Just did a 6th and 6th port clean. Replaced oil lines that run on vacuum. It starts fine every time, revs to 3 grand, then dies. Will continue running if I push on the throttle. Doesn't sound terrible, but not great either. Had trouble reading vaccum diagrams. Any suggestions?

 

The oil injectors actually receive metered air, not vacuum, but this shouldn't be an issue if you hooked them back up to the original location.

Did you replace the intake gaskets when you reassembled the manifold? A vacuum leak is the most likely cause of the problem you're describing. It can be hidden at higher RPMs, but a large enough leak will stall the engine when it tries to idle.

 

Yeah metered air makes sense. I'm not too experienced with vacuum systems, but I do have experience with working on engines (out of vehicle)

Does it matter that the oil lines were not primed aka. they are full of air?

Yeah I replaced the resolution chamber gasket, reused the metal intake gasket after cleaning it and the surfaces it seals. I'm sure I hooked something up wrong with the lines. I'll post a pic tonight. For any of you experienced 13b-ers, hopefully you'll be able to help me identify the problem(s).

Thanks,
Richard

 

The oil lines don't need to be primed. You can't exactly run the engine with the whole UIM (upper intake manifold) off, and the air will just be pushed out into the engine by the metering pump.

By resolution chamber do you mean the dynamic chamber/plenum (right after the throttle body)? If you removed whole manifold to expose the intake ports, you would have 3 gaskets:

1) Plenum to UIM
2) UIM to LIM
3) LIM to block

The OEM Mazda ones are paper gaskets. I don't think I've ever seen a metal one before. Something else to consider is how the manifold was bolted back down. If the support bolts on the driver-side of the engine were tightened down before the ones along the runners, it can created a gap between the LIM and UIM.

 

https://www.rx7club.com/2nd-gen-archive-72/how-cleaning-5th-6th-port-sleeves-51210/

This is the thread I was referencing while working on the car. I didn't have to take off the plenum...

 

Anything seem out of place?
What's that brass looking nipple for in the middle of the upper intake? lol. There's a real noob question.

 

CHECK OUT what came out of my exhaust the first time I fired her up! lol.

Also thanks Rocket for your solid info on the possibility of a vacuum leak. I think that was the problem.

You know where the intake branches off before the throttle body? 3/4 inch or so tube that runs along the firewall to the drivers side? The lines there are really loose I think that was my problem. I'm going to hose clamp all those connections tomorrow and hook up a vacuum gauge to see where I'm at. But the good thing is today I got it idling!! lol. What a triumph.

 

The brass connection in your first picture is the cold start assist valve. That system was recalled because it never worked properly. The valve can be removed, and a block off plate can be placed over the opening on the UIM.

The ~3/4" hose runs over to the AWS valve & BAC, which are part of the 3K RPM warmup system & idle assist. A leak there could definitely cause some headaches.

 

well she's running - sort of. Vacuum measured out to be only 13 I replaced many of the lines already. Going to pressurize system tonight if I get a chance and see what's up. Idle is good.

 

Arrrg. Back to taking it all apart again. Oh well, it can't hurt to get more familiar with the engine ;-) I'll post again after I get it back together...again. (probably a week or so)