Acceleration Hesitation at Low RPM - Page 2

shamrock 05 · 08-05-2014, 01:10 PM

Are we all having this problem

Mines seems to do it once its rained and its very humid but its literally only from like 1500 rpms to 2000 rpms and then the car drives like normal. 2004 wrx

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MLG_2EZ · 08-06-2014, 07:32 PM

Add me as well. Ive got an 05 wrx that has some very similar issues others have posted. I'm going to start with the cleaning of sensors. We should keep this thread active since there seems to be many more reporting this.

brasstacks · 08-07-2014, 09:54 AM

Stage 2 and hesitation too. It's fine if you roll onto the throttle. If you step on it there is a hesitation and it bucks before it goes. Is this the same thing you guys are all experiencing?

poopeebum · 08-07-2014, 06:53 PM

Quote:

Originally Posted by brasstacks

Stage 2 and hesitation too. It's fine if you roll onto the throttle. If you step on it there is a hesitation and it bucks before it goes. Is this the same thing you guys are all experiencing?

Yup!

Updating my post from earlier: Since my first post in this thread its still happening. However now I have a VF48 and custom tune but this issue is still happening. I have replaced the following:

- crank shaft position sensor
- timing belt
- fuel pump with walbro 255
- DW 650 cc injectors
- in tank fuel filter
- tried a known good MAF

Irish Adam · 09-15-2014, 11:17 PM

I seem to be under the same umbrella of hell as everyone here. Mine is a 02 WRX with a 4EAT and I just got back from a 1300 mile road trip. like 450 miles in I noticed the tone of my exhaust changed while driving and also I lost power.
mods:
full rebuilt EJ205(internals machined and balanced)
207 cams
machined 205 heads w/ PnP
walbro 255 FP
nameless 2.5" up 3" turbo back
cobb sf intake and box
cobb 3Port EBCS(map supported)
Cobb APT w/ stage 2 +EBCS HWG map

just changed my plugs and they were fouled out in less than 7k with a nice red-ish brown color to them. hesitates like hell when I tap the throttle at idle and then it will rev slower than normal all the way to 5k rpm. cam and crank sensors are new, fuel filter has like 11k on it, and the FP has 11k on it too.

Kinda sounds like a stutter in and out of gear, has backfired on me a few times and felt it in the intake once before and it went away after I did a stock turbo replacement. its acting up and I'm going to fix it, got too much into it to walk away and I can't stand driving it like this.

Will post up what I am able to do to fix the issue.

bushflyr · 09-16-2014, 12:22 AM

Don't despair. I fixed mine. Unfortunately I had totally forgotten about this thread and the issue and can't for the life of me remember what I did. I've been chasing/ throwing parts at a high RPM misfire and the low RPM stumble was fixed as collateral damage.

Uncle Scotty · 09-16-2014, 12:26 AM

Quote:

Originally Posted by DZXN

Does your idle hold steady or rise and fall? Check IACV threads and see if it sounds similar to your issue. The gasket is $8+-, cleaning takes 20 minutes, and getting the screws out is the toughest part.

drive
by
wire
motors
do
NOT
have
ANY
iacv

so don't post this about ANY 06 or later Subaru....

did ya get that guys???

THE OP HAS A DBW CAR THAT HAS NO IACV

Uncle Scotty · 09-16-2014, 12:31 AM

Some of yew d0000ds may wanna add a couple extra grounds...I did one to the tb and it helped

natsirt · 09-16-2014, 02:34 AM

Could it perhaps be a knock sensor problem? On my old '98 Legacy BD 2.5GT, I'd get a rare, random little hesitation blip at low RPM's. Eventually it worked itself to a CEL, code came back for a knock-sensor fault. Changed it and the car ran perfect from then on. No more little random low-RPM hesitation. My 2cents.

Irish Adam · 09-16-2014, 01:08 PM

I'll try the extra grounds. I have some extra cables from previous toys that I had wrecked or decided to salvage and sell. I will see what happens, going to clean and test everything today. The grounding issue may be an issue too.

Sent from my LG-VS450PP using NASIOC mobile app

Irish Adam · 09-17-2014, 05:42 PM

Well I cleaned the MAF and added a bottle of HEET injector cleaner. My throttle when warm responds better. Did make the same hesitation immediatley after cleaning the MAF. Going to pull the O2 sensor and check it also add extra grounding wires where I can. But so far the MAF is the main culprit.

Sent from my LG-VS450PP using NASIOC mobile app

BeastianSTI · 09-18-2014, 02:58 PM

Quote:

Originally Posted by Uncle Scotty

drive
by
wire
motors
do
NOT
have
ANY
iacv

so don't post this about ANY 06 or later Subaru....

did ya get that guys???

THE OP HAS A DBW CAR THAT HAS NO IACV

2004 sti+ or 06+ wrx or later

Sent from my SM-G900P using NASIOC mobile app

Jswick1988 · 09-22-2014, 02:12 PM

I just bought an 04 Wrx and I think I might have the same issue. It also sounds like its got a random miss at idle. I'm going to try some seafoam in the tank and look at the maf. It also has a greddy bov so it might need adjusted.

TonyySubieguy · 02-10-2025, 12:10 AM

Wow so many people post asking for help.. but did any of them figure out the issue? got a 05 wrx rebuilt motor and still does this hesitation, slight lean, if gas is pressed even a tad bit aggressive, after 2k rpm it feels better, but if you shift and press the pedal hard again itll do it again! driving me nuts..

anyone?

