03 PAU Rough/high idle now

[Jfridge92]

So I don't usually work on this car because my dad is going through a rough patch money wise, but he finally has the money to do some much needed maintenance on his Park Avenue Ultra.

So here's what I've got lined up, especially from Ed's list:

LIM gaskets, Supercharger gasket, throttle body gasket, VC gaskets if they're seeping, new injector o-rings, metal coolant elbows, flushing the radiator, new T-stat, new plugs and wires, as well as checking any other gaskets for leaks (oil pan, etc).

I haven't worked on the SC motors much, is there anything really maintenance wise I should check for? Pretty much just rotor wear and any play in the coupler?

[nos4blood70]

Check for play in the coupler. Unless your father is hugely concerned about performance, a little rotor wear is okay.

[Jfridge92]

And coupler play is spinning motion on the pulley right (with the belt on)? Not in and out? I'm assuming there should be no in or out play?

[nos4blood70]

To check for coupler play you need to remove the belt, and turn the pulley by hand. You'll know right away if the coupler is bad.

[xcbullet]

Change oil in super charger, while it's off, takes two bottles. You would think they would sell it by the pint instead of 8 ounces. Over priced spindle oil most likely. Spindle oil can take more pressure compared to hydraulic.

[Jfridge92]

Alright, getting ready to order all of the parts for this. What's the consensus or preferred iridium plugs for the L67? I run tr55s, but my dad wants iridiums. Is it a myth that the iridiums will outlast the copper tr55s, especially since his car is by no means a performance car, just a grocery getter. I want to throw tr55s in it, but are the iridiums worth the extra $$?

[nos4blood70]

Iridiums last much longer than copper. I'm not too savvy on which are which, just make sure they are no colder than 1 step versus stock.

[Jfridge92]

So I did all of the work today. I got the plugs, lim, supercharger, tb, and valve cover gaskets swapped, as well as the oil pressure sending unit since that died last week. I got everything back together, and it ran great while I was there, then of course on the way home I get a call saying the check engine light keeps coming on hahaha. He's going to get it scanned tomorrow, so hopefully I just left a sensor unplugged haha.

[Jfridge92]

Well, Dad got it scanned this morning and it turns out the TPS went bad. Not really sure why, but maybe when he cleaned out the TB he didn't take the TPS out, and the TB cleaner might have killed it. Either way, he picked up a new sensor this morning, so hopefully that will take care of it

[nos4blood70]

At least that's an easy replacement.

[Jfridge92]

Agreed! He got the TPS replaced and said it's running better than ever, and for the first time will actually chirp the tires at takeoff haha. I haven't ever driven it too much, but from the condition of the gaskets and the way the plugs looked, I'd say it's been down on power for a good while.

[Jfridge92]

Alright. So dad said it's still setting the ses lights. He had it turned off at advance, but it came back 10 minutes later. He said the guy told him it was a wheel speed sensor setting it (his abs and trac lights are on) but would the speed sensor trip the ses light too? He's coming to my place tomorrow and I'll pull the actual code number then, but I didn't think the wss would set an ses light too?

[nos4blood70]

I haven't heard of that personally, but I guess we will find out when you pull the actual code.

[Jfridge92]

Alright so I pulled the codes, and after resetting everything the only code that keeps coming back is p0122 for tps low voltage. Obviously the tps was already replaced, and it could be a new bad sensor, but what else will trip that code?

[Jfridge92]

So maybe the 3rd time is the charm lol. Dad took the new TPS back to advance, and got them to give him a new one (lifetime warranty part) and said that when he put that one in, the SES went off as soon as he started it for the first time. So crossing our fingers that it doesn't come back again lol, but it sounds like he maybe have just gotten a bad TPS out of the box for the replacement.

[nos4blood70]

Doesn't seem completely out of the question, hopefully third time is the charm. Don't see what else could throw that code except some damaged wiring.

[Jfridge92]

Okay so this is starting to get crazy haha.

So dad changed the TPS out yesterday and it was running great, plenty of power and a smooth idle.

This morning he went to go to work, and texted me saying it was idling at like 2000+ rpm, and is idling really rough (no check engine light or flashing though). I can't get up there to see the car, but I have him checking the plug wires to make sure one didn't pop off of the plugs (they fit a bit loose, but did click when I put them on.

I'll have him check for vacuum leaks too, but it's just weird that this happened after the TPS was swapped to one that won't throw a code, yet when it is throwing the TPS code it runs great hahaha.

[95se]

if it is idling at 2000 rpms, no matter what the idle air curcuit is most likely dead heading itself inside of the throttle body causing high idle. if you can get your hands on a fsm for the car look up the wiring to the iac(idle air curcuit) and test it with a volt meter and see if voltage ranges while you give it gas and back down to idle. voltage should be anywhere from 1.0v to 5.0v and resistance should be anywhere from 7.0-13.0 for a gm iac. hope this will help you.

[Jfridge92]

Thanks, I'll see if I can track down that info and send it up to him to test the IAC. Apparently, when it was running super rough and idling high there was no SES light on. Then it threw an SES light and started running perfectly normal, so something is up causing it to revert to default tables in the PCM. I wish I lived closer to him to take a look myself, but hopefully he can find something. I'm leaning towards IAC now, even though it isn't throwing a code, because even if it was a vacuum leak that big it would run bad all the time rather than just some of the time, then running fine when it pops a code.

[nos4blood70]

The IAC is super easy to pop off, so just give it a look and see if the plunger moves freely.