Idle issues after plenum pull.

[prophetickai]

As mentioned in the post title, I performed a plenum pull. I replaced my spark plug guide seals, made sure all my fuel lines were in good shape, and just generally ensured all my vacuum, water, and fuel lines were in good condition. After putting my plenum back on, I had a nice little rpm bounce. This had happened to me in the past, but was usually only a high or low idle. Which usually after a few test drives and minor adjustments to my idle screw, it would go away. However, this time is not the case. I'll start with my attempts to fix and list the occurrences after.

1st, as always with a bouncing idle, I thought of the TPS sensor. If I move mine, even in the slightest, it jumps instantly to around 4-5k and stays there until I adjust it back, even if I move my idle screw on the throttle body or if I move the one towards the back of the plenum. However, a small side note that suggests to me that something else is wrong - Since I bought my Z, the TPS sensor has been maxed as far as it can turn to its most clockwise position.

2nd, I tried my cas sensor to see if I could at least stabilize the bouncing idle. Another side note, same as my TPS sensor, this is maxed to its most clockwise position. Turning it counterclockwise only made the pause between revs shorter.

3rd, I took it on a quick test drive to get an idea of any other problems that might give me a clue where to start. IF I'm in 1st, the car jumps with every rev of the engine until around 3-4k rpm, then it drives normal. Any other gear, no such issue. HOWEVER, if doing normal highway speeds (55mph where I am) and I let off the gas pedal, it runs and idles smoothly under its own power, as it normally would. But if I press the gas pedal during that point, it hesitates almost like a cylinder is down. If I push in the clutch and it goes back to 'neutral' the rev still occurs.

4th, Thinking perhaps when reconnecting the wiring harness I had accidentally somehow plugged a connector into another by mistake and not its correct place, I double checked to make sure my O2 sensors, VTC solenoids, coil packs, and everything else I could visibly see a color coded wire was in the correct spot and made sure the connection was not loose.

Needless to say, my issue is still present and I'm currently too frustrated to think of anything I might have overlooked.

I did however take a small video of the idle jump, and can take pictures or videos of anything else anyone can think of that might help.

http://www.youtube.com/watch?v=gYtHQmax-ew

[prophetickai]

And here is one driving down the road, be forewarned there is much change and rattling interior pieces which normally you can't hear thanks to the stereo system :P Also, camera is shaky due to having someone hold the camera as I drove and him having to hold his arm above mine as I shifted…

http://www.youtube.com/watch?v=XTvmFP9eZtk

[Retro-Cow]

Read through these pages if you haven't already.

http://home.swipnet.se/e-solutions/IdleTech.html
http://home.swipnet.se/e-solutions/IdleTech2.html

Make sure you adjust the TPS to the voltage specs as well.
I know after my plenum pull my idle was extremely high and wouldn't adjust with the screw, took me a while to find out what was happening, turns out my buddy overtightened the throttle cable.
Doesn't explain your bouncing but you may want to look at it and the cruise control cable just in case.
Other than that I hope those links help you out.
Good luck!

[prophetickai]

I know my throttle cable has given me issues before. Would you happen to have a picture or diagram of how it should actually be routed? I checked the voltage specs on the TPS and it is in spec, but I still have a new one en route anyways.(Simply because I don't like how if I barely nudge it, it instantly goes out of whack.)

[t.mcginley.jr]

When you say barely nudge it, do you mean touching the TPS itself? or if you nudge the gas pedal?

As for the throttle cables, you can see how they are routed from these pics:





The main throttle cable attached to the gas pedal runs out of the firewall by the brake booster, goes through a little black bracket/holder on the driver side of the intake plenum, then through another little holder closer to the balance tube, then under the throttle cover and onto the actual throttle linkage that you can see in the 2nd pic. The other cable is just for the cruise control, it runs from the cruise control actuator to the other part of the throttle linkage.

[prophetickai]

If I move the TPS sensor itself. As in less than a millimeter adjustment and it instantly revs up to around 4k and stays until I adjust it to the exact spot it was before. And I'll definitely have to move my throttle cable back to the spot it was originally intended. Since I've owned the car it has always been under the balance tube and I never really had any issues out of it, but its one more thing to cross off of the list of things that could possibly have any issues relating to or in conjunction with my current ones.

[Z-owned]

Which spark plugs you running and have they been checked for proper gap? There is a little more to adjusting idle on the iacv then just turning the screw the aac connector needs to be unplugged first. Something i have seen happen a few times with plenum pulls is when it's put back on people pinch the wire for the det sensor at the back side of the plenum causing it to not seal properly on the plenum gasket. Main concern i saw from reading your post is the cas not being near the center of adjustment, this is typically a sign of the timing belt being off a tooth and everything else has been retarded to compensate.

[prophetickai]

Running NGK's, and I verified the gap already. I finally got some time off work and got to spend a few minutes under the hood and found that I've got an air leak from the plenum. My assumption is either the gasket bunched up or I pinched the stupid det sensor like you said. I don't have a timing base cover behind my crank pulley because mine was bent and ripped from the previous owner. I'm pretty sure he used a crowbar or something stupid instead of getting a pulley puller to remove the crank pulley at some point. I've been looking for a new one for about a year and a half, but it seems no one sells them, or at least I've not been able to find it yet. Perhaps i'm searching under the incorrect item name. I've been pretty sure it was a tooth off judging by how my cas and tps sensor were so far out of whack. I'm just glad I have the wife's car to get back and forth, otherwise I'd be up the creek. If anyone has any idea as to where I can get a timing base plate, I'd greatly appreciate it. I plan on buying a timing kit since I have no clue when it was last done and going ahead and doing some overdue maintenance. She was badly neglected by her previous owner and I've been sorting all kinds of electrical bugs and issues since I've bought it. I think I've probably put around 500 miles on her in the almost two years I've had her, mainly because I don't want to push her too far until I know exactly how well together she's held up under the lower plenum and heads :P