Low throttle input/won't idle in park

[James Archer]

I've been chasing the little gremlin for a couple weeks now. Once the truck is is park it idle surges a few times then eventually stalls out. When leaving a light or stop sign if I don't get on it more than 25% throttle it'll either brake up and stalls or picks up and goes.
Here's a list of what I've recently does and the current setup.

- Just did head gaskets and top end gaskets.
New stock manifolds, y-pipe to a 3" summit
-muffler then nothing behind the muffler.
- 6 degrees advance timing ( unplugged battery to relearn timing curve.
- reset the IAC settings
- idle is set to around 700-800
- new injectors, distributor, EGR, all new vacuum hoses, fuel pump, all fuel lines, TPS sensor

I was considering going back to 0 degree timing and resetting the IAC and TPS sensor but I've read that these motors run a little better on 6 degrees

 

[Schurkey]

WHAT VEHICLE?

WHAT ENGINE?

I would connect a scan tool, look at the data stream. Find out which sensors/outputs aren't happy.

Verify fuel pressure.

HOW is the "idle set to 700--800" when it should be controlled by the computer???

 

[James Archer]

WHAT VEHICLE?

WHAT ENGINE?

I would connect a scan tool, look at the data stream. Find out which sensors/outputs aren't happy.

Verify fuel pressure.

HOW is the "idle set to 700--800" when it should be controlled by the computer???

89 k1500 with the 350 TBI
I set the idle to 675ish then the computer turns it up to 700-800.
Fuel pressure is 12 psi

 

[James Archer]

I also run a 165 thermostat in it. For some odd reason the thermostat doesn't open up till around 180-190 then when it does it drops to around 160-165

 

[Schurkey]

I set the idle to 675ish then the computer turns it up to 700-800.

Did you follow the service manual procedure, or did you turn a screw and hope for the best?

Shitcan the 165 thermostat.

 

[James Archer]

Did you follow the service manual procedure, or did you turn a screw and hope for the best?

Shitcan the 165 thermostat.

Yes I followed the service manual. Bought the OBD1 to USB reader for my laptop so I could see exactly what the truck was reading and bought the Haynes manual.

And I agree with you on the thermostat. I had a 180 in it before but it was doing the same thing as far as not opening till late. Was almost 210-220 before the gauge dropped. I'm not quite sure why it's even doing that to be honest. That's new ever since I put new head gaskets and intake gaskets in. Every senor on the motor is new besides the coolant sensor on the back of the intake. Which I didn't even know was there until I ripped the intake off.

 

[Schurkey]

Yes I followed the service manual. Bought the OBD1 to USB reader for my laptop so I could see exactly what the truck was reading and bought the Haynes manual.

Haynes manuals in general, make good emergency toilet paper. You need a REAL, Genuine GM service manual.

The Haynes manual might have the correct procedure for setting base idle. Maybe, maybe not.

And I agree with you on the thermostat. I had a 180 in it before but it was doing the same thing as far as not opening till late. Was almost 210-220 before the gauge dropped. I'm not quite sure why it's even doing that to be honest.

Thermostat should be a 190/195.

That's new ever since I put new head gaskets and intake gaskets in.

Are you sure you got the lifter preload adjustment right?

Did you use the TBI-style intake gaskets, or the generic gaskets with a big coolant opening at the rear?

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Every senor on the motor is new

New sensors doesn't mean the computer is getting good information. Use a scan tool, verify the sensors, AND the wire harness. Also verify the outputs--AIR (if used), IAC, etc.

besides the coolant sensor on the back of the intake. Which I didn't even know was there until I ripped the intake off.

I don't know about any coolant sensor at the BACK of the intake. One for the computer, on the front of the intake, one for the dash gauge in the left cylinder head, towards the front of the exhaust side.

There's an oil pressure sensor on the engine block behind the intake manifold, near the distributor.
There's a coolant outlet to supply the heater core on the right rear corner of the manifold, but it's not a sensor.

 

[James Archer]

Haynes manuals in general, make good emergency toilet paper. You need a REAL, Genuine GM service manual.

The Haynes manual might have the correct procedure for setting base idle. Maybe, maybe not.


Thermostat should be a 190/195.


Are you sure you got the lifter preload adjustment right?

Did you use the TBI-style intake gaskets, or the generic gaskets with a big coolant opening at the rear?

You must be registered for see images attach

New sensors doesn't mean the computer is getting good information. Use a scan tool, verify the sensors, AND the wire harness. Also verify the outputs--AIR (if used), IAC, etc.


I don't know about any coolant sensor at the BACK of the intake. One for the computer, on the front of the intake, one for the dash gauge in the left cylinder head, towards the front of the exhaust side.

There's an oil pressure sensor on the engine block behind the intake manifold, near the distributor.
There's a coolant outlet to supply the heater core on the right rear corner of the manifold, but it's not a sensor.

I'll look into the GM manual today and get a 190 back in the truck. I did use the TBI intake manifold gasket. They looked weird to me when I got them so I had to research those beforei put them in. After the truck does it's little breaking up act it opens up and pulls great. Holds 65 mph with no issues. I'll replace that coolant sensor when I do the thermostat too. Now that I'm thinking about it just cause I don't remember. Do I need to reset the position of the TPS sensor after I timed it and recalibrated the IAC?

 

[Schurkey]

Why are you replacing the coolant sensor without TESTING it via the scan tool?

Use the scan tool to verify TPS sensor idle voltage.

Scan tool, scan tool, scan tool.

 

[James Archer]

Why are you replacing the coolant sensor without TESTING it via the scan tool?

Use the scan tool to verify TPS sensor idle voltage.

Scan tool, scan tool, scan tool.

I'll give that a shot in the afternoon after work. For ***** and giggles I just checked for codes the old fashion was. Just realized there's a code 32 for the EGR stuff.