ohm
Spray pattern	Conical ~20°	Split dual 22° @ 90°

[Lago Blue]

Hi Sir,

I can't comment on the red and black ones, mine are the grey 931 type I got from Patrick Carlier (mod originator?) years ago. These still appear available new on the net, would those not do?

[John.]

I too got mine from Patrick, don't know the spec but they're grey in colour.

RTurner992 Patrick Carlier was the man who invented this modification/upgrade, 034 then stole his idea for their own financial gain !

[RTurner992]

Thanks for the info and back story. I had no idea the concept was stolen by 034! Does anyone know if Patrick is still active? I’d happily cancel my adapter order from Epytec and purchase the adapters from Patrick if he still makes them, assuming Patrick has no association with that company either. I’m bey much against that kind of behaviour and would always rather support and credit the original creator.

I’ll double check the spec on th 931 adapters. It does sound like you John. likely have the 931 grey Bosch ones as well. I was interested in the other two, and potential 116 option after reading about the stock injector spec being lean at WOT. Supposedly after testing (by 034) the 945/095 perform better and are ‘perfect’, though I’m not educated enough to look at the ratio figures they give of whatever the values were to prove this. It is documented that 034 did move from the grey one to the red ones after testing.

I guess I’ll keep looking and gather more info and get more educated to make a decision. Good to know the grey ones are still available too as another fall back. I kind of feel like it’s an ‘if it ain’t broke don’t fix it’ kind of thing. If the grey 931 injectors match the Hitachi spec then maybe that’s the right route to take.

[Lago Blue]

Consider that the 931 type, also called the LS1 injector takes its name from the Chevrolet Corvette / Firebird / Camaro LS1 5.7 ltr. V8 engine where it was used. This means it saw service on cylinders of 712 cc displacement vs ours of 460. It therefore may be that this injector is capable of delivering what we require, if given the proper conditions. For example, the FPR simply can't give back full fuel pressure towards WOT, if it hasn't first taken it away at idle. What this really does is keep the pressure differential that the injector sees (between its' inlet and nozzle), equal between idle (when the the high engine vacuum is sucking the fuel out of the injector) and nearer to WOT (when it is not). That full range of modulation keeps the fuel delivery within a range the electronics can then manage.

An injector with higher than stock capacity could perhaps mask a WOT fuel delivery issue that may simply be a lack of vacuum.

I've had success with:
a) ensuring 18 inHg of vacuum at warm idle to allow the FPR to then deliver its full range of fuel pressure modulation (see image below), and;

Audi FPR schematic Screen Shot 2025-10-10 at 11.08.12 AM.png

b) As the air-filter box has a square-edged exit that degrades MAF reading accuracy (due to turbulence over that edge) as you move towards WOT, that can be improved with a velocity stack similar to what most other Audi's have right from the factory.

Forgive me if you know all this already.

[John.]

I was interested in the other two, and potential 116 option after reading about the stock injector spec being lean at WOT. Supposedly after testing (by 034) the 945/095 perform better and are ‘perfect’, though I’m not educated enough to look at the ratio figures they give of whatever the values were to prove this. It is documented that 034 did move from the grey one to the red ones after testing.

In an email from Patrick I remember him saying that the 7A will run lean at WOT (I think), will try and find the info.

[John.]

From Pat.

The real restriction in the intake is the mass air flow meter .
It's bore is smaller the the large flap in the throttle body .
You can feel that the last 15% of the accelerator really doesn't accelerate anymore .
Once you've reached the same passage in the throttle as the mass air flow meter , you're done .
There have been experiments with a mass air flow meter from a V6 which has a huge bore .
It fits quite easily but the real challenge is that it requires remapping of the ecu .
The engine runs to lean with the large airmass meter , the ecu gets wrong information from it .
Estimations are that in combination with the chip power can rise above 200 hp this way .

The original 7A injectors have a flow of 305 cc/ min @4.2 bar .and are rated 61Hp/injector .
The kit I used to offer had a flow of 301cc min @4.2 bar . Tested on a flow bench .
I've tested dozens of injectors , and this was the closest match I could find .

[RTurner992]

Consider that the 931 type, also called the LS1 injector takes its name from the Chevrolet Corvette / Firebird / Camaro LS1 5.7 ltr. V8 engine where it was used. This means it saw service on cylinders of 712 cc displacement vs ours of 460. It therefore may be that this injector is capable of delivering what we require, if given the proper conditions. For example, the FPR simply can't give back full fuel pressure towards WOT, if it hasn't first taken it away at idle. What this really does is keep the pressure differential that the injector sees (between its' inlet and nozzle), equal between idle (when the the high engine vacuum is sucking the fuel out of the injector) and nearer to WOT (when it is not). That full range of modulation keeps the fuel delivery within a range the electronics can then manage.

