My car runs really good, but sometimes bugs out and just shuts of when ideling. It will run for like 30 seconds with no problem ( ideling) after that the rpms just start going up and down ,Then it just shuts off. I would think it would be a vacume problem. Does the little black thing that connects to the master cilinder go bad? Will the master cilinder go bad . I really dont now what it is.

Can any one help me ? What can it be?

 

Stalling out at idle can be caused by numerous things. When was the last time the car had a good tune up. A bad 02 sensor, clogged fuel filter, timing off, and dying fuel pump are some of the common problems.

 

The car has a new fuel filter, oil change every 2500 miles, k&n filter, spark plugs , old spark plug wires, and other little parts. When im running with the a/c it will not shut of. The car when i got it timming was at 0* , and two days ago i put it up too 4*, becouse at 0* it was doing it , but the problem still consist. You think it could be the fuel pump?

 

Did you unplug the EST when you set the timing. I assume you did. You could have a failing 02. Do the problems only occur when the car is warm or does it do it when it is cold as well. Your pump could be dying but you usually have driving problems as oppsed to idilng problems. You can check the feed line pressure by installing a gage in the feed line.

 

Yes i did unplug the EST when i did the timing . If you think it is the fuel pump then i guess i should put a fuel pressure gauge. At it being cold not really , i havent noticed .I think its only when the car is running at normal temp. The reason i havent changed the o2 sensor is becouse im waiting to get my shortys. What should i do? Change the o2, or put the fuel pressure gauge?

 

I would change the 02. I would get your car running right before you add any other mods. That way you can rule out anything that mnay go wrong during the header install. Plus you can just transfer it over one the headers arrive.

A bad fuel pump will usually only cause you problems when the engine is under loaded conditions. I would look into a pressure gage that can be spliced into the feed line just to keep an eye on it. You can get the stuff for about 20 bucks or so and can help diagnose a potential future FP problem.

 

Thanks alot, Do you think changing the o2 solve my problem?
changing the o2 sensor should be an easy thing write? my buddy has a psi gauge that went bad, "cheapy one". What brand should i use that i now it will last more that a month at least?

 

I would replace your 02 anyways if you think you have the origonal one. They should be changed when your car has around 50 to 80k miles. I have seen them go much higher though and when they fail the car will barely run. Go with the AC delco one over Bosch. It is a little more money buy Bosch 02's plain suck and will make your fueling off a bit.

As for fuel pressure gage try a search or two. There is some stuff out there that has all of the summit part numbers you need. Come to think of it. If I can get some good links to pold thread on the matter I will add it into the sticky.

 

Check the ignition coil. If your o2 sensor is bad, it should trip the SES light (I think).

 

Not always. It will not come on in open loop and come and go in closed loop. I have seen some GM cars with a completely shot 02 without a code.

 

on my 5th o2 sensor.

never once have i gotten a code.

 

I put the psigauge and at first it reads at 9-10 and when i get home or go some were it goes down too 3-4 , i guess it is the fuel pump. I am now changing it.

 

If you are at 3 or 4 at idle than you need to change that puppy.

 

Ok now i finished changing the fuel pump, put the gauge, and changed the o2 sensor. The problem still happening. The gauge now reads when cold about 10 - 12 , and when hot around 6-8 .Are these #s good? What else can it be?

 

Did you replace the pump with a stock replacement? 6 to 8 psi is still a bit on the low side. You should never see below 8 to 10.

 

Yea i put a stock replacement. Or maybe its to dark and didnt see the right #s, Ill check again . If it isint the fuel pump then what else can it be?

 

It could be a bad coil or ground somewhere. It is hard to track down wiring problems. How old are the plug wires? Does the car ever run rough before it stalls?

 

The plugs are pritty old, i bought the car about 3 months ago, the car came with these spark plug wires. when i put the spark plugs I never changed the spark plug wires. When i took off the spark plug wires to put new spark plugs, the spark plug wires where broken and melted into the old spark plug wire. So me being cheap i fixed it my self "ASE SERTIFIED" LOL, i put them back on. Yes it does get rough before it shuts off, - First for about 30 seconds it idels good the around 45 second the rpms start to go up and down, not so dramatical like it may go down too some were around 500 rpms then it will go up too around 1500 rpms (dont have tach "broken" i just say it to tell you more or less). Have you ever heard one of those dsm (egal talon- eclips ) turbo when there mass air flow senseor gets bad? Not like that. It will go up and then about 10 seconds later it will do it again. But when the rpms go down it gets a kick of power and the rpms go up again. i will give it a good 2- 3 minutes on ideling on till it shuts off.

 

Well if your wires are that bad I bet you have found your problem.

 

Well changed the spark plug wires. Put accel 8mm , but problem still consist. What else should i change , that will solve my problem? Tommarrow i will change the coil and the modual, Is this a good idea? Also today i put a new starter and when i turn the key too start the car it does every thing perfect but makes a winding noise, what do you think it is? Maybe i didnt aline the starter write??

 

Boy I hate to see you keep throwing parts at the car and hoping one of them will cure the problem. I geuss I would look at the module before the coil. They can go bad and I know a few people that had a similar problem that tunred out to be the module. It is just not very common.