09-15-2014, 11:17 PM	#30
Irish Adam Scooby Newbie Member#: 353785 Join Date: Apr 2013 Chapter/Region: South East Location: Naples, FL Vehicle: 2002 Impreza WRX Obsidian Black Pearl	I seem to be under the same umbrella of hell as everyone here. Mine is a 02 WRX with a 4EAT and I just got back from a 1300 mile road trip. like 450 miles in I noticed the tone of my exhaust changed while driving and also I lost power. mods: full rebuilt EJ205(internals machined and balanced) 207 cams machined 205 heads w/ PnP walbro 255 FP nameless 2.5" up 3" turbo back cobb sf intake and box cobb 3Port EBCS(map supported) Cobb APT w/ stage 2 +EBCS HWG map just changed my plugs and they were fouled out in less than 7k with a nice red-ish brown color to them. hesitates like hell when I tap the throttle at idle and then it will rev slower than normal all the way to 5k rpm. cam and crank sensors are new, fuel filter has like 11k on it, and the FP has 11k on it too. Kinda sounds like a stutter in and out of gear, has backfired on me a few times and felt it in the intake once before and it went away after I did a stock turbo replacement. its acting up and I'm going to fix it, got too much into it to walk away and I can't stand driving it like this. Will post up what I am able to do to fix the issue. Last edited by Irish Adam; 09-15-2014 at 11:19 PM. Reason: add comment

02-10-2025, 12:10 AM	#39
TonyySubieguy Scooby Newbie Member#: 540247 Join Date: Feb 2025	A decade later... Wow so many people post asking for help.. but did any of them figure out the issue? got a 05 wrx rebuilt motor and still does this hesitation, slight lean, if gas is pressed even a tad bit aggressive, after 2k rpm it feels better, but if you shift and press the pedal hard again itll do it again! driving me nuts.. anyone?

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08-05-2014, 01:10 PM	#26
shamrock 05 Scooby Guru Member#: 120057 Join Date: Jul 2006 Chapter/Region: MWSOC Location: outskirts of motor city Vehicle: 2018 WRX (base) 6spd WRB	Are we all having this problem Mines seems to do it once its rained and its very humid but its literally only from like 1500 rpms to 2000 rpms and then the car drives like normal. 2004 wrx * Registered users of the site do not see these ads.

08-06-2014, 07:32 PM	#27
MLG_2EZ Scooby Newbie Member#: 384445 Join Date: Mar 2014	Add me as well. Ive got an 05 wrx that has some very similar issues others have posted. I'm going to start with the cleaning of sensors. We should keep this thread active since there seems to be many more reporting this.

08-07-2014, 09:54 AM	#28
brasstacks Scooby Newbie Member#: 321391 Join Date: May 2012	Stage 2 and hesitation too. It's fine if you roll onto the throttle. If you step on it there is a hesitation and it bucks before it goes. Is this the same thing you guys are all experiencing?

09-16-2014, 12:22 AM	#31
bushflyr Scooby Specialist Member#: 89628 Join Date: Jun 2005 Location: Hawaii, Oahu Vehicle: '02 Wagon VF39'd & Quick Racked	Don't despair. I fixed mine. Unfortunately I had totally forgotten about this thread and the issue and can't for the life of me remember what I did. I've been chasing/ throwing parts at a high RPM misfire and the low RPM stumble was fixed as collateral damage.

09-16-2014, 12:31 AM	#33
Uncle Scotty * Banned * Member#: 16200 Join Date: Mar 2002 Vehicle: OK buy Nates beans westcoastroasting.com	Some of yew d0000ds may wanna add a couple extra grounds...I did one to the tb and it helped

09-16-2014, 02:34 AM	#34
natsirt Scooby Newbie Member#: 401759 Join Date: Sep 2014 Location: Calgary, AB Vehicle: '98 Legacy RS-B EJ20R	Could it perhaps be a knock sensor problem? On my old '98 Legacy BD 2.5GT, I'd get a rare, random little hesitation blip at low RPM's. Eventually it worked itself to a CEL, code came back for a knock-sensor fault. Changed it and the car ran perfect from then on. No more little random low-RPM hesitation. My 2cents.

09-16-2014, 01:08 PM	#35
Irish Adam Scooby Newbie Member#: 353785 Join Date: Apr 2013 Chapter/Region: South East Location: Naples, FL Vehicle: 2002 Impreza WRX Obsidian Black Pearl	I'll try the extra grounds. I have some extra cables from previous toys that I had wrecked or decided to salvage and sell. I will see what happens, going to clean and test everything today. The grounding issue may be an issue too. Sent from my LG-VS450PP using NASIOC mobile app

09-17-2014, 05:42 PM	#36
Irish Adam Scooby Newbie Member#: 353785 Join Date: Apr 2013 Chapter/Region: South East Location: Naples, FL Vehicle: 2002 Impreza WRX Obsidian Black Pearl	Well I cleaned the MAF and added a bottle of HEET injector cleaner. My throttle when warm responds better. Did make the same hesitation immediatley after cleaning the MAF. Going to pull the O2 sensor and check it also add extra grounding wires where I can. But so far the MAF is the main culprit. Sent from my LG-VS450PP using NASIOC mobile app

09-22-2014, 02:12 PM	#38
Jswick1988 Scooby Newbie Member#: 402180 Join Date: Sep 2014 Location: Terre Haute, Indiana Vehicle: 2004 Wrx Wrb	I just bought an 04 Wrx and I think I might have the same issue. It also sounds like its got a random miss at idle. I'm going to try some seafoam in the tank and look at the maf. It also has a greddy bov so it might need adjusted.