Just posted this in TPI but it's more tech related. (sorry for double post then)

Well, my car's been having hesitation problems when I accelerate from a stop, and it doesn't accelerate like it used to either. My tranny was rebuilt about a year ago.

So this mechanic told me my third fuel injector was bad. I wanted to fix it myself, so I bought the injector, and intake gasket to fix a leak, while I would be down there.
Anyway, so yesterday I used my friend's mechanics stethescope to listen to the injector, and they all sounded good? Was the mechanic pulling my leg? Could it be an intermittant problem? Also my check engine light comes on sometimes. I haven't checked what code it is yet. What might cause this hessitation when I accelerate from a stop or from when I'm going slow? I've replaced the o2 sensor and the fuel filter already. Any ideas?
I don't think I can return the injector now.

 

I have a 90 RS.. its my first fuel injected car , i have a 71 chevelle and a 82 camaro that are carbureted. ive tried pouring the fuel injector cleaning stuff in when i goto fill my tank up, it doesnt seem to fix it.. i called and asked places how much gettig them professionally cleaned would be , it was like $60..

Sometimes when I accelerate it will hesitate a bit, and my car rumbles a little bit so you can also hear it.. its really annoying. it is kind of a puttering sound. So helping him would prolly help me too..

If ya need to know its a 3.1 Automatic MPI

Thanks

 

I know this will sound stupid, but have you cleaned the backside of your butterflys?
Best way is to remove throttle body and clean from back-side, but they can be cleaned pretty well by opening them all the way and scrubbing with a tooth brush and some B-12 carb cleaner.
Don't shoot red tube down intake like I did once.

I've seen this cleaning do wonders for Ford f-i systems. Assume Chevys would benefit also.
Mainly helps idle and just off idle transitions.

Find out what that code is. Maybe a TPS code.

 

i dont know too much about fuel injection.. but when i get to it ill take it apart, and check it out . is it ok to spray carb cleaner into fuel injected cars? my code also pops up every once in a while ..

i dont really know how to check it though.. i went to autozone the lady gave me a key type thing to connect the 2 pins... and she said turn key to on position, but dont start car , then put key in. count how many times that the check engine light flashes , i went in and told her it sounded like the computer turned on ? (made a small humming sound) went - flash, flash, pause, flash a couple times over and over ... then she told me she didnt know why it did that, and she said that the check engine light has to be on at all times for it to read properly.

does that check really know what shes talking about? or is she just trying to sound smart?

 

Ya don't have to take anything apart, except for removing the big rubber air hose from the throttle body. Open throttle and look in there with a flashlight and see if the backside of the butterflys look dark and sooty or clean and shiny.
Carb cleaner is OK for F/I.
If you shoot a bunch of carb cleaner in there, and don't allow it to evaporate, starting may take a little longer than normal, but once it starts if will be OK after that.


I think you are supposed to install the "key" into the ALDL connector, then turn ign switch to "run". If there are no codes. Light should flash once, pause, then flash twice,, longer pause then repeat. This is a "12" which means everything is OK.
If it flashes twice, pause then twice again; that would be a code "22". Keep counting the flashes and write them down. There may be more than 1 trouble code. After they all flash, they will repeat so you can double check them.
Disconnecting battery cable for 1 min will erase the codes.

The humming was probably the elec fuel pump. It should come on for a few seconds then shut off if eng is not running.

 

ill take the hose off and spray butterfly thing down with some carb cleaner...

a few posts said that it could be bad to put the 'key' in and then turn it on ... says to turn on then put key in .. and the humming sound only starts when the 'key' is inserted .. and stops when i remove it..

and the light does flash once , then pause, flash , flash longer pause then repeat .. sorry bout that , got em mixed up.

and if its ok .. what does the service engine light come on for? when im driving its usually not on until about 5-10 mins of driving.. then it will be on for a little bit , then it will go off... and when i have the car in on position without running, the light is on.

ill probably end up going to advance auto parts and buy the haynes manual on the computer, and the one for fuel injection, for $15 each...

 

OK, remember your trying to clean the back-side of the butterflies. Cleaning the front won't do any good.

I don't remember for sure abt if ign should be on first or not when installing shorting clip to ALDL for reading codes. I use a scanner,which is definately connected with switch off. I'm sure you can find out my doing a search on the site.

It's normal for light to be on with key on and eng not running. It's telling you there's no oil press with key on. Also acts as a light bulb checker.

My light would occasionally come on if I was coasting down a long hill. Thinking maybe computer saw vehicle speed high with throttle closed for a certian amount of time and assumed the TPS was inoperative. When I connected my scanner, there would be no codes. I don't worry abt it anymore.

 

thanks a lot man , is the butterfly fairly easy to open so i can get to the back of it?or is it gonna be a pain?and also is this 'butterfly' the same as the flap that opens on carbureted cars? cuz i know what those look like

maybe my light does that too, i never really payed much attention to when it does it, i just notice it on a few times...

 

When ya take off the big hose on the top/front of eng, you can't miss them. They do look like carb butterflies. Circular plates abt the size of a silver doller.
To open them for inspection/cleaning, simply rotate the lever the throttle cable connects to.