Rough idle has turned to horrid knocking...

[Little Jerry]

Hello everyone,
A few days ago my CEL came on and the engine began to idle rough. The idling didnt seem to serious... revs would occasionaly drop a little low, engine would act as if it were about to stall, then revs would pick back up. If i gave it a little gas the revs would fall a little low and repeat the process.

Well, today I drove it on the highway and noticed afterwards an odd feeling in the stick. When I got off at my exit I was sitting at the stoplight and it felt like someone was tapping on the other end of the shifter. I immediatly pulled over and got out to inspect. There was a disturbingly rough sound the engine didnt normaly make(usualy its very quiet...). Drove it home and noticed at another light a knocking noise. The noise comes and goes... sometimes worse than others. There doesnt appear to be any loss of power, or fuel economy at this point. There IS definatly something wrong though....

So, I was wondering if any of you have any suggestions for the problem before I go to a mechanic like a helpless tit.

Its a 1995 Protege DX manual.

[Project Protoge]

does it knock at idle or only at higher rpm's. Is it a metal on metal sound or is it a cylinder misfiring pinging sound.

[Little Jerry]

does it knock at idle or only at higher rpm's. Is it a metal on metal sound or is it a cylinder misfiring pinging sound.

It knocks at idle, and I *think* its a metal on metal sound. I'm not exactly sure what this misfire pinging is supposed to sound like.

[Project Protoge]

misfire pinging is more of a fast kind of quiet noise that you would hear climbing a steep hill with bad gas. The knocking could be rod bearings, but I have heard that the valve springs on that year of car were recalled because they were to weak. A good way to find the location of the noise is to get a piecs of hose and hold one end to your ear and the other around the valve cover. Check all around the valve cover for the noise. Next try the oil pan under the car. If the oil pan is your problem area you mostlikely will need new rod bearings and mains. If the problem is up by the valve cover then it is usually a simpler and cheaper fix. Also while you are up by the injectors listen to those, if one is louder than the others it could be causing the noise.

[Little Jerry]

misfire pinging is more of a fast kind of quiet noise that you would hear climbing a steep hill with bad gas. The knocking could be rod bearings, but I have heard that the valve springs on that year of car were recalled because they were to weak. A good way to find the location of the noise is to get a piecs of hose and hold one end to your ear and the other around the valve cover. Check all around the valve cover for the noise. Next try the oil pan under the car. If the oil pan is your problem area you mostlikely will need new rod bearings and mains. If the problem is up by the valve cover then it is usually a simpler and cheaper fix. Also while you are up by the injectors listen to those, if one is louder than the others it could be causing the noise.

its not pinging then. Ill check for where the noise is comming from when it stops raining. Talked to a mechanic today and he said it sounded like it was misfiring for whatever reason... We shall see on monday when I take it to the shop.

[Little Jerry]

Ok. I took a hose and tried to isolate the location. I cant find the exact source, but its NOT at the oil pan.

[Project Protoge]

Thats real good. That means it is not internal damage. When was the last time the oil was changed? Also your last tuneup?

[Little Jerry]

Oil was changed ~3000 miles ago. Tuneup ~2000 miles ago with CV joints replaced.

[Little Jerry]

Well... I got it back from the shop today and after $250 they didnt do jack ****.

He replaced spark plugs, cables, and rotor cap and said there was carbon buildup.

When I went to pick it up he said everything was fine and one of the guys was driving it around the block. When it got back I jumped in the car and... THE F'ING CEL WAS STILL ON! I walked back in and asked the guy and he sait that he couldnt figure out how to connect the engine diagnostics so he poked around the engine till he found some carbon buildup. He told ME to go home and disconnect the battery to see if it actualy worked! ASSHOLE! Listened to the engine and it STILL sounds the same! I didnt encounter any knocking, but it still idled and ran rough.

Hell will freeze over before I go back.

[beetle_orange]

what a RIPOFF!

[skullone]

Ill do that level of tuneup for you for $25!
Ill even vaccum the car, and shine your shoes!

[bhkrause]

This is a bit of a long shot, but take a good look at the corrugated rubber hose between the air box and the throttle intake. They have a habit of drying out and developing cracks that you can't really see unless you take the hose out and bend it a bit. You could be getting air in after the MAF, and that would give you all sorts of weird idling/knocking issues as the vacuum/air/everything would be way off. My 96 did that, and the CEL cam on and stayed on for 2 years, always a bit of a stumble. Ran fine any other way tho.

Bernie

Jeez, never mind, next time I'll check the posting date first!!

[Sunset]

scan the car. It could be your crankshaft sensor

[low323]

the crankshaft sensor ( idle control sensor ) wont come up on the scanner, ive been told that they are water cooled and sometimes can get blocked try tapping it with the handle of a screw driver when the idle is rough i had simular trouble and one of the mechanics went around tapping all the sensors with the handle of the screw driver and the revs just corrected it self he told me its commen with idle control sensors that are water cooled

[PaulinGA]

noise at idle

If the noise is only at idle and with the AC off, or if you can stop the noise by turning the ac on, its probably the ac pulley. Mine had a knocking or low pitched chattering noise that came and went about every 6-8 seconds at idle with the ac off. Turning the ac on stopped it. If thats what it is you can buy a stethescope at AutoZone and put the end on the ac compressor and check it that way. The bearing for the pulley is failing. If you remove the belt and spin the pulley it will sound rough. Mine had a small amount of play and sounded dry when spun.

If that is your problem you can replace just the pulley or the compressor. I went the compressor route because of age and miles. If I do the cheap thing to get by I get to do the expensive thing to fix it right within a month.

Paul