87 n/a bouncing idle
 

I cannot figure out why I have a bouncing idle. I have replaced the lim gasket and the mid gasket. The lower was a paper gasket and I replaced it with a MLS gasket. I removed the rats nest. But it's still doing the same slow buncey regardless of what rpm it's at. It accelerates clean and only bounces when trying to maintain a certain rpm. I can get the 5/6 ports to open by reving the engine in neutral so I'm thinking I may have a partially clogged cat. Does anyone have any thoughts on this.....I'm ripping my hair out in frustration.

tps?

Yea. . I'd check the TPS voltage. . . Make sure the idle adjustment screw is set right while adjusting the TPS voltage. .The idle adjustment screw shouldn't be all the way in, or all the way out, to get it to idle.. . . . .

I'd also change the water temp sensor behind the alternator simply because it's so cheap and by doing so you can take bad temp sensing out of the equation.

The field service manual has the procedure in it.

The idle screw does nothing at all when I screw it in or out. I did set the tps to 1v but changes nothing. I will replace the temp sensor.
I also checked the tps for a clean sweep up to 5v which it does have.

bouncing idle is usually an indication of a vacuume leak. Could be something as small as a cracked vac cap. Have you tried the "spray starter fuild everywhere" trick to check for leaks? Or if you have access to one, a smoke machine is great for finding tiny leaks. Not sure if a small leak would cause bouncing at higher RPM thought, either way, it's good to eliminate this possability.

Replaced temp sensor under alt and now it won't idle so I'm gonna try and adjust it. But here's a video of what it's doing.

Have you checked the AFM? A lot of times if it goes bad (which is rare. Most likely a wiring fault if it's an AFM related issue) it will cause some odd issues. Try checking it per the FSM. Check the harness as well. Make sure your voltage and grounds are good

Also when attempting to adjust idle, do it per the FSM. You need to jumper the initial set coupler (green 2 prong connector by leading coil) when doing idle adjustment.


Edit: try checking and cleaning the ECU ground as well. Can cause all sorts of weird issues.

Ok I checked grounds . One thing I forgot to mention if it makes a difference is when I start it up no matter if it's in gear or not it revs to 6k and sits there...I know it's only supposed to be 3k.

Really sounds like a vac leak. Have you smoke tested it?

Ok well today I did a lot. It got smoke tested and found no leaks. Did a fuel pressure test and with regulator unplugged its at 39psi with it plugged in its at 36psi. Sprayed starter fluid into airbox and idle cleans up and idles correctly. Pulled injectors out and tested them. all tested good ohms wise but when we did a spray pattern test the primaries were a solid stream and secondaries were sort of a fanned out spray. so we back flushed them and they got better. Checked spark plugs and found out that the last owner put four trailing plugs bur9eq in both leading and trailing.
I installed bur9eq and bur7eq in proper location.

After all this it still runs exactly the same way as the video I posted.

Whenever I have a bouncing idle it is because of a mis-alignment between the TPS, idle adjustment screw and temperature sensor during warm up.

Make sure the idle adjustment screw is not all the way in or all the way out to get it to idle.. . . it should be in the middle

If you changed the temp sensor and it is acting differently now, that is a good thing.. . . Assuming the new sensor is acting like it should.

Other things to look at is the AWS linkage and thermowax valve linkage.. . .They both effect air flow if the car thinks it's cold.

Another thing to try is letting it get to temp with the new temp sensor and then doing the initial set coupler. . . .Throw it into open loop and follow the instructions per the FSM on how to set the idle. . .. . . Only do this if you are sure of no vacuum leaks and a good AFM. .. . .Usually the adjustable resistor doesn't play a role here but it might be good to check it.

Well I figured it out....it was a combination between the wax pellet being bad and improperly adjusted secondary throttle plate set screw.