I have a 2000 C5, 86000 miles, Vararam CAI and swapped out for a Z06 intake and BBK TB. After installing per BBK instructions, letting the car idle for at least 10 minutes to reset the idle speed (doing this several times, even pulling the #16 and 23 fuse per other instructions), then driving at various speeds for 50 - 100 miles, the idle is erratic.

When the car is in motion my idle goes to 1500-1800 but when completely stopped (wheels not turning) drops down to 800-900. I understand that when the car is moving the PCM causes the idle to increase somewhat, up to 1100 rpm or so, but not 1500 or more. I've called BBK and they don't know except maybe the TPS or a vacuum leak. I've checked for vacuum leaks and can't detect any and the engine runs fine otherwise, but when cold has some hesitation and cutout while accelerating. I have noticed my gas mileage increased to an average of 29 mpg, but because of the high idle my temp goes up beyond 240 degrees when I'm in traffic. Normally it never goes above 180 since I installed a 160 tstat.

Everyone once in awhile I get the code P0507 (Idle Speed High) and I reset it but it comes on again.

Anyone have any idea what the problem could be? Thanks in advance.

 

Im assuming you have an auto and if Im correct then it takes much longer to relearn the idle speed than ten min. With a manual you have to pull the fuse, wait five min, start the car and let the colant reach 172 and then turn the ac on for another five min, after that you have to turn the ac back off and just let it idle for another five min, finally you cut the car off. Im not too sure how it goes with an auto but I would think you would let it get up to temp, leave it in park with ac on, neutral with ac on, park with ac off and neutral with ac off and finally cutting the car off with five min spent at each point. Not sure about the combination of that at all though because I didnt need that so I just glanced at it. I do know Bill Curlee posted it though.

 

This must be a typo...I'm sure you don't want the OP to have warped heads, do you?

 

mine did this exact same thing after intake was pulled off & put back on.

My 1/8th hose from the back of the intake (underneath the MAP sensor) had popped free and it created a nasty vac leak. That hose feeds the vacuum resevoir. Alot of people I've read extend the 1/8 hose to make it alot easier to reconnect it back up (it's a freaking pain)

 

My car does the same thing after I ported the TB. I didnt do any idle relearn procedure. When I start the car it will instantly go up to as much as 2000rpm. Then settle to a normal idle. Then sometimes after driving and coming to a stop the car will idle at 1500 or so until the car has come to a complete stop. Then settle to a normal idle again.

 

Thanks I fixed it, it was getting pretty late.

 

My bad, no I have a manual and per BBK's procedure:

Step 12: Reconnect the neg. battery terminal and start the vehicle allowing it to idle for approx. 10 minutes. During this
startup period do not rev the engine or put the vehicle in gear – just simply let it idle.

Step 13: After idling period put vehicle in gear (automatic models) and note rpm. At first the vehicle may jump up in idle
rpm when switched between gears, therefore be sure to firmly depress brake pedal when making gear changes
on automatic equipped vehicles. The increased rpm should subside once the engine has warmed up and
after the vehicle is driven for 50-100 miles. Due to the complete computer control of the throttle body (no cable)
and the larger bore of the throttle body, a small increase in engine rpm may continue after break-in period,
however it should be comparatively small to that during the break-in period.
Step 14: After driving the vehicle for a period of time, at first the check engine light may illuminate. If this occurs try
disconnecting the neg. terminal and go through Step 12 once again. If any problems persist please call
our TechLine for more information, however do not attempt to make any adjustments without
consulting a BBK technician (951) 296-1771 or email tech@bbkperformance.com.

The other procedure I read about: Turn the key on but don't start the engine. Remove the number 16 & 23 fuses from the under hood fuse box. Turn the key off. Replace the number 16 & 23 fuses. Start the car and let it run @ 175 degrees or warmer for 5 minutes. Shut down the engine for at least 30 seconds, then drive the car for about 30 miles at varying speeds.

The 1/8 in tube: I especially checked this as it was difficult to hook up after the intake was on but it may have come off after I put the intake in place and for me to check it now is impossible as I can't get my hands back there so I may have to pull the manifold again and put an extension on it...grrrr

I'll do that this week and try the relearn again. I'll let you all know what the outcome is.....av

 

Update. After getting my stock TB back, I pulled the BBK off and noticed that it had the infamous hole drilled in the tb plate. I swapped the tb's and now the car runs normal. Some things I noted about the other tb, the idle was about 150-200 rpms faster at normal idle. Whereas with the stock tb, it idles about 700 and then increases to about 850-900 when in motion, the tb with the hole in the plate idles at about 850-900 and then jumps to 1000-1100 when in motion. I'm assuming thats because of the increase air through the tb from the hole. At any rate, I wish I could have kept the BBK but at this point, I neither have the tools or a garage to mess with it much and will just run with the stock. As for the 1/8 vac tube, I never could get to it without pulling the intake back off. I had even cut a hole in the top of the fairing under the wipers when I relocated the oil pressure sending unit but still could not get to it but as long as its running, I'm going to assume that its still connected. Thanks to all for your inputs. Aviator....

 

This is the one I was referring to, I tried searching for it but that didnt turn up any results so I just went through this past months history and found it.

 

When the car is in motion my idle goes to 1500-1800 but when completely stopped (wheels not turning) drops down to 800-900.

I had the same thing.

It was fixed with by a tuner (COW), there is a setting, and you need to find someone with a tuner in your area that can fix that for you.

 

if you ever find out what that setting was...let me know please.

 

I have a predator tuner, just not with me. Though I haven't actually used it, after reading the manual, I don't remember any setting that compensates for an increased air flow, though I'm sure there is something for that. But all is well with the stock tb and I only actually lost 7 or so hp.