Bucking, Stalling under light throttle

[Flatliner]

Well the car was running 100%... and I figured I better resolve my disformed JLT RAI. Tucker's gonna take a look at it for me... so I pulled out my bin, found my brand new CAI I had never used to slap on. Since I had the air intake removed I figured good time to change the plugs. In went the Autolite 103's and on went the CAI.

I took the car for a ride and monitored the A/F and got on it... :headbang: Later in the day we went to Jeff's picnic only to have the car stall on me a few times when decelarating and also had a slight bucking under light throttle. I figured that the cause was forgetting to reset the battery. That night disconnected over night and life went on. Sat. was track day... and low and behold in the morning I had no issues at first... 15 minutes to the meeting place and still issues. I slapped the RAI back on Sunday night and guess what... still the same issue. Last night I pulled the plugs and all look perfect.

I've researched this but no one has really pin pointed it... tonight I will buy some electronic cleaner and clean the IAT and MAF sensors... what is weird is even though I took them off the RAI and on to the CAI, there was NO WAY I touched them.

Confusion...

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[Jimy Bilmo]

Well the car was running 100%... and I figured I better resolve my disformed JLT RAI. Tucker's gonna take a look at it for me... so I pulled out my bin, found my brand new CAI I had never used to slap on. Since I had the air intake removed I figured good time to change the plugs. In went the Autolite 103's and on went the CAI.

I took the car for a ride and monitored the A/F and got on it... :headbang: Later in the day we went to Jeff's picnic only to have the car stall on me a few times when decelarating and also had a slight bucking under light throttle. I figured that the cause was forgetting to reset the battery. That night disconnected over night and life went on. Sat. was track day... and low and behold in the morning I had no issues at first... 15 minutes to the meeting place and still issues. I slapped the RAI back on Sunday night and guess what... still the same issue. Last night I pulled the plugs and all look perfect.

I've researched this but no one has really pin pointed it... tonight I will buy some electronic cleaner and clean the IAT and MAF sensors... what is weird is even though I took them off the RAI and on to the CAI, there was NO WAY I touched them.

Confusion...

Almost sounds exactly like a MAF, clean it up, and if that still doesn't work, just borrow someone else's MAF and put it on and see what the results are. I am 80% sure this issue sounds just like a bad MAF.

 

[Flatliner]

At this point I am surprised, you would think it would throw a code or something. End of the day I need to datalog to see if there is any voltage change or such.

 

[Jimy Bilmo]

At this point I am surprised, you would think it would throw a code or something. End of the day I need to datalog to see if there is any voltage change or such.

If it is bucking and stuttering a large amount, I too, am suprised!

Very awkward.

 

[Flyn]

You probably have an air leak somewhere in the intake between the MAF and the engine. Check all your tube connections, especially the bottom of the tube where it joins the MAF and where it joins the throttle body. Unmetered air will cause exactly the symptoms you are describing.

 

[01GTvert]

Bucking under light throttle input is more than likely a lean condition which is why the problem clears when you reset the computer. My car does the same thing just a lot more pronounced. My A/F at part throttle was off the charts lean (18-19/1 with ltfts @ +10 or higher) when it should be closer to stoich (14.7/1) and +/-5 on the fuel trims. Could be that CAI is leaning you some. Can you check your fuel trims at part throttle?

 

[Flatliner]

Bucking under light throttle input is more than likely a lean condition which is why the problem clears when you reset the computer. My car does the same thing just a lot more pronounced. My A/F at part throttle was off the charts lean (18-19/1 with ltfts @ +10 or higher) when it should be closer to stoich (14.7/1) and +/-5 on the fuel trims. Could be that CAI is leaning you some. Can you check your fuel trims at part throttle?

Shane mentioned this to me at the picnic... which put me into panic mode of course. When it continued I put the RAI on back on, FORGOT AGAIN TO RESET THE COMPUTER, and it did the same thing. So last night I reset the battery again, but the RAI is on it's way back to Tucker. The CAI will go back on today with a tune adjustment, just waiting for my Xcal 2 to arrive to finish up the datalogging to take a look at what is happening. I am pretty sure the tune adjustment should resolve the issue, but figured I would clean up the sensors as well. Thanks for the input! :biggthump