periodic surging
08-30-2010, 02:49 PM
#1
Instructor
Thread Starter
periodic surging
My car developed a problem where it would lose power suddenly and fail to rev above 1500 or so. After a few seconds of pumping the throttle, it would rev high and then all was normal again. I've been taking it on test drives to try to establish a pattern.
Today, it was running normally, then the problem suddenly developed at a stop sign without going away. Pulling a way from the stop sign, the car failed to rev past about 1800. If you hold the gas at any significant throttle position, it will rev sluggishly to almost 2000 then fall back to 1000, then rev almost to 2000, fall back to 1000, etc., for apparently as long as you want to watch it doing it.
It will make some power and hold the RPM at 1000-1500 or so. I got it home by extreme short shifting, and it ran normally in the low RPM.
I have good vacuum, and I recently checked the AFM using the Clark's Garage method.
What is a good thing to check next?
Today, it was running normally, then the problem suddenly developed at a stop sign without going away. Pulling a way from the stop sign, the car failed to rev past about 1800. If you hold the gas at any significant throttle position, it will rev sluggishly to almost 2000 then fall back to 1000, then rev almost to 2000, fall back to 1000, etc., for apparently as long as you want to watch it doing it.
It will make some power and hold the RPM at 1000-1500 or so. I got it home by extreme short shifting, and it ran normally in the low RPM.
I have good vacuum, and I recently checked the AFM using the Clark's Garage method.
What is a good thing to check next?
08-30-2010, 05:41 PM
#5
Nordschleife Master
if the bahaviour changes (improves) without the TPS connected, the TPS IS the source of the problem...
My guess would be the idle micro switch isn't turning off properly...
09-01-2010, 09:21 PM
#6
Instructor
Thread Starter
I put on a new TPS tonight, and the problem is resolved. The car runs much better at all RPM than it has in a long time, perhaps ever. Runs smoother and seems to be making a lot more hp. Thanks John and Manny.
