PrettyPinkPonies

I started up my car this morning and the rpms fluctuated from 700 to about 1200 the it dipped down to 500 and it just about died and I gave it a little gas and it was fine after that. I installed a new BBK CAI 2 days ago and it did a similar thing yesterday. The CEL came on yesterday so I remounted the intake and it didn't come on after driving for about 5 hours today in diff types of traffic.

On my way home after an oil change at the dealership I felt the car kick doing 45ish going between 1800 and 2100 rpms. I got it to repeat the effect and found that it would only do it around those rpms. It kind of feels like it's coming from the transmission it doesn't sound like an engine knocking this is more of a thump than a knock or ping and it doesn't do it at idle only when driving and between those rpms.

There is about a half second lag between when press of tap the gas pedal (in that rpm range) to when it actually kicks/thumps and it kind of feels like the harder I press down or tap down the gas the harder it does it and it only does it at each initial tap or press of the pedal within that rpm range.

Any ideas? I've felt a similar occurrence on my manual silverado when I'm in say 3rd gear and put it in 4th and tap the pedal down about half way quickly and it proceeds to kick or thump which brings me back to the transmission theory. but why does it only do it in that rpm range and what does it mean!? Does it have to do with the recent BBK CAI? The CEL hasn't come on and everything else feels/sounds fine from what I can tell.

I've got an sct tuner with VMP custom tunes as well as a MAC cat back dual exhaust on the way should be about 2 more weeks.


I know it's my first post but I'd appreciate any feedback!! I've skimmed the forum and others online and haven't been able to find a similar issue (though I'm sure there's a thread out there).

MoneyShot

Try disconnecting the battery for about ten minutes, reconnecting it then following the owners manual to relearn the fuel trim:
Because your vehicle’s engine is electronically controlled by a computer,
some control conditions are maintained by power from the battery. When
the battery is disconnected or a new battery is installed, the engine must
relearn its idle and fuel trim strategy for optimum driveability and
performance. To begin this process:
1. With the vehicle at a complete stop, set the parking brake.
2. Put the gearshift in P (Park) (automatic transmission) or the neutral
position (manual transmission), turn off all accessories and start the
engine.
3. Run the engine until it reaches normal operating temperature.
4. Allow the engine to idle for at least one minute.
5. Turn the A/C on and allow the engine to idle for at least one minute.
6. Drive the vehicle to complete the relearning process.
• The vehicle may need to be driven 10 miles (16 km) or more to
relearn the idle and fuel trim strategy.

When you have completed that, recalibrate the throttle position sensor by turning the key to ON (DO NOT START THE CAR!) and wait till all the normal lights in the dash go out, then slowly press the gas pedal until it is floored and release. Turn key off, wait about 6 seconds and then start your car.

Also check to the MAF sensor installed in your CAI is pointed the correct direction. It has an arrow which should point towards the throttle body

Nuke

Make that battery disconnect 20-30 minutes.

Typically, a computer reset and or a new tune will require you to put a few miles on the car before the PCM "settle down".

alkemist

Make sure your CAI is mounted correctly and there are no leaks. Apparently the BBK likes to leak very easy. My first mount was bad. It was done by someone else. At first I was disappointed because it felt heavy and less responsive and would idle odd at stoplights, etc. I remounted and ever since it has been different. I think I will have to check it again because before I had to send it to the bodyshop, the idling issues were coming back. As for the engine light, I had mine come on for lean fuel mixture. I forced the light off, did the (2nd) mount and it never came back. Like I mentioned in another thread, I am speculating that the CAI is runnning lean but not enough to trigger the light. In the long run will just do damages. Good idea on the tune pickup. I just got one from brenspeed and waiting to get my car back.

PrettyPinkPonies

Thanks for the tips everyone I'll be d/c the battery and do the fuel trim relearn tonight. The intake seemed to have been doing better after the re-mount but I am not certain as if to I feel the car more or less responsive I can't tell but it's not as fast on take off now it seems like but again I am not sure I just need to drive it more but the roads have been wet here and will continue to be until later this week so I have to wait to be able to really compare it to the past ><

The car computer shows that my MPG has gone up from 16.5ish to 17.9ish since the intake went on that's always nice.