I just bought today a 95 z28 with a automatic transmission. The problem is when i start it up it idles weird.. The rpms goes up and down not much but you can hear the difference. Some guy said that it looks like it doesnt know where to idle.. When i am at a stop light it like wants to take off it pulls when im breaking just a tiny bit.. I have to make sure im breaking right if not it will take off.. Also when i step on the pedal at first like 0-30 it studders after that its just sweet.

Any ideas on what might be causing this?

-Ben

 

Sounds like possibly a vacuum leak

Take alook under the hood and see if there are any lose hoses

 

It could be several things. My first thought is a faulty throttle position sensor.

 

Remove the air inlet elbow on the throttle body, look for dirtiness....

Throwing any codes?????

Might be dirty IAC valve??????

Vacuuum leak???

PCV clogged????

Etc.????


Could be one or more????

 

The service engine light turns on at times not all the time though... I took it to autozone so they can tell me if its throwing any codes but some error came up and didnt read it. Im guessing there is something wrong with the connection port. Ill be taking apart the throttle body in abit and ill let ya know..

Thanks For the responses

-Ben

 

A lot of the new scanners at the auto parts stores are junk. I had to go to 3 before it would get my codes. The older the car the hard to find one that works. It could be a dirty maf that can be cleaned with a spray can made for that only and costs $5. Maybe a tear in the snorkel going into the throttle body. I would change the fuel filter, pcv valve and get that scanned by somewhere that can do it. Check the transmission fluid and make sure its not burnt or to dirty.

 

I took a look at the IAC valve but how do i know its working? I removed the 2 star screws from the sensor part turned on the car and it seemed like the prob was gone ... But then i put the sensor back with my hand with out screws and i could hear the idle going up and down... Could it be the sensor? and not the valve? How do i know if the valve needs to be changed?

Ive also changed the PCV hose. It was a little torn where it connects to the TB. Idle still goes up and down from .6 to 1 rpms .. Before i did this it wouldnt let me burn rubber it would just studder now it does let me but idle is still bad.

Can Any one help?

-Ben

 

I think i took off the wrong thing .. Yeah i know im a noob.. I took off the sensor on top of the IAC whats that called?

To take off the IAC is it easier taking off the whole TB? instead of leaving it on and trying to unscrew it?

-Ben

 

Ok heres the update. I figured out what part is what blah blah.. Thing is PCV valve is not cloggged. I removed the TPS sensor that didnt help since i dont know how to check if its working. But this does happen when i disconnect the MAF sensor connection it doesnt idle weird or bog down any more. Is this telling me its the MAF sensor? It was a little dirty i cleaned it but it still bogs down with it connected.

IAC valve i cant get to it . I can only see 1 screw the other one I think i might have to disconnect some hoses from the water pump am i right? Or can I just check it with a ohm meter like it says on the shoebox tech site?

One other thing after like 5 misn of driving the car i get a smoke smell i dont know if thats because they cleaned the engine before they sold it to me or it has to do with the prob i have.

If anyone can guide me i would really appreciate it . Thanks alot

-Ben

 

I replaced the IAC with a new one and its still doing the same thing. It seems its not bogging down any more when i accelerate hard but idle still moves up and down.

Ne ideas?

-Ben

 

Have you reset the computer????? In the fuse panel on the driver sdie there is a fuse ECM/BATT or PCM/BATT... Remove for 30 seconds and replace.....

 

Ok ill try that.. How can i figure out if there is a vacum leak? Ive seen posts about spraying the motor with carb cleaner?

-Ben

 

spraying with carb cleaner is the easiest way to do it, just spray one spot at a time and listen for a change in tone or idle speed, that and just listen under the hood real good and maybe you will be able to hear where it is coming from

 

Carb cleaner works, but might dry out your rubber vacuum elbow/hoses..

 

Find a shop that can scan it and find out why the SES light is coming on. Much better idea than guessing and replacing parts. Do you realize your 95 has an OBD-I PCM, and an OBD-II ALDL data connector? Most auto parts stores don't know that either. They hook up the OBD-II scanner and get an error message. That appears to be what happened in your case. Find a shop that has an OBD-I scanner and the correct adapter plug, or get them to hook it up as shown on Shoebox's website.



By the way, Shoebox has virtually every piece of info you need for your 95.... photos of all the sensors and other parts, instructions on how to check the IAC motor and TPS sensor, etc. You need to spend a bit of time looking over the info he has there.

http://shbox.com/1/4th_gen_tech1.html