[Kellenpickle]

I have a 1991 s10 pickup woth the 4.3 liter fuel injected and I have replaced pretty much all the pars I could thing of for a rough idle and still can't figure it out. Just replaced the coolant temp sensor thinking that might fox it and still nothing. Also the pickup will not warm up past about 100 according to the temp meter. What do I do !!!

 

[aitch]

I have a 1991 s10 pickup woth the 4.3 liter fuel injected and I have replaced pretty much all the pars I could thing of for a rough idle and still can't figure it out. Just replaced the coolant temp sensor thinking that might fox it and still nothing. Also the pickup will not warm up past about 100 according to the temp meter. What do I do !!!

Welcome to the forum. Perhaps the first thing to do would be to list "all of the parts you could think of" so members know what has been done. Are the replaced parts OEM or aftermarket - not all parts are created equal. We can only react to what is posted, and the initial description leaves a lot of issues unaddressed. Is the truck stock or have there been any mods to it?

 

[Kellenpickle]

The pickup is 100% stock and all parts are oem. I just replaced a coolant temp sensor and I've done plugs and wires, map sensor,charcoal cannister, fuel filter, fuel pump, distributor and pick. Egr valve. And also gone thru all the vacume lines and it all seems to be just fine but still rough idle. I'll also be replacing the thermostat today but I'm sure that wouldent solve my problem. Unsure where to look next

 

[Kellenpickle]

I mean the thermostat won't solve the idle problem but hopfully the temp problem

 

[MyWorkInProgress]

Which temp sensor did you change? There are two of them, you may have changed the one for the ECM and not the one that sends to the gauge.

 

[944v8indfw]

Have you checked the timing? Checked the voltage on the throttle position sensor? Those seem to be the 2 main factors in idle quality of the TBI 4.3.

 

[Kellenpickle]

I have not checked the timing but the coolest temp sensor I replaced was just to the left of the thermostat. I also replaced that today and the pickup will warm up to temp not but still stutters. I will check the voltage of the test here momentarily

 

[Kellenpickle]

Voltage of the tps

 

[MyWorkInProgress]

That is the temp sender to the ECM, not the gauges. The sender to the gauge is on the passenger side head, that being said whos to say the gauge isn’t itself dead.

 

[Kellenpickle]

Well I changed the thermostat today and not the temp is where it should be and the gage is working so I know it's not dead

 

[S15E83]

Ever check fuel pressure at idle, and bleed down?


Sent from my iPhone using Tapatalk

 

[Rhotpursuit]

Well I changed the thermostat today and not the temp is where it should be and the gage is working so I know it's not dead

Not dead doesn't mean accurate...

 

[Kellenpickle]

I haven't checked the pressure at an idle but I got a throttle position sensor on the way. Once I change that we will so from there.

 

[TIms ZR2]

I haven't checked the pressure at an idle but I got a throttle position sensor on the way. Once I change that we will so from there.

Have you checked the Idle Air Valve? Could be the pintle needs cleaning to seal properly. Cleaning may help your idle, just something else to look at. Use throttle body cleaner.

 

[Kellenpickle]

I have also replaced the idle air valve

 

[944v8indfw]

I have also replaced the idle air valve

was it rough idle before or after the IAC replacement?

 

[TIms ZR2]

was it rough idle before or after the IAC replacement?

I have also replaced the idle air valve

My rough idle, it wasn't much, was before I cleaned it. Make sure you clean where it seats as well. I did notice an improvement afterwards. Also, double check all of your vacuum lines for tight security.

 

[aliencowboy01]

I had a rough idle and dying sometimes, 91 GMC Sonoma, 4.3, replaced distributor and that solved the problem.
The cast iron piece inside the distributor was broken.

 

[Kellenpickle]

was it rough idle before or after the IAC replacement?

Yes it was rough before replacing it. Nothing really changed

 

[Original_Owner_86]

Welcome to the forum. Perhaps the first thing to do would be to list "all of the parts you could think of" so members know what has been done. Are the replaced parts OEM or aftermarket - not all parts are created equal. We can only react to what is posted, and the initial description leaves a lot of issues unaddressed. Is the truck stock or have there been any mods to it?

Vacuum leak?
Inspect every single vacuum line carefully for cracks, or if they're even attached.
Then spray WD40 along edge of intake manifold while idling. Listen for changes in RPM. A change indicates a manifold gasket leak.