vrracing

iTrader: (1)

On an S5 JDM throttle body adjustment...

1) Just to confirm, is the primary throttle valve the lone one on top?

2) On page F2-35 it says "If the clearance is not within specification, cam adjusting
screw to get the proper clearance is obtained." means what exactly?



Where is this adjusting screw of which they speak? I'm guessing it is the pink cupcake while the orange sun is the idle set.



3) when the primary is all the way open should the secondaries be level?

The TB is in the fridge now to make sure the wax is thoroughly chilled.

Have a wire to check with gap at the bigger setting but have to strip some electrical wire to see if I can find one for the smaller gap.

Since this is a JDM and the idle adjustment screw on the BAC is just a red herring, I assume I need to ground the ISC and then adjust the idle with Mr. Sun, right?

Thx

vrracing

iTrader: (1)

In the TB adjustment section there are these two seemingly random items thrown in at the end...



I dont recognize the Water Thermovalve so am guessing that is a S4-only item?

I also dont recognize that hose with the checkvalve anywhere on my throttle body.

satch

iTrader: (1)

In the first diagram the Thermovalve would be at the bottom left. Yours might have been deleted as the pic of yours does not show that part of the throttle body.

satch

iTrader: (1)

After doing a little searching, the JSPEC throttle body does not have the Thermovalve.

Post #3. https://www.rx7club.com/showthread.p...DM+thermovalve

gohorns

does your car hit 3k on cold start? and how much does the rpm drop by?

vrracing

iTrader: (1)

Thanks for clarifying, Satch. Any ideas about the check valve?

gohorns, JDMs dont have the AWS (accelerated wear system) of the USDM cars.

We've been reverse engineering the linkage and there is no adjustment to control when the secondaries open; at least with the JDM throttle body. It seems like the only way to do that would be to somehow shim the actuator that is indicated in the second illustration with the up and down arrows. I wonder if the bushing or the little cams are worn.

The FSM seems wrong with regard to setting the Fast Idle as well. I'm assuming coolant at 77 degrees is still cold especially given how **** everyone is about setting the TPS when the car is FULLY HOT!!!! So if you follow the FSM instructions and align the green tipped dowel with the top mark at 77 degrees, when the engine is warm the dowel falls off the top of the cam. However, we found that if you align the green dowel to the bottom mark when it is cold, it will move to the top mark when it is warm and the plunger extends. That makes a lot more sense.

So we heated it up with the blow dryer (it was in the fridge before) to about 150 degrees and aligned the top mark with the green down. Then we adjusted the pink cup cake screw so that the green tipped dowel was in contact with the fast idle cam. Then we adjusted the idle screw so that the primary valve was open at the specified .4-.5mm with a .45mm wire.

When hot we checked the TPS using an ohm meter and we have .99 on the narrow at idle but 1.34 on the full range. This is a new from Malloy in the last few years so that is annoying but IIRC no one thinks the ECU pays that much attention to the full range TPS.

satch

iTrader: (1)

It won't have that particular valve I believe. And pouring boiling water works to see how the Fast Idle Cam works. And if you held down that part of the linkage down as far as it would go it would simulate a fully warmed up engine so this could be done w/the engine cold. And if the Green/Red wire measures 1 volt in a fully warmed or simulated warm condition then that's all you need to worry about. And the secondary plate opens when the primary is about 20% open or so.

Post #7 https://www.rx7club.com/showthread.p...dm+thermovalve

gohorns

ahh makes sense then why you dont have the thermovalve since that works with AWS to bring down the rpm

vrracing

iTrader: (1)

The blow dryer works well and is less likely to scald!

Here's a picture of the fast idle when it is warmed up. You can see the green dowel lined up with the top mark.



When we put it in the fridge the piston drops and the green dowel lines up with the lower mark and the throttle opens a bit.

