i went to the dragstrip saturday and ran consistent 15.30's...last year i was running 14.60's! my 60foot time wasnt all that bad at 2.26 but the car seem like a real dog after 5500rpm. i noticed lately it has felt slower but dont know why. i have a new knock sensor and all new oxygen sensors and a new engine! this same setup ran awsome last year! no check engine lite either. new fuel filter and air filter. i think my fuel pump is bad. anyone had this problem?

 

You need a tune up i guess. 15.3 isn't bad for a lightly modded let alone stock 4th gen. Did you do a 5spd conversion?

 

its had a tune up! where did 7 tenths go? and my trap speed was only 88mph! it used to be 95-96mph! i'm so pissed!

 

Wow something is wrong here... Maybe its teh weather....

 

thats what i thought at first but its really slow in the top end. i dont think its injectors cause it idles okay and no cel. i think i am going to get a walbro fuel pump. i dont know what else it could be!?

 

what about your exhaust set up? you might have leak some where. Mines felt really slow and i replaced just about everything you could do on a tune up.. It ended being my flex section had a hole and I was lossing back pressure.

 

put some air in your tires
and make sure you only have just enough gas

 

Clogged cat?

 

Hello!?! He said he lost 7-8 mph! A full or empty tank of gas isn't going to make a difference.

It has to be something serious then. What was the weather like with the 14sec pass and the 15.3? Compression test? Change your fuel filter, plugs?

-Paul

 

obviously i was joking...

 

Do you have a auto to 5 speed tranny swap? Running 14.6s@96mph in a auto GLE with the typical bolt-on is unheard of. 15.3s@88mph sounds perfectly normal for an auto GLE with normal bolt-ons. If you still have an auto, then I'd point my finger at bad track timing equipment when you ran the 14.6s.

Give me a run down of your mods, the conditions you ran in, and a run down of your 14.6 and 15.3 timeslips.

 

oh ok then. lol I hope you were joking.

Like Dave said, give us some more info and we can help you out better.
-Paul

 

Dirty or clogged air filter, TB, or injectors? Check your coil packs.

 

its a stick gxe...and it was the same track both times! ordered a walbro fuel pump...dont know what else it could be? got a high flow 2.5inch cat from w/s a while back so i dont think thats the problem and like i already said the fuel filter air filter and plugs are all new!

 

Yhea, there is something really messed up going on.

Car seems to run fine?

What are your mods?

Your gonna be looking for something major to lose 7mph. Like a non working MEVI (if you have one), a busted y-pipe flex section (but that still would not cause 7mph loss).

No codes?

Were others running normal times that day?

 

yeah...it was a little warm but everyone else was running fine! times where about .1-.2 higher than usual but not .7! my 60foot wasnt to awful at 2.26 and its really slow up top so its has to do w/ horsepower after 5k.

 

did you every dyno before? if so you should redyno to compare...the AFR graph might show you what is going on...

mines been like that lately...where it definitely doesn't feel as fast anywhere in the powerband and I have brand new everything imagineable sensors, filters, etc....additionally, I dynoed right where I should have for my mods...and my compression test checks good...so I am at a loss...I would strike it up to all mental...but you have the times to prove it's not mental...my guess would be something with the drivetrain...example, my car might dyno really really well, but if it can't put the power to the ground...then I will get beaten by a lot of cars that are much slower...ie. flywheel or clutch problem...or even slack in the shafts/gears and bearings, all cost time which adds up! ex. if your car takes another .2 seconds to get into gear between each shift...there is your .7 seconds extra right there in the 1/4 due to multiple shifts...and .2 seconds would barely be noticeable to a driver between each shift unless you know your car really well...I think this pretty much explains your time loss if everything engine/power related is in order...and you dyno really well...I think this best explains my slow feeling car that puts down great #'s on the dyno...

btw...how much of a difference do broken flex sections/exhaust leaks have on the performance of the car...? wouldn't he hear it if he had any sort of exhaust leak...wouldn't the car be a lot louder?

 

coil packs mabye? man that sucks .

 

well with coil packs I would think there would be a hesitation symptom, and if they were really bad, it would throw a code for a misfire...

 

true. i guess just check the exhaust . what about the clutch is it slipping at all?

 

well...even if a clutch slips even a little (very un-noticeable to the average driver), it can seriously hurt a 1/4 mi. time as it involves multiple shifts...

 

same track/elevation? same tires? same weather conditions(more hot than before maybe)?

 

i got the clutchnet 6 puck sprung hub and it grabs like an animal! i am still leaning towards a fuel pump i think...i know its something else other than the drivetrain because it was just a few months ago that i ran my personal best of 14.63 at 96mph! my 60foot was 2.21 then. my engines only got 37k on it. thanks for everyones help so far.

my mods are...headers,y-pipe,high flow cat,2.5inch cat back,intake,underdrive pulley and lightened flywheel.

 

umm did you forget about the Ghost Code of the all Stupidlike KS

 

knock sensor is only 6mos old

 

i would pull codes, if the ks was over-tightened or anything else is wrong with it, or something else that would pop a ghost code, that could be you're culprit right there.

 

Clean your TB and some seafoam

 

whats seafoam?

 

disconnect the ypipe from the cat and look thru the ypipe...make sure the flex section is the correct size inside.

my old ypipe fell apart inside and was the size of a DIME by the time i figured it out. talk about air flow restriction...

 

Did you gain a little weight???

 

Ive noticed on some vehicles in the past when the o2 sensors were new the car was slower and the gas mileage sucked right away. Just changed the one in my wifes alero and i notice it on hers to. I thought they were supposed to help fuel economy when they are new, we averaged 29 mpg on highway b4 now it is 24-25. (Bosch o2)

 

I noticed the same thing...right after I changed my factory originals to brand new bosch ones...

 

me three. only with the one i just got though the first one was fine.

 

i changed mine like a year ago...they are not brand new.

 

its funny that you say that because mine does the same thing. After I got my WS catback put on I cleared the CEL and ran three 9.4's. CEL comes on, car drops to 9.6's. Now I have always heard that when the CEL is on showing a catalytic converter eff. code, it has no effect on performance. Is this true?

 

What planet have you been on lately? Read the stickies. Its a product you can run through your brake booster hose and add to your crankcase and gas tank and a lot of .orgers swear buy it, particularly the brake booster hose application. I haven't tried it before.

 

its not ur fuel pump..u jsut wasted money on one.....fuel pumps either work or they dont usually.....u would have more symtoms of a dying fuel pump then a bad day at the track