Hesitation in acceleration

[onitsway]

Hello all. Just joined the site. I bought a 1995 740iL and love it. It is a project car and I can't wait to get started. I have a problem with cold starts and acceleration. I have replaced:

MAF
cleaned the ICV
changed the plugs and coils
changed both O2 sensors
changed the fuel filter

I start the car in the morning and after it warms up it idles fine. As soon as I put it in gear, it hesitates even if I floor it like it lost power then it kicks in and goes. I never have that instant throttle response like I think I should. I appreciate any help.

[witeshark]

How does the 4.0 run during a longer drive? Is it very cold where you are?

[onitsway]

It is cold. During long drives it is fine under slow acceleration. As soon as I step on the gas for a pass it bogs down than kicks in and goes. Also, if I drive normal and park somewhere with the engine running--5 mins later I put it in drive to go and get the same sputter like its flooded or something--then it kicks in and drives normal.

[Acaminero]

I have the same type of problem with my 323i 1999...it starts like it shoild and once I drive for a while and park it for 5 minutes it will start right off and when put in drive it will shut off, it also has a very slow response when I take off , it slowly pick up speed ...and it runs nice .. but it doesnt respond as it should...I just got the car
and would like some help in ttrying to solve this...thanks

[Alandi]

This sounds like a fuel system problem. What grade gas are you using? Does it seem to burn gas rather quickly? May need to change the ICV. Even if the CEL isn't on you may want to get an OBD done.
Also by chance do you smell fuel at anytime when the car is operating or even when parked. I had this same problem with Millenia S Type (Millercycle engine) I had. Drove fine until I tried to punch it. Came to find out there was a leak in the fuel line.

[marti5]

I would have a look around the spark plugs, OIL ????? or your PCV valve is shot.

[Acaminero]

I looked at spark plugs, change gas pump, new air filter, no gas line leak problem..it runs nice and when cold I get no hesitation on my 1999 323i...there is no leak on vacumm hose...do not know if there is a pcv valve, or if hesitation could be on presure gas regulator... it start hesitating about 15 or 20 minutes after started....need more leads to look for ..thanks

[BMW_V8]

by the way u replaced all the coils? the local bmw shop quoted me around 100 per coild thats 800 dollars lol u must have a thick wallet lol

[Acaminero]

NO, I do'not think that is a place to look for..since it runs nice on cold and it jhust get lazy on hot..its got to be around fuel delivery..

thanks

[nnamdi]

Sounding more and more like a fuel line problem. A nozzle or two may not be happy. water in the fuel tank, dirt in the injector rails. That solved it on my 318, changed 2 nozzles and cleaned out the rail.

[omarhr]

I own a 1999 323i as well; I also had the same problem. I took in the car to a BMW dealership about five times for this problem; two times they kept the car for more than a week. They never found a problem with it, but I know that there was one. just a couple of weeks ago I took the car to a garage where the mechanic had asked me to bring the car when this was happening, after he connected the snop on computer he also was unable to get a code for the problem. It was very hot that day and we noticed that when the car was running the fan would go on and it blows a lot of hot air towards the sides and the back of the engine. I noticed that there was a big peace of plastic missing on the housing of the air filter intake this is the peace between the radiator support and cover of the air filter box. We put some silver tape around this part to cover the hole and it seems like that did it. The car is running a lot better I noticed a big improvement and as the days go by the car seems to be running a lot better. I knew it had something to do with the temperature. Since the car was horrible to drive in hot weather. I called the dealer, the part is going to cost me $28.00 that way I will remove the old one with the tape on it. Check that part in your car it seems like the hot air just burns it and as soon as you touch it, it breaks. The part is L shaped.

[witeshark]

Thanks omarhr for sharing that. This will help anyone with similar issues!

[Numark318i]

maybe PCV valve?

Does the car tick?

[Acaminero]

I Like to give my feeback on to you all with the same type of problem,
I had done all the mentioned possible causes, ended up replacing the camshaft sensor and finally got the car running perfect , more power and no hesitation at all, replacing the sensor was a 15 minutes diy job, and got the sensor for less than 100 dollars. just have to have the right tools. if you need instructions let me know.
it is recommended to change both sensor, but I believe otherwise, since camshat sensor is the one that causes the hesitation, the other is a CO2, and may not be damaged, so I took the chance.

thanks

Originally Posted by onitsway

Hello all. Just joined the site. I bought a 1995 740iL and love it. It is a project car and I can't wait to get started. I have a problem with cold starts and acceleration. I have replaced:

MAF
cleaned the ICV
changed the plugs and coils
changed both O2 sensors
changed the fuel filter

I start the car in the morning and after it warms up it idles fine. As soon as I put it in gear, it hesitates even if I floor it like it lost power then it kicks in and goes. I never have that instant throttle response like I think I should. I appreciate any help.

[omarhr]

Hi Acamireo I went to the BMW dealership to buy the camshaft sensor for my 1999 323i but they are telling me that there is 2 sensors in the camshaft one is an intake sensor and the otherone is an exhaust sensor can you please tell me which one is the one you replaced.