Ok its not camaro related but it is TBI related so i thought yall could help me out. I have an 89 S10 Blazer with a 4.3 It recently started nocking so i got an engine from a buddy of mine that was running fine. I swapped it in and hooked everything up and it runs but not well at all. It wont idle at startup, you have to hold it at about 1500 while it sputters and after about 20 seconds it smooths out and will idle, not great but ok. Then when you take it and drive it, it is hesitant and wants to burp out of the throttle body. I havent timed it yet but will tomorrow, but advancing or retarding timing doesn't affect it. And the only sensor unhooked is the Oxygen sensor but it didnt have one before and it ran fine. Im a carb guy so yall plz help me out on this one before i get pissed of and put a carb on it.

 

same engine? more details, hoss

 

Don't even worry about it untill you get the timing set correctly (est wire unhooked). Then clear the codes and see what coes come back up. You most likely forgot to hookup a sensor or something. Not hooking up the coolant sensor will make it act this way. You also need to get the O2 working, this will take care of any fueling differences between the old motor and the new.

 

Ok i noticed 2 sensors unhooked, Map, and the water sensor thats by the thermostat. Also i installed a O2 sensor. With those hooked up it runs better, it will rev fine but wont idle. It wants to idle at about 1000 but it surges down to 500 and back up eventually till it dies. Im going to take the negative battery terminal off for 5 mins and clear the ecu.

Also the new engine is the same as before, a 4.3

 

I had a 4.3 with similar issues and it blew out completely the gasket between the throttle body and intake. I replaced that and my idle problems were history.

 

Hmm ill try that. Well i tried a new Dizzy and a Coil. It idles now but still pops and sputters throughout the rev range, expecially at idle. Well i think mine is ignition related because with the timming light on it i notice that it wants to skip a beat, its kinda an old light but since the motor is missing to that leads me to believe that its the motor not the light.

 

You'd be surprised just how crappy a TBI engine can run with the base gasket gone. Mine completely burned away in the back and it ran awful. Misfires and horrible idling was the norm...

Don't forget to block off, err..., check, the EGR valve as well. That went bad first and made my gasket burn soon after.

 

Alright, i changed the throttle body gasket, and noticed a change. Idles smoother but i still can hear a sputter, but its very slight now. So i took it for a spin, still some problems. It wont shift into OD and it still sputters and pops expecially when i give it gas. Well with the trans prob aside, the thing it is doing now is that if i just cruse i notice a slight sputter, but if i give it gas it want to fall on its face and pop out the Throttle Body.

 

Are you sure you got the temp sensor hooked up? What codes do you have set? What's your intial timing? Did you set it up with the est wire unhooked?

 

Temp sensor by the thermostat is hooked up. What do you mean by codes set, and timing is not set yet but it is on the timing tab. And whats the est wire unhooked.

 

spark plugs? have you checked them lately?

 

Brand New Plugs (AC Delco)

 

Just because the sensor is hooked up doesn't mean it's working.

To properly set the timing on a TBI equiped car you have to unhook the EST wire (brown with black stripe) there is a connector located near the heater box. If you set the timing "on the tab" with the wire still hooked up your timing is about 20 degrees retarded and your engine will run like poo. Even if you set it with the wire unhooked, "on the tab" is not really close enough to rule out timing problems.

By codes set, I mean what check engine codes are set in the ecm?

 

x2, cause I was just about to post, replace the temp sensor! or check all wiring for frays, etc.. also make sure all your grounds on the engine block are secure, specially injectors.

 

I cant check my ECM Trouble codes because my check engine light does not work, i think its missing a bulb. Also i could not find the EST connector, so i bought a Haynes manual and looked up the section were it talks about the EST system. It says to ground the test terminal on the ALCL connector, but where or what is that.

 

Your timing is retarded about 20-30 degrees.....so quit buying parts. The tan wire with a black stripe that runs from the dissy towards the heater box has a connector that you HAVE to disconnect to set the timing. The haynes manual is completely wrong, don't go by it.

Go look again I promise it's there somewhere, probably tucked up inside some wire loom. You also need to get the light working, without knowing what the codes are you are really just shooting in the dark and throwing money out the window.

 

I found the tan and black wire but no connector. I traced it all the way to the firewall and no connector. But i kinda think that that is not the problem. Because if it was retarted 20-30 degrees, then advancing it would help right. But if you advance or retard the timing the motor starts running even worse and dies. I got a few other parts laying around that im going to try swapping, like dizzy, Map sensor, and a Throttle Body. If that doesn't help im going to take the gauges out and check the check engine light. The truck has Digital Guages that i dont think it came with so i think that the bulb is just missing.