So on recommendation for a hesitation issue this truck had earlier at 1500 rpm I changed the spark plugs in the truck and that got rid of our hesitation issue.

Before we did the plugs the idle was at 800-900 RPM.

It had OEM Champions in it and I replaced them with OEM Champions mind you there was nothing left of the electrodes and the gaps were pushing .070 or higher. (guy told my father that it had lifetime plugs in it) So there was at least over 100+K on these plugs.

*NO CODES

The truck has a high enough idle in drive that it accelerates on its own to over 60 km/h slowly but, when you hit the gas and go to say 90 km/h it takes forever to drop back down to 60-70 km/h but it won't go any slower. (This is all with the foot far away from the throttle.)

Should I just adjust the Grub screw on the Throttle Body to drop the Idle down or what else could possibly be the issue? I check the TB and the throttle is closing as far as the grub screw allows it, probably around 1/8" of the grub screw sticking out.

I did not touch anything else, would a vacuum leak cause an Idle this high?

Or would a stuck TPS sensor cause the issue?

What is the resistance value for a new TPS sensor?

Would unplugging the battery clear the ECU and change the timing or TPS position? I did not unplug the battery when I changed the plugs.

Any help is appreciated!

 

Truck Year and engine???

 

2003 4.7 1500

 

double check your vacuum lines around the intake plenum if i remember right there is one on the drivers side. but check the passenger side just in case

 

vacuum could be culprit. Dirty IAC valve could also be since you have a 4.7L. Do you have plug wires? One could be cracked.

Let's start with the free stuff....I would unhook your battery for 1/2 hour and see if that does anything first. if you dont want to wait 1/2hr you can unhook both leads and touch/hold them together for 20sec and that will drain any residual capacitor power from the pcm units. there may be a small spark, but thats to be expected.

 

Which valve is the IAC valve? Is it in the vac lines or on the TB?

 

And no no plug wires just coils on each plug.

 

Okay I remember what the IAC is from back in my 2.2 turbo days. I'll clean that reinstall and pull the TPS and clean / check resistance.

 

Cleaned the TB and IAC made sure we had full Voltage at iac sensor harness.

Checked the resistance on the TPS .005 closed and goes from .005 to.001 at WOT.

Checked for vac leaks and have none.

Only thing I can think is the iac is not adjusting for idle speed.

You cannot adjust the idle grub screw as it uses a torx centre pin screw so that rules that out.

Got these 3 codes but that's just cause I removed the clips to all 3 parts when the engine was running. Disconnected the battery for over an hour too.

Any other ideas. Would a bad coil boot cause a high idle? I wouldn't think so myself.

Cannot explain why we get this issue after just changing spark plugs.

 

Did you reset the battery?