Engine Hesitation on Cold Starts

[CDsDontBurn]

Just about every time - for several years now - my car has a slight hesitation on cold starts.

Basically, whenever I start my car, it fires up no problem. I let it sit for a minimum of 30 seconds before I take it out of Park in order to ensure that the fluids are fully circulating in the engine. It's when I start driving that this happens, typically within the first 20 feet of moving, where the hesitation occurs. Over the years, I've learned that when the hesitation happens to just let off the throttle to let the engine "catch up" and then give it gas. Before my CEL, I would need to do this just once, sometimes twice, before my car is fully "caught up" and starts working perfectly.

I have already replaced the IAC valve before a couple years ago for a separate issue, and I thought that doing that would also fix this issue, but it never did.

One thing I will say though, is that it appears to not occur at all if I let the engine warm up for a longer period of time, say 5 minutes.

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[james'99]

Throttle body clean? New A/F sensor?

 

[xci.ed6]

What do you have to read the ECM? To look at the PIDs?

 

[CDsDontBurn]

Throttle body clean? New A/F sensor?

TV should be clean still. When I installed new VC gaskets, grommets, and cleaned out the EGR port last year, I also cleaned out the TB. I used cleaners, rags, and sand paper to get the hardest to clean caked-on stuff.

I could try an AF sensor.

What do you have to read the ECM? To look at the PIDs?

I have a cheap OBDII scanner that only pulls codes. I also have a BTOBDII scanner that I use Torque to interface with. But it's not really working right lately, so I can't rely on it.

 

[Anwar]

Replace your upstream O2 sensor. If it still happened, clogged EGR ports can cause hesitation. let us know if this solved the issue.

 

[CDsDontBurn]

I'll the the o2 sensor. EGR ports are clean. I cleaned them out less than a year ago. Previous experience from tearing down my intake manifold tells me that it takes at least two years before they plug up.

 

[xci.ed6]

Does it do this in the afternoon, like on the way home from work?

 

[CDsDontBurn]

The video I took was in the afternoon on my way home from work. But the time of day and season of b year doesn't matter to the car for this issue. It'll happen anytime anywhere so long as it's a cold start and the engine isn't properly warmed up.

 

[Anwar]

also check the IAC connector/plug, the MAP sensor and TPS sensor to make sure they are not loose. you can also disconnect the TPS sensor to see if you notice any difference in idle or driving, do same with TPS sensor. good luck

 

[xci.ed6]

I get the feeling that it's your IACV. It takes a lot of heat when it's running, so it changes. Your dizzy senses rpm, then reacts to your ECM, and that all works. If it didn't work, it wouldn't start. Same with injectors. Fuel pump doesn't take heat, so fuel pressure doesn't change.

On to the trans, check the fluid (change it if it's been more than a year), but those usually act up when they're hot, or cold&hot, but not only when they're cold.

Other ideas are maybe the ECT or IAT, but usually they are flipping the MIL when they're faulty.