Issue starting if cold...? (1 Viewer)

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ElmoTheDestroyr

ElmoTheDestroyr

Joined
May 23, 2016
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Location
Anacortes, WA
Hi,

I have a 99 LC and have a sort of odd issue.

When I start it when it's cold, it runs fine... However, if I drive a short distance (such as the gas station 3 blocks from here), then shut it off, and try to restart it 5 minutes later, it doesn't like to start.

It "starts" then tends to want to die... Tonight I had to restart it 3 or 4 times in order to get it to stay running.

Once it "catches", and I can rev it up to 1500-2000rpms for a few seconds, it can idle down and seems ok.

I'm not terribly mechanical and this is extra confusing because when its stone cold, it starts up fine.

Any ideas ya'll have would be really appreciated!

Thanks!
 
Obviously I am only taking a educated guess but I would look at 02 sensors, clean Maf sensor and clean your throttle body. Have you got access to techstream? The reason I say this is that your 02 sensors are ignored when the vehicle is stone cold. Fuel pump is another item that would be getting my attention. Does it smoke at all when it eventually starts or smells of fuel. If you could look at your fuel trims in techstream you might be able to see if there is a fueling issue.
 
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It is flooded. When a fuel injected engine is cold the fuel injectors run wide open (full choke like on a lawnmower or dirt bike) because a cold engine needs more fuel than a hot one.
So the reason for the hard starting would be weak spark, bad spark plugs will not combust the fuel enough to clear the cyclinder's of the excess fuel and it will run really rough or not at all. Thats why revving the engine clears it out, the excess fuel is being pushed out the exhaust valves and not being burnt instead of flooding out the spark.

A clogged air filter will not allow enough air into the engine to properly combust the fuel. Revving the engine sucks in more air and pushes the excess fuel out the exhaust valves.

You could leave it running while getting fuel/coffee/donut/smokes until you can fix it.
 
Spike555 said:
It is flooded. When a fuel injected engine is cold the fuel injectors run wide open (full choke like on a lawnmower or dirt bike) because a cold engine needs more fuel than a hot one.
So the reason for the hard starting would be weak spark, bad spark plugs will not combust the fuel enough to clear the cyclinder's of the excess fuel and it will run really rough or not at all. Thats why revving the engine clears it out, the excess fuel is being pushed out the exhaust valves and not being burnt instead of flooding out the spark.

A clogged air filter will not allow enough air into the engine to properly combust the fuel. Revving the engine sucks in more air and pushes the excess fuel out the exhaust valves.

You could leave it running while getting fuel/coffee/donut/smokes until you can fix it.
Click to expand...

It starts ok when cold, warm start up is his issue.
 
Julian Stead said:
It starts ok when cold, warm start up is his issue.
Click to expand...

Correct, starts fine when cold, but when you shut it off after driving it 3 blocks it is still cold. It is still in "full choke" mode.
 
When you drive it the 3 blocks the cylinders are flooded with fuel because of "full choke" and incomplete combustion.
Then you shut it off, and the cylinders are now flooded enough for it to not start.
If you let it sit for 20min without trying to start it, it would start fine because the excess fuel would have evaporated by then.
 
Thanks for the ideas!

I should add... It has new spark plugs (gaped properly) in an attempt to fix this. I've also scanned the ODB codes and there are no codes. The air filter is a K/N and it's clean.

Haven't had a chance to check anything else yet... Thanks again for the ideas! :)
 
The cylinders would be hot after 3 blocks, put your hand on the exhaust to find out(Don't). The engine only stays open loop for a few minutes, you can check this if you have techstream or equivalent, I have been checking mine recently as I have been diagnosing a emmisions issue, I was surprised how quick it did change to closed loop for such a old vehicle, mine is a 98.

Any more information? Does it ever run rough other than the starting issue, has it had a timing belt done recently.
 
Sadly I can't provide much more information, I've only owned it for about 500 miles so far. :)

The only other symptom I can think of is when it IS completely cold and you start it, it always starts, the RPM's jump to 1100ish RPM's or so for a for a split second then instead of dropping down to idle like normal, it usually drops a bit below it then catches itself, and then it goes back up to a regular idle. Runs fine, and never dies, but it does have a momentary dip down to like 500ish RPM's for a moment before it catches it and fixes it and idles normally...

No, I do not have techstream. I do have a bluetooth ODBII scanner w/Torque ODB software.
 
Without techstream

Compression Test/valve timing check
Fuel pressure test
Clean Maf
Clean throttle body

With

Crank sensor- you can check resistance with a multimeter
Coolant temp
TPS
Upstream 02's
MAF sensor readings

I would start by cleaning the throttle body, MAF sensor and try reading the coolant temp on your obd2 to make sure it climbs as expected, also if it gives you your LTFT readings make a note of them, they should read close to 0, this could help point out if you have a weak fuel pump.

What does it start like when it is hot, after a longer run.
 
To be honest, I always start with the battery. This can cause any issue you can think of. Were the coil packs Denso?, it does seem odd that it starts cold/hot but not warm. Like I said try and read your coolant temp from your obd2, the gauge uses a different sensor so don't go by that, clean your MAF and throttle body and go from there.
 
Anything specific I should be looking for with the temp, other than making sure it's getting up to up to 180ish? What's a "normal" amount of time one of these takes to get up to operating temp?
 
You can just watch it go up in a orderly manner, they normally jump about if there is a issue. Remember it isn't the gauge but the reading in the ECM, it should rise like the gauge in a steady manner.
 
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Another thing is does your obd2 read 02 sensors, make sure that when they are warming up that they are switching properly, maybe the heater element is a bit off and it is slow responding until the engine gets hot enough to get it to function, just a thought. You have two sensors so just compare, it might be slower to respond than the other or stay at around 0.4 volts for to long, so it goes closed loop before the oxygen sensor is up to temp.
 
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