C5 idle surge from a newbie
#1
10-01-2007, 10:53 PM
C5 idle surge from a newbie
Hi. I am brand-new to this forum. Purchased a rather nicely modified 1999 C5 a few months ago and have been in love ever since.
I realize that if I actually took the time to really search and dig through this forum I would find the answer to my question, but I thought I would take a moment to both introduce myself and to ask a question to all the members of this forum who know their...well..."stuff".
I encountered my first problem with my car today. It involves idle surging. When I shift into neutral to coast or come to a complete stop in neutral the car often times starts to "surge". The idle dips as low as 400-500RPM and then kicks up to about 900-1000RPM only to repeat the cycle several times. At first I wasn't overly concerned, but today, for the first time, the car actually stalled during a surge. The problem has only been occuring for a couple days.
By the way, my car is a 1999 C5 coupe. It has an ATI Procharger, a Lingenfelter intake, a Nitrous Express NXL Direct Port Nitrous System (not currently hooked up), JBA headers, a Magna Flow exhaust system and lord only knows what else.
I'd really appreciate any input any of you C5 veterans might have in helping me diagnose my first (of hopefully few) problem.
Thanks in advance!
By the way, if any of y'all are located anywhere near Birmingham, AL, please let me know.
I realize that if I actually took the time to really search and dig through this forum I would find the answer to my question, but I thought I would take a moment to both introduce myself and to ask a question to all the members of this forum who know their...well..."stuff".
I encountered my first problem with my car today. It involves idle surging. When I shift into neutral to coast or come to a complete stop in neutral the car often times starts to "surge". The idle dips as low as 400-500RPM and then kicks up to about 900-1000RPM only to repeat the cycle several times. At first I wasn't overly concerned, but today, for the first time, the car actually stalled during a surge. The problem has only been occuring for a couple days.
By the way, my car is a 1999 C5 coupe. It has an ATI Procharger, a Lingenfelter intake, a Nitrous Express NXL Direct Port Nitrous System (not currently hooked up), JBA headers, a Magna Flow exhaust system and lord only knows what else.
I'd really appreciate any input any of you C5 veterans might have in helping me diagnose my first (of hopefully few) problem.
Thanks in advance!
By the way, if any of y'all are located anywhere near Birmingham, AL, please let me know.
#2
10-01-2007, 11:22 PM
RE: C5 idle surge from a newbie
Here is a post about this very thing. Hope it helps
Here's the thread https://www.corvetteforums.com/m_19986/tm.htm
It's for a C4 but the systems are similar
Here's the thread https://www.corvetteforums.com/m_19986/tm.htm
It's for a C4 but the systems are similar
ORIGINAL: mech259
Surging or "hunting for an idle" is usually caused by carboned throttle plates and bore. Clean the bore and the back side of the plates with carb spray and a brush by having someone step on the throttle and holding it wide open while you spray and clean. Then reinstall MAF duct. Then disconnect your battery for about a minute so the computer can relearn idle posistion. Start car and go drive it for 3 or 4 miles in stop and go to relearn. [8D]
Surging or "hunting for an idle" is usually caused by carboned throttle plates and bore. Clean the bore and the back side of the plates with carb spray and a brush by having someone step on the throttle and holding it wide open while you spray and clean. Then reinstall MAF duct. Then disconnect your battery for about a minute so the computer can relearn idle posistion. Start car and go drive it for 3 or 4 miles in stop and go to relearn. [8D]
#3
10-02-2007, 09:01 PM
RE: C5 idle surge from a newbie
Thanks,
I'll give it a shot. I noticed that the idle surge is not an issue until the engine is warm. Cold starts are no problem. But after driving in the highway for 30 minutes and then hitting city traffic, the idle dips as low as 400 and then surges to about 700 and then back to 400 and so on and so forth. It isn't all the time. In fact, on my drive home today, it acted up a little but on a few occasions, it idled fairly steadily at about 750RPM with no surge. But for the most part, when it is warm and I hit stop-and-go traffic, it surges and on at least two occasions it actually stalled.
I will attempt to clean the Throttle Body tomorrow and see if I see an improvement.
Thanks very much for your advice!
I'll give it a shot. I noticed that the idle surge is not an issue until the engine is warm. Cold starts are no problem. But after driving in the highway for 30 minutes and then hitting city traffic, the idle dips as low as 400 and then surges to about 700 and then back to 400 and so on and so forth. It isn't all the time. In fact, on my drive home today, it acted up a little but on a few occasions, it idled fairly steadily at about 750RPM with no surge. But for the most part, when it is warm and I hit stop-and-go traffic, it surges and on at least two occasions it actually stalled.
I will attempt to clean the Throttle Body tomorrow and see if I see an improvement.
Thanks very much for your advice!
#4
10-02-2007, 09:15 PM
RE: C5 idle surge from a newbie
You might have a vacuum leak. This will cause even a lawnmower to have loping idle. The original plastic intake will flex with the block, but the aftermarket intakemight have to be re-torqued a few times...
Direct PORT nitrous? Are the ports plugged??? If they're suckin' air, you'll get a lope.
Direct PORT nitrous? Are the ports plugged??? If they're suckin' air, you'll get a lope.
Thread
Thread Starter
Forum
Replies
Last Post
