ehall

So, first of all, please excuse my ignorance. I know very little about the ins and outs of fuel injectors. I have a number of questions.
1. What should the spray pattern look like, from a good working stock 951 injector? I ask, because I have a fairly strong feeling that what I saw from mine wasn't close to what would be normal. Of course, I don't no what normal would look like, so there's that.

2.Are there kits. etc, for reconditioning them, or do they need to be farmed out to a vendor?

3. Is it possible to upgrade to larger injectors without changing software? I ask, because I will eventually upgrade to a MAF system, for this car. If I have to spend money to repair or replace the stock injectors, I may as well just upgrade, if possible.

4. If I have to send them off, who is the go to vendor to handle the job?

5. How much fuel should come out when the injector fires? I used an empty clear 2 liter, and fired of each injector separately. Not much came out, of any injector, so I'm trying to get a baseline understanding of what "normal" might look like.

Okay, that's it for now. Thanks in advance!

ehall

To give a bit of background. The injectors sat in place, in their ports, for about 9 months, including a Summer and now a Winter. I suspect that they are fouled. I have great spark and plenty of pressure at the rail. I'm getting a wicked misfire condition, and a lousy running engine. We've diagnosed it down to being a fuel, rather than spark issue.

azbanks

http://witchhunter.com/

$22 per injector to clean and flow test per injector.

I've never dealt with them but I've never heard anyone say anything bad about them. I'm sure they could answer all your questions.

ehall

Awesome. Thanks!

gpr8er

This is my go to. I've set numerous sets there and they come back with a before and after flowsheet and look brand new. FAST turnaround and and no BS.

http://www.rceng.com/Fuel-Injector-Cleaning-P43C0.aspx

Voith

Should look like this.



http://www.witchhunter.com/spraypattern1.php

jerome951

I had mine done last by Injector Experts. Quick turn around and fair price. They're in NE Ohio so shipping time should be fairly short.
http://cleaninginjector.com/contact-us/
Owned by a friend of my brother and they sponsor his drag car.

My car frequently sits for a couple months between drivings (especially in the winter) and my injectors were pretty gummy.

Tom M'Guinn

1. See google.
2. No kits really, just O-rings and new hats. You can try running an injector cleaner...
3. Not really. If you get bigger injectors without changing fuel tables, you'll get too much fuel and run too rich or not run at all. If you used a MAF with a piggyback controller, like Vitesse, you could use the piggyback to scale fuel in the meantime before installing the MAF, but you might as well do it all at once.
4. Witchhunter is great. Cheap, fast, and with a nice printed report card showing before and after.
5. There is a spec for that in the factory manual (I'm pretty sure).

ehall

Thanks for the pic. That is about what I imagined it should look like. Mine definitely do not look like that.

ehall

Thanks Tom, and the rest of you guys.

Dash01

Try this trick before spending big bucks:

You probably already have an old Schreder tire valve, or can get one free from any tire or bike shop. Could just use jumper wires with alligator clips, and briefly connect the car battery terminals to the injector terminals.

Otherwise, you could just fill the injectors with carb cleaner an let them soak overnight.

In other words, your decades old injectors may be basically fine, just need cleaning. These are cheap and easy ways to find out.

ehall

After 28 years, it makes more sense to spend the money, and have it done professionally, with some new parts. It really isn't that expensive. In fact, shipping cost more than half of what the charge was for the actual work. I don't intend to need to do this again, so it was the right way to go.

Dash01

It's your car and money, so do as you wish. This is sorta like calling a plumber at $100/hour to fix a clogged kitchen sink, when all it really needs is some Draino or scalding hot water poured down it to melt and flush out the waxy crud buildup.

That said, the essentially cost-free method shown in my video link above will give an excellent idea of proper flow and spray pattern in your injectors. It's as good a bang for the buck procedure as there ever was.

Plan B (if you have, say, a nearby PicknPull junkyard with a 944 Turbo) would be to try uber-cheap used injectors, about $3 each last I checked.

Plan C would be to spend the money to have the injectors diagnosed, repaired, or replaced as necessary by others.

It's all a matter of budgetary priorities.

Tom M'Guinn

That's a great shade tree video -- will keep that in mind for sure. Thanks for sharing it. The pro shops give you a before and after flow and spray pattern report, which is nice, and test the electrics, and they're cheap, so for an occasional test like this it still makes sense to me to send them out. That said, I can see myself obsessing on making up some good fittings and flow test chambers after seeing that video...

Dash01

You could expand on that video, rig up a simple way to apply constant fuel pressure for a given flow period, say 30 seconds, and squirt the fuel into a calibrated test tube, or similar way to gauge fuel flow. This way, you could compare actual flow rates of your 4 injectors, and see their respective spray patterns.

Start by back-washing the injector with the video contraption, to flush any debris from the internal screen.

On the BMW E34 forums, lots of guys go with Bosch/Mustang 5 injectors, a plug and play replacement of the OEM units. The Mustang injectors are a newer version, with four little squirt holes instead of just one, so the spray pattern is more of a mist, burning cleaner and more completely. Otherwise, the duty cycle pressure, etc. are essentially the same as OEM, and the computer adjusts for the slight difference. I get about 10% better highway mileage, notably better throttle response, and smoother idle with the Bosch/Mustang injectors vs. the originals. However, among the BMW guys there's a longstanding debate about whether the newer Bosch/Mustang injectors are more efficient because they have four hole nozzles, or because they're clean vs. dirty OEM removed from the car. A side by side clean OEM vs. clean Bosch/Mustang test would be interesting.

Some folks send their injectors away for testing (as has been discussed here), but over the years my impression from their posts is that when an injector is out of spec, it's most likely due to being dirty. So fix that and she's generally good to go. Hence, my suggestion above is to start with the cheapo cleaning method in the video, spend a few bucks on a good new filter, and if that doesn't work, then start spending money on other procedures and equipment.