JMoneyLSB

1985 12A

Just did a bunch of work to the intake system and can't get the car to run properly now.

Freeze Plugs in the coolant ports
New intake gasket and o-rings
Rats nest gone
Carb is stripped
No ACV, new gaskets for ACV block off plate

Start the car with no choke **** for fast idle. car immediately revs to 4000rpm. Tried adjusting mixture and idle to get it down, car stalls.

Any baseline for mixture and idle screws? I read a sticky in the FAQ that says baseline for Mixture should be 3.5 turns out.

Any ideas?

diabolical1

iTrader: (3)

if the car was running fine before you did the work you described, you're likely looking at a vacuum leak.

JMoneyLSB

It wasnt running fine. Coolant leak at the manifold was seeping into the housings, making it run like poo... Not very many places left for a vacuum leak, unless its between the carb and plate, or plate and intake manifold. Any other ideas?

Update:
Turned mixture screw until it bottomed out - 5 complete turns. Readjusted it to 3.5 turns out.

I backed the idle adjustment screw out as well. Car started, and will idle above 2000rpm but wants to stall below that.

Pulled the plugs which were fouled and ordered a third set of plugs. When they come in tmo I'll pop em in and see how it runs.

KansasCityREPU

iTrader: (9)

I'm of the mind to fix what is wrong and get it working so you know what the baseline performance is. Then mods can be made. Without that, who knows what introduced the high idle. We this type of thing all the time on this forum. Someone gets a non-running RX-7, fixes know issues and starts making mods before it's running correctly.

What's the compression reading?

diabolical1

iTrader: (3)

well, how did it run before the coolant leak?

nothing you've said so far has me thinking it's not a leak. that said, i'm also not there and seeing it for myself. i don't know what you've done and how thorough you have been.

my thinking ... (1) if it were the cable binding, it probably shouldn't stall with adjustment screws. (2) i suppose bad timing could possibly create a situation like this, but that should also probably bring starting issues with it. are you having any starting issues?

it's too easy to miss a vacuum line here or there with the rat's nest removal, and given the fact that you took the whole manifold off, there are other lines to consider as well. given the fact that you said it will only fast idle, it's probably not something big/easily seen. big lines/leaks tend to rev, then stall immediately, that is if the engine will even start at all. small lines tend to give a weak, shitty idle or fast idle that can't be brought down without stalling.

have you done the spray check (carb cleaner, starter fluid, brake fluid, etc.) yet?

it's obviously too late now, but for future, i would have to agree with KansasCityREPU. don't modify anything until the car is running well because now you have no idea if the thing was ever capable of running right.

personally, i suspect your compression is probably fine, but it is still a valid point that you should explore and confirm one way or the other. i'm also pretty sure new spark plugs will not likely improve your situation significantly. there is something else wrong.

if it turns out NOT to be a leak, then my next guess would be a carburetor issue.

JMoneyLSB

I picked this one up in March. Had an issue with stalling when i drove it home. Figured it needed a new tank of fuel and some seafoam. That did not solve the problem. Also a bit hard to start.

Which then lead me to the rats nest removal. The ACV valve and air pump were already removed when I got the car, also a RB header was installed. PO said the motor was rebuilt less than 25000km ago (after removing intake, i doubt that). After the nest was gone, started fine, and passed the ether test for leaks. But i did notice quite a bit of white smoke, and a slight loss of coolant. That lead me to believe the intake gasket was leaking.

With some spare time on my hands while waiting for my new gasket to be shipped from RB, i pulled the manifold and carb. That was a nightmare on its own. The **** built up inside the coolant ports, the crappy silicone replacemnet orings, the gasket that was falling apart. 100% coolant leak. When the motor was "rebuilt" the manifold had had the two lower ears broken off and siliconed back together. I brought the manifold to a local machine shop and had it re-welded and the face machined.

While i was waiting for that to finish i figured i would take on vipernicus' carb stripping instructions. Went quite easily while following the instructions. Also cleaned the old gasket maker material off the bottom of the carb, top and bottom of the phenolic spacer. Degreased everything and made it sparkle again!

My manifold returned, installed with all new gaskets (intake, and block off plates).

Thats when i had the high idle problem after everything went back together.

And yes i do have starting issues, now with new plugs it wont fire at all. I did a compression check audibly as well as with a standard tester - 95s in the first housing, 100 in the second.

Hope this helps the back story abit

KansasCityREPU

iTrader: (9)

I say massive vacuum leak somewhere.

wankel=awesome

Yeah, youre missing something here man. Can you take pictures of everything and post them up? If it never had the high idle issue before, it has to have come from the work you did under there. have you done a full sweep of the carbs linkage? Does it bind anywhere?

JMoneyLSB

Ill swing by my shop tmo and snap some pictures.

The only thing i can think of is the phenolic spacer. The PO had silicone gasket maker smeared on both sides that i had cleaned off. Could it have been hiding something?

Everything else seemed good when it was put back together. I could always pull everything back apart and reassemble it again. My new intake gasket should be fine to reuse though, correct?

JMoneyLSB

No binding in the carb linkage. Everything moves nice nice.

diabolical1

iTrader: (3)

check the back of the intake manifold (rear rotor, secondary port), nearby where the bend of the header passes, and see if the nipple/port (not the one for the brake booster) back there is either open or if the hose attached to it is broken or otherwise compromised. i really can't remember the name (honestly, i'm not even sure if i ever knew the name of that line), but if you're having trouble finding what i'm describing, post up and i'll see if i can get the info or a photo for you.

Jeff20B

iTrader: (13)

Get a good used intake manifold (make a want to buy thread in the appropriate section). Then block off all the necessary stuff. I think the machine shop might not have gotten things perfect.

JMoneyLSB

So i pulled everything back off except for the intake manifold. I think I may have found where my problem was...

When i took the bolts off for the carb, I remover the three easy ones first. I noticed that the carb was already a bit loose even though the back drivers side nut was not even cracked yet. I pulled the carb right off and tried to see how far I could get the nuts down on the studs of the intake manifold. The driver aide rear stud would only allow the nut to thread down so far before tightening up. I chased a die down each stud to get all the crap and rust off them, and made sure the nut would bottom out. Cleaned everything else again to prepare for reassembly.

Took me about 35 minutes to get everything back together and tried to fire it up to see if the problem had been solved. It took a minute of cranking but she fired and held idle at 2000rpm.

I played around with the idle adjustment screw after it had warmed up. Got the idle down about 800rpm. I let it run for about 30 minutes after that, shut it down and waited another 30 before firing it up again. Started no problem.

I am 100% sure that the nut had not tightened the carb down enough in the drivers corner and was allowing air to bypass creating a huge vacuum leak.

In the end I have come to the conclusion to make sure i double check that **** and ensure all is well.

Thank you for the help everyone!