what could cause this problem? sorry its long

[FlipDsM]

well, i've been getting this hesitation lately. heres how it is:
...it usually happened between 2nd and 3rd gear only. mostly after starting my car after idle to get it to normal operating temp and then drive it, it seems like my car wouldnt give a gas, even it sounds like its revving and me steping on the gas. this is all happening under light acceleration(weird). anyway, early this morning, the temp was low 60's,. and this time, it was a bit worse that before,..@ 3rd gear(under light acceleration), i felt like there is something fulling my car backwards. so then i let off the gas and sit for a minute, then afterwards, its gone and never happened again all day today....

any input?

....also, am wondering if this problem is related to: " my car wont start after a short drive problem?" ...coz everytime i drove it for a short distance and turn off the engine, the next time i get on it and start the engine, it will take me minutes(10min. atleast), and several try's of turning the car over to make it start. and once it start, my car wil sputter a bit.

both this problem happens to me at least 2-3 time a week

thanks.... appreciate any help/suggestion..

 

[doug]

The "won't start after a drive" problem sounds like it could be vapor lock. The other thing sounds to me like you're getting timing pulled (because of knock), but it's strange that it would be worse at cooler temps. These are admittedly just total guesses, though.

 

[FlipDsM]

hhhmm. could that(vapor lock) be the reason of my walbro 255lph fuel pump? coz, u know, i dont have any kind of fuel management(yet). by the way, the symptoms is actually kinda also like when u step on the gas a few times while the engine is off then start it them wouldnt go,.. but after a few times it will, but bog for a moment and go.

anyway, about timing pulled., i dont hear a knock at all. but, am curious,.. how do i fixed that timing pulled?


thanks

 

[doug]

Originally posted by FlipDsM
hhhmm. could that(vapor lock) be the reason of my walbro 255lph fuel pump? coz, u know, i dont have any kind of fuel management(yet). by the way, the symptoms is actually kinda also like when u step on the gas a few times while the engine is off then start it them wouldnt go,.. but after a few times it will, but bog for a moment and go.

I wouldn't think that the fuel pump would cause vapor lock-- vapor lock is just when the fuel that's in the line between the tank and the engine gets hot and evaporates. My wife's BMW is doing the same thing right now-- if you try to start it when the engine's warm, it'll start for a second and then die unless you press the gas pedal pretty good. The other possibility is that with a 255lph pump and no fuel management, the engine is getting flooded, but that's a total guess-- I would think that the fuel pressure regulator would be able to keep flow down enough to get the car started, even if you're running rich. Is it a 255 HP or a regular 255?

Originally posted by FlipDsM
anyway, about timing pulled., i dont hear a knock at all. but, am curious,.. how do i fixed that timing pulled?

You can't hear knock, which is also called pre-ignition and is a precursor of detonation. Your engine has a knock sensor that picks it up and tells the ECU, which retards your timing to help prevent more knock. Retarded timing means less power. There's a good article on it at howstuffworks.com but I don't have the link handy-- look through the automotive section. To fix it, you'd need some kind of tuning tools, such as an S-AFC or DSMlink so you could adjust your fuel and timing curves to prevent knock. To verify that this is what the problem is, try to get ahold of a datalogger of some sort, such as a pocketlogger. Ask around in your area to see if a local DSMer has one you can borrow-- it just plugs into your car's OBDII port under the dash so it's completely portable.

 

[FlipDsM]

Dude, i really really appreciate your input.

....anyway, to tell you the truth, am not really sure if my fuel pump is the Hp or Lp. all i know is that, it whine like crazy.

about timing,..you know, if my car is on 1st gear and let off the clutch slowly w/o stepping on the gas, my car would just cruise it self. is this a sign of bad timing? i know most car will just die.. have any idea?

and yes, i think am gonna get/barrow my self a datalogger.

thanks again..

 

[doug]

You're welcome, but like I said I feel like I'm just guessing. About the timing question, I don't think the 1st gear thing is a sign of bad timing. Like you said, getting a logger is going to be the only real way to tell. I wish I had more ideas-- good luck with finding out the problem.

And you're right-- a whiny pump doesn't necessarily tell you which one you have. Both of the Walbro 255s seem to be loud from what I've read and experienced, and even a few of the 190s.