The brake booster line (foreground, not in focus) and these two hoses I'm holding that go to the idle control valve (large, left) and the crankcase (smaller, middle) are the only lines connected to the intake manifold. The manifold is not under vacuum at idle, unlike cars with one throttle body. And since we run a MAP sensor, we can actually run the car as you see here, without an intake manifold! And we did, and on the dyno—more on that soon. Feel free guess how much power is gained sans manifold in the comments below.
So here is TPS #2, which is screwed onto the throttle actuator. It is the same unit as TPS #1. Unplug it, and remove those same two crappy screws. If you strip them you’ll have to remove the throttle actuator valve, which then means necessitating a throttle re-synchronization at the dealer, which costs hundreds of dollars in labor alone…unless you have AEM Infinity (haha again!).
Giving the car a full-throttle rip with a new TPS #2 now installed didn’t change anything, unfortunately. But before plunking down the dough for the throttle actuator, we cruised over to Modified by KC, where owner Chad Charlton could access the AEM Infinity software to synchronize the throttle, like they do at the dealer, hoping it was the last thing needed.
It took only a few minutes. And when Chad was all done, I took the car around the block and gave it several rips, and we had success! Or so we thought. You see, it was raining heavily so it was hard to tell if all the power was there since it broke the tires loose easily.
When the weather had dried up, however, I couldn't seem to break the tires loose in first gear, when I can usually get the car to break the tires loose in a second-gear roll-on! Something was up. The car was down what felt to be at least 60whp. So with the key turned to “on” and the manifold off, I looked through the windshield into my opened hood, and pressed the throttle pedal down, only to see that the throttles were only opening about 30% of the way!
We performed a second TB synchronization the next day and this time verified visually that the throttle plates were opening all the way. You'd think we'd be good, but now, when driving the car at wide-open throttle, it would buck hard at 5000 rpm, trip the EML light, and shut itself off again! This was a different symptom ending in the same, dead-car result. The only thing left to swap was the expensive throttle actuator—it had to be the culprit!
To swap out the old throttle actuator with a new one from the dealer, which runs about $600, we were back removing the intake manifold again. Fortunately it only took about 1-2minutes to remove the manifold because we were keeping the runner couplings on loose and running around with no cowel or airbox since the car is tuned with Speed Density (MAP). The hardest part on the actuator installation is the lower bolt. Just shove a small 10mm socket on there and get 'er done. It’s got two connectors on it and the little arm, which can be easily popped off.
With everything in place, I needed to perform a new throttle-synch again. But by this time I’d loaded up the software to an old laptop of mine (I use a Macbook and AEM software doesn’t work with Mac OS), and was able to do it myself. So, with fingers crossed, the throttle was floored and …4000… 5000…. 6000… 7000… 8000… and no EML light. True success this time! The power is back and the car absolutely rocks! At this point I’m not even thinking about the cost for the part (although I looked at my statement yesterday and cried).