An injector with higher than stock capacity could perhaps mask a WOT fuel delivery issue that may simply be a lack of vacuum.

I've had success with:
a) ensuring 18 inHg of vacuum at warm idle to allow the FPR to then deliver its full range of fuel pressure modulation (see image below), and;

Audi FPR schematic Screen Shot 2025-10-10 at 11.08.12 AM.png

b) As the air-filter box has a square-edged exit that degrades MAF reading accuracy (due to turbulence over that edge) as you move towards WOT, that can be improved with a velocity stack similar to what most other Audi's have.

Forgive me if you know all this already.

Thanks, I appreciate the input and understand what you're saying. To make sure there's no confusion (and not saying you misunderstood), I'm not personally experiencing a lean mixture at WOT via testing; that information was solely pulled from 034's write-up about what they saw when testing the Hitachi injectors, and I believe the same for the 931s. With that in mind, that information can only be trusted if they also took into account precisely what you've just written, so their testing is fair, accurate and from a solid base. You'd like to think all areas had been covered and tested before any testing was carried out.

The information that John. has just provided, also throws 034's testing into question in a sense. We can't know without asking Patrick directly whether he tested the 095 and 945 injectors as well, but still found that the 931s were the better choice for a stock 7a. There seems to be a lot of conflicting information online about this, depending on the source. At this point, as someone who is only gathering info through search rather than practical tests, I am more inclined to trust what Patrick has said in his email and lean towards the 931s.

There's also conflicting information regarding the V6 MAF. Motorgeek is full of people discussing this topic, and several on here. I appreciate that Patrick mentioned the V6 MAF while also including the important caveats. I had a look through the 20v-sauger-tuning.de website, which has an entire section on many interesting things, including the V6 MAF. There's a statement above the links to the info on that page that reads.

"NOTE:
Recent findings have shown that the air flow meter conversion described on the following pages is useless (apart from the visual aspect).
According to flow bench measurements, the large air flow meter alone has 10% more flow than the original 7A when installed; in other words, when combined with the air filter and suction hose, the "small" air flow meter is 3% better!
This is due, on the one hand, to the Venturi effect/flow velocity (smaller diameter = higher flow velocity) of the small air flow meter, and, on the other hand, to flow turbulence caused by the central web in the large air flow meter, which, in conjunction with the subsequent curved suction hose, creates dead water zones in the flow, making it effectively inferior to the small air flow meter.
Another point is that, according to the manufacturer (Hitachi), the measuring unit of the small air flow meter has a larger measuring and detection range than that of the large version (480 kg/h vs. 400 kg/h).
The following pages therefore serve only as documentation..."

This website also covers the injector upgrade with the following information.

"The following Bosch injectors can be used for the conversion:
0280155931 (grey) – matches the original injector’s flow values
0280150945 (red, old design) – for a slight increase in performance (ideal for 2.5 L conversions)
0280155759 (red, new design) – for a slight increase in performance (ideal for 2.5 L conversions)
0280156095 (black) – same data as the red injectors, but may be easier to source locally"

(I would post the direct links to the pages, but on every page, the URL is that of the homepage)

As I've just pasted that here, I noticed it says 945, 095 and 759 are ideal for a 2.5L conversion, linking us back to Lago Blue point.

As I'm writing this post and the input so far, I'm answering a lot of my own questions. I don't mean for this thread to be a whole load of nothing, as I appreciate this topic has been covered plenty of times. All of this is relatively new to me as I'm coming up to one year of ownership of my CQ20v, so I'm doing homework everyone else completed years ago haha. This modification was created a long time ago, and my original curiosity was whether anything currently outperforms the injectors tested back then. As I said earlier, it is starting to feel like " if it ain't broke, don't fix it", and I should probably go with the tried and tested 931s.