 

Well im just going to put both of them on new becouse its old and should be replaiced. Also everything you have told me to put on have either made my car look nice/run well/and just need to be replaiced any ways. Anything about my starter?

 

My bad about the different screen name. My buddy was the last on too use my computor and his name was still loged in. -Eric

 

I was gonna say

Anywhoo, Not sure on the starter. If it starts and engages just fine changes are it is meshed correctly. There are only 2 bolts that hold it in and when tightend should pull it up into place.

 

Have you checked the coil yet? How about the ignitor or pickup coil (located inside distributor)? Adjust your idle too.

After reading your post again, I'm thinking the idle could be set too low.

Also, disconnect the coolant temp sensor, then start your car. See what happens.

 

Ok i took of the coolant sensor and the car didnt want to start i put it back on and it still doesnt want to start . Why did you tell me to do this man?

 

That's a way to check if your CTS is bad. Did you re-install it correctly? Check if the CTS is installed correctly, disconnect the battery for a few minutes, then try to restart the car.

Have someone start the car, while you check if there's spark coming from the ignition coil.

 

Whats the cts?

 

CTS = coolant temperature sensor.

If CTS was bad, your car would behave like it's running on 3 cylinders. But if you remove the CTS, the engine should startup right-away, but you'll get crappy idle. But since it didn't start Coincidents maybe.

Also check the TPS sensor. Unplug the TPS sensor, start the car, hook up a multimeter to TPS, and raise the engine's speed (give it gas). As the engine's speed increases, so should the multimeter numbers. If the multimeter number drops at anytime(as you give it gas) the TPS is faulty.

 

how do u adjust the idle?

 

There isn't really a way since the ECM controls it. You can trick it though by adjusting the idle screw and IAC adjustments.

 

So i should change the coolant sensor? Is that the sensor that is on the manifold?

What is the tps? were is it located?

 

Test the Coolant Temp Sensor (CTS) before you replace it. And yes, it's on the intake manifold, located near the thermostat. I think it has a yellow and black wire.

The TPS is on the TBI. If your car drove okay w/out any problems, then it's not the TPS.

Anyone know how to diagnose a MATS sensor or it's location? Might be a good thing to check too, since 90tbi305 mentioned the RPM went up, then the car died.

 

The MAP sensor is on the top of the fire wall right next to the AC stuff on the passenger side.

 

how do you check the mats sensor?

 

Do you mean MAP? There is no MAT's. I am not sure how to test it frankly. I would have to pull out one of my manuals.

 

If you still can't get the car to start after hooking CTS back up, then press the accelerator to the floor next time you try and start it. This will put the car into 'clear flood' mode.
The computer reads the CTS for your fuel/air mixture. When I tried that trick it flooded my TBI with gasoline. (started for 1 second, and then died) It was explained to me on here, that when you do that, it tricks your computer to thinking that your coolant temp is somewhere like -40º or someting, and therefore floods you with gas. I was also advised to try unplugging the MAP sensor before starting the car. Not knowing the consequences of this; I have yet to try that one yet
And if your starter is making a whining noise, it either has too many shims installed, or needs one. Try loosening the bolts slightly, and then retorque them; before-hand though. I have seen this happen before.

 

opps..wrong post...delete this plz and thnx

 

interested to know if you tried the MAP sensor replacement. and how it turned out.

 

Sounds like the samething I'm going through, except it will sometimes start to run crappy while I'm driving not just at idle. I'm pretty sure my problem is the fuel pump or my timing. My auto teacher set it to 0 and thats about the sametime it started running funny, but I also hear a loud noice sometimes from the back of the car. So maybe its both. I also had a lean 02 sensor reading.

 

i had gotten a lean and rich code, then i got a 33 (map sensor). code.

 

When was the last time you changed your O2 sensor? They get old and alot of owners neglect them. Your computer is not going to tell you it is going bad, it just throws all kinds of codes about wrong readings when it goes, and alot of times, shows codes for other systems (ie: map)

 

i'm sure it has not been replaced for a while. I will try it, thanks for the feedback.

 

I tested mine, and it was working properly.

 

Could it be that the injectors are clogged and not spraying properly? Just a thought, man you seem to have tried everything else.

 

Maybe. I never thought to check/clean or look at them. I'll try that later. When there's sunlight.

 

Let me know how it works. I am curious. It seems like people are having this very same problem all the time and end up switching every sensor, but don't check that out.

Good luck

 

I got some injectors from a 91 350tbi from a van. Im gonna throw those on there and see what happens.

Ray D.

 

Do you have a 350? They might put to much fuel in and throw off your setup. I don't know though, I not a guru with fuel injection.

Bill

 

I'm inclined to agree with Bill on this about the injectors. The combustion chamber for a 305 is smaller than a 350, so you don't use/need as much fuel. You will more than likely get the effect of over-jetting a carburetor. The only difference I'd think, is that the ECM will try to compensate for that by cutting back on the advance (losing more power), and/or trying to adjust the mixture. Also, I am no guru w/FI either, just my take on it.