Well I just ported my intake manifolds (almost exactly as mazdaspeed7 did his) and the car holds a 3000-4000 RPM idle. The temp hit 180*F and it still sits up at 3k.

Popped the hood, and revved it from the throttle body, still idled high. I checked all the cables (throttle and cruise control), nothing is stuck.

SO! I forced the throttle DOWN so it brought the idle to 750, but it just STICKS in that steady ilde spot, and if i try to rev it, it will go into the "high idle" mode and wont go down unless I force it down, but if I rev, it goes to high again... and so on... very undrivable.

So i have the throttle body off, and I cant seem to find what exactly will make the single plate at the bottom stay all the way closed (where the idle is good). What screw/nut should I turn? Anyone have some pics?

---PLEASE HELP I ONLY HAVE 1 DAY TO FIX THE IDLE---
(this is my daily driver )

 

PS - I'm not getting any check engine light (codes).

 

There is a throttle stop screw. It has a 8mm nut on top of it. Tiny in size. Just look harder, you'll see it. If your primary plate is cracked open, then loosen the jamnut and adjust it closed. If the primary plate is closed, take a look at the secondary throttle stop. Similar to the primary throttle stop. Might have to adjust it the same way. If both sets of plates show no daylight, then its another thing screwing you.

 

I took my throttle body off and scanned it. Heres the jpg with a toothpick and a red mark showing the approx position of the stop screw. Not good definition here, just an approx location:

 

alright i'll try the jambnut and the 8mm screw. YES, the bottom plate is cracked open just a hair....

at least it's not a leak... *PHEW*

 

OK, i looked at it, and the tab isn't even TOUCHING the little 8mm nut . I loosened this nut and it got it to be just a hair away from the 8mm nut you pointed out. What else is there that can make it close more or touch the little nut? ALSO, can some one quickly operate their throtte plates by hand and tell my if it just goes SNAP to full closed position or it it hits a small "bump" then slowly closes all the way...

THANKS




-----------PS--------

This pic is not of MINE, it's HAILERS. I just used to reference what I'm talking about.

 

It sounds like you bumped the high idle cam on the TB. Sorry, but I cant give much more details on it, I havent really messed with it before.

 

Does the high idle cam controle the primary (bottom single) plate or the secondary ones? Cuz it's teh primary that wont close all the way, the secondaries are SHUT tight.

 

OK OK, i adjusted the high idle cam, that one nut in the picture, and did some other adjustments and now i got it to idle normally.

HOWEVER, when cold, it idles erratically and stalls if i dont baby the throttle (I didnt do the full TB mod, just removed the plates, that shouldn't effect it any, right?). But once it's warmed up, it's just fine. I had to adjust the idle screw on top of the throttle body ALL THE WAY open for it to hold a 750 rpm idle when warm.

ALSO, my atomspheric pressure sensor vacuum hose is unplugged. I searched and seached for where it could go to but I cant find it. Could this be a cause of my idle problems?


- PS - Took it for a spin too, feels a little faster at high RPMs . At least a 10hp gain.

--PPS-- OR is this just normal for ported intakes?

 

Ah! I thought when a person did the throttle body mod they removed the fast idle cam and the thermowax at the same time. If I thought you had a normal car I would have mentioned adjusting the thermowax and the fast idle cam. When set cold, the primary throttle plates will be open something like .016 inches. Then as the thermowax heats up, the roller falls off the cam and the plates close completly on the primary plate. See the manual for setting the thermowax and fast idle cam. Attached is a page out of a 87 manual. Yours is similar, not exactly the same. Use at your own risk.

 

ahhhh... so you think the stupid thermowax/high idle roller is the cause? hmmm... damnit, that means i'll have to take off the TB again .

When I adjusted it, i tightened the screw all the way to make the spring tight. Would that make for a horrible cold idle, and semi-decent 750 hot idle with the idle screw (on top of TB) set all the way out??

 

Ok ok, just took her our for a few HOURS of driving. Idles was ROCK STEADY at 750 the whole time.

So idle is perfect when hot... hopefully it'll be good at cold too.....


Oh well I'll see in the morning.

 

Glad to hear your idle is doing better. I want to hear your thoughts on ported vs stock manifolds. I noticed it moved my powerband up higher. I dont notice power starting to fall off until nearly 8500.

