My idle is irratic and the motor will die in about a minute or less sitting in traffic. I have a new IAC valve, MAP, and TPS. None of those parts can be the problem and I don't have any vaccum leaks. The idle will drop to 1500 when I stop then 1200-1000 and be very irratic. Sometimes it holds but dies quickly. If I have my idle adjusted correctly then what might be causing the problem. Could it be timing or spark. Other then the idle the car runs great. It is an 89 2.8

 

Yeah that happens to me as well, I'm not sure what it can be, I've gotten so far 7 solutions.
1. Idle speed incorrect
2. fuel filter clogged or impurities in the fuel system
3. choke improperly adjusted or sticking
4. distributor components damp or damaged
5. faulty emissions system components
6. faulty or incorrect gapped spark plugs and spark plug wires
7. Vacuum leak at the carburetor/ fuel injection unit, intake manifold or vacuum hoses

On mines sometimes when I turn it on, the idle goes up to about 3,000 then drops back down to 1,000, and yeah when I'm in traffic it starts to buck, most of the times it stays on but every other day it will turn off on me, the worst part about this whole ordeal is being the first one at a light (a short light) and have your car turn off on you right before the light turns green, people get mad and start honking and by the time I turn it back on and put it in drive only I can cross the light before it turns red again. Like Nick Cage would say "come on eleanor (firebird) don't do this to me now, come on, not now!"So if you figure out what it is, drop me a line, it can only be a few things, so try to fix one at a time starting with the one you think it might be until the problem is solved, but we would appreciate it if anyone else had any other other suggestions other than the listed above to what the solution to this problem might be.

 

I think that it was a combination of idle and ignition. My motor does not like to idle even at 1000. It would be more like at 1200 to be smoother. I plan on rebuilding my ignition system and see if that fixes anything. I am goin to try to get my idle a little lower. If I can.

 

Do you know what the defualt ideal speed is? You know my car was running good until a mechanic who didn't know anything about fuel injection started messing with the idle speed, it was my dad's friend, I let my dad borrow the car for the weekened and he brought it back like this, now we can't find this guy. LOL. he knows what he did. But yeah is it ok to mess with the idle speed? And like I said I need to know out the factory what the idle speed was or what is the ideal RPM that the idle should lie

 

I think that the idle should be around 700 RPM. I have found out the hard way that it is bad to mess with the idle speed but it was messed with before I got the car. I have been trying to get mine lower without it dying. I think it is a combination of headers and the fact that I have a broken bolt on my head for the header. I can get about 1200 RPM before it gets really rough.

Check this page out. I had a high idle and this pretty much well explaons what needs to be done to get the idle down if nothing else is wrong with the motor (TPS, IAC valve, etc.)
https://www.thirdgen.org/forums/v6/4...ting-idle.html

 

don't forget to also check your vacuum brake booster by unplugging it from the vacuum hose and then plugging the line...

 

What will that do for me? I don't understand how unplugging the brake booster and plugging it will help but I will try it when I get home tommorrow. It comes off pretty easy but it holds on there. I can only get the idle so low till the motor wants to quit. The magic number for me seems to be ~1200 RPM. Anything under and the motor just goes up and down until it dies. Could this be bad injectors, fuel pump (which is louder than it used to be), plugs, wires?

 

it tells you if the brake booster is giving you a massive vacuum leak...

I had the EXACT same symptoms on a fiero with mpfi 2.8... it was a MASSIVE vacuum leak from the lines that hook up under the top half of the plenum...

 

Are you talking about the booster itself or the line. My line is fairly new I belive but I will go outside and plug it and see what happens.

Took the line off and plugged it while the engine was running and the RPMS definately increased. I guess that that is one of my problems.

Another question, any idea why my fuel pump has gotten really loud over the past few days. You used to barely be able to hear it in traffic and now it has gotten to be an annoying mid-pitched hum.

 

Because it's going bad...

GM vehicles have always had noise concerns with their Fuel Pumps, but if it gets louder, it's not a good thing.

 

I figured that it was going bad. The weird thing is that when I filled up the loud hum went away. I can hear it when I just let it prime. I guess that a bad fuel pump can explain why start up can take a few cranks or just one. Cranking the car is also inconsistent. Sometimes its right up and others it takes a few attempts.

 

Should I just buy another booster or try and find the leak myself and buy replacement parts? Where can I buys parts?

 

Is there any way to notice if one has a vacuum leak, what I mean is can one actually see the liquid leaking, and where would we look or do we have to take something off and see the residue on that part?