Engine hesitation... :(
 

Hey guys, i have a problem :(
So on a snowy day in new york, i was driving home from a long day at school.. (12-8) when i tried to rev the engine a little bit (after it was warmed up of course) it wouldn't rev smoothly.. Also, my coolant light comes on periodically on the highway (and only on the highway -_-) but my coolant temp is steady at 180 (cobb ap) and it's topped off.. i've attached a video.

my 8:
2005, 41xxx miles, manual, NA,

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Coolant issue is probably the coolant sensor.

I take it the not revving smoothly was it getting to 8k and just topping out there on the first two tries?

it revs to 8 and it stutters then flies up to 9.5.. it's really weird

That is weird. Can you describe the sound I hear when you're stuttering at 8k? My laptop speakers isn't very life-like in sound production.

Hopefully other people chime in :(

WTF, sounds like a two step.

that's EXACTLY what it sounds like.. like it's on launch control or something

At work so I can't view the video, but did you check the VDI to make sure its operating properly?
Figured the valve opens above 7250RPM so it might be something to consider.

Just had a chance to watch the video.
Think it could be the accelerator pedal?
It has positioning sensors and may cause something like that if they started to act flaky.
Just something else to consider.

thanks for the tip jon.

i checked the sensor for my accel pedal (with the cobb) and it's fine..

something weird that i figured out today on my way to school. The car revs smoothly in gears 1 - 3 when i'm punching it, but when i'm up to speed (around 70-80 mph), the car chokes at 4krpm in 6th gear... and i can't go any faster than 80 :S.. i'm gonna reset my ecu, or reflash my stage one map and see how it goes

thanks charles :) i'm gonna do that before i leave the parking lot today. good looking out man!

i have the same exact issue.
the plugs have been changed 6 times, numerous flashes.
i think my vdi or wires -peers at charles-

so i reflashed it.. and it's still doing the same shit. i think i'm just gonna take it to KDR. gonna check my intake to see if there's any oil in there first, then see if my sparkplugs are up to code.. i'll keep you posted

i'll check for codes in a bit..

*update: the engine only hesitates when i'm lightly pressing on the gas.. it revved better when i was more aggressive. Do you guys think it might be my mini battery? Will that make a difference? The battery is 450 CCA instead of 600CCA. it cranks and starts up just fine

as long as you can maintain more then 12v u are fine should be around 11-14.7
in my case light or heavy it hesitates at exactly 7500 (or least audible/tach visualble after that point) only applies after 3rd gear or is only noticable after 3rd.

id check the plugs, then vdi then the wires
i belive in my case its the wires but requires futher testing.
either that or my cat is starting to block.

my last car did the exact same thing but at like 4,000 rpm then seconds later there was coal buring on the ground and the car wouldnt start again. the explosion was a combo of a blocked cat and a coil that died, extreme backfire that had nowhere to go.

spoke to my tuner and he told me that it's definitely my fuel pump... so i swapped it out for the walbro that i had sitting in my 'to install' parts box hahaha

new issue.. the car still chokes at higher rpm, but seems to rev a LOT smoother. i'm gonna drive to kdr to see if dave can tune it so it doesn't idle so rough either.. anyone else have this issue with the walbro? (rough idle)

on a side note... that fucking fuel pump was a nightmare to get off..

ill film my issue
at 7500 it hesitates (ever since the bhr coils/pump install)
perhaps ill crack open my fuel pump as well and check the line.
i couldnt use the oem hose that goes from the siphan to the pump as it had a pinhole leak in it. i had used another hose that didnt like the flex for the radius. perhaps it has become pinched giving me the same result.
and for nightmares i had to install and remove the walbro 3 times due to the hose issue. after the first it becomes easy. just make sure it goes back on really tight. dont ask me how i know mine wasnt...

i pulled my pump and found that the line was kinked.
this afternoon i will update with the result
i fabed a new hose and placed a stainless steel spring inside to prevent future kinking
aint it kinky?

lol talic, did you fix it?

so the car is now running normally after the first highway cruise.. no more hesitation. BUT now i've got a check engine light.. and it's a 3** (forgot exactly what it was..) but it said something like air injection unit 2? what the fuck is going on with my car!!!????

I'm sure you know the fuel filter/pump requires a special tool for easiest removal & replacement. Did you also change the sock filter since you were in there?

Don't forget to check/clean your MAF as well. Sometimes it's the simplest things ....

yeh i know, but the tool wasn't available at any of the pepboys/autozones near me.. i did get it off, and i put it back the way it was supposed to go.

i cleared the code with the cobb, but i'm gonna take my car to KDR sometime this week.

The car feels really healthy now.. It's weird. It might just be in my head, but the revving is way smoother, and the fuel economy is normal.

yeah i put the line in and after 25kms the spring ripped through the line when the pumnp ramped up after idle.
i put in another one (used fuel line off of a benz that was s shaped, it fit perfectly however after 50 kms the line ruptured.
now ive got a 300 bar line in place with a spring to keep its shape
so far so good (so i think its been over 8 times ive had to open this thing up. go go chizel and hammer!!
i took the video on my crapberry driving into the sun on the way to work
unfortunatly i took 3. it recorded one correctly and the other 2 it recorded after my runs. stupid track ball... i miss my iphone -tear-
ill bring the digital on my trip home and get 4th 5th and 6th

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the unkink didnt fix my problem.
looks like ill have to rip out the vdi
and looks like my trip to usa is postponed as i have to armor an merc s500
2 f550 buses and 4 apc projects -grr- no time for my personal project -tear-
so wont beable to have the bhr coil system tested.
however the dekink smoothed out my powerband (obvisously)

talk about nightmare.
since the upgradation of the bhr pump ive gone through 6 lines.
looks like this line has failed/came off yet again
ive taken the plastic ring off over 17 times due to the lines
and to do it again -cry-
i think im going to order a new ring since this one is starting to look scetchy
and laser out my own tool for easy removal for future
so my problem probibly lies with the pump area or my cat is fully blocked or all coils dead. unfortunatly no check engine light. time to make the exhaust for the rear mount and see what happened to that cat.

k steam cleaned the intake/exhaust and got a hose that finally the car liked
when doing the removal and reinstall of the plastic ring i put some petrolium jelly to make it silky smooth for future removals. and since its petrolium based. wont hurt if contact with the fuel. my hesitation is gone.
did anyone notice that the bhr pump when installed for first time (or when the tank is reopened and then closed) it makes quacking sounds while pressurizing the other tank? or just me? the whine has always been nice

Wow - 17 times !!!!!! Must be some kind of record LOL