Do our injectors make noise?
 

My 87 CIS 930 started making a ticking noise under load that seems to start around 2000 rpm and goes away once boost comes up. It does not have any regular rythm to the noise sounds similar to a vacuum cleaner going over the kids dirty room, as it pulls up little bits of junk, only much quieter. I can only hear it with the windows up. I am afraid it is detonation, but it seems odd that I cannot hear it at higher or full boost. I have checked my plugs, normal. Checked AFR, very rich throughout the entire operating range. just adjusted valves (backside method) thinking it could be noisy valves, that wasn't it. My GSF headers glow slightly in the heater box. I can see inside because I still do not have the proper size hose to connect them. I used the crappy exhaust gaskets supplied with the kit. I can't tell if they are leaking or not. I ordered some good ones but have not yet installed them. I have not pulled the injectors yet. Has anyone ever heard these injectors make a noise similar to this?
Anyway, if anyone has any thoughts on this, I would love to hear them.

Eric
87 930 gsf headers fabspeed single out, K27S, Kokeln IC, C2 style diverter valve, Tial wastegate.

Hello Eric,

Yes, they do. One of the most clever things about CIS is the little needles fitted to the ends of the injectors. They chatter audibly at a high frequency directly related to the volume of fuel injected. They are one reason that CIS injectors have better atomization than EFI injectors. You can definately hear them working, and after around 30 years of listening, you know there is a problem when you can't hear them. The sound can fool some people because it does sound like mild pinging and is related to pedal position.

Paul

Check to see that the plugs to the air injection ports are tight and that none have fallen out.
I have had them drop out on me twice already....though that usually leads to a loud noise.
Worth a shot.

Psalt, I thought they did make noise, I just haven't really noticed until now. Come to think of it, I think there is some sort of "chatter test" when testing them If that is what I am hearing, that would also explain why it goes away at higher boost, maybe because of lower pressure, and enrichment.
Fredmeister, I thought of that also and checked them this weekend when I adjusted the valves. They were all tight. Did you notice a slight glow on your headers when you installed them? If I remember correctly you also have GSF, and where did you get your heater hoses to connect the heat boxes?
Well hopefully the injectors are what I'm hearing, I don't know what else to check. The plugs seem healthy AFR is good, although possible that I could be running lean on one cylinder. I guess I will just keep an eye on the plugs, hopefully they will cue me in if I'm pinging.

Thanks Guys
Eric

yeah you can bench test them and clean them with a special tool, i would use the vw tool for cis injectors. same stuff and its pretty cool to hear them hum when your pumping them up.

CIS injector test:
http://forums.pelicanparts.com/uploa...1203042570.jpg

Remind me and I can find a video of my injector test -------

just sick man

Fredmeister, I thought of that also and checked them this weekend when I adjusted the valves. They were all tight. Did you notice a slight glow on your headers when you installed them? If I remember correctly you also have GSF, and where did you get your heater hoses to connect the heat boxes?
Well hopefully the injectors are what I'm hearing, I don't know what else to check. The plugs seem healthy AFR is good, although possible that I could be running lean on one cylinder. I guess I will just keep an eye on the plugs, hopefully they will cue me in if I'm pinging.

Thanks Guys
Eric
Eric,

Fredmeister, I thought of that also and checked them this weekend when I adjusted the valves. They were all tight. Did you notice a slight glow on your headers when you installed them? If I remember correctly you also have GSF, and where did you get your heater hoses to connect the heat boxes?
Well hopefully the injectors are what I'm hearing, I don't know what else to check. The plugs seem healthy AFR is good, although possible that I could be running lean on one cylinder. I guess I will just keep an eye on the plugs, hopefully they will cue me in if I'm pinging.

Thanks Guys
Eric
Eric, I noticed a pretty significant glow on my headers while letting it idle last week. Never noticed it before, but it has been in storeage for the winter and I only noticed it because it was twilight and saw the glow.
As far as the heater hoses, I needed to buy reducer pipe from a local auto parts store to get from the larger OEM metric hose down to the smaller tubing GSF chose (for some stupid reason) to use going into the headers.

Yeah, I would never have noticed it if I had the heater hoses connected. Oddly enough, the glow is only from inside the heat boxes, doesn't glow anywhere else. Not bright, just a slight glow.
Eric