NCharlebois

iTrader: (2)

I adjust my thermowax with water at 77 F and then put it in the freezer to set it around 32 F.

My cam adjust screw is almost totally screwed...

Is it possible that the thermowax still moves, but not 100% of what it is suppose to ?

HAILERS

Why not pour boiling water over it to see how far it extends? And the pour cold water on it and watch it retract.

What's the problem? If you want the cam roller to seperate sooner.........you turn the screw clockwise more. If you want the cam to seperate later.........you turn the screw anti clockwise more.

NCharlebois

iTrader: (2)

I have a cold engine idle problem. My car runs like a new when fully warm. I have an S5.

My idle bounces when my car is warming up. The engines cut and drops 300-400 RPMs then come back up, then stops again to drop. It does not bounce, the engine cuts off... like if it would have a signal that the RPM cannot go that far up, it must go down. It slowly decreases till my engine is warm. I can play with the bounces around the 1100 RPM mark when I turn on and off the A/C...

BAC valve is perfect.
TPS is perfect with the led lamps.
The TB is adjusted perfectly I think (secondary, primary, thermowax...).

I've not check yet the AWS selenoid (doing that tomorrow) : my car doesn't go to 3000RPMs for 17 sec like it is supposed to do.

Another thing, my car is a 5 speed swap. The problem started almost at the same time as I unpluged my auto trans computer. I've been told that it is not related... but I feel stupid I've not verify by plug it again ! I'm going to do that when my intake is going to be back on.


That's why I want to know, could my cold idle probem be related with the thermowax that doesn't "move enough" ?

jjwalker

NCharlebois, I have the exact same issue. All of my systems are working properly (or so it seems) as well. I have just come to live with it although i would like some insight into this issue as well.

arghx

iTrader: (3)

I found the thermowax adjust procedure to be useless because it never idle like it's supposed to afterwards, even if you check clearances with a feeler gauge. I just had to physically adjust the thermowax and TB screws as the car warmed up, until I was eventually happy with it.

na5

do you still haave all your emissions equip

freemanrx7

The FSM says not to adjust the thermowax!

Since you have a 5spd swap I wonder if your car will rev to 3k if you leave it in neutral. That might have something to do with it. Do autos do the 3k rev? I've read that thermowax's can get clogged if the car has had dirty coolant.

NCharlebois

iTrader: (2)

No mods.

My car was ok (3k rev and everything) , then it changed... around the time I unplugged the auto trans cpu. It's been a year and a half, so I can't recall if it made everything changed.

When I did the swap, it was writing to take care of the Idle, but nothing more. That's what I did. With what I know now, i would have observe alot more. Anyway...

So the marks on the thermowax aren't precise... ok, I'll take good note. But how the hell can you adjust will runnig ??? I barely can touch these with my fingers !!!

arghx

iTrader: (3)

on a relatively stock car yes

freemanrx7

OP if you have no mods you shouldn't be touching the thermowax. You've been told it wasn't because of your 5spd swap but did you start having this problem right after the swap?

HAILERS

The 3000rpm rev during a cold start is a function of the BAC and Air Bypass Valve.

The water thermowax is what causes a cold engine to idle around 1300rpm cold and as the water temp comes up to operating temp, gradually lowers to a 750rpm idle give or take a bit.

You seem to have a problem around the 1100 rpm figure and to me sounds a bit like fuel cut. I mean fuel cut as in the normal operation of the car when your DRIVING (not idling). When you driving along and let off the pedal, the TPS senses that and the ECU will either cut fuel to one rotor or both rotors. Depends. Then as the rpms drop, the injectors start working once more. Around the 1100-1300 rpm figure, but that's memory.

But your problem is at idle only...............so I'm wondering if your ECU is seeing that your shifter is in neutral or not??????? It might be that or some other signal missing since you did the auto to manual swap. So as a starter idea, I'd go to the ECU and find the Neutral wire on the plug and shift in/out of neutral to see if that signal is coming and going.

As step two I'd look at the ECU and see if it's seeing the clutch input signal also.

As far as the water thermowax, I've no problem with adjusting it. There's a given procedure in the FSM for doing so. I've done it and others have also. Not a problem. But it's not going to make a difference in the *fuel cut* your experiencing. It needs to be set where the cam and rollpin are seperated when the engine is up to running temp (180F). IF that does not happen, then any TPS adjustment is not going to happen right. Waste of time and effort.

I almost want to disable my neutral and clutch switches to see if I can duplicate your problem. Almost.

jjwalker

Based on Hailers description, my thermo wax is sticking out too far at cold start because my engine tries to idle at 1800 rpm but the ECU seems to cut fuel and it will drop to 1400rpm before fuel comes back and it jumps, then fuel cut again.

Either that or my base idle is too high.

HAILERS

Look at the items in the jpg attached that effect fuel cut. See what I mean?

jjwalker

Hmm, my car will start warm but it takes a bit longer to crank. I wonder if my water thermo might be bad as well? Who knows.

In my case, my neutral switch works and so does my clutch switch so I am pretty much at a loss.

HAILERS

************************************************** ************************************************** ************************************************** **

IF the engine idles at 1800rpm cold, but then drops down to 750-800rpm when the water is fully warm, then you'd want the screw that sits on the end of the thermowax to be screwed clockwise more so the cam/roller will seperate sooner and also so the throttle plates won't be cracked open as much when the water is cold.

That's IF there are not other *problems* like air leaks, fooled with idle screws/stops etc.

jjwalker

unfortunately I would have to pull the whole throttle body off to fix that.

