I have an 89 na rx7 with street ported engine with headers and stock na injectors that were cleaned not too long ago.

So hears my story, the engine only has about 15-20k of mileage on it and after I removed the intake manifolds to replace a leaky gasket, it now refuses to idle at all. The way it works is that the car will lower to 1000 rpm and then completely shut down. It hasn't ever done this before to me and has never been beated on and fluids are always taken care of early. If I was to play with the AFM, it has no effect as it can't go below 1000 when I play with it. Can it be a gasket on the LIM that is causing this? Also, I notice that the thermowax lines were previously changed by the old owner and are wondering if changing the order of them can affect anything.

I have gotten pretty annoyed with it as I changed my gaskets and vac lines on my s4 vert and haven't had a problem since.
Oh and before I forget! The compression is a consistent 110 in each chamber.

 

Did you check for any vacuum leaks?

 

What did you touch? Sounds like a bad vac leak to me, or you left something unplugged

 

I checked for leaks, but have not found any at all. I removed only the vacuum lines that were attracted to the uim so I was able to replace the gaskets. Is there a another way to test for vac leaks? I'm planning to remove all the manifolds again and check the gaskets however, like the other 10-15 times I did, it shows no leaks at all

 

I'll list what I touched when changing the gaskets.
Uim
Lim
Bac
Acv
Coolant lines to the back of the tb

 

I would check everything again, take it apart and make sure you didn't miss anything.

You can try having someone hold it steady at a low RPM and then spray carb cleaner around all the manifolds, if you hear it speed up you'll have found the leak. That might not work since you can't get it to idle though.

 

My issue with the carb spray is because of my headers, I'm concerned that it cause a fire. I have used quick start on the top and middle intakes, but can't really know test the intake that bolts to the engine as it's covered up mostly

 

I just realized also, that when it gets warm, it refuses to start back as well. This is sorta new, never knew it did this too me.

 

carb spray wont catch fire. it will however smoke a little. if you are that worried about it keep a hose or a fire extinguisher close.


although in 10 years of doing this trick ive never had a problem with it flashing or catching fire

 

Tried the carb spray. Still haven't found a leak... I'm really confused at the fact that I can't find this... Is a vaccum leak the only possible answer at this time? When I try to idle it at 1800 (lowest it will go), it makes a weird stuttering sound and smells really bad. I'm assuming it's running lean? It's actually enough to burn your eyes if you stay around it for too long

 

you sure your thermowax valve is working properly? i just took mine apart to fin the passageway completely blocked.

try adjusting that a little with the engine hot and see if that drops the idle at all.

 

Maybe you pinched a fuel line under the manifold?

 

The thermowax seems fine but the coolant lines that run to the back of the tb don't look right. Is the BAC coolant line supposed to be upper or lower coolant nipple?
I'll check the fuel lines, no signs of pinching, but doesn't hurt to try!

 

its rather hard to see that thermowax valve. try adjusting the screw with the motor running. half a turn and you'll instantly know.


the hose that goes to the BAC should go to the throttle body on the top side of the throttle body. the one that comes out of the keg goes to the underside of the throttle body.

EDIT: this is with reference to my S4 TII, not sure if its the same for everything, but i cant see why this would be different.

 

The s4 tb is slightly different from the s5 ones as I noticed. Ie, coolant nipples are arranged different and the tps mounts kinda funky. I checked the fuel lines and they are cool, no rips, or pinching. I did notice that my intake does not have a sub zero port and I don't mean like a block off plate, there just isn't one there. Also the vac lines to the dashpot are slightly different from the vac diagrams I see in the fsm. Dash pot has 3 nipples instead of 2 like the fsm says. Will be picking up some carb cleaner and some new gasket sealer tomorrow

 

Ok update! Still not working properly, but when I removed the gaskets, all were good except for the LIM which still shows a "wet spot" in the lower left side. I am getting the feeling that my intake could be warped? I ran it once for a lapping event in April and it was still -2-3 degrees celcius that whole day, could it be the hot and cold has somehow warped the face? Lucky, I have a spare complete intake that I can get my hands on.

Also, is the LIM intake face supposed to be flat, or is there a specific surface that is needed. I never scratched the surface, I just sprayed Deep-Creep to remove the broken bits of gasket that were still left on there. I ran my hand on the surface, and it does not feel even at all at the far left and far right. So before I flatten the surface, I want to check if its supposed to be flat or not :P

I know some people would think that this is a stupid question and all, but the s5 engines for some reason are more of a **** off than the s4 and the 13bre,rew and 20b -_- I sorta wait till I get a response before I poke at the intake anymore. I don't want to create a larger mess that I have made already.

EDIT: I was retarded enough to think that the flange is supposed to me "wavy" but clearly it is not supposed to be so. I ran it hard that day at Mosport and it really looks like the extreme hot and cold temps screwed make the ends of the flange "open"? I can't declare that I fixed this as yet, but I will try all day now and see what the hell is really up here.

 

Update, still not working.... No leaks and no solution atm.... I really have no clue what is going on!

 

use a little RTV to get it to seal up.

if its a little warped this is your only choice other than taking it off and taking it to a machine shop to have decked.

 

Well, It literally has ZERO leaks now, I sprayed carb cleaner left right and center with a straw for more accuracy and it has not affected the idle at all. I used my vac gauge that I had laying around and it also shows no issues. It looks like I may have to pull the engine -_-

 

Just a thought, did you check for leaks between the maf and TB? You won't hear a vac leak because there is no vacuum, but it still throws off the reading on the maf and makes the idle go nuts. Happened on my T2.