Engine surges at low rpm
#1
Racer
Thread Starter
Engine surges at low rpm
I've had this problem off and on for a couple of months and can't get a fix on it. I spend alot of time driving in the 30-40 mph range. My car is a A4 and has BBK intake and throttle body LG long tubes with high flow cats, X pipe and Borla exhaust. I also have 3:42 gears with a 3200 stall.
Here is the problem: the car will start to shutter and shake when the I'm in the 30-40 mph range. It is intermitten and will some time make the check engine light flash but will go out once Igive it more rpm or the torque converter unlocks. It will generally set a to rich bank 1 and 2 and intermitten misfire codes even though the check engine light is not on. The car has a good tune on, done by charlie at RPM. I'm lost. Any help would be apprectiated. Thanks, Laurence
Here is the problem: the car will start to shutter and shake when the I'm in the 30-40 mph range. It is intermitten and will some time make the check engine light flash but will go out once Igive it more rpm or the torque converter unlocks. It will generally set a to rich bank 1 and 2 and intermitten misfire codes even though the check engine light is not on. The car has a good tune on, done by charlie at RPM. I'm lost. Any help would be apprectiated. Thanks, Laurence
#3
Race Director
Member Since: Nov 2000
Location: Beverly Hills (Pine Ridge) Florida
Posts: 10,152
Received 525 Likes
on
374 Posts
Ran tank almost dry, and filled with Shell Premium, and within a mile the engine was running like it should.
I have a theory (and it is only that at this point) that with the usage of 10% ethanol, some stations are salting in water as a "filler" and pocketing some extra change. Ethanol absorbs water (and then mixes with gas), and would be easy to add, and most people would not notice the difference. Back in Illinois, when Ethanol first came out we found several stations increasing the percentage of ethanol significantly. The law said no more than 10%, but we found some stations always ran 16%-18%, and others in between. The Shell and Amoco (BP now) always ran on the money at 10%.
In other words, try a different gas.
Plasticman
#4
Racer
Thread Starter
I only use Chevron and not from the same station. This problem has been going on for about 3 months now. It seemed to start when I put a trans cooler on and bypassed the radiator. I've been wondering if the trans is running to cold and when it locks up it won't unlock when the engine starts to bog down. Thanks for the inputs, anyone else because it has me frustrated. The car runs great under brisk acelleration