I have adjusted the base idle screw before (per the FSM) because the car would just die when cold, but now that it runs fine cold, it takes longer to start warm and the engine does the fuel cut thing when cold. Annoying to say the least.

NCharlebois

iTrader: (2)

Ok, I'll let go the thermowax and leave it like that !

I'don't have the clutch and neutral switch, I don't think the wires are there in an auto trans car. When I played with the wires, I bypassed the neutral safety switch and connected my back-up lights.

In the 1R position, I don't have the neutral switch, but probably the EC-AT control unit. I'll check the wiring diagram when I come home later to check the P and N range wires go.
In the 1Q position, I can check but would it be weird that I have it because it's manuel trans related ?

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I've check the Decelaration Control Unit diagram, and there is no equivalence for the auto trans...

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Would it be logical : because of the absence of sensors, the ECU doesn't know that the engine has no "resistance" so it its revs up till it is too high, then it cuts the fuel. Then when it is too low it revs back up and so on.

When the engine is warm and I let go the gaz, it is supposed to slow down around 1100 because of the injectors are back on ? My revs go back down and then go up.

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When I'll have time, I'll check the air bypass valve (don't know wich one it is, going to do my search !) and the AWS selenoid (see attachment), the water thermosensor and the wiring diagram when I come home later to check the P and N range wires for the 1R position on the ECU.

NCharlebois

iTrader: (2)

Did you swap an auto trans to a manuel one ?

HAILERS

I'm just saying that I'm GUESSING the ECU thinks it's being driven on the road when it's looking at the map sensor/tps/clutch switch/neutral switch etc , therefore it's cutting the fuel above???12-1300 rpm when you idle.

That fuel cut should not happen in the driveway when reving the engine or idling. Fuel cut should only happen when actally driving down the road and letting off the pedal.

About the thermowax: I'd make sure that after you install it, that when the engine is fully hot the cam/roll pin seperate. If they don't seperate, then the TPS can't be set right.

I took your word for it that you don't have a air leak anywhere and that the vacuum lines are going to the right places.

AWS is the air bypass valve I mentioned . CAlled air bypass on a series four. It only works for the first 17seconds of a cold start and never again.

jjwalker

Nope.

Spectator

iTrader: (1)

That actually makes a lot of sense, but it's sadly not the case. It would seem that the problem is not related to the auto to manual swap since I have seen the exact same problem on a manual vert just like his own, an S5 90.

And, having worked on both engines. I can confirm that there are no vaccum leaks on either car. Idle is perfect and runs like new when at operating temp. The idle bounces 1100 to 1600 when cold and its smooths out as the engine heats up, like so: 1100 -1600, 1000 - 1450, 900 - 1150 and so on until the car reaches a perfect idle. Give or take a few rpms of course, and its really like a fuel cut, like as if someone was playing with the throttle. If he turns on the AC when the car started warming up, the idle becomes instantly stable but you can feel the engine "struggling", as somethings not right...and of course, when it gets at operating temp, this goes away also.

So what are we left with?



Air bypass selenoid valve? He checked almost everything else. But why would it bug him until the car heats up and not for 17seconds only? At start up, is the thermo sensor the main sender? Is the air temp sensor used in anyway for idling purposes at start up?

Spec.

HAILERS

I doubt the AWS is involved in any way. It was mentinoned somewhere up there and I made a response about the 17seconds, implying that it was not a player.

Maybe try pulling the BAC plug off the next time it happens and see if that effects it. I really don't see the BAC being a player in anything at that high a rpm though. BUT as you can see in the attached jpg, the BAC gets effected if the A/C is turned on and you said things got better doing that.

If it's adding more air, then that might change the mixture enought to make it run smoother? Got me. I was under the impression the BAC was functionless over 800rpm or so. As in it wouldn't open/shut anymore than it was at 800rpm. That's an assumption of mine. But that does not seem to be the case on the car your working on.

I'd look at the BAC's duty cycle and maybe you can see something there. Like seeing the duty cycle rise and fall in rythmn with the engines cycling. So if your meter does not have a *duty cycle* feature, you could pull the BAC plug off as the cycling is going on and see what the results are i.e whether the cycling stops or not.

BAC's go full open when the key is HELD to Start, after that they return to their normal duty cycle given the load on the engine.



The water thermo sensor is a fairly big player. It'll cause the ECU to run rich until the sensor sees around 120*F and at that point the mixture drops about 1AFR from my experience. Then around 150*F or so some other change in the afr happens.

As far as the air intake sensor....I can't say, but it's easy to see if it's functioning right by probing the ECU pin that it's connected to and comparing your reading to the FSM *Control Unit* section.

NCharlebois

iTrader: (2)

I've check the BAC valve in any possible way : even unplugged it to see it vibrating when the A/C is on. I doubt it would be the problem but I'll unplug it for sure next time I start my car.

I'll add that to my list to do !!! And I'll come back with the results probably next weekend and the beginning of next week.

NCharlebois

iTrader: (2)

By the way, when I unplug the TPS, ithe idle stops bouncing but doesn't feel smooth.

I've check it with the led lamps and the volts, but I don't remember the Full Range and it looks to be involve in the diagram.

jjwalker

I wonder what grounding the test connector would do during a cold start. Judging by the FSM, that would at least rule out the BAC it seems if the idle is still bouncing. I am going to try that.

It is amazing that 3 guys with 3 verts, all have the same issue ( me being one of them).