mmarsh3014

I just noticed this started happening on Saturday afternoon. When I'm cruising around 40mph or more and shift into neutral to slow down, the idle rolls down to 400 RPM and back to 900 about 3 or 4 times before settling at about 800 when coming to a complete stop.

After my initial confusion of what could cause that, I reloaded my Brenspeed 93oct tune. This tune has been flawless for the past 13 or so months that it's been installed, so I doubt it's the problem.

Anyhow, this morning on the way to work, im doing about 85mph on the highway and I got out of 5th and into neutral while I approached my exit. Next thing I knew, my lights dim and my blower motor slows from my RPM drop. I downshifted into 3rd while coming down past 50 to keep my RPMs up as I continued onto my exit ramp.

What would suddenly cause a rolling idle only on deceleration on a mostly stock car with 11,000 miles? The last thing I want is for the dealer to tell me I ****ed it up by putting in an aftermarket tune. I'm confident that's not the problem. But to them, anything that differs from OEM is wrong. Thanks for any imput

top00cat

check your throttle body. sometimes they get dirty and cause irratic idle. It could also be a vac leak but I doubt that being that you have not taken any hoses apart lately

Nuke

+1

I'd start with cleaning the MAF and TB plus replace the fuel filter. plus check all the intake hose clamps. If it persists (or maybe even do this first), reload the stock tune and install the stock airbox to at least rule out the tune.

Red Beast

id suspect the TB, i was having problems with an inconsitant neutral. i took off my air intake and inspected my TB, cleaned around it carefully. put it back on and it got alot more severe for a min then leveled off to a regular idle position.

top00cat

let us know how it works out

mmarsh3014

Thanks for the ideas guys. I'll check everything out on Saturday and post what I find.

Question: If I take the throttle body off to clean, is there a paper gasket or an o-ring behind it? I don't want to take it off and risk tearing the paper without having a back up.

Blacksmoke

Here ya go...
http://www.brenspeed.com/tech.html

DO NOT use a Carb cleaner despite what some
people say!!! Our TB's have a protective coating that
Carb cleaner will eat off.

Use CRC throttle body cleaner for the
TB and use CRC MAF for the MAF.

mmarsh3014

Well guys, I feel like a dumbass. It was as easy as popping the hood to find my C&L intake tube disconnected at the TB coupler. I suppose I tightened it down too far when I installed it a year ago and it finally vibrated out. No big deal, easy fix. But thanks for all the quick responses. I guess next time a simple visual inspection under the hood would be appropriate before going ahead and assuming the worst.

Nuke

I'm VERY surprised that you didn't throw a CEL. And maybe even MORE surprised that this is the first time you've popped the hood since reporting the problem.

Anyways, glad it was something simple. And I'm thankful that there are other dumbass's out there to keep the REST of us company.

mmarsh3014

lol Thanks Nuke. I am very good at overlooking the obvious