Well, I was driving home just now when i was almost to my house i was stopped at a stoplight and my car started idling poorly, like stumbling up and down, and the exhaust with kinda backfiring and making noises. I had been driving kind of fast before this but i dont know what happened. It cut out at one stop light and the vacuum was vibrating low, but would drive fine above like 2000 RPM so i slowly drove home and let it idle in my garage and put it on jackstands and tried to see where the noise was coming from ot what was wrong. The only thing i noticed was that the cat was making a strange noise. It was like rattling inside of it, and the exhaust was also puffing. I am goign to wait for it to cool off so i can take of the cat and see if i can see anything (im actually not sure what i will see there, Do you guys know?) What do you think could have happened? Or what do you think is wrong? Im thinking its just like a clogged cat or something and im hoping its not a bad engine. Please help me out. Thanks.

 

Map sensor vacuum hose. Check that.

 

Map sensor vacuum hose. Check that.

 

Any smoke from the exhaust?

 

sounds like ur running in "limp home" mode...the EXACT same thing happened to me after i drag raced my FD a few times. Check the map sensor hose like vudoodoodoo said. Mine had fallen off, and the second i re-connected it, everything was back to normal

-Zach

 

isnt limp mode where it wont go above like 2k RPM, mine drives good above there. THe only problem is that its really choppy below 2k. I checked the map senor on the map sensor side and it looks good, where does the other side go? i couldnt follow it. Any other ideas of what it could be?

 

and there might have been a little black smoke from the exhaust.

 

You say it drives fine above 2k, how about boost, do you get a normal pattern?

Cat making noise, especially rattling inside, could be a blown/clogged cat, but the car should run better in lower rpm's if that is the case, so that doesn't add up. Could be a different problem alltogether.

 

yeah, i let it idle somemore and checked all of the lines that could i could see, the cat only makes the sound when its warm. The car drove normal as far as boost goes as far as i could tell but i didnt want to push it too hard because i didnt know what was wrong with it. Im thinking it might be a vacuum leak now but im not sure where i should look exactly. The boost gauge is bouncing from like 10 to 11 at idle and isnt steady at all when accelerating which makes me think vacuum problem.

 

It's not limp mode. I hate when people make uninformed posts like this. It makes you have to weed through the crap to find the real information. You're right: in limp mode, the engine will cut out above ~3k rpm under any kind of a load.

Anyway, the other end of the MAP sensor goes to a nipple behind the throttle body, between the UIM and the fire wall. If your map sensor is ok, it really sounds like you might have a blown apex seal. You should do a quick compression test before you start tearing stuff apart. You could also have a leaking fuel injector, which could cause this sort of problem.

 

i thinkit could be a leaking injector because it does seem to be running really rich, bc of the black smoke and i think more than usual gas smell, but i cnat be sure. When you blow an apex seal does it run like normal in the higher RPM's? bc as far as i can tell mine is. Thanks for the input.

 

With a blown apex seal, it will sometimes seemingly run fine at high rpms. When I blew mine, the idle was crap, the high rpm power was terrible too, and I was blowing out black smoke because of the unburnt fuel. But I've heard of people who only broke one seal (I broke 3), or chipped one, and their high rpm power was fine.

A compression test will tell you for sure.

 

when I chipped 1 seal my car ran awesome above 1500 rpms I couldn't tell a difference in speed at all. It just had a hard time idling and was hard to take off from a stop so I raised the idle to 1300 and it was fine for 1000 miles until I blew the entire seal out I think.

My car may have run really well with a chipped seal because I had 4000 miles total on the motor after a rebuild. If yours is original I'm not sure if it would run as well.

 

Does your idle stablize around 850rpm when you put the car in N? If so, your LIM gasket is probably leaking.

 

darnit, i hope its not the apex seal but ill get a compression test. I think when its warm, it stabilizes at about 600 now down from 800 or 1200 but im not sure, ill check. HOw much does it cost to have your motor rebuilt or get a reman with installation and everything anyways, I think i might need to start saving.

 

 

reman is around 2000 but labor depends on the place. not including if anything is wrong with the twins. that stuff just keeps adding up.

 

My apex seal(s) went out last month. The vaccuum went from 480 on the FFC to about 330-360. When it first happen at IDLE the tach went crazy. Above 2K rpm the car felt almost normal.

Turned out to be 2 apex seals in my front rotor.