It's all put together (except the PVC intercooler is subbing for the TMIC) and we'll see how it runs tomorrow.

vrracing

iTrader: (1)

Alight, we got an even idle between 875 and 900 rpm and the TPS is at .96v. We pulled the BPV off and capped off both ends to address a vac leak at the rock hard, formerly rubber elbow.



The BAC doesnt seem to work. Plugged, unplugged, ISC grounded or not, a/c on or not, the idle doesnt move out of its range. I can hear a vibrating noise coming out of the cone air filter when its plugged in and it goes away when it is unplugged which suggests the solenoid in there is working. We'll have to look at that later. Maybe try to clean it out.

Thanks for the help, guys.

vrracing

iTrader: (1)

When I was a kid my Dad would emphasize the value of walking the aisles in the hardware store just to mentally catalog what they had should it be useful in the future.

So to plug the BPV ports I used a couple of those Home Depot treasures in the form of rubber feet for folding tables and chairs. They are rubber, come in a variety of inside diameters and worked great.

The white one on the hot pipe is a 5/8" and the black one on the TID is 3/4". Our HD is a crappy small footprint store so a better stocked one might have all of the sizes in black.





Maybe someone else will find these useful as well; like those joining the "No BOV" club.

vrracing

iTrader: (1)

The car idles beautifully now when warmed, the RPMs increase a needle's width when the a/c goes on and it hot starts and idles nice. Pulling up to a stop sign with the a/c on and the idle drops to about 500 and recovers no fuss no muss. When the engine was hot we were at .96v on the TPS.

I suspect the BAC ain't right since I would guess the RPMs should increase more than they are.

But while it is warming up the idle bounces. This is a JDM Tii so it doesnt have the USDM cold idle bounce usual suspects - the thermo valve and "stupid Americans can't drive" diaphragm secondary valve controller Mazda put on the USDM car.

We sprayed ether liberally and then pressure tested and the only leak was the small one at the BPV elbow so we pulled it as noted before. The BPV is off and the ports are capped but I have 3/4" silicone hose coming from Verocious and we'll use a 3/4" copper elbow to reinstall it nice and secure. At that point we'll do a data logging on the Zeitronix from cold to hot. Ah, the joys of 80s tech.

I dont think we'll join the No BOV Club but the car sure pulls nice.

JakeMG

I had a real nasty idle problem, found out the idle air control valve had a stick-of-gum sized hunk of silicone from the last person to do a water pump. This gave me a high rev that would it 1.5k rpm then the TPS would catch it and retard the fuel to bring it back down. Long story short, to fix it I had to remove the screw that touches the plunger on the idle air control valve along with 45 mins in a parts washer cleaning 165k miles of grime off my valves. After this, and a little work with the idle screw on top of the throttle body, it idles bang on... Now my high idle on cold start up is my foot lol, but I live in GA so it's all good. I hope this helps anyone with this issue or similar.

This is on a '91 NA

vrracing

iTrader: (1)

Thanks, Jake. We started this recent adventure trying to fix a small idle bounce that showed itself only when the engine was hot and most prominently when the vent fan was on; but it seemed to disappear if the vent fan was off or the a/c was on. The engine was prone to stalling at stop signs with the a/c on too.

Then I broke the charge pipe taking it out and so we did a complete reset on the intake system. Now the idle is perfect if the engine is hot but bounces during warm-up.

btw, the idle air control valve on RX7s is called the BAC or "bypass air control" valve. There is a another device on USDM cars called the AWS or "accelerated warmup system" that revs the car on first start to IIRC 1,500rpm so it too is an "idle air control" valve.

I don't think we have similar root causes but I'm curious to know what to what you are referring. The reference to "plunger" suggests you cleaned the thermowax which has coolant flowing thru it and when it heats up the plunger rises and lowers the idle. The coolant passages can clog rendering the thermowax ineffective. But I dont know what valves you cleaned.

We didnt touch the BAC so it seems unlikely that anything changed there.