[hoshanaeckhart]

Hi all,

In my quest to solve my hot start issue and generally improve my setup, I've decided to upgrade the injectors. I'm having trouble importing the 034 kit from the US, so I'm taking the alternative (and cheaper) option of purchasing the fuel rail adapters from Epytec, making my own bypass loom for the resistor and sourcing injectors. I know it's been widely discussed on here and over the internet in general that the injector choices are typically

- Bosch 0280155931 (matches Hitatici spec)
- Bosch 0280150945 (Red)
- Bosch 0280156095 (Black)

As these are pretty old now, I can only find clones or refurbished units. There's one company that can supply me with a set of refurbished 095 injectors and a test certificate, which has given me some confidence and is likely my backup plan. However, ideally, I'd like to find something more current that's readily available new. The only Bosch injecteur citroen I can see that seems to be the closest match is the 0280158116. Through all the info I can find, I can't see anything drastically different to the 945 or 095, other than the impedance being 12ohms, which I'm led to believe isn't going to be an issue. Some sources claim them to be 61mm, while the others are apparently 60mm. Even if that is the case, a set of washers under the fuel rail at the mounting holes should shim it to offset any minimal height difference (I hope).

Honestly, I'm not that clued up with anything else to look for apart from the obvious of comparing data sheets. I'm wondering if there's anyone else here with more knowledge than I have who wouldn't mind having a quick look at these and letting me know if they spot anything I might be missing.

Thanks

The Bosch 0280158116 injectors are a suitable modern replacement for the older 945 and 095 types. Their flow rate and spray pattern are nearly identical, and the 12-ohm impedance won’t cause issues once the resistor pack is bypassed. The small height difference can be adjusted with washers under the fuel rail.

[RTurner992]

I decided to go with the 095 injectors and managed to find some time today to attempt to install them. I seem to having an issue seating the injectors properly into the manifold and wondered if anyone can shed some light on what’s going on.

When seated, there’s around a 6mm gap between the rail mounting points and the manifold. I’ve read on occasions people see around a 1.5mm gap which is solved with washers to keep the injectors straight, but 6mm seems excessive.

The manifold has been vapour blasted so there’s no debris and the openings are clear. The adapters are fully seated into the rail, and the injectors are fully seated into the adapters. The lower O rings from the Hitachi injectors aren’t stuck in the manifold either.

From what I can see, it’s almost like the pintle cap is the obstruction but I’m not sure. The lower O ring isn’t making contact radially or axially with the manifold, which I’m assuming it should do?

If anyone has any experience or thoughts on this that’d be great. I’ve attached some pictures for reference.

[RTurner992]

Ok I may have figured this out. After a quick search online I’ve realised there’s different types of pintle caps (I had no idea). My assumption is that I’ve not to the correct ones. I’ve had a look on Mr injector UK and noticed that there’s fluted (which I’ve got), stepped and flat. So the question now is, does anyone know if I need stepped or flat?

Flat

https://www.mrinjectoruk.co.uk/products/5-cylinder-volvo-0280155-0280156-series-seal-kit?_pos=5&_sid=343ef4291&_ss=r

Stepped

https://www.mrinjectoruk.co.uk/products/bosch-denso-v6-injector-seal-kit-23?_pos=7&_sid=343ef4291&_ss=r

[hoshanaeckhart]

Hi all,

In my quest to solve my hot start issue and generally improve my setup, I've decided to upgrade the injectors. I'm having trouble importing the 034 kit from the US, so I'm taking the alternative (and cheaper) option of purchasing the fuel rail adapters from Epytec, making my own bypass loom for the resistor and sourcing injectors 9657144580. I know it's been widely discussed on here and over the internet in general that the injector choices are typically

- Bosch 0280155931 (matches Hitatici spec)
- Bosch 0280150945 (Red)
- Bosch 0280156095 (Black)

As these are pretty old now, I can only find clones or refurbished units. There's one company that can supply me with a set of refurbished 095 injectors and a test certificate, which has given me some confidence and is likely my backup plan. However, ideally, I'd like to find something more current that's readily available new. The only Bosch injector I can see that seems to be the closest match is the 0280158116. Through all the info I can find, I can't see anything drastically different to the 945 or 095, other than the impedance being 12ohms, which I'm led to believe isn't going to be an issue. Some sources claim them to be 61mm, while the others are apparently 60mm. Even if that is the case, a set of washers under the fuel rail at the mounting holes should shim it to offset any minimal height difference (I hope).

Honestly, I'm not that clued up with anything else to look for apart from the obvious of comparing data sheets. I'm wondering if there's anyone else here with more knowledge than I have who wouldn't mind having a quick look at these and letting me know if they spot anything I might be missing.

Thanks

The Bosch 0280158116 injectors should work as long as you account for the 1 mm height difference with shims, ensure O-rings seal properly, and confirm your bypass loom handles the 12 Ω impedance. Also, make sure the flow rate and spray pattern are compatible with your setup.