ssheets

iTrader: (1)

Go get some vacuum line plugs and disconnect the PCV and Evap line and run with them plugged. This is what Jesse told me from day one and I finally got some plugs. I think my prob was the throttlebody, but if I were you I'd plug off thse vacuum lines and see what happens. Better yet, if you can unplug one at a time and plug it while its actually doing the high idle it might tell you if you found it? I'm not sure if it will take a few seconds to adjust out, but you should hear a change in idle immediately.

I bought new PCV hose to be safe too.

Mine seems to be fixed. I put the PCV hose back on and run for awhile and if all is well I'll put the evap line back on too. Process of elimination.

Good luck, and here's what I would do:

Check all intake manifold bolts and throttlebody bolts connections.
Disconnect and plug PCV and test run.
Disconnect Evap and plug Evap and test run.

It's got to be vacuum, that's what mine was and I chased it for a week!!!

Black98Z28

iTrader: (8)

Im pretty sure i fixed the problem.

PCV is not an issue since i have deleted it and put a breather on the valve cover.

The tranny was pretty low on fluid so i went to the store and got 2qts of ATF.

Talked to Jason at TSP and he told me to turn down the idle set screw all the way closed (mines inverted on the TB) and then turn the car on, this did not fix the problem.

I topped off the tranny with fluid and did the opposite on the idle set screw, i backed it out 4 turns from where it was closed and now she idles perfect, i drove her around the block, perfect, let her idle for a good 10mins, shut her off, went for a drive perfect.

Put about 10miles on the car. Im relieved that the problem is fixed, still unsure what the deal was lol. Thanks for the help guys.

Black98Z28

iTrader: (8)

Well I guess its not fixed.

I replaced the IAC/TPS/MAF/Temp Sending Unit on the driver side head and have checked everywhere for a vaacum leak. I am stumped.

I started the car yesterday and idled for about 25-30mins as I was detailing her, I had just replaced the Temp Sensor on the driver side head. I drove the car for 34miles and then all of a sudden the car started to pull and wouldnt go back down to idle, it stayed at 1500-2000.

If i put it in park or neutral it goes up to 3000rpm. I messed with the idle set screw and closed it completely, the car then rev'd up to 5000rpm and I shut it off right away, I turned the screw counter-clockwise about 3 full turns and the car turned on and idles right at 900. I started to drive away and it began to pull again but not nearly as bad, I came to a stop and the car was idling fine for a few seconds then jumped up to 1500 then back down to 900 then back up to 1500, did this about 6 times then just stuck at 1500.

So I decided to drive her home, well i put it in 1st just to see what would happen, the car engine brakes fine until it gets to about 1500rpm then it just stays there and wont slow down. I am really pissed off about this situation, could it be my tune or something?

ssheets

iTrader: (1)

Did you have your AC on or the defroster? Mine seems to be triggered by the AC being turned on.

Black98Z28

iTrader: (8)

No A/C in the car, and defroster never is turned on

ssheets

iTrader: (1)

Hmmm, good luck. I'm putting the intake back on right now. I'll keep scanning data and scratching my anatomy.

super_fro_daddy

iTrader: (29)

I dunno if you've checked the back of the intake, but on the passenger side there is some really small hose running to the back of the intake. It is barely on there. I think it forms a T and goes into the manifold and on to somewhere else. Mine kept sliding off when I changed intakes. It is unbelievably hard to get back on, but that could be causing it.

I know you just changed header gaskets, but all that moving around may have pulled one out.

ssheets

iTrader: (1)

In my case, checked, double checked and now triple checked. I also pulled a vacuum on it and it held for minutes. I can't run the AC through it's paces, but it passes a static test.

Black98Z28

iTrader: (8)

Car just threw some codes, about to get the car scanned here in the next 30mins or so.

Black98Z28

iTrader: (8)

P0507 Idle Control System is what the car showed, what causes this?

colamotas

P0507- Idle control system, RPM higher than expected

Black98Z28

iTrader: (8)

What causes it? Vacuum leak? Sensor? Electrical?

ssheets

iTrader: (1)

Mine throws that too. If the motor runs at high RPM at 0% throttle it throws the codes. I don't know the exact RPM off the top of my head, but that's just the computer's way of telling you what you already know. Unforetuntely in this case it's only cause and not effect.

I scanned mine tonight and got an interesting log. After I reassembled the intake I started the car, let it warm up and then turned on the AC. My IAC count went through the roof to 310 and sure enough my idle went up past 2,800RPM.

I'm about 100% positive I DO NOT have a vacuum leak. I don't what RPM an IAC step count of 310 equates to, but I can see it happening on the log files.

Here's a screenshot and I've attached a log file for any EFILove users.

Black98Z28

iTrader: (8)

Well after deleting the code I went outside to check on the Intake Manifold, to my surprise every bolt was loose. I tightened them all down, and checked the vacuum lines behind the manifold, they were sturdy.

So I went for a drive, I went 23 miles and I had a scanner on the car to view the data this is what I got at idle

RPM 879-930
Load% 4.3-4.7
MAF(LB/M) 1.4-1.57
MAP 13.3-13.9
TPS% 0.4
Coolant 178 Degrees
IAT Temp 70 Degrees
IGN ADV 25.0-28.0

The car doesnt even hang anymore, every stop light I came up to tonight, I had to have atleast hit 9-10, the car idled perfect and didnt pull as I was driving. I checked for any current/pending errors and none came up.

ssheets

iTrader: (1)

Well I hope you got it...not to sound like a pesimist, but I thought I did the same thing. I checked my throttlebody bolts and they were a little loose. I tightened them up and the car ran great for days...and then high idle again. I've just about taken everything off the top of the motor in the last month. Jesse at wait4me told me to buy EFILive to track down the prblem so I did...and I am. I hope yours was air leaking around the mainfold. Good luck.

Black98Z28

iTrader: (8)

I really hope so too.

I dont drive the car that often especially now since its winter. Hopefully I dont have to deal with this issue come spring time. I will keep this thread updated, hopefully you can track down your issue!

ssheets

iTrader: (1)

Yea same here. It was snowing today as I worked on it in the shop with the heater and games on. My car is an 02 and just broke 10k miles. At first it was very intermitant and I was just chasing gremins, but I feel like I"m starting to track it down now...at least now I can reproduce it by turning on the AC and I can see it change the IAC steps on the log files. I just wish I knew something about tuning so I could actually understand the log files. Well this is how we learn.

FreByrd

iTrader: (1)

Fixed my prob too, car ran great in summer then came winter and every cold morning on 1st startup it would immediately shoot up to 3krpm then come down and die. Repeat that for about 5-6 times and slowly it would hold idle but run really rough, once it warmed up the idle would hold and smooth out. FINALLY fixed it, intake manifold bolts were not torqued enough. I must have sprayed 3 cans of carb cleaner all over the engine trying to find a leak and nothing, that method failed.

So its been 2 cold morning starts and the car is just fine, no probs at all.

Having autotap definitely helped as well.

Black98Z28

iTrader: (8)

Awesome looks like you found your problem, I sprayed starting fluid all over that motor and I couldn't find the leak either. I really hope that was the problem, It makes sense now how that could have been the problem this whole time and I didnt realize it until yesterday.

I had swapped header gaskets because the stock ones had blown and were leaking pretty badly, well after swapping gaskets, now that there was no leak it obviously had to go somewhere, and had pushed up on the manifold which was leaking out the sides.

Black98Z28

iTrader: (8)

Drove the car quite a bit between the past 2 days, put 96 miles on her and she hasnt acted up yet. Hopefully that was the problem.