I'm really running out of things to try here, and I think I know what the problem is, but I want to see what you guys think.

I have a 94 RX7, just turned over 86K miles. I'm not sure if its on its original engine or not, but I suspect that its original (is there any way to tell? Like finding an engine serial number and cross referencing it with the vin # or something?). Anyway, it has a high idle problem that I can't seem to solve for the life of me. When started cold, it idles a little over 3K, but if I blip the throttle it drops down to 1.5K, and never goes below that. If I turn on the headlights, it idles between 2.2K and 2.5K, and if I blip the throttle at this point, it'll drop down to 1200 or so for a second, then go right back up to 2.5K.

I've done TONS of research on this forum, and I think I've tried and checked everything. I just got done with a vacuum hose job. I found one hose with a large hole in it, a bad check valve, and a bad injector o-ring, but other than getting rid of a gas smell, the car runs exactly the same. I replaced all gaskets, the fuel pulsation damper, and injector o-rings.

Things I've tried:
1. Grounded TEN and GRD, and turned in the air bleed screw. It was already out 3 turns, and turning it all the way in did absolutely nothing.
2. Tried to adjust the screw/locknut combo for the throttle stop, it is already adjusted to the point where the throttle plate is competely closed. I removed the throttle body this morning and confirmed that I can't close the plate any more.
3. Checked AWS system. It seems to be working properly. Once warm, it does not move the throttle plate.
4. Checked the idle air control valve solenoid. The only check the service manual has is to check the resistance. Mine checked out good.
5. I thought that maybe the AWS soleniod was screwing up (I'm not really sure how this part of the system works), but I pulled off the small hose off of the intake elbow and plugged it to see if it affected idle. Nothing.
6. I even unplugged the idle air control solenoid just to see what would happen. No difference.

Conclusion:
Since I think my motor is original, I'm wondering if I have a leaking lower intake manifold gasket. Does this sound reasonable? Could the leak really be this bad?

Also, I noticed this morning when I started the car, the fan came on about 15 seconds after starting it. Is this normal?

Another thing.... when I'm under heavy boost, I can smell a fuel-like smell if I have the windows/moonroof open. Its not a raw gasoline smell, its not really strong, but its some sort of fuel smell. I know I'm not leaking gasoline, because I just replaced all fuel related o-rings and the pulsation damper, and I only get the smell under heavy boost. I'm wondering if its from a blown lower intake gasket.

Sorry this is so long..... any suggestions are appreciated.

Paul

 

lower intake manifold gasket leak went on my car at 48k miles. an dyes it could very well be your problem, the syptoims are high idle. do you have a boost gauge? what vaccum readings are you seeing?

anyway, good way to test is to spray some WD-40 or starter fluid around manifold and all intake, boost plumbing. if engine stubles for a bit then there is a leak. replaing the LIM is a pain inthe ***, the guy before me paid about 1300$ christ at that price and with 84k on engine I woudl just pull engine too and port it and rebuild.

or it could be a much simply vacuum leak, or some aspect of the control system.

 

I don't have a boost gage yet. I just bought the car, and its completely stock. I'll have to get one pretty soon... I'm not even sure if I'm getting the correct boost.

Do you know if there are any major problems with driving the car with a blown lower intake gasket? The car seems to run fine except for the idle.

$1300 to replace the gasket?? That seems extremely high! If I remember right, on KD Rotary's website, they quote $600 for the job.

Paul

 

just because it is a good time to replace everything.

I woudln;t try to drive it much, until you know what is going on.

 

Another thing I forgot to mention...

I'm getting a check engine light for the EGR valve position sensor, or something like that (Code 16). The light doesn't come on all the time, but pretty frequently. I don't think an EGR valve sticking open would cause this problem, but I'm not really familiar with rotary engines either. I know on a piston engine, an EGR sticking open will cause it to idle low/rough and possibly stall.

Paul

 

This may seem a bit simplistic but you didn't mention it one way or the other in your post so....

When started cold and the transmission in neutral, it will idle at 3k. If you start the car in ANY gear with the clutch pushed in, it will idle normally.

 

I've tried starting it in first gear, and in neutral, and it still doesn't make a difference. Ever after warmup, it never idles normally. When its warm, it idles at 1.5K without lights/AC on, and 2.2K with lights/AC on.

Paul