orion84gsl

iTrader: (5)

Good point. I guess this is what happens when you skim posts. Information goes unread and you end up assuming. And we all know what happens when you assume.

henningmd

First of all thanks for all the help/suggestions.

I've compiled a lot of information from searching this forum and other web sites. I have gotten a copy of the Haynes manual and a copy of the factory service manual, timing light, and vacuum gauge and have ordered a laser tach to help me narrow down the problem that I am having. A friend of mine is coming over Saturday morning to give me a hand with it as well. I am trying to put together a plan of attack for the problem and would like to run it by you guys for any suggestions.

1) Check the vacuum line that runs from the #2 AAB valve to the lower rear of the intake manifold. Might as well check it when the engine is cold since it is so close to the exhaust, right? Seems like a likely suspect if the vacuum is really 10" as the dealer tech. told me. This brings up another question. Where should I connect the vacuum gauge to check the actual vacuum?

2) Check the ignition wiring for proper routing; wires going to proper plugs, ignition coils firing proper plugs, etc.

3) Check leading and trailing ignition timing. Since the idle is set higher then the 750 rpm it's normally set at (according to the dash tach and where it had been idling historically) will this throw off the adjustment of the timing? I don't know if I can get it to idle at 750 rpm like the FSM calls for when setting the idle.

4) Check for other vacuum leaks. Can I disconnect all the vacuum lines and plug the ports on the spacer plate, carb and intake manifold? It appears that all of the lines are on the driver side except for the one going from the#2AAB valve to the rear of the intake manifold. Are there any other ones that are hidden or in a different position? I was thinking that if I couldn't find a vacuum leak with everything connected that I would break it down into various sections. Such as tracking down the connections to one port at a time. Has anyone else tried this?

5) Oh boy, here goes! Try to remove the rats nest! I truly hope that it doesn't get this far as I'm not all that mechanical but in for a penny in for a pound!

henningmd

Okay here's what I've done so far:

Removed the vac hose that runs from the #2 AAB valve to the intake manifold. It was fine not burned thru, real soft or brittle.

Checked the timing when warm and both the front leading and trailing were right on.

Took it to another shop and told them the problem with the high idle and the pinging under acceleration. They returned it after "scoping it", and adjusting the carb and timing. Guess what? Same thing as when I dropped it off!! Wonder if they even touched it.

I ran most of the gas out of it and put in a can of sea foam filled the tank with fresh gas. So far it runs the same.

I want to check the vacuum to see if indeed I have a vacuum leak. I purchsed a vacuum gauge for this purpose. What should the vacuum be on a 12A carburated engine and where/what line do I attach the gauge to?

I am leary of the timing as the engine is now idling at about 1200rpm. Is the vacuum advance already affecting the timing at this point.

If I don't have a vacuum leak and can't get the idle down to 750rpm would you guys suspect that the dealer messed up when he rebuilt the carb.? I didn't have the pinging issue before the rebuild of the carb.

j9fd3s

iTrader: (3)

i teed a vacuum gauge in with the vacuum advance on one of my 12a's, i recall getting around -18psi at 850rpmish idle.

i suppose you could put the carb together in a way that its got something wrong where it idles high like that, its got a lot of pieces.

the advance works like this. at zero throttle, (it does have a throttle position sensor) the vacuum advance is OFF, above zero throttle the vacuum advance is ON

at 1200 rpms though the mechanical advance is starting to come in, its probably only adding a degree or two though, so not a big deal.

jinxed4dub

iTrader: (7)

since he's having vacuum trouble, wouldn't the timing advance be messed up? So how can timing be on if there's not enough vac pressure.

I'd just go through and replace every vac/emissions hose. I'd also check the pipes that run on the firewall to the brake booster. It can't hurt to replace the fuel filter anyway. after a couple years that things gotta be clogged up pretty good.

Kentetsu

Go to Sterling's site and read up on how to tune the idle: www.sterlingmetalworks.com

henningmd

Okay guys, it's been quite awhile since I got back to the issue of my '85 Rx-7 GS not idling when warmed up and the pinging on acceleration. I ended up in the hospital with a heart attack and it's been awhile since I've done anything with the car. So here goes!

After the first dealer played around and got the car running worse then when I took it in, I took it to another dealer. The mechanic there found the cause for the pinging was due to the first guy replacing the coasting valve in such a way that it was messing up the shutter valve and it was stuck kind of in the closed position causing the car to run lean. At this point I coulddrive the car again but it still wouldn't idle.
It turns out that the mechanic who worked on it also works on the cars on the side and is into racing them and rebuilding them on the side and is a lot cheaper then the dealers. So, I took it to him and here are the progress reports from the mechanic:

I have not gotten anyware on your car unfortