Okay I have a 1985 Camaro Iroc z-28. With a 700r4 transmission and a 350 tpi.

First my car was idling really bad (jumping up and down RPMS and then eventually the engine would stall). So I replaced the idle air control in the throttle body.

Well now the idling is mostly fixed. It barely jumps at all and sits pretty good. However, while driving and usually between 20-30 miles my engine will completely cut off and it'll be hard to break and I'll have to restart the engine.

I did a bit of research and found it could be a vaccumn leak but I'm not exactly sure what that is. Could be a host of other things to perhaps.

Any advice?

 

just for argument sake, have you checked all of the obvious stuff like the fuel pump, fuel filters, air filter, etc?

not saying that will fix it, but you'd be surprised what a clogged fuel filter will do...

2. does it always happen after pretty much an exact amount of time? or just, periodically... and, does it ALWAYS do it?

3. have you been watching your gauges to see if anything is changing over the 20-30 minutes? like temp or oil...

4. could very well be a vacuum leak or an intake gasket, or several things.

unfortunately though, i'm having a very similar problem with my TBI motor, and no one has responded to that thread yet either lol. but mine doesn't die after driving, only when it idles, until it warms up, but i haven't put enough miles on it to know yet if it dies while driving..

but.... fyi, the "hard to stop and steer" thing is because you have power brakes and power steering... powered by "the motor" so to speak, so if the motor doesn't work, neither do the other things..

it REALLY sucks when a car dies and you're in a sharp turn.....

 

I just replaced the fuel filter and the air filter so I know those can't be the issues. Have not checked the fuel pump. Though the fuel pump on my camaro is wired odd- it makes the buzz sound all the time and never cuts off...

I still have yet to check the intake gasket or for vacuum leaks so until I do that I guess I have nothing else to report on.

 

sounds like you hit the nail on the head !!!

 

How do I go about checking for vacuum leaks? I'm not trying to pay a mechanic and the carb cleaner method seems kinda dangerous.

 

carb cleaner works well, I like to use propane !!

 

I can't tell if you're sarcastic or not. I'm pretty sure I'll catch something on fire if I try this.

 

im not sarcastic, if you put a hose on a propane touch you can use that don't light it or anything. small amount of carb cleaner sprayed around the intake ports and plenum as well.

 

Okay, I'm gonna try this today or tomorrow. Will report back if I find something.

 

as for checking the intake gasket for leaks (and a lot of people may argue with me about this)

an easy way is to take the air cleaner assembly off the carb or whatever you have *i forgot what year yours is

and while the car is running, pour a little bit of water in various places along the gasket line... if it bubbles, there's a leak.. in theory, it shouldn't suck the water INTO the motor, because the motor will be pressurized... but it will bubble air out of the holes.

there may or may not be an area between the heads, block, and intake near the timing chain cover area too depending upon if the all of the parts or stock or not.

sometimes there can be close to an inch of gap that needs to be filled depending upon the parts that are on it.

or if it's ever been taken apart...

there's likely to be a leak there...

for clarification, if you're standing directly in front of the car looking under the hood, it would be the area in the top front of the motor where the intake meets the block... there may be a gap between the intake and the block and it may not be sealed...

it's not very likely, but it's a possibility...

as for checking for vacuum leaks, the best way to do it is by ear.... turn the car on and listen for sucking sounds that you normally wouldn't hear on a car........

this can be difficult if you haven't had the car for very long and don't know what it SHOULD sound like...

it's a pain in the ***...

beyond that, maybe your idle is too low, maybe you had bad gas in it or the wrong octane,

check the oil and make sure there's no water in it, make sure your radiator has water in it,

that's a few more things to look into if you haven't already....

as for the fuel pump, you probably have an aftermarket fuel pump in it, in which case, it will always hum and won't turn off while the car is running.... if it turned off, it wouldn't pump fuel...

walbro's are fairly loud and hummy, as are most of the non stock / in line fuel pumps.... in tank pumps aren't quite as loud, but are still loud...

they kind of sound like a computer fan but much louder...

either way, that's not to say its GOOD still, im just saying, a lot of fuel pumps DO hum and make noise, especially if they are larger than stock for high flow....

 

This was it! Thanks a ton. I put a vacumm cap on that. And I got an oil change and my car is running 10x smoother and it hasn't stalled out yet. Though the idle still jumps a little bit (my car even still jolts itself forward a little) but no stalling.

 

Awesome!! Congrats dude.. glad you got it 1 step closer.. now for te fine tuning huh? When u have money, get a throttle position sensor and some of the other sensors and clan out your injectors.. also make sure you're running the right gas in it. Not sure what it preferrs but it makes a difference. Maybe someone ele can chime in with preferred octane. Id like to know too

 

Well I just replaced the TPS ....couldn't get the second screw in though its stripped :/

My Mass Air Flow Sensor is going bad now too. Looking at replacing that. Seems like when I fix one issue another one pops up.