Diagnosis to a weird idle on t2
 

87 t2 bone stock with a ported wastegate.

First off, when I start the car in the morning it does its usual high idle to 2k rpms and slowly back down to 1.5. Problem is as it warms up it goes up to 2k rpms, and not down to 750 like it should. Funny thing is though sometimes when I start the car when its warmed up the idle will go up to 2k like it should but drop back down to the original 750. Is this a sign of a faulty tps? Or as simple as adjusting the idle? Personally I dont think its the idle adjustment, because like I said it sometimes idles properly but its not very often.

Wax pellet
 

Started my 87 t2 stock with ported wastegate earlier after driving home from work and it barely started, had to pump the gas to get her going but once it started it idled warm at 1k rpms. Weeeeeeeeeeird!! Initially the car starts its warm up from 1.5k rpms like it should then rises to 2k rpms instead of going down to 750 rpms. Is this a faulty tps?

Probably TPS, or a vac leak.

and your bump has been deleted... bumps are forbidden here in the 2nd gen technical section

+1 for vacuum leak, these are the most common "all of a sudden" failures, one of the dry rotted hoses cracks off.

Wax pellet
 

First off. I have an 87 t2 that when started cold the idle increases from 1.5k rpms up to 2k rpms. After a drive the idle will pulse from 1.5k rpms to lets say 1.8k rpms. Would this be a wax pellet issue?

Anyone with a detailed description on where it's located and how to take it off? I got quoted at a local rx7 shop $90 for the pellet and $200-$250 for labour. If I can avoid it I would rather just do it myself and save $200.

Didn't catch the idle on surge, but here's the only video I have of the idle.

http://www.youtube.com/watch?v=N14ibIwHHas

(I have made about 4 threads regarding this issue and no responses.)

No, your TPS is out of adjustment.

The throttle body thermowax only keeps the throttle open to around 1500 rpm and that drops as the engine warms. It will never pulsate.

Your TPS is out of adjustment.

and your multiple threads, that have already been answered but you ignored that answer, have been merged into this one. Of course it seems like your symptoms have changed as well, since before the idle only went up and now you say it surges...

Did you ever check for vac leaks? I doubt it.

Is your interior really that quiet??? If it is, you are a lucky bastard. :)

You the man batman.

First off, when the car warms up it increases from 1500 rpms to 2100 rpms. Clearly wax pellet now that you mentioned that. The engine started to pulsate because I adjusted the tps. I read to adjust it to 1ohm, then read further after finding out it didn't idle to smoothly at 1ohm, that the tps should be set at 1v. Didn't check for vac leaks yet.

Went to a 7 shop to get the wax pellet checked out. Conclusion was the cam wasn't lifting so he lifted it up and it idled like new. So he asked me if I still want a new wax pellet or to see how the pellet behaves during a cold start up. Later on that day I cold started the car, came back the cars ideling at 1500 rpms. Took it for a drive still at 1500 rpms, further driving dropped to 1200 rpms and seen it at 750 once. Looks like I need a new pellet.

Car is now back to pulsating after a drive and ideling at 2k rpms sometimes sitting at 1.5k rpms. When I was at the rotary shop, he checked the tps and it was set right.

You gotta love the support im getting. Rx7 mechanic isnt exactly sure if its wax pellet, no one here is responding. I might as well go tell the wall how my car is running.

More likely than not the water passage to the water thermowax is clogged or the feed hose is blocked or the outlet hose is blocked or one or both are not connected to the throttle body.

Remove throttle body. Make sure both hose were connected to the throttle body. Remove the water thermowax. Clean the passage on the throttle body. Reassy.

Pour a pot of boiling water into one of the water passages. See if the piston moves outward as you do that. If it does, then put the throttle body back on. It's fixed.

Or the sucker could be out of adjustment. See the free, online FSM for rigging it.

P.S. the TPS could not have been rigged right if the fast idle cam had not fallen off the roll pin. See FSM for location of roll pin and fast idle cam.

^^ There's the information I'm looking for, thanks alot man! Nothing like saving $300 and doing it yourself.

If the outlet hose or feed hose are blocked, how would I safely clean it? I have never been inside of the throttle body but shouldn't be to hard.

Go to the BAC. Remove the aft water line attached to it. Blow in the HOSE, back toward the throttle body. Blow hard. After about fifteen seconds or so, water should flow from the other hose attached to the BAC. If that happens, then the water feed line / return line are not blocked.

If that is the case, I'd try adjusting the water thermowax device per the Fuel and Emissons seciton of the manual.

Or, and I've never done this, get a tea pot of boiling water. Have the intecooler off, Now slowly pour the boiling water in the hose and watch the piston on the water thermowax extend or not extend. That should give you a clue without removing the throttle body.

IF the water return line is not attached to the BAC, as in having been removed, then reattach both water lines to the throttle body. One on top goes to the fitting on the side of the BAC. The feed line is at the bottom of the throttle body.

^ Will do that tomorrow.

This is a weird symptom right here.

Today when I left work the car was doing its old 2k rpm idle, got home shut it off. A couple hours later I started the car up, the car was ideling at 1.5k rpms with a bit of heat in it and went for a drive. About an hour later I started the car up again and the temp gauge was just a touch above cold. AND IT WAS IDELING AT 750!! WTF!! Drove it for a bit and went for a cruise cause I was so damn excited to see it behaving, even though I knew in the morning it wouldn't be the same. After some driving the idle was around 1200 rpms.

Is 25 degrees celcius fully warmed up?

It might be the heat of the engine bay finally got the thermowax hot enough to expand and shove the cam off the roller. Or it might be another thing altogether.

It could be the previous owner capped off the water hoses to the throttle body. That' a thought.

The boiling water in the hose on top of the throttle body might not work since there might not be enough flow thru the throttle body. Never hurt to try though.

Still haven't worked this problem out. Usually now in the morning the car is ideling at 2k rpm warm. When I go for a drive it lowers down to 1.5k rpms and pulses. Longer drive and the pulse may disappear and it idles at 1.5k rpms. Shut the car off for 20 mins lets say, and the car idles at 750 rpms....

Skipped a few lines posted...but some of the above is dead on.

I put my money (well, your money if you pay a mechanic) on the fast idle cam not disengaging and you adjusted the TPS with the plates a bit open. I use a flat head screwdriver to push down on the lever the wax pellet pushes. You'll see the throttle plates closing a tiny bit further. Then adjust TPS.

When I push down on the fast idle cam off of the cam roller it just goes back to sitting on the roller. I have adjusted the screw that sits ontop of the wax pellet and the pellet doesnt follow, it's like its seized.

Well. The piston only moves when the water gets hot. You've got that a bit backwards. The PISTON of the thermowax moves the screw and what else the screw is attached to. The screw does not move the piston of the thermowax. Only heat or hot water will make the piston move out from its housing, which in turn moves the screw and all the linkage attached to that screw.

Try this. The screw on top of the piston. Turn the screw all the way clockwise or all the way in. Then the cam and roller should have seperated. Try to remember how many turns you had to turn the screw til it bottomed out so you can return to the original setting if you want to.

Does this throttle body have the water hose going to it? One on top and the one on the bottom really can't be seen. Just check the one on top.

Actually if you do what I say above, then on a cold start the rpm will sort of fall on its face and maybe the engine will die. Until the engine gets hot you'd have to feather the throttle to keep it running. Once hot the rpms would settle to normal 750-800 rpms....depending.

Two jpg attached. One with the wax at room temp, the other having boiling water poured over it. See the piston extension. It is ohly a .100" more, but enough to move the cam from being on the last hash mark cold to moving off the roll pin completly when hot.

Is a s5 wax pellet any different looking then the s4? Because from that picture that looks nothing like my s4 wax pellet. I don't see the cam roller or fast idle cam.

I was just outside testing the tps, it was at .659ohm so i set that back up to 1ohm. Hopefully that will fix my surge.

In my last post, I stated that when the car is driven for a while then shut off and restarted it idles at 750. Well I just checked how the wax pellet behaves when it idles at 750 rpm, and the fast idle cam is still sitting on the cam roller. In theory you would think with the engine idleing at 750rpm the cam would be off the roller. :Wconfused

I also tested if the water lines are blocked off, and they are open.

Haven't done the part Hailers mentioned where you poor boiling water into a hose. Don't really know which hose you meant? I took it as the hose at the rear of the firewall coming from the intercooler. But that doesn't sound right.

That IS a 1987 Turbo throttle body. View looking from the aft side

Just get a teapot full of Boiling water and pour it over the exterior of the thermowax/piston. It'll expand and kick the cam off the roller.

Back from the dead.

Currently having an issue with the idle surge, goes from 1500-1700(approx). It idled great before I put in new injectors and cleaned the TB up. By bypassing the TB with the coolant, will this be the cause for the surge? I did change a few of the dried old Vaccum lines as needed. I have since checked the TPS reading and adjusted it multiple times to 1V/ 1k ohm. Also gone through the BAC and it is operating as properly as can be.

if you bypass the thermowax it will never close and will always hold the throttle partially open and cause an idle surge/high idle condition.