Cold weather staring problems already

kamps989 · Nov 17, 2014

OK so my truck is running like a champ as I just put a flex fuel sensor emulator in (should have done that years ago) however it still has not solved my cold starting issues. It has been in the single digits here and my truck will only start if I give it some gas, after that it starts and idles beautifully at around 1,000 RPMs and starts fine thereafter until it cools back off.

One thing that it doesn't do that I seem to remember it doing back in the glory days was idle real fast for a while until the engine warmed up a little bit in cold weather.

I was digging around and am wondering if someone can confirm this as a possible temp sensor issue? I am planning to ohm it out today if I can.

THANKS!

kamps989 · Nov 17, 2014

Alright so I got antsy and put a new one in haha
Cheap part and easy to replace so I figured why not? We will see what that does in the morning.

Which brings me to my next issue that I was hoping would be solved also with this fix. My fan seems like it never stops, EVERY time I open the hood that thing is spinning, It was 15 degrees out just now and I looked at it while idling for a while, after driving, and after it was warm and restarted. always running, no way is it that need of cooling I wouldn't think.
After it ran I tried to spin the fan by hand and it does put up some resistance, I have searched how to diagnose a fan clutch on here with little success.

Any thoughts would be appreciated! My truck seems to be having every maintenance issue occur at once

Rearanger · Nov 17, 2014

Clutch fan will always spin, but spinning in un-locked mode will not produce a lot of cfm. They usually fail to lock up when hot. Also when cold and sitting the liquid inside takes a little time to spread evenly in the clutch so you'll get some roaring initially.

kamps989 · Nov 17, 2014

I see I see. The other thing that makes me think that there is something wrong with my fan clutch though is that whenever I am driving down the highway there is a whirring sound coming from the front end that sounds like it could be the fan cranking away, but there is no way to be sure.

Rearanger · Nov 18, 2014

kamps989 said:
but there is no way to be sure.

Remove fan belt then drive to see if "whirring" is still there. Fan belt probably also drives water pump so you won't have a lot of time before overheat.

Could remove just fan blade but bolts may also hold WP pulley, in which case you'd need shorter bolts to keep functioning pulley/WP.

RonD · Nov 18, 2014

The fan clutch has a bi-metal spring on the front, this spring is heated by the radiator heat, not engine heat, as it heats up it closes a valve causing the fan to spin closer to engine RPM pulling more air in thru rad cooling it and more air into engine compartment cooling it.
In the winter months the radiator may not get very warm, so fan clutch doesn't ever engage fully, that's normal.
If fan clutch is failing you will see temp gauge go up when you are stopped and idling, that's really the only time the fan is needed with full force, so if temp gauge isn't going up sitting at stop lights fan clutch is fine.

As for the other.
There are 2 temp devices on the intake or thermostat housing.
The temp gauge "sender", it has 1 wire connected and that goes to the gauge on the dash.
The other is the ECT "sensor", this has 2 wires connected and is only used by the computer.
This sensor sets the "Choke" on a computer controlled engine, and yours sounds like it is bad.
When you turn on the key the computer looks at the ECT sensor data(temp), if it shows cold, then computer runs engine rich with high idle, 1,200rpm, just like a choke did on carb engine.
If your current ECT sensor is showing engine is "still warm after driving" even though it is stone cold, then it would be hard to start and have a lower idle than it should on a cold start.
If ECT sensor was dead then CEL(check engine light) would come on, but if it is just reading the wrong temp. i.e. 80degF when it is really 32degF then no CEL would come on.

Earl43P · Nov 19, 2014

For your cold-start idle problem, clean or replace the IAC. It controls idle.

I always recommend PRIMING a fuel injected vehicle before starting.
Turn key to Run, wait 2-3 seconds while the fuel pump runs and the idiot lights "test".
Turn key to Off. Repeat.
Then CRANK the starter.
See if that helps yours.

Typical fan clutch behavior goes like this:

Cold-Start truck and immediately drive away at a slow steady speed (25 or so).
You should hear a significantly loud whirring noise, which is the fan clutch fully engaged.
Within 1/10-1/8 mile, that loud whirring should noticeably go away.

In my case, I back out of a short driveway, pull out in second gear and the whirring dissipates before the end of my street (7 houses/city lots), which is just about far enough to grab 3rd gear, but I usually just stay in second and let the gas off instead of using much foot brake approaching the stop sign. I rarely stop completely at that stop sign and just roll back into the gas pedal, still in second gear, never touching the clutch. The fan clutch roar never comes back until the next cold start.

bucko · Nov 24, 2014

By the way, how are you "giving it some gas" to get it started? With fuel injection, there is no longer a "gas pedal", but rather a "drive by wire" pedal. No longer is there any type of accellerator pump to squirt gas. With the key on, the fuel pump delivers fuel pressure to the fuel rails, and the injectors squirt.

enjr44 · Dec 2, 2014

Did changing the ETS (two wire) fix the cold start rpm problem?

kamps989 · Jan 28, 2015

Changing the stat seemed to help but I think it was a placebo affect. In order to get it to start cold EVERY time I have to almost floor the gas pedal. It starts every time but is annoying none the less. My truck also idles like crap still and throws a misfire on cylinder #2 constantly. I changed the plugs and wires within the year which didn't help and was going to ohm out the coil pack but from some things I have seen ohming the pack doesn't really prove much. Where is the IAC located and is there a way to easily test it with a multimeter? I am pretty frustrated with this idle/starting issue.

Thanks guys

RonD · Jan 28, 2015

IAC(idle air control) Valve is used pass air around the throttle plate when it is closed, basically a "controlled" vacuum leak.
So it will be located near and usually opposite of the throttle linkage, it will have 3 wires connected.
Usual wire configuration is:
top
Power
Signal
Ground
bottom

If you unplug the IAC valve while engine is idling the RPMs should drop, engine may even stall, either is fine, it means IAC Valve closed when power was removed.
Engine off, IAC valve wire disconnected
Measure OHMs between Power and Signal pins on IAC, 7 to 13 OHMs is spec
Test OHMs from Signal pin to IAC's case, should be very high, i.e. no connection.

IAC Valve is a good guess as the problem, valve should open all the way for starting engine.
You having to open throttle manually lets more air in, IAC should already be doing that.

OHMing a coil pack WILL show if primary or secondary wiring is bad.
What it can't do is tell you that it is good under operating conditions.
So testing a coil pack this way is useful if you have the time and tools to do it, but it doesn't take the coil pack complete "off the table" as possible cause.

kamps989 · Jan 28, 2015

That sounds like it would cause my symptoms to a T. Will check tomorrow after work, fingers crossed!

kamps989 · Jan 29, 2015

OK well I replaced the IAC because my old one was filthy, she seems to start and idle slightly better but I was stomping the gas to start it once the engine cooled off again. I am really at a loss for what this could be? I checked my coil pack and all seems to be well with it.

kamps989 · Feb 14, 2015

Ok I am coming to my wits end with this. I replaced my coil pack with a screamin demon and all my plugs (re-gapped accordingly). I figured why not since it might be a fun upgrade anyways (which it wasn't much of haha). But my idle is still crap and I have to floor the gas to start it about 5 times a week. I have replaced the IAC, coil pack, plugs, computer tstat, and checked the voltage output on my TPS. Any thoughts on further troubleshooting? Would ohming out my injectors and checking pressures be a wise next step?

Rearanger · Feb 15, 2015

K&N CAI, FFS Emulator

Where's your MAF and IAT sensor on that CAI?

What's an FFS Emulator and why did you install one?

Cold weather staring problems already

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