What would cause the car to idle up to about 2000rpm when I pull up to a stop light ? It idles down after about 5 seconds. When I got the car it idled up to about 1500 rpm and dropped off pretty quick but the last few days it has started idleing up to about 2000 rpm and hangs there for a few seconds before dropping off.


Would a change in gas do this ? Chris was using 93 octane with 10% ethanol. I am useing 87 octane with octane booster added to the tank with no ethanol .

Thanks Rusty.

 

Pull your codes and post what you get. Let us know if you don't know how to do it or just do a Google search or YouTube search on how to. Pulling and posting codes is always a first step in seeing what may be going on. That is the nice feature of the C5.

 

Thank you for the response. I will google how to do it at lunch and post what codes I get.

 

Here are my codes.

U0128
U1301
U1016
U1096
U1255
U1064
B2282
B2283

Thanks for any insight into my problem.

 

That is a lot of communication hits. Let's clear/delete all these U an B codes and then take it for a drive. BEFORE you turn the car off, pull your codes again and let's see what comes up.

 

There is connection under the drivers seat that works loose from time to time. I am guessing that is where all the lose of communication came from. I cleared them all last night and took it for a short drive. No codes were displayed when I got home.

 

Unfortunately, I had thought that none would come back. On the bright side, maybe that indicates it is not a serious issue and hopefully is not hard to find. There were a couple that were PCM related but obviously they are old. I do not have any experience with C5 engine issues like this and the FSM addresses a number of problems but not this one.

With that said, I did some searching and found that similar issues (not identical) relate to the MAF and unmetered air, see below. If some experts don't chime in, I will PM a couple of them a link to this Thread and ask them to help out.

http://forums.corvetteforum.com/c5-t...clean-maf.html

Another Thread quote:
I am sure that you have already read above having a clean MAF sensor about also make sure the motor is no pulling un-metered air from a loose hose, IE, Throttle body air bridge or MAF connection. This can also cause the high idle condition you are describing. My 01 Z06 also did this after I inadvertently over tightened my air bride to throttle body hose after installing a SLP air bellow. It happened right after I started the car.

PS: In order to get as much info as possible, if you stop the idle GOES UP from wherever it was to 2000 rpm, correct? Also do you have a manual or automatic? Not sure that matters but more info is always better. Also, after it idles down, if you rev the engine does it do the same thing?

 

Here is what I know about the car. This is a question I posted on the Vengeance forum a week or so ago. The car is a manual transmission.

I will drive the car at lunch to see how it acts. If when I stop and rev it up if it will pick up in RPM before it drops off.


I recently purchased an 2001 C5 Corvette from one of your customers. I have had the car for a week now and have noticed a ticking noise coming from the right side of the engine . It has a Fast 90 intake , LS2 90mm Throttle body, Nasty Performance LSXR 102mm billet fuel rail kit , A Vengeance Custom Camshaft, Revised Comp 918 valve springs (.650 lift), Comp 7.400 hardened pushrods, Katech C5R timing chain and a Melling hi volume oil pump for LS engines . It also has full length headers with competition cats and Billy Boat exhaust. Thats all i know about it . Now my question is , in your opinion what is causing the ticking noise ?

 

For the 3rd paragraph in this Thread, I think you need to create a new Thread so it gets to the right people here on the Forum. The info is good to be here for your idle issue but others may not pick up on your ticking issue.

PS: Sounds like a nice performance setup, hope the ticking issue is not something too serious.

 

I talked to David at Vengeance about the ticking. He said it is nothing since he knew the the car and not to worry about it. I just copied that from where I posted in the vengeance forum. I guess I should have deleted the part about the ticking. I just anted to post what was done to the engine.

 

Since i cleared all my codes all has been good . Well for a few short drives . Today it started acting up again . When i push in the clutch the idle would go up to about 2000 RPM then drop off to 900RPM about 5 seconds after i come to a stop . I pulled my codes and got U1028 and U1096 today . I guess if i cant figure it out in a day or two i will take it to my dealer for service .

 

I'm sorry, i didn't pay attention to which ones the codes were under. I cleared the codes but will drive it tomorrow and make sure i post which the codes were listed under .

 

In regards to your idle question: Had the same problem as you, similar modifications as well. Took it to a tuner and he fixed her up. Several different tables, trims, etc had to be adjusted. This of course assuming you don't have a vacuum leak

 

I wish i knew where to take my car. This is my first Corvette and i am new to tuning and modding them. I live in Donalsonville Ga 39845 and don't know of any shops in my area to take it to other than a Chevy dealer. Tallahassee Fl is pretty close to me but don't find many speed shops online . Not to mention i am afraid if i take a chance on one they will not be competent . So if any one knows of shops close to me please tell me about them .

Thanks , Rusty

 

sounds like the problem is in the tune. I would take it back to the tuner

 

Worst possible choice...they won't have a clue how to handle your modded engine.

 

what type of octane booster are you running to get the octane level up high enough to avoid detonation?

 

I don't remember what kind it was . just something i picked up at the auto parts store. The reason i am running 87 octane non ethanol is i own a service station and don't carry 93 octane because it doesn't sell. Would i be better off running 93 octane E10 that is sold at the local convenience store ?

 

Took it for a short drive during lunch after clearing all codes. I return home and have 1 code 10-PCM P1028. I have googled the code but don't find it anywhere .

 

I found an explanation for the 1028 code. Says the water temp isn't at the thermastates operating temp. The car runs about 150 degrees when cruising at 65 mph.