I just purchased my '93 two days ago and got it on the road today. I'm noticing a high speed ticking sound that only occurs when I'm on the throttle, even a little bit. The instant I apply any amount of throttle, it comes back. It's coming from about around the air pump area. Almost sounds like a boost leak, but it's too rythmic I think. Any known issues with that thing going bad (clutch? bearings?) and why it would only manifest itself under throttle? Could it be something else entirely? Sorry I know nothing about these things yet but I'm learning as fast as I can. TIA!

 

is it like a noise similar to when you wind up a toy? if so check the return line from your midexhaust section(midcat/pipe) back up to the rear of the engine block. i dont have one and mine makes a noise as i described when that line is not there.

 

I believe that is your air pump making that sound.

 

It's a high frequency (as in repeats very fast) clicking sort of sound. I've driven around a bit more and it only happens at lower RPM ranges and under part throttle. Further, the rate does not increase with engine RPM, it remains a constant frequency.

 

what modifications does you FD have?

 

None really. It has a catback exhaust, silicone vacuum hoses... New motor by PFS about 5k miles ago. Nothing else that I am aware of, though I cannot attest to what the previous 2 owners have or have not done.

 

One more tidbit, the clicking sound it makes is like the sound you hear from the brushes on an electric motor like your hvac fan under the dash when it wears out. It's definately originating in the engine bay but it's very loud in the cabin. Annoyingly so.

 

Most likely it's the cycling from your wastegate and is normal.

 

Think so? I have my doubts though... It's louder than my exhaust, it's louder than any other engine noise. And it doesn't change at all with engine RPM. I've always used my ears to troubleshoot and they're telling me something isn't right.

 

take it back to PFS and have them take a look. kinda hard to diagnose a noise like that unless you're there physically.

 

Fair enough. It sounded like a common question that comes up from time to time. Maybe it's not the wastegate though. Your intuition is probably going to be better than my guess.

The fact that the frequency doesn't change with RPM, and that it comes from the passenger's side of the car was leading me to believe that it wasn't anything connected to a belt.. as that should sound different at different RPMs. The wastegate solenoid operates at a constant frequency and is audible when you have a downpipe installed, particularly when driving just to the left of a jersey wall or other large object.. but if you're saying it's LOUD then it might not be..

You can disconnect the air-pump wire to disable the clutch on it if you want. The pully will just freewheel. That should diagnose pretty easily.

 

I'm with you on this one. Because it's consistent and only happens under part throttle conditions, I was thinking some sort of solenoid or a really loud relay chattering, but I have absolutely zero experience with these things and don't know what's what yet

I will give that a try, thanks for the tip!

 

newburn has some good conclusions. the only things over in that area are the intake, turbos and the dp. perhaps the dp isnt bolted on correctly?
if its louder than the exhaust than i cant imagine itd be the airpump. guess it depends on your exhuast though.

 

Does the car have to be moving for this to happen? Will it do it standing still in neutral?

Another thought... Since it keeps the same frequency regardless of RPM, maybe something is vibrating (at the natural frequency of the engine mounts, or at its own natural frequency) in the engine compartment when the engine is slightly torqued over under light acceleration. Maybe some shield doesn't have enough clearance to the body, etc.

 

It happens in neutral and when not moving. The frequency never changes, and the sound happens immediately upon touching the throttle and stops immediately upon releasing the throttle. It also seems to dissapear above a certain RPM. It definately seems to be electrical/mechanical in nature.

 

Not the wastegate then. Need boost for that to move.

 

Okay the jury is in. It is definitively the air pump. Per NewbernD's recommendation I disconnected the electrical plug to the pump and the noise immediately ceased. I don't know what exactly is wrong but at least I know where to start. Any guesses as to what a new replacement costs?

 

Where in VA are you? I have one in Laurel that I don't use any more if you feel like making a trip.

 

Fairfax, so you're probably not much more than an hour or so away. That'd be great, how much are you looking for? Yes, I definately feel like making a trip! I haven't driven my car ANYWHERE except 2 miles to and from work at 25 mph Any excuse to drive the new car somewhere. Unfortunately, I'm out of town this weekend at a road rally in NJ on Sat and then a Rallycross in VA on Sun. I'm totally open Thxgiving weekend, or perhaps some weeknight? Let me know what works for you. Thanks, I appreciate the help!

 

PM sent

 

New replacement is exorbitant, don't even bother. Just post a wanted ad in the Parts Buy/Sell forum.

Dave

 

I still don't understand how something that is driven by a belt at engine RPM can make a noise that does not change with RPM. That makes me suspicious that either the magnetic clutch is chattering (from getting a low voltage?), causing your noise, or something else downstream that is fed by the air pump (ACV, ACV solenoids, etc) is actually causing the noise when supplied with air from the pump.

 

I thought the exact same thing. Does the air pump output a fixed volume of air regardless of RPM/intake airflow or is it variable. Since the sound is sort of a clicking sound (like a relay switching really fast) I thought maybe it's electrical in nature - perhaps the pump's clutch or some control electronics. But it's loud like a boost leak (only there's no boost when it's happening).

Hrm, more to consider... Any ideas on how to isolate/eliminate these possibilities? How complicated is the air pump system? Maybe I should have stuck with DSMs!

 

The secondary air system is described in the FSM, page F-115. There are tests that you can do that will help diagnose it.

Dave

 

Hmm i have an identical problem with the ticking noise, it doesnt change with rpms......but here is the kicker, i dont have an air pump!!! So what is my problem???