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changed throttle body, now idling at 2,000 RPM??

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12K views 30 replies 14 participants last post by  user unknown  
M
#1 ·
Hey guys, this is my first time actually posting on this forum, although I do come here whenever I come across a problem. So I was throwing an engine code that pointed to the throttle body sensor. I ordered and changed out the whole throttle body and sensor, as it was only a few bucks more than the sensor itself. On the first test drive, I noticed it had a hard time idling back down. When I stopped at a light, it was idling right about 1200rpm. When I stopped and shifted into park, it went from 1200rpm all the way up to about 2000-2100 rpm and just sat there. If I shift into a gear, it drops back down, but then back to park, then right back to 2000 rpm. Would this have anything to do with the mass air flow sensor? Or possibly a broken wire? as I did notice the wires connected to the throttle body sensor were warm after that test drive.

any help is greatly appreciated!
 
M
#5 ·
some more background:

This started as I was driving I noticed the rpm would fluctuate as I was driving, it would jump 200-400 rpm then back down below where it should be, then back up. I dont remember the code # as I didnt write it down when I got home
 
#6 ·
Throttle learn procedure:
  • Start and idle the engine in PARK for 3 minutes.
  • The ECM will start to learn the new idle cells and Desired RPM should start to decrease.
  • Ignition OFF for 60 seconds.
  • Start and idle the engine in PARK for 3 minutes.
  • After the 3 minute run time the engine should be idling normal.
 
M
#7 ·
I went out and tried this, 3 minutes on at good idle. 60 seconds off, then another 3 minutes at good idle. Once the engine warms up, idle goes right back to 2000 rpm. I am baffled as to what would make it idle like this...
 
#13 ·
hi im having the same issue, 2010 impala lt 3.5l ffv just changed out my whole throttle body maybe an 1hr ago previously acceleration was sluggish was jerky, idle was bouncing between the 0 and lets say 850 rpms when at a stop and about 40 or 50rpms idling after warming up from cold start, when driving/acellerating rpms would jitter from 1-250k did the whole negative and positive terminals from the battery on off 60 second 30 second thing, rpms slowly crept to 2k rpms and stayed, so i drove it and when i let off the gas it didn't decelerate.
 
#14 ·
July 18, 2021

My 2011 Impala's been babied and maintained very well. Needing exhaust and brake work before getting this years Inspection Sticker; I let my son and his hot-rodding buddies save me some dough. They outfitted me with new powder-coated calipers and vented aluminum rotor binders and a stainless Cat-back system which cost far less than galvanized sheet metal pieces MIDAS™ wanted nearly a Grand to hang and clamp on my Chevy.
The stainless Cat-back system is from North East Stainless out of New Jersey. It's a single resonator and muffler kit that bolted-on without fuss.
Although not considered a performance mod; the Chevy's running better and a hell of a lot quieter than she did with the stock exhaust. I doubt the Cat-back's got anything to do with the issue bugging me.
One warmed-up good the RPM's hover at 12 to 15 hundred.
The Throttle Body's been cleaned and inspected several times. A Marine recruit would be proud to hand it to his Drill Instructor.
No Codes.
No pending.
No Air leaks.
Just this high idle situation we can't seem to bring down after everybody wants to blame on exhaust work.

What am I over-looking?

Rick Massey
Boston
73 years old and still wrenching!
 
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#22 ·
I just cleared the codes. I had it disconnected from the battery for a couple days while I was doing other work. I started it up before even attaching the Tech2 and it initially idled fine then it did the sine-wave surge again. I attached the Tech 2 and it was fine. Very odd.
 
#23 ·
Well crap. The car is doing the oddball idle again. I should note that the car has not physically moved since I cleaned the throttle body and installed the plugs. I have went over everything 3x to make sure I didn’t leave something unplugged. I checked the air filter components to make sure there are no cracks. I suppose I’ll light up a cigar and see if there is some sort of intake leak I’m missing. When I push the gas pedal in to at least 1k rpm’s it stops but anytime it goes back down to idle it varies from 550 to 800 or so in a rhythmic pattern. Tomorrow morning I’ll take this for a rip on the expressway and see if an Italian tuneup fixes the issue.
 
J
#24 ·
The answer to the problem is the speed sensor on the passenger side the wiring connector, the wiring loom that has thermal tape wrapped all around. Unravel it and follow it. You will find that alot of wiring harnesses have been affected l. Causing multiple electrical issues. Repair these oroblems and the issue will go away.
 
#25 ·
The post is 2+ years ago. I'm thinking he solved it. My first guess would have been a vacuum line was left off. Maybe he will chime-in.
 
J
#26 ·
I know but there are people who view these post regardless of how old they are. My post was to help anyone reviewing or scrolling through forums trying to figure out how to fix the problem. For me, my car had identical symptoms. The speed sensor, wiring and connectors were the problem. Once all those issues were resolved the problem went away. Hopefully it helps anyone else this problem.
 
J
#29 ·
I had all the issues that are posted on this thread. The solution for me was the speed sensor and the surrounding hiring looms that are covered in thermal tape. The wires were covered in power steering fluid. The wiring eventually became exopsed. And i started getting different types of electrical problems over a long period of time. Eventually when i replaced the throttle body, my car began to over rpm and when driving without pressing on the gas pedal the car wouls accelerate on its own. You most likely have a wiring issue snd not a vacuum issue as most would suggest
 
#31 ·
trailbrake_ss said:
Is there a throttle learn procedure with a scan tool?
Click to expand...
Yes there is; I own a Tech 2 and I ran the procedure with no resolution to the issue.

jerrymacias2000 said:
Keep in mind i talikng about the speed sensor located on the passenger side close to the cv axle joint. Not the abs speed sensor on the wheel hub
Click to expand...
The next time I do maintenance on the car I will definitely search for this!
 
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