7A replacement bosch injectors discussion
 

I've been looking at putting bosch injectors in my 7A.

By means of comparison; The original hitachi injectors are quoted as 305cc - but at what pressure - I guess 4.2bar?

Already bought the adapters and some injectors some time ago after some initial research. Here's what I found out.

The current 034 kit comes with 0280 155 759 red injectors; rated at 315cc @ 3bar AFAIK

A few people on various forums discussing this modification have said these are too large for the 7A unless you are looking to make significant modifications to it.

I've been looking at the grey injectors used in some articles I've seen; 0280155931 including this one; http://www.audiworld.com/tech/eng83.shtml which are the original injectors sold in the 034 kit, and documented in the June 2006 audi driver magazine article 20vcqdriver kindly sent me.

Some of the data I've found suggests these are 300 cc injectors but I have just found some info on an American forum that says they're actually more like 250cc (@ 3bar), and there are a few other sites advertising them as 24lb/hr @ 3bar

http://ls1tech.com/forums/fueling-in...155-931-a.html

There is an alternative 250cc @ 3bar bosch injector; 0280 155 832 pink fitted to Volvo straight 6s - the difference is the impedance is 12 ohm instead of 14 ohm. These injectors are readily available and cheap as chips compared to the greys. So cheap I took a punt on some.

I'm curious as to whether 12 ohm impedance is sufficient to not fry the ECU when I ditch the resistor pack. I will be doing some measuring this weekend to see if it is!

Anyone have any thoughts/comments? :)

Gaz

The 7A uses a 4.2 bar FPR so an injector rated at 250 at 3 bar will be flowing closer to 300 at 4.2 bar.

The spec for the injector is 100-120ml for 20 seconds.

It's the grey LS1 injectors I'm using in mine. Had no problems with them. A set of 8 cost me $120

That's a great price! I got 6 Volvo ones for £75. Quick look on eBay for the 931s and they come up at around $100 each!

As for the pressure I was just using 3 bar as a reference as that's what's normally quoted. so as long as what I have are the same flow rate as the greys are at the same pressure, I should be good to go!

Think I got lucky as it was about 4 years ago.

No idea if the Volvo ones will work but if they flow ~250 at 3 bar, you won't be running lean. I don't see the resistance being a problem. The Hitachi resistance is about 2.5 ohms per injector

Thanks for the reassurance - The key seems to be the impedance, the dimesions of injector are the same - the '155' part signifies that. They are 4 nozzle and other than that I don't know how else they could vary. I guess in a lot of ways internally but info is scare on that level.

The only negative would be the colour I guess! :crazy:

http://images.oreillyauto.com/parts/...155832left.jpg

vs

http://images.oreillyauto.com/parts/...155931left.jpg

:o

Actually - just noticed the position for the retaining clip is in a different place. but I don't think the retaining clips are used with the adaptors?

Update on this... The injectors are now fitted onto the manifold. Had to take the manifold off because the injector ports were filthy and taking the manifold off seemed like the only way to clean them. I took the white disc off each injector nozzle but retained the rubber seal. This seemed like the right thing to do. Old injector seals were knackered
- at both ends on some of them

The resistance of the original injectors I measured to be 2.5 ohms with the resistor pack coming in at 6.5 ohms so approx 9 ohms in total. The pink injectors are 12 ohms so all good.

how's this going?

Starting it up next weekend hopefully

Excellent I'll keep my eyes peeled for an update

Now running, you can see no1 injector is nice and pink! :crazy:

Haven't driven it yet but I'm not expecting there to be any issues.

http://i1084.photobucket.com/albums/...psrhcf9rve.jpg

Looking at changing the injectors my 7a, how are you getting on with the pink bosch injector?

It all seems fine. Must admit I've not had it checked on a dyno or anything but it starts well, runs smooth and sounds lovely. I'm getting low 30s on a run. Expected a little more but I've a heavy right foot and the cars not exactly aerodynamic

On paper they are the same as the greys apart from slightly lower impedance (closer to, but still higher than that of the original low impedance injector+resistor pack combo)

I'm having the car dynoed at the end of Jan at a club rolling road day (in association with club polo) so should have some info from that.

Hi PoloGaz, Keep up the good work about the fuel injector upgrade, My audi coupe conversion to 20v 7a engine now has a youtube video, see and hear it at "B2 Audi coupe GT 20v 7A conversion first drive"
I would also like to change the standard injectors to Bosch injectors but which ones do you go for, as you have posted there is some conflicting information out there on the internet.

If you have any doubts go for the greys I guess? I think my manfold has provision for a second lambda, perhaps I should invest in a wideband

I have a spare pink injector - if anyone has a spare grey id be willing to have them compared at an injector cleaning place

Haven't been on here for a while, but here's a rolling road print out of the engine in my passat with the pink injectors, stainless exhaust and piper cams

http://i1084.photobucket.com/albums/...pskcqq3qmg.jpg

I think I was maybe expecting a bit more from it - wouldn't necessarily put it down to the injectors though as it's not mapped for the cams AFAIK (was Error404's engine)

I used to work for Aldon many years ago. :)

Update on this

Been running the pinks for a few years now no problem. I think for a stock 7a they do the job

I can’t help but feel that there is more to give from my engine. So I decided to have a look around for some bigger injectors

The 034 kits started coming with Bosch 0280155831 brown/orange injectors. I’ve managed to find out a few things about these

Again they are Volvo injectors, fitted to 5 and 6 cylinder turbocharged engines. 320cc They are a newer version of 0280155759 fitter to earlier Volvo turbos. They are the same flow rate but have a twin cone spray pattern. The 759s spray a single cone. I would think the twin cone was developed for better performance in multi valve heads, though the Volvo’s in question were always multi valve! (I guess Bosch hadn’t developed them yet)

The ones I have now 0280155832s Will more than likely be for sale if anyone is interested! They’re 250cc, dual cone

The 831s are readily available. I’ve just bought some 2nd hand for £40 on eBay I’ll get injectortune to service them. I’m going back to aldon next month, so it’ll be interesting to see what a difference it makes

Hi, been reading your thread with interest as I am looking at replacing my injectors as well overt the next few months. The Bosch 0280155831 look the best bet so I will be going for these, but I cant work out, did you mod the resistor pack like the 034 kit ? or did you leave the resistor pack as OE and Audi built it from factory ?

Thanks for the write up on this, been real helpful, just the resistor pack issue now to sort out.

Cheers

David

The resistor pack needs bypassed if you are using Bosch injectors. Easiest way is to buy replacement connectors and run a small loom of 3 wires joined together in place of the resistor pack.

I ran the Volvo brown injectors for a while. Think they're rated at 305cc @ 3 bar. The car ran far too rich.

I got the grey ones overhauled by Mr Injector and switched back

Thanks for the tip, Grey ones part No 0280155931, will be used then.
I know I can look on the parts list but do you happen to know off hand what the part number of the 2 plugs for the resistor pack might be please, I would rather go this route than cut and crimp, as the car is totally original, abet wanting some work.

Cheers
David

So would you say I’m better sticking with the pinks? Were they too rich all the time or just on full load?

Don't think you'll see any benefit flowing more unless you plan to make other changes

Do you have any suggestions? It’s cammed but running stock ECU map. Free flow exhaust...

Think there's a mod you can do using the 2.8 maf. Don't know much about it. Other than that you're looking at more capacity or turbo.

I had 190bhp with my 7A and around 180Lb/ft before going 20vt, had the larger V6 MAF the grey injectors adjustable FPR, standard cams and the Patrick Carlier re-map. Still all happenned after 4k which is why I moved to the 20Vt but it sounded awesome:rock:

Is it a straight swap?....or do you need the airbox as well, pipes changed, wiring plug??

Will try and dig out the Audi driver article I did on it but think it needs a remap to work properly and the right version of the MAF so its a plug in replacement.. Send email address via PM and will send article... if I can locate it :smilewinkgrin:

I too have a Patrick chip'd ECU.....I wonder if it just needs the MAF to finish it off?!:hmmm:

Patrick further modified mine to take into account the MAF signal change (larger bore MAF slower airflow speed for same rpm ) Have to ask him if he can still do this :tup:

I think I'll just leave it for now Dave, the car's not getting much use at the minute anyway. Food for thought though.