alrighty. for those that missed my first thread, i found why my engine would fire and die. turned out i forgot to put bolts in 2 of the 4 omp intake holes. car fired up but would only idle roughly at about 500rpm w/ the adjustment screw all the way out. i tried taking it for a spin and made it to the nest street before having to turn around and then barely made it back. after looking around, i see i left the afm unplugged. so i get happy at such an easy fix, plug it in, and then go to fire up the car. no dice. it'll catch then die. i screwed the idle adjustment screw back to normal. no good. all the way closed, no different. so i back the screw back out, unplug the afm, and it fires up again and barely holds the same idle as before. i'm guessing i have a vacuum leak still. not sure where it would be though.

history: the motor lost comression due to carbon on the apex seals. motor was rebuilt. i have eliminated the omp, air pump, and rats nest. the omp is hooked up and dangling in the front of the engine bay. all the vacuum ports are capped at the moment, including all the ones around the secondary injectors. pictures are at http://home.insightbb.com/~patryn/its.htm .

 

Sounds to me you have a large vaccum leak. Your saying that your secondary injectors arent hooked up at all? (plugs not connected?) You need to connect them, but i'm not sure if those not being hooked up will affect if it will idle.

Have you taken off the upper intake manifold? if so, check to make sure that your gasket is in usuable condition.

 

all the gaskets are new. secondary injectors are hooked up. my middle intake does have a broken section on the outerbolt hole. i might be leaking there. however i sprayed it with carb cleaner and didn't get anything of note out of the motor, so i fifured it was still sealing. i'll check it again tomorrow. i've still yet to buy a replacement. heading to the forsale section......

 

how could you spray carb cleaner in there and check if your car doesnt even run?

if you are trying to do it with the afm unplugged, you wont find any change.... it is a set fuel map

 

you didn't read my post. the car runs now. but only with the afm unplugged and the idle adjustment all the way out.

the idle is pretty rough as well. i checked all the sparkplugs for spark when i couldn't get it to stay running. they are fine. the cas adjusted all the way to one side smooths out the idle. i moved a tooth or so over but it never fully cleared anything up. i'm sort of stuck at this point. i thought maybe the broken section on the vdi manifold was causing a vacuum leak, but i sprayed starter fluid on the area and didn't get any change in idle. i've sprayed just about everywhere looking for vacuum leaks without having found squat. another note is that the idle speed increases when i pull a vacuum line off.

 

you ghave a busted airflow meter. get a new one. your welcome.

 

i dont call what your car is doing 'running'

you have a big leak

push the flapper on the afm open with it plugged in....

it should run then...


dont bother spraying starting fluid, you arent even using the damn afm... the fuel amount is a set value from the ecu.


re-read what i said

 

I don't even know where to start to figure this one out. Check for air leaks big time like the others said.

Remove the afm and ohm it out to the FSM is another step. Make sure the vane isn't sticking. Got me.

 

the carb cleaner has nothing to do with the afm, it will still change the idle if there is a leak. I had the same problem and after i ran it a few times it just kept getting better until it starts right up with the afm. Make sure the car is warmed up before you plug the AFM, if it runns then its about tuning. Mine was just hella rich with the afm plugged in. After its warm I could get it to run good. I asume you have the fuel pump on a switch cause otherwise it wont run very long without the AFM. Also what they said about leaks and to hold the flapper open when trying to start. Get a vac gauge and youll know if its got leaks. 15 or more is good.

 

still won't run with the afm when it's warm. i'm getting a new vdi manifold from a local guy. i'm going to scour everything when i put it on. i don't have a switch on the fuel pump and it's running w/o the afm plugged up.

slpin: no flapper door on a 91, but i'll give what you are saying a try.

 

ok, bought a vacuum gauge. rough idle at 500rpm netted into the needle bouncing from 5-10. holding my foot on the pedal to hold 1k netted in the needle bouncing between 14-15. another note is that the car is half driveable until it warms up. once it warms up, you can't touch the throttle w/o it stumbling and possibly dying. now i've never checked vacuum but i'm guessing the needle shouldn't be bouncing. when i revved the motor cold, the needle would hold solid as i revved up to 20-30 on the gauge.

 

If the rotary works the same as a cylinder engine than in order for the car to run it has to have a vacumn. If you hook up a boost gauge to your car it will read a vacumn and a boost side and then at 0 should be outside pressure. So in theory your car should be pulling a high vacumn at idle like 18 or 19 on the boost gauge and be a 0 at WOT unless you're boosting. Now if your car has avacumn leak the idle will be at something like 15 or less causing a crappy idle. Look out the back of the car and see if you have any black smoke comming out when you try and go WOT. If there's some immediatly then you have a vacumn leak just like everyone said or there's an issue with the measuring part of the air. Otherwise the only other thing it could be is the spark.

 

it's not a turbo.

however that's my question. what should vacuum be at idle and should it hold solid?

 

.

 

I would imagine it's close to the same. You need a good vacumn for a good idle.

 

what you get in vac seems good. It will bounce if the motor is struggling to run. Does your AFM make any difference plugged in or not. You mght want to see about checking it out per FSM with a voltmeter. Ive never done it but there must be a procedure. Does the car seem very rich? If you have a good vac then move in the direction of a fuel mix problem, too much or not enough. THe afm would cause this or possible a bad primary injector.

 

quick update. finally purchased a good vdi manifold. installed it and still getting the same issue. so despite the broken piece, it was still sealing well enough.

i think i'm going to move towards the injectors. bd94, the car won't run with the afm plugged in. however i checked the resistance and it's within spec. it takes 5 or so cranks to get it to hold idle. it'll fire and die. then around the 5th time or so, it'll hold an idle. plugging the afm in raises the idle really quick and then it dies. i'm guessing it isn't a vacuum leak since i can pull a vacuum line and the idle raises.

 

Jeremy, what ever happened with your car? Did you get a new afm to test?

 

I'm having the exact same problem with my S5 TII J-spec swap. If you you've found the solution to your problem please post.

 

I'm surprised he didn't listen to you. I agree 100%.

Spec the AFM. If it's out of spec, replace it.

 

alright. for those who smartassed the answer "afm", you were wrong. my ghost problem turned out to be a cracked and leaky oring on the fuel pump. mazda also can't just give you the oring, they want to sell you a 3 piece set with the plastics included. anyway, i figured a few of you might find it useful. my advice, get gauges and make sure everything (like fuel pressure) is correct.