Engine stumble when coming to a stop, while in gear.

[AK Ranger]

Okay all, I was finally able to take a trip around the neighborhood in this truck after getting the transmission installed, flushing the coolant system, replacing the thermostat and getting it all refilled.

Before all the work listed above, we did a brake job, as well as plugs and wires.

The truck runs okay, but it want to die when coming to a stop sign. It will also do when in Park, if you hold the RPM’s higher than idle, then let off quickly. Generally all it takes is to tap the throttle a time or two and it starts to act right.

But… my son being a new driver, I don’t really want him to have to keep tapping the throttle at a stoplight or sign.

I do know the exhaust sometimes smells rich, but not sure where to go with that, as it’s not throwing any codes.

Looking for some ideas from the masses.

 

[franklin2]

Is this the 1999? What engine?

 

[AK Ranger]

Is this the 1999? What engine?

Sorry about that, yes, it is the 1999 and it is the 3.0l and the VIN lists it as a Flex-Fuel engine, but I’m not sure how to verify that.

 

[fastpakr]

Could be as simple as a dirty iac.

 

[AK Ranger]

Could be as simple as a dirty iac.

Good to know, thank you.
I’ll look into cleaning that today.

 

[AK Ranger]

I cleaned the IAC, but it was surprisingly clean to begin with. I’ll be able to test drive it in a bit and see if it’s any better.

I almost think the OP might have started addressing this, as the IAC was so clean already.

 

[AK Ranger]

Well, I won’t be able to give any meaningful feedback right now, as I was not able to take it for a run last night.

I can say the cold start / idle seems smoother. It would rev and settle, rev and settle for a bit until it finally settled. It did not do that this morning when I fired it up to see how it would act.

I will report back in a couple weeks.

 

[AK Ranger]

Well, I finally got a chance to go take another drive around the neighborhood. It is still doing the same thing. While driving, if you either let off the throttle, or come to a stoplight/stop sign, the engine idle drops to 500 or less and stumbles real bad.

As stated above, the IAC Valve was pretty clean even before I cleaned it.

I plan to do the Intake/Throttle Body Seafoam treatment, hopefully tomorrow. That may help some.

Is there a way to test the IAC Motor?

 

[SenorNoob]

The only test I'm aware of to unplug it while parked at idle. Engine speed should drop, it might even stall. If it drops or stall, that's good. If it doesn't change, something is wrong.

 

[AK Ranger]

The only test I'm aware of to unplug it while parked at idle. Engine speed should drop, it might even stall. If it drops or stall, that's good. If it doesn't change, something is wrong.

I’ll give it a try tomorrow, thank you.

 

[Brain75]

snipet out of an article:
"
If the idle air control valve is hot (50°C to 100°C), you expect a resistance value between 21.5 Ohms to 29.5 Ohms.

A cold IAC (-13°C to 50°C) is expected to have a resistance between 17 Ohms and 25 Ohms. In some car models, the resistance value goes as low as 7 Ohms.
"

How To Test Idle Air Control Valve With Multimeter (GUIDE)

If you're having problems with your idle air control valve, don't worry. We created guide about how to test idle air control valve with multimeter.

electrouniversity.com

 

[AK Ranger]

Thank you Brain. I’ll give it a shot when we get home from church.

 

[AK Ranger]

snipet out of an article:
"
If the idle air control valve is hot (50°C to 100°C), you expect a resistance value between 21.5 Ohms to 29.5 Ohms.

A cold IAC (-13°C to 50°C) is expected to have a resistance between 17 Ohms and 25 Ohms. In some car models, the resistance value goes as low as 7 Ohms.
"

How To Test Idle Air Control Valve With Multimeter (GUIDE)

If you're having problems with your idle air control valve, don't worry. We created guide about how to test idle air control valve with multimeter.

electrouniversity.com

I get cold, and that’s no problem here.., as it’s winter time. For the hot, is that coolant temperature, or does that mean actual intake air temperature?

I am assuming coolant temperature.

 

[Brain75]

50C is super hot, like right at the hottest the atmosphere ever gets even in death valley if I remember the ballpark - something like 125+F.
based on that I am thinking it must mean engine temp... right up there on the intake though I wouldn't think it would get all that hot with cold air going through it.

 

[AK Ranger]

For this test, I have 8.8 ohms cold and 11.4 ohms at operating temperature. The meter was set on the 200 ohm setting. (I’m not really good with electrical meter testing stuff, but I try to fumble through it)

i also tried unplugging it while it was running and it died immediately.