hesitation problem

[bobbyd]

i have a problem with my car and i cant really remember if this has been happening since i bough it or not.
basictly what it does is that when it gets to 50mpg all the way to 60mpg it hesitates and feels like the car falls in its face.

any ideas on what this can be? i changed plugs, wires, cleaned air filter, maf sensor, tb etc.

basictly when it gets to the 50mph range it changes gears so its at a low rpm.

anyone experienced anything similar? any ideas on what to check for next? im going to be changing my fuel filter again and see if maybe thats the culprit

[basballny2]

could be a fuel filter, but i dont know if i would change it considering your getting 50-60 mpg

[c5z28]

lolz^
check the car for codes with a code reader via any local car parts store that lends them out. kragen etc.

[bobbyd]

could be a fuel filter, but i dont know if i would change it considering your getting 50-60 mpg

lol failed. typo meant to put mph not mpg.

theres no codes i got a aeroforce gauge and the only codes i got are the ones for the air pump.

i got the fuel filter will install it tomorrow and see if that was the problem.

will update tomorrow.

[cammed goat]

Keep us posted. I too am thinking the fuel filter.

[bobbyd]

Keep us posted. I too am thinking the fuel filter.

i changed it today but havent driven the car yet. ill drive it tomorrow and and post back with results.

[bobbyd]

Update well today i drove back home frommy parents houseand finally got to drive the car wth a new fuel.filter. well it seems like that was my problem after all doesnt seem to hesitste bog down anymore. Hopefully it doesnt come back i will update during the week to make sure its still running strong with no bog/ hesitstion

[cammed goat]

Making progress.

[Badass WS6]

From my past experience with my z28, if it's not the fuel filter it's the fuel pump. What a fun job changing that was.

I was having the same problems that you described so I put a new fuel filter in and it solved the problem for about a month. Then one day, out of the blue, it wouldn't start. Wouldn't even turn over or anything. I took it to my mechanic and he diagnosed it and it was the fuel pump. I replaced it and have had no problems since.

Good luck, and I hope it just needed a new fuel filter and not a new fuel pump.

[Durango]

Your maf fuel filter or fuel pump

[bobbyd]

Well after driving with a new fuel filter for about 5 days now it is hardly notisable now. Still can feel it s little hesitstion but not as much. I will clean my maf and seeifthat gets rid of it completely. It is a bif differnce though nowitoicks.up fastr.
Hiw can i check to make sure my fuel pump isnt fsiling etc?

[bobbyd]

update. well the fuel filter did make it seem like it had fixed the problem (a little) but the problem still exist.

i cleaned the maf vey good and it helped alittle aswell but still happens.

one thing i did notice was that when it starts to hesitate/bogdown i get some knock retart (this was scanned via a aeroforce interceptor) no missfires, no o2 codes.

what can be causing the knock retart? my o2 sensors i have a bosch (corvette rear) on the drivers side and a denso on the passenger, can this be the problem?

what else can i check? ideas? also it migh be in my head but it seems that when its not as hot out the car runs better still hesitating but not as much. other times it hesitates a little more than other times.

[cammed goat]

There are members here who advise against using Bosch O2 sensors.

[bobbyd]

There are members here who advise against using Bosch O2 sensors.

yea i've read about that. i got another denso sensor last week. i will probably install it this week and see if that was the problem. but the thing is that the readings arent slow (atleast i dont think. i was scanning both sensors readings/switching and both were almost switching around the same.

wont hurt to swap it out and try it though

[DaddySS]

If you're running lean, that will cause knock retard. First think to check is fuel pressure, if that's OK, then go after the MAF, 02s, etc.

[bobbyd]

If you're running lean, that will cause knock retard. First think to check is fuel pressure, if that's OK, then go after the MAF, 02s, etc.

checked the fuel pressure at idle and its good. 58psi.
it ran good right now when i was coming home from work. im thinking its going to be the bosch o2 sensor being slow possibly. hopefully thats the problem.

[20ws6speed01]

whats fuel press when driving or after driving awhile?

[bobbyd]

whats fuel press when driving or after driving awhile?

i have no idea i have to get a longer hose to be able to see the gauge while driving. i will see if a hvac hose will fit on it so that i can look or have someone look at the gauge while im driving.

[35th-ANV-SS]

If you have 58 PSI at idle you are fine.

I would guess O2 sensors.

[Cutlass]

bobbyd:
Year, Make, Model?? Any modifications?