Please don't be dying or badly maimed

March 3, 2013 2:16 PM

What are these problems with my car? Including: an intermittent moaning noise when my foot is not on the gas, some startup strangeness, and very rare RPM revving in park.

I have a 1991 Acura Integra GS automatic transmission with 167k. Bought it used in November 2012. I was told by the seller that not too long before I bought it the head and some other engine parts were replaced. I've just checked the oil and it's full, maybe a little too full. Unfortunately, I really don't know much about cars.

Issue #1 (most concerning)

Sometimes when the engine is on, I will hear an intermittent sort of moaning sound (not like a knocking or pinging—the sound comes and goes). It seems to happen more in colder weather and/or a colder engine). When I step on the gas even slightly, it goes away. If I'm driving along and let off the gas to slow down for a stop light, the moaning, if present, will happen. I seems to have a sort of inverse relationship with RPMs-something like the lower the RPMs go, the noise gets higher in pitch/more distressed.

If it's groaning and I stop and shift into park, the noise changes and sounds even worse. In park the noise goes up in pitch when I brake. The noise is still present when shifting from park to neutral. I've also noticed while hearing the noise in park that my RPMs were near 2k, which seems pretty high for park to me. The time that I noticed that, I shifted into reverse and started backing up and the RPMs immediately dropped and the noise severely diminished. As I was going down the driveway, I heard the noise go up for a second and observed the RPMs hop up slightly at the same time.

This issue has been present for about a month and seemed to have started happening maybe 3/4 of the way through a 3 hour trip. If it's relevant, I had more weight in the car... lots of moving boxes. I checked the oil pretty soon after that and it was fairly low so I filled it up but the issue remained.

Issue # 2

Sometimes when I start the car, I have to try it a couple times. When I do get it started, it's because I hold the key cranked for a little longer. Otherwise, it sounds like it's started but then immediately turns off. I also had one startup try where it just cranked and didn't start, but I haven't had that happen again. The issue is also intermittent and I have no idea when it's going to happen.

This issue has been present for a week or two.

Issue #3

Very occasionally when I shift into park, the engine RPMs will "rev" up and down. Shifting into a drive gear stops the revving. If I need to park the car and wait for something when this happens, I'll just turn off the engine in park. I've done some Googling on this one and it seems this is caused by a vacuum tube issue. This is pretty minor, really. I just wanted to mention it for completeness.


Are issues 1 and 2 serious? What can I do/check on to fix them? Should I take it in to a mechanic?

posted by nrobertson to travel & transportation (10 answers total)

Should I take it in to a mechanic?

Yes.

I can't get much from your descriptions, really, including likely seriousness. because I can't say that it isn't serious, it is probably safer to assume that it is likely to leave you stranded and/or potentially dangerous (or at the very least expensive to ignore). The intermittent start issues and the revving randomly suggests some kind of air leak in the induction system to me (or vacuum leak) that would match with the temperature related aspects of it. That, on it's own, is clearly something a mechanic needs to fix based on your apparent knowledge.

With any intermittent fault, I strongly suggest spending some time and effort trying to work out how to make the problem happen. Nothing makes an intermittent issue go away like having someone that can fix it stand there. Any tricks or wiggling you need to do that will increase the likelihood if it happening is valuable to the mechanic.

I don't know if the noise is related or not. My best guess is some kind of bearing issue - this is likely to be expensive, I suspect. Alternator bearing or Power steering pump or air con compressor? Again, if you can make it happen with something - ie more likely with the air con on, more likely with the car turning, more likely with the lights on or rear window heater on (high electrical load). Other than that, I can't help much from this description I'm afraid.
posted by Brockles at 2:42 PM on March 3

FYI, nrobertson, Brockles is one of the mefites most knowledgeable about cars. If he says to take it to a mechanic, you should take it to a mechanic.
posted by ocherdraco at 3:02 PM on March 3

Regarding #2, I had a '90 CRX (honda...your acura is just about the same thing) that just sometimes didn't start. Making sure the distributor contacts were clean helped to make the problem happen less often. My brother inlaw/mechanic couldn't ever figure out the problem.
posted by notsnot at 3:27 PM on March 3

Could be a dirty idle air motor. Or whatever Acura used for that at that time. Before going to a mechanic, do the easy stuff. google for videos on how to clean that thing, and check to make sure the air cleaner is not dirty. Then take it to a mechanic.
posted by gjc at 4:42 PM on March 3 [1 favorite]

Yeah, what brockles said. I will add that issue #1 could be a slipping belt. You say you had the head off recently and the engine in your Integra has what is called VTEC which is a fancy term meaning the engine can somewhat tune itself throughout different RPM ranges and if that wasn't re-installed properly it make cause all 3 of the problems. Do make sure that there is nothing loose on the intake manifold/plumbing as that could also cause all the problems and would also fit with the head being recently replaced. Anytime you do major work like that you have a certain shake down period as you trouble shoot any little things you might have missed when putting it back together. That may not have happened in your car. My money would be problems 2 and 3 are related and 1 is independant of 2 and 3.

BTW you did a great job explaining the problem it is just that there are several things that could cause this and its really hard to say without an experienced eye and ear to diagnose which system to chase first.

The good news is, this car is basically the same as a honda Civic and there are a TON of these around and every mechanic knows the ins and outs of them and parts are available and cheap.
posted by bartonlong at 5:26 PM on March 3

I would also make sure the car is full of coolant. Low coolant levels can cause the surging you're describing.
posted by razzamatazm at 11:41 AM on March 4

Seconding gjc and the idle air control, either because it's sticky or because a vacuum hose is leaking or disconnected. Similar behavior on my '93 Subaru Legacy was resolved for good and all (well, 100k miles, anyway) by cleaning the IAC.
posted by jet_silver at 8:09 PM on March 4

I took this to a mechanic in a neighboring city and got it fixed several weeks ago. Turns out there was a problematic hose, attached to something up at the top of the engine, I think he said crankcase. I looked up crankcase and it sounds like that could be the thing.

The hose wasn't the proper kind and had deteriorated from oil. It had collapsed and thus created a fluting kind of noise and ill mechanical effects. He took it off and showed me, it was squishy in some parts, definitely a damaged hose. Replaced with the proper kind.

$42.
posted by nrobertson at 9:10 PM on March 29

Awesome. Sometimes the swing on luck is in your favour. Glad it was something so minor.
posted by Brockles at 6:58 AM on March 30

Also, I should say the issue that was obviously fixed was the noise, but I haven't had the other problems again either, so I'd say those are fixed, too.
posted by nrobertson at 5:42 PM on April 23