 

do you have pics of the ported manifolds

 

Its on my site. Click the pic in my sig, and look under how-to's.

 

BAH! I still need to baby the throttle until it's all the way warmed up (180* on temp guage) or it'll stall out.... anyone wanna share their expertise on this ?

I'll post a FULL write up on how to port and what i used once i fix this damned idle.

 

please do i've ported only my tb and dynamic chamber but will port the maniflods soon but ever since then it idles around 1000-1200 depending on temp. but when it's cold it's 750-800 like it should be can't figure the thing out but it's not to bad

 

I cant get my car to idle until its warm either. I would really like to know why, so I can fix it. I would really like to fix it, but havent had any luck. I did the full TB mod, and Im sure that has something to do with it. my car runs too rich until its warm. I dont know why its so rich(maybe the missing thermowax), but my car wont idle b/c its so rich until after its warm.

 

OK, i KNOW that people with the TB mod can get their cars to idle when cold... and i haven't even DONE the full TB mod.

OK here is my problem. before the porting, the car ran PERFECTLY. And I dont think there is THAT much more air comming into the engine at IDLE for it to do this. SO, i ported the intake manifolds, and got rid of the doubly throttle plates/rod. DID NOT do the full TB mod, THERMOWAX is still there.

Here is the problem: Car does NOT want to idle AT ALL when cold, stalls out unless i baby the throttle. AT about 174*F the idles stablizes at 750RPM and i can then drive the car normally. I am gettin no check engine lights either.

What i did : I just took off my TB. (engine was WARM, 174*F) The thermowax rod seemed to not be extended all the way. So i left it to sit for a few hours... the rod HAD NOT MOVED at all. Didnt adjust anything, put it back together and started her up at 110*F engine temp. It seemed to idle at 2500 for about 10 seconds, and I thought everything was alright, then it just DROPPED and ONCE AGAIN, would NOT hold an idle until warm

It seems that the thermowax is not working is misadjusted..

MY QUESTION : If i did the full TB mod, would I get and idle on cold engine start-up? If so, I live in MN where it does get below 0 sometimes in the winter, would the car still start/idle then? OR is there some way to fix this damn thermowax/high idle/cam/roller system so it works?

I DOUBT the porting would affect the cold idle, it's something wrong with the TB. I have also looked and looked for vacuum leaks, and cannot find any. BUT MY PRESSURE sensor vacuum tube is UNPLUGGED and i cannot find where it goes. It appears from a diagram, that it bridges up with another tube and both go into the same nipple. could that be the problem?


MY LAST QUESTION: WHO has ported TB or intake manifolds, or both, and HOW does your car run? I hope this isn't a side effect of intake manifold porting...

--I'll probably make this a new thread if not enoughpeople/no one helps out

 

YES! Got it fixed, holds a nice 2k-2.5k RPM idle when cold, warms up and the idle slows down to a "787B sounding" lumpy, *INTIMIDATING* idle around 1000 RPMs (900-1100) nicely. No change in normal operating temperature, just below 180*F. OH YEAH!!

THANKS FOR ALL THE HELP GUYS!

 

What did you do?

 

it won't idle until warm because you took off the double-throttle plates

 

Ok, it was a problem, like you said, with the fast idle cam adjustting screw. Look in the HAYNES manual for a diagram and instructions on how to adjust it.

I had the engine warmed up all the way, then took off the TB (left the hoses on the avoid hot coolant though ), and noticed that somehow, it was adjusted out of spec to the marks on the thermowax CAM. SO i readjusted it and then adjusted "that bolt" in the pic above.

THEN i had to wait SEVERAL hours for it to cool. Then I noticed that the other screw controling the plates was out of spec .016-.020 with the primary plate, so i adjusted that and VOILA! Everything started working, cold AND warm .

Sorry Mazdaspeed7, I think you did the TB and dont have the thermowax, which was my problem. So i can't really offer much more help . Good luck though!

blu_gxl, I made that write up, it's here

 

Glad it all worked out. Im thinking of getting a stock TB, and just removing the double throttle plates, but leaving the thermowax. I am kinda tired of my car not idling until its warm.

 

LOL! I've said it before, Hailers WHAT HAVEN'T you scanned on that scanner of yours!?

BTW, thanks again for the info--I needed to know the size of the throttle stop nut.

Brian