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View Full Version : Flat Spot at 3k rpm?



CrtchRktRcr
06-09-2010, 01:23 PM
I've noticed when i'm on the throttle any decent amount right around 3k rpm it flattens out for a second and then is just fine. I was wondering if anyone else felt something similar? I am on stock tuning, test pipe and cone filter. Plugs are new and gapped correctly..

I searched and couldn't find anything

99 aeb 1.8tqms.

bikerbob951
06-10-2010, 07:28 AM
Do you have an anti-fouler on your rear O2 sensor on the test pipe? If not, the car could be doing goofy things because it thinks it's running rich. Just a thought. Also, could be a boost problem, since the boost starts to kick in about 3k.

CrtchRktRcr
06-10-2010, 07:54 AM
Do you have an anti-fouler on your rear O2 sensor on the test pipe? If not, the car could be doing goofy things because it thinks it's running rich. Just a thought. Also, could be a boost problem, since the boost starts to kick in about 3k.

yeah Bob i have the spacer and no CEL. I was thinking maybe the motor kinda prepares itself (may the cams turn a bit) for boost since that's when it kicks in. I am boosting just fine, no leaks and hit 7psi (stock) just fine. I was thinking it was just how the stock software works and is tuned.

viceprp
06-10-2010, 11:40 AM
I have this problem but it usually happens at 4k. I recently replaced my MAF and it made the hesitation more noticeable at 2300 RPMs now. I'm in the same boat and dumbfounded. Im going to check my coilpacks once more but i just replaced all 4 last year. Been like this since I bought the car.

CrtchRktRcr
06-10-2010, 11:42 AM
I have this problem but it usually happens at 4k. I recently replaced my MAF and it made the hesitation more noticeable at 2300 RPMs now. I'm in the same boat and dumbfounded. Im going to check my coilpacks once more but i just replaced all 4 last year. Been like this since I bought the car.

does yours feel like a missfire? mine just seems flat...that's just the best way I can describe it

viceprp
06-10-2010, 11:44 AM
With the old MAF it seems like a hesitation. With the new MAF its a major hesitation (almost 1.5-2 seconds) but after that its smooth all the way to red line. I had a misfire with the wrong spark plugs before and its nothing close to that. Also, no CEL

CrtchRktRcr
06-10-2010, 12:56 PM
hmmm... the no cel thing really makes matters difficult to pinpoint. I am sure you have gone through all the reasonable trouble shooting techniques. Plugs, maf,coils....

protocol_droid
06-10-2010, 02:25 PM
I had the same problem with a weird hesitation. Turns out I had some old cracked hoses running to and from the manifold. I replaced 3 hoses that were cracked to brand new ones and my hesitation was gone thereafter. The one directly underneath the intake manifold was a bugger to get at but needed replacing.

CrtchRktRcr
06-10-2010, 02:43 PM
sweet dude thanks.. yeah i'm pretty sure the check valve under the manifold is cracked.

viceprp
06-11-2010, 02:07 PM
The new MAF pulled a code. Swapped out to the old one and only have the hesitation at 4k. Also, does your RPMs jump up and down when you put up your windows? Not sure if our car's windows run on vac, but the vac gauge jumps as well. Same goes when i turn on the air.

CrtchRktRcr
06-11-2010, 02:35 PM
Yeah the windows drop my volts bad. It's just pulling more power so it's ok. Yes my brakes feel sloppy and car is a slug with the ac on. GOOD thing is live in Arizona! it only gets to 118* during the summertime! I have to run air and windows up cruisin at 1am!