JakeMG

After I pulled the silicone out of the thermowax, i tested it by dunking it into hot water to see if it would move the plunger, I found no movement so I figured it was seized. I don't have the money to buy a new one so what I did is removed the screw that touches the bottom of the plunger which adjusts for the high idle on cold starts.

Sorry if this is confusing lol I just got this car about a month ago and it's a work in progress.

vrracing

iTrader: (1)

Ha! They are always a work in progress!

What's annoying is the behavior is inconsistent. So this morning it started fine and rev'd to 1800rpm (remember that there is no AWS but the ECU doesnt know that) sans bouncing. Then after 10 seconds or so it started to slowly decrease in revs until it got to ~1200 and it started bouncing for about 30 seconds then when it got to 1100 is smoothed out again. Once fully warmed it idle smoothly at ~900 but it started dying at stop signs again.

The inconsistent behavior could be the result of stiction in the linkage. Do folks grease the throttle body linkage? Since it is all exposed it seems like grease or oil would just attract dirt.

gohorns

man same here with the inconsistant idle behavior. most of the time mine is ~1K at normal temp but every once in a while goes to 750-800 when it feels like it so I dont even know if its worth messing with.

btw I had the bouncing idle issue at cold (1500 to 2500) while I was adjusting the tps but it went away once tps was in spec. my throttle cable had also come loose and seemed a bit beat up. I adjusted it but will replace it in the future.

vrracing

iTrader: (1)

I believe the TPS is right on but I'll check it again. With the Zeitronix its easy, just plug the USB cable into my laptop. I have the TPS logged as user1 but for some reason the Zeitronix gauge lets you display user2. That's weird and annoying because it would be nice to be able to check the TPS on the a-pillar mounted multigauge.

I'm focusing on the BAC. When we bought the swap from TigerJapanese (what a cluster-frak) the nipples on the BAC were broken off and we bought one used; probably here on the forum. The idle has never been right but serviceable. I think we'll pull it off tonight, clean and test it.

Anyone know how many rpms should drop when you unplug the BAC? Or how much the rpms should rise when the a/c is turned on? The FSM is... vague.

satch

iTrader: (1)

^ about 500 rpm w/very little load (foot on break).

vrracing

iTrader: (1)

Really? Wow, we arent seeing anything like that. That would mean whenever the a/c was on the idle sits at 1,250?

JakeMG

Did you clean the grime out from around the flaps in the,throttle body? Is it dying,when,its cold? Since I took my aws off the car wont hold the idle if its just starting up when its cold, about 2 mins of driving and it will hold its idle fine.

vrracing

iTrader: (1)

Yes we did. The inside of the tb really wasnt that bad. And the fast idle thermowax is still in operation; the JDM cars dont have the AWS hardware.

Funny thing... the kid just came home for lunch and as he pulled into the garage it started pulsing while hot. For three days it has been perfectly fine while hot except dying at stop signs with the a/c on. And now it starts pulsing.

I guess the N370 running a car is like a chicken doing math. It's not the fact that it occasionally gets the wrong answer, it's amazing it can do it at all!

I checked the TPS last night when he got home and it was at .96v. There looks to be a slight drag in the pedal/cable/linkage because if I would verp it (the engine was off but the key was on) and the TPS would read 1.16v. If I put foot under the gas pedal and pulled it back it would drop back to .96v. But 1.16v is still in the acceptable range.

vrracing

iTrader: (1)

Satch, 500rpm seems too high. I found this in the S4 N/A training manual and it shows only 50rpm increases with the a/c on.

satch

iTrader: (1)

My response was to your query of how much it drops to when unplugged. So when unplugged it drops to a level of 500 rpm w/little load and not it drops 500 rpm. If the idle dropped 500 rpm from 750 rpm the engine would likely die so that would be more than a 500 rpm drop. I think you misunderstood me.

vrracing

iTrader: (1)

Ah, I actually embedded multiple questions.

So, if if we are idling and unplug the BAC the idle should drop to 500 or about 250 rpm.