Hey guys,

Recently my cars been doing this strange hesitation thing during cold starts only when the rpms climb and hover up to 1500rpm the car will choke 2 or 3 times as if a plastic bag was put over the intake for a brief second to choke the car. Once the car is warmed up, it idles fines and revs fine. I have all my power during WOT pulls and no DTCs show.

I remember reading a while back that there were some other LNFs experiencing this wierd start up shutter and it turned out to be the cam phaser actuator... I think? Does this seem plausible?>

No codes so far. No lights, No wacky fuel trims or funny AFRs. Car runs fine. No missfires.

I will say Ive noticed more 1 or 2 ghost missfires on the Aerforce Interceptor during cruise or WOT then I remember seeing. Cylinder 2 seems to be the culprit mostly. I would say on a 15 min drive to work I could count 8-12 missfires which in the grand scheme of things is nothing.

Am I worrying about this too much and should let it go? Or try to record it and bring it to the dealers attention? Im 100% sure I can catch it happening one of these mornings, thats how often it occurs now. Oh and yea this just started happening, and becoming more frequent on morning start ups.

My last event where I may have hurt the car was Ocean City Cruise week where I got on it for a sec to make a blow off noise and I was welcomed with a series of like 30 missfires and power stalled. No CEL, no codes. The missfires stopped and the car drove normal as fast as it occured so I ignored it and babied the car the rest of the week till my ride home when I was pleasantly surprised to find the car ran like a Champ with no stutter or mishaps during a fun WOT pull.

 

I know my car hesitates pretty hard in cold start, above about 1800-2000 rpms.. Runs fine once it gets above 90 degrees.. No codes

 

Someone else who knows more about the LNF then I do can correct me if I am wrong. Does that have something to do with the warm up cycle for the car. I remember something about the heated Oxygen Sensors and what-not. I am pretty sure it can change the amount of fuel that is being put in the engine. Like I said just something I remember seeing on here about this once.

 

mine does this too, it bucks when its cold and I have to let off the gas and wait till it calms down then I can ease into first. Only when Cold though, once it warms up above 100 it is good. subbed for answer

 

happens to me on occasion too.

 

Cold out or "cold engine" even though temperature outside is high. Say 70?

 

Are you only noticing this after it rains hard the day before?

 

my car has a hesitation when its cold when lightly accelerating, i just say to myself (well if its going to break hopefully it does it before the warranty is out.)

 

I have same issue on cold start up car sounds really spuratic at idle ill record mine in morning. After she warms up its fine.

 

my car does the same thing joe, i probably need to get the cat warm up deleted, but after it is warm it is fine, when i cold start my car everyone thinks its cammed

 

Deleting cat warmup isn't as easy as it sounds. It requires that you are very close to 0 LTFT, and you have to boost the idle based on coolant temp. In the end, it's a wash. I ended up going back to turning it back on.

 

nah, it seemed like everyday but I think im wrong about that. Had two cold starts since I made this thread yesterday and it didnt happen either time... had the camera waiting, lol. So I think I maybe just alittle paranoid and I will try to catch it if it happens just to get a documented sound of whats occuring, probably watch the rpms cause Im sure they bounce on that hesitation.


After hearing everyone elses comments, Im guessing that I am paranoid and its a common thing. Either that or we all have a bunch of F*cked up LNFs lol.

 

I have a '10 LNF with the RPD. I have it showing my fuel pressure. When i start up it shows my fuel pressure around 1700 and stays there for around a minute or so. Then it slowly drops to about 400-500. If i drive the car without letting it sit and letting the fuel pressure drop, the car will buck and hesitate a little. Once the fuel pressure drops to the 400-500 range the car drives fine. I guess this has to do with the Cat Warmup. Just let the car sit for about a minute when you first start it up and you should be fine.

 

my car does this as well . doesn't happen everyday but somedays worse than others. even when the temperature is warm. it's normal i think.

 

Mines does the same thing, Its weird...Its like cat warm up isn't gone once its warm shes is good to go.

 

My car does it to, no big deal

 

I had this on the stock turbo. After fixing a cut in my coupler I never had this issue again. How long have you been tuned? Could be your fuel trims.

 

I'm leaning towards something to do with cat warm up. But i have never noticed it when the weather outside was like 30 degrees. Only on warm days.? Like 70 degrees.