Cougar Cold Start Hesitation

[Harrison]

Originally Posted by skater

Okay, so my theory about the transmission is probably not correct.

Could it be some sensor dealing with the transmission though? When the car was in neutral it did not hesitate at all, but when it is in drive or reverse on the cold start, it begins to do it for the first minute or so at idling speeds.

[skater]

Possibly. I think we've ruled out major transmission problems, but some sort of range sensor or something might cause a problem like what you have. I'm no expert on transmissions though, and I have zero experience with the CD4E (I have an MTX) so I'm not going to be much help.

[The Jamie]

Rather than start up a new thread... I'm posting in this one. My 00 MTX is doing the same thing... after sitting all night, for the first 5 miles or so that I drive it bucks when I accelerate, and it doesn't seem to matter what gear I'm in or my RPMs, it's done it in all gears, and anywhere from 2k-4k RPMs.

Had a tune up less than 10k ago, had fuel pump replaced 2 months ago and had an oil change last week.

I hadn't noticed the problem in the evening until today, however until today I'd drive my car on my lunch, and today it sat the whole time I was at work. It seems after I drive a few miles she's just fine.

The first day this issue happened, I got a CEL before I noticed the bucking, I wasn't able to check the code that night and the next morning it was off... it came back on today - I'm just going to take it in to the shop tomorrow if I can, I'm just curious as to WTF this is

[B3NN3TT]

Even if the light goes out, the code is still stored in the ECU, and can be pulled with a standard code reader.

Report back when you have some data.

[wanderingmind]

Just throwing out an idea here: bucking and hesitating can sometimes be the fuel pump. However, with a faulty fuel pump it usually happens at faster speeds. So, I am not sure if the fuel is the issue. But, it is another possibility to look at.

[B3NN3TT]

Originally Posted by wanderingmind

Just throwing out an idea here: bucking and hesitating can sometimes be the fuel pump. However, with a faulty fuel pump it usually happens at faster speeds. So, I am not sure if the fuel is the issue. But, it is another possibility to look at.

Have you ever had a fuel pump failure?

When mine failed, it was fine at high speeds and high RPMs. It bucked at LOW RPMs, under load, JUST LIKE a spark issue - but it only happened when coming out of a hard corner.

[The Jamie]

When mine failed, my car ran fine until it refused to start one morning

[The Jamie]

So Ford just called me, they couldn't duplicate the problem, she ran just fine for them, and the CEL was just for too much fuel pressure (they say, didn't give me what code it was). They're going to keep her overnight and drive her after she's been sitting to try to duplicate it.

would too much fuel pressure cause flooding when I accelerate?

[The Jamie]

Diagnosis (for my car at least): it was the fuel rail pressure sensor going out.