CamaroJosh

Lately i've noticed that my car has a horrible loss of power. This all started about a week ago, at the same time my car started smoking a bit on start up. Sometimes it hesitates in lower RPMs.
I also changed my oil about a week and a half ago, and my oil pressure is pretty low only when idling

I have a completly stock 88' Iroc-z

91-Z28-L98

First make sure you don't have any vaccuum leaks. Then I would check the ignition timing. Other possible problems are low fuel pressure from clogged filter or bad pump and some kind of misfire. For the misfire, listen for a steady spitting sound coming from your tailpipe. If its this, then you are either losing spark, fuel, or compression on one or more cylinders.

I've had problems with all of these. Vaccuum leaks are easy to check for. A timing gun costs like 30 bucks and is worth it if you ever want to advance your timing or replace your distributor plus its pretty easy to use. Fuel pressure gague is more expensive at 40 dollars but it was worth it for me as it nailed one of my problems. Misfire opens a whole new can of possible problems, so hopefully thats not it.

krow

You may have a fuel injector down. Sometimes the check engine light won,t come on if 1 injector is clogged. Check your spark plugs to see if any are loose or disconnected. You may want to think about how long the cat. converter has been on your car. When the converter starts to clog it make your car run rough, sputter, loose power, or smell like a nasty fart. Just listen to the exhaust, and that will let you know what it is.

AutoRoc

Check for Vac. leaks like they said and Id also reccomend cleaning the MAF sensor(MASS AIR) wire/filament. Remove it from the car and give it a quick blast of O2 cleaner, maybe use a Q-Tip to clean it also. Maybe a new O1 sensor and usual tune-up stuff also. Goodluck

V8 Slayer

How do you check for vacumm leaks?
When does a new fuel filter need to be done?

91-Z28-L98

You check for vaccuum leaks by looking for loose, cracked, or removed hoses that should be attached to the plenum. Also, you can listen for them. Major ones will make a loud hiss. If its not coming from a hose, it may be hard to detect the leak. I believe soapy water can be used to pinpoint leaks in gaskets but don't dump it on the engine while its hot and avoid hitting electrical components. Be sure to check the bottom of the plenum as well, as there are a few hose connections there.

Listen for the steady spitting sound coming from the exhaust. If its there, you have a misfire. Come back and ask again and we'll give better answers.

V8 Slayer

I have a semi growling spitting sounds from my exhaust but I just got a high flow cat and catback not too long ago.

CamaroJosh

I don't think the cat has ever been replaced, and i'm thinking about getting it removed... All of this started when i removed the Air intake from the throttle body, to make it easier to get to the radiator hose that i had to replace... Mabye this could have something to do with it... Ever since i did that my check engine light has been on

CamaroJosh

Update!!1 Yea i have a loud hissing sound coming from the exhaust, just went out and checked... What do i do from here?

V8Rumble

Easiest way I've used to check for vacuum leaks is to have the engine running, & spray short bursts of something flammable (brake cleaner in my case) at areas where you suspect that there might be a vacuum leak. If the engine speeds up, then it was able to "ingest" the flammable spray that you introduced. That once allowed me to find a degraded intake runner gasket that was allowing "false air" into the engine...

V8Rumble

OK... I know this is a dumb question, but...

Did you put everything back the way it was when you started?

(Not trying to be insulting, but I've found that it often pays to ask the "dumb" questions...)

And I've got a question about your exhaust/cat too - if you crawl a bit under the passenger side of the car (when it's COLD!) & smack the catalytic converter, does it make any kind of rattle? If so, then the "brick" inside of it (assuming it's the original cat) is probably blocking at least some of your exhaust flow...

CamaroJosh

I spent about 30 mins trying to get that damn boot back on there, but i'm pretty sure i put everything back together right...

Trust me, i'm not insulted haha My knowledge of cars is very limited, i've only recently began trying to work on my car, so you gotta work with me

I'm pretty sure the cat is bad, and i know it hasn't been replaced... Ill run out and check the knocking thing

V8Rumble

OK, I once had a friend tell me "Your eyes are sometimes the best diagnostic tools!" He's been right once or twice, so it's worthwhile to sometimes just look at what you've just worked on.

(Confession: When I first got my car, I spent part of a Saturday doing most of the free mods, put it all back together, & when I fired it up, I was almost instantly greeted with the dreaded SES light! After a second or so of unreasoning panic, I got back under the hood & double- & triple-checked everything. Smacked myself when I saw that I'd forgotten to plug the MAF back in... )

Hey, no problem, everyone starts with knowing nothing! Different people learn from different methods, but speaking personally, I learned a little bit from spending a little time with this book - it sorta helped me learn a bit of how some of the theory "fit together"...

I'd also recommend that you check out the resources at ThirdGen.org - there are some people that (probably) know thirdgens better than they know their family members...

91-Z28-L98

Usually when your cat is bad it will glow when the engine is hot. Unless this is happening, I wouldn't jump on the bad cat bandwagon just yet. If you just did something to the car and suddenly the car is running bad and the SES light is on, the what you did probably is the cause. Since the SES light is on, it wouldn't hurt to get it checked out. You can either buy an OBD1 scanner at autozone or go the cheap route and just jump the test terminals to get the computer to reveal the codes. I believe the procedure is in thirdgen.org somewhere.

91-Z28-L98

By the way, the spitting that comes from a misfire sounds like puh puh puh and is accompanied by bursts of air. Put your hand behind your tailpipe. If it doesn't feel pretty continuous, then misfire may be the problem. I don't know what could be causing the hissing that someone stated...