S-10 Forum banner

1 - 20 of 28 Posts

·
Registered
Joined
·
42 Posts
Discussion Starter #1 (Edited)
Well here's the deal. I have my 94 S10 Blazer with the 4.3 Vortec(W) has 180k miles on it.

just got done installing a new exhaust system, only reason was because the converter was toast and there were holes everywhere including the muffler.

Im still having problems ... Im getting absolutely no codes on computer. The only code I was getting was the IAC which was replaced and it went away.

So here's my problem and what ive done.

Im getting a really bad idle jump, it will go up and down when warm or cold and when you stop or in park or at a light or stop sign. It seems thats the only problem right now is the sporadic idle. Ive cleared almost all of my other problems.

So far I have replaced:

Starter, Fuel Pump + Sending Unit (60PSI on the Pressure), Exhaust System (Muffler and Cat) and IAC

What else can I look into replacing? Should I open up the intake plenum and check the injectors and the fuel lines and see if the injectors are leaking? Why isnt it throwing codes if its still having problems?
 

·
Registered (Ab) User
Joined
·
4,137 Posts
The pre -'96 trucks are bad about not throwing codes when something is obviously wrong.

How old are plugs, wires, cap & rotor?

Opening the manifold would be a good idea if the above parts are OK. Click here for a thread with pics and helpful tips.
 

·
Good Bye SonomaST
Joined
·
7,145 Posts
O2 sensor?
 

·
Registered
Joined
·
42 Posts
Discussion Starter #4
yeah forgot to add that, when i purchased the truck last month I did a full tune-up including rotor, wires, plugs, fuel and air filter and oil change.

dont know how to check the O2 to see if its broken.

but i guess its coming down to checking the damn lines and spider. while im at it I might as well change the FPR and Tubes for $100 if the spider isnt leaking
 

·
Age: 15 1/2
Joined
·
2,679 Posts
Check your fuel pressure and connect a vacuum guage, or keep replacing parts?
Could just be a sensor or vac leak or Fuel injection leak...................

Good luck
 

·
Registered
Joined
·
42 Posts
Discussion Starter #6 (Edited)
Check your fuel pressure and connect a vacuum guage, or keep replacing parts?
Could just be a sensor or vac leak or Fuel injection leak...................

Good luck
as far as I know its not a vacuum leak, i did the ever soo good spray around vacuum lines while car running with carb cleaner.

Fuel pressure is a constant 60-65 psi as stated above.

Im gonna replace the Engine Coolant Sensor for $10, and than get the spider checked after running a can of seafoam through it one last time. and while checking the spider, ill replace the FPR and clean the EGR
 

·
Age: 15 1/2
Joined
·
2,679 Posts
The vacuum gauge is for diagnostics. A simple test if it's a vac leak would be to open a small vac line. That should cause the idle to rise. If it rises but becomes stable....
ECS is a good place to start testing. A simple Volt/ohm meter will accomplish that.
Cap & Rotor, bad plug or wire, leaky fuel injection, intermitent fuel pump, valve issues, egr issues, MAP sensor, TPS...... can all cause these kind of issues.
Good luck

Good l
 

·
Registered (Ab) User
Joined
·
4,137 Posts
as far as I know its not a vacuum leak, i did the ever soo good spray around vacuum lines while car running with carb cleaner.

Fuel pressure is a constant 60-65 psi as stated above.

Im gonna replace the Engine Coolant Sensor for $10, and than get the spider checked after running a can of seafoam through it one last time. and while checking the spider, ill replace the FPR and clean the EGR
I would suggest running the Seafoam after doing the work inside of the manifold. That way, if there are any signs of washing, the seafoam will not disturb them.
 

·
is out cruisin...
Joined
·
1,619 Posts
my gut feeling on this one is the MAP sensor but use a voltmeter like YOGI suggested and make sure you are getting the correct voltage to and from the sensor before you start throwing any parts at it...
 

·
Age: 15 1/2
Joined
·
2,679 Posts
Not if you have unlimited funds, a good auto parts store close by, and the extra time to spend.
A lot of times people get lucky.
Hope your luck is good.
 

·
Registered
Joined
·
42 Posts
Discussion Starter #12
unfortunately i dont have unlimited funds, ill grab myself a volt meter and start testing along with a vacuum tester. can get both for under $10 at harbor freight.

I have an autozone right down the street and very good friends with the manager.

But if when I do take off the plenum ill be changing the FPR if i dont see any problems, since its a cheap $30.

But i can do the FPR, ECS, and the MAP for $75
 

·
Mr. Sparkle
Joined
·
10,040 Posts
You have replaced the parts that i would have recommended. I would advise to make sure that your timing is spot on. Pretty easy to check along with adjust. Here are a couple other good threads to look at which might help to resolve your problem :)

http://www.s10forum.com/forum/f107/ect-sensor-02-sensor-or-other-342742/

http://www.s10forum.com/forum/f107/4-3-tbi-voodoo-curse-328629/

Both of those have similar symptoms. I myself have had Idle problems with my truck. I first replaced the fuel filter which resolved it for a while. I ended up buying a new TBI unit which seemed to fix the problems. but anyways good luck.
 

·
long live italy.
Joined
·
636 Posts
lmfao dude, im not a n00b when it comes to vehicles, just chevy's ive been working on my dads subaru legacy and my ford bronco for years now..
hey nobody said you were a noob...err...n00b.
Just warning you.
I've always believed in "if it aint broke, dont fix it"
and even if you're a mechanical master, auto zone can still jedi somebody.
they're ninjas man they'll be jumpin out of trees sayin "this gives you 3mpg!" :D
 

·
Registered
Joined
·
42 Posts
Discussion Starter #17
well right now the main thing is getting it registered and tagged so its legally driveable.

A law here says if you go to a registered emissions service station and spend $200 to have it fixed you will get a free emissions pass. So i called a local guy, he said for $75 to bring it in and from head to toe they will test everything and give me an idea. And he said if they find something wrong and I dont want to fix it right now they will sign the waiver form for me and I can go get it tabbed.

I found my voltmeter but my dad took the truck to work (yeah its no legal to drive lol) so gonna have to wait..

Should i go do the $75 and garuntee it gets tabbed or keep trying to fix it?
 

·
is out cruisin...
Joined
·
1,619 Posts
personally i would fix it and have pride that i did a good job and the truck is running good on the streets but thats just me...
 

·
Registered
Joined
·
42 Posts
Discussion Starter #19
personally i would fix it and have pride that i did a good job and the truck is running good on the streets but thats just me...
im going to fix it, but in order to drive it, it has to be legally able to drive. Tabs are 1 month expired and im not even allowed to register it in my name till its passed emissions.
 

·
is out cruisin...
Joined
·
1,619 Posts
well in the end it's all up to you anyways but i would get it fixed to pass emissions and register it in your name
 
1 - 20 of 28 Posts
Top