jimmydanny

I have now swapped my TPS twice, last time due to getting a new throttle body with TPS's installed.

My idle was going up slowly and then dropping down fast, same on higher RPM if I held it on a certain RPM (3k would be 2.8k-3.2k fluctuation in neutral).

Now my idle is going up and down slowly, so probably getting the double butterflies back helped a bit.

But it is still doing the fluctuating thing, and it does it a bit in gear while driving as well, and it is annoying the ***** out of me.

It is not the TPS, I have checked ALL vacuum lines, all gaskets are swapped recently, new orings and all that on the injectors. BAC is working as well.

Timing is adjusted as good as I can get it with the fluctuation.

I am really at a loss here, just went through my biennial vehicle inspection, so this is all I need to get a car I would 100% enjoy to drive again.

Thanks.

texFCturboII

iTrader: (17)

Was the car fully warmed up before setting the TPS?

w0ppe

You try running codes on your S5 engine?

ben.farnath

Series 5 engine in a s4 car right? So s4 afm? I had similar issues and changed to my spare afm and now is pretty damn normal in that respect.

jimmydanny

S5 all engine except front harness.

The TPS was adjusted when warm, yes. No codes at all.

jimmydanny

I don't know what CAN cause things like this except BAC or vacuum leak, which I have gone over so many times, even the most unlikely ones. Also all idle stuff on the throttle body is restored to stock. What else can cause this? I mean, I know if you adjust the secondary throttle butterflies to get the idle up if it is stalling, it can become bouncy unless you hit the exact spot, but that should not cause it to bounce on higher RPM as well, am I right?

I do have a N370 ECU on a N374 engine, I know N370 engines aren't too happy with the N374 ECU's, might it be the opposite as well?

jimmydanny

I have been checking around while mounting the thermosensor for my el-fan. Can't think of or see anything. Here is a list of what I have checked:
Vacuum
BAC
Plugs
Plug wires
AFM and wires to it
MAP (I connected my S5 cluster and the turbo gauge to it, it works)
Boost solenoid (Wasn't connected due to custom intake from AFM to turbo, now connected)
Put in new intake temp sensor
Changed the whole throttle body to a 100% stock one
TPS, no dead spots!

Now, does anyone here have an idea, cause I am out of those now. I can get a vid up later, but the sound is kinda not good, but you see the revving.

jimmydanny

RX7 FC S5 unstable idle and hold revs - YouTube

There ya go. Not too much of the idle, but it is the same as the 3k rev hold but slower fluctuation. Annoying as ****, as it does it in gear as well.

RXSpeed16

iTrader: (41)

What idle speed are you using when you adjust timing, setting tps, etc?

If you unplug the BAC does it still bounce? Same for AWS and knock sensor.

Have you sprayed brake cleaner around to check for vacuum leaks? Spraying under the uim and other areas you can't see very well.

dwb87

iTrader: (22)

I keep seeing that you've verified that the TPS is good. BUT..... hear me out.... Has the TPS been properly adjusted to 1 Volt?

Also, I've seen nothing mentioned about the thermowax and fast-idle cam.

ben.farnath

I would try another Afm if you can borrow one. That 3000rpm bouncing(which is frustrating to no end) is exactly what my car was doing. it was also idling high and bouncing at idle too.After setting tps 3 times , pulling the tb and cleaning and adjusting it and checking everything I could think of, I swapped afm with a spare I had. Now it's fine (bar other electrical oddities. Unrelated) I'm not saying it's 100%what's wrong but if you can borrow an afm I would try it. There wasn't anything visually wrong with the afm I could see either.

jimmydanny

It still bounces with the BAC out. The TPS was adjusted with warm engine, timing was set when my idle was lower.

I have tried with brake cleaner, or starting gas, but that does the same trick (it did when I actually had a vacuum leak once).
Yes it has. The fast-idle cam and thermowax wasn't there initially, but I added it with the "new" stock throttle body. Same behaviour before and after, maybe a bit less aggressive bouncing than before, more smooth now.
I swapped AFM a year ago when it was my ECU that got shorted out by moisture in my car. The car didn't change in any way by me changing the AFM.


One thing that I did forget to mention, sorry for twisting your brains so much, but can an exhaust leak between the block and the manifold cause this? I know it causes my turbo to boost later, not less though, but still. You never know, I have seen weirder things than that cause similar problems.

jimmydanny

I think I found the problem... You know all the vac nipples on the side of the UIM? Apparently, all of them aren't vacuums, some of them are between the butterflies and the turbo, not between the butterflies and the engine, ergo no vacuum.

jimmydanny

Okay, as the "vacuum" nipples apparently aren't all vacuum, I would love to get help with those.

As I am using a N/A BAC for the moment, I can't use the vacuum source on the passenger side of the UIM, as it is blocked by the BAC.

So I need another source for this. The problem is, atleast two-four of the nipples on the sides of the UIM are actually 0 and up on boost, no vacuum, while one or two (probably not more) are vacuum.

I have a feeling I can source a LOT of my idle issues to these.

I checked the front center one with connecting it to my boost gauge first, then to my MAP sensor (and thereby the stock cluster boost gauge), none of the read vacuum, and bounced like crazy due to my lack of blow-off valve (from the turbo flutter).

I guess I could split the top one and let it go to all my vacuum needing sources, of course, but it would be fiddly nonetheless, and there might be more vacuum sources as well.

jimmydanny

Anyone? I don't have the rats nest and the solenoids, only things of the emissions is the BAC and the stuff on the throttle body (one needing vacuum or boost). Rest is stuff like MAP, boost gauge, thats it.

jimmydanny

Come on people! I have checked so much, there is this little thing like the injector grommets that makes this problem, but I have checked all I can think of now! I have fixed the front vacuum so I only use the top of the three nipples there. On the rear side I still have the injector air bleed, the oil injector air bleed (spider), which I really don't need, but I don't wanna remove it till I remove the OMP and plug the injector holes for good.

So, brainstorming time!