The Forgotten On

As the title states I would like to know which gen III bosch or equivalent modern injector would fit a stock 2.5 8v engine.

I recently acquired a 1987 base auto (more on that later) and it is running a touch lean on cylinder 1 according to the plugs when I pulled them. It also barely passed smog with near the max on NO.

I think the injectors have done their job for the past 31 years and it is time to replace them with a fresh set instead of having them refreshed.

Anyone have any leads?

odonnell

Look up Ford Racing AA302 injectors. They will physically fit directly and are 24.3 lb/hr at 2.7 bar fuel pressure.

However, newer injectors like this are "saturated" where stock injectors are fired using a peak and hold control scheme. Do a few google searches to get up to speed on the differences. Stock engine management is not designed for them, they may run fine though, maybe someone else can chime in with real world results.

I run the Ford Racing BB302 injectors on my '83 which are ~30lb/hr but I have standalone engine management. I did notice smoother running at idle and quicker starting when I swapped over from EV1 style Saab injectors. I switched when one of the old injectors started leaking at the body, but now that I have felt the difference I wouldn't run EV1 injectors again unless I absolutely had to.

aussie944cab

I replaced my old injectors on my S2 and fitted Bosch ones 0280155831 FOR 98-09 VOLVO 2.4-2.5-2.9 L-TURBO,
but I also have standalone, so not sure if compatible with Motronic
It was worth it just to get rid of the TICK TICK TICK
Some reading for you
https://rennlist.com/forums/928-foru...e-ii-info.html

V2Rocket

physical fitment is no problem, its the flow rate and impedance to watch for.
newer 4-hole injectors do run smoother for sure (and are quieter) but most are high-Z which "should" work but who knows until trying.
FYI 944 NA are low impedance ECU.

aussie944cab

Isn't there a bank of 4 resistors wired in series to each injector to increase the resistance to a level that the Motronic can handle, I removed these resistors on mine, doing this allows for high impedence injectors to be used

V2Rocket

only on certain MY of S2.

the 944 NA, turbo, and S don't have those resistors.
however the turbo has 5.5 ohm or so built-in "medium impedance" and the S is high-impedance by design.

The Forgotten On

The trouble is finding peak and hold injectors with the proper flow rate. My 81 928 requires the same flow and impedance (2.2-2.5 ohm) injectors as the 944 does, just a different style.

I can find 30lb injectors no problem. The correct sized 24lb'ers are so hard to find when using Bosch OEM numbers.

V2Rocket

remember that bosch injectors are rated at 3 bar so a 24# injector might only be 21-22 at the 2.5 bar 944 FP.

aussie944cab

Talk about making it up as they go along, Whether there was a lack of "correct flow" injectors at the same impedance for all their models or something else, it does show the Germans have a sense of humor

odonnell

The ones I listed:
Bosch 0280155931
GM 12561462
Ford M-9593-AA302

Given that they are slightly larger than stock these are probably not good injectors if you want to pass smog. The O2 sensor will compensate some percentage but I wouldn't recommend these as plug and play, they are just the closest that I am aware of. Ford Explorer (forget which years) injectors are almost the exact same flow rate but they are the "short" EV6 style and need spacer hats to fit.

aussie944cab

This http://users.erols.com/srweiss/tableifc.htm helped me choose the right one for my project
these require a groove to be dremelled into the top https://www.google.com.au/search?biw=1203&bih=636&tbm=isch&sa=1&ei=B4YIW6nEMMWQ8wWf-q6oBg&q=0280155849&oq=0280155849&gs_l=img.3...77871.80342.0.80915.6.6.0. 0.0.0.368.1070.0j4j0j1.5.0....0...1c.1.64.img..1.3.714...0j35i39k1.0.5hs SmHUJeMU

These have the correct(ish) groove but are 22.5 @3bar https://www.google.com.au/search?biw=1203&bih=636&tbm=isch&sa=1&ei=2IYIW_6-I8j08gX9x65g&q=0280155832&oq=0280155832&gs_l=img.3...112902.115683.0.116 364.6.6.0.0.0.0.190.908.0j5.5.0....0...1c.1.64.img..1.4.725...0j35i39k1. 0.EMQJTV6eTBo but according to this website, they are 25lb/min http://fuel1.net/Bosch_Injector_280155832

aussie944cab

just found this https://www.turnermotorsport.com/p-4...-injector-set/, not saying they'll work perfect, but they are the closest I can come up with, Re. the slot, you just have to elongate it a little so the clip fits over it fully, ie the sides of the clip are parrallel with each other, You'll see what I mean when you trial fit the clips

The Forgotten On

What stinks is that the 944 base's motronic uses a real peak and hold circuit that would possibly fry high impedance (saturated) injectors due to the high "peak" current of around 4.5 amps.

Most other cars of this era used a resistor bank to run low impedance injectors on a high impedance (saturate) circuit. This makes their injector options quiet large.

aussie944cab

Didn't have to look that far into it when I was changing mine as I had VEMS standalone ECU, What is the general concensus in that 928 thread I posted, I was more interest in the physical compatibility compared to the electrical

odonnell

Damage will occur if you run low impedance injectors in a car designed for high impedance. Current is too high through the driver (think ohms law). However a high impedance injector in a low impedance circuit, which is the case here, may not necessarily cause damage. However the pulse sent to the injector is inherently different so the behavior you get from the injector will probably not match up to what the ECU thinks the injector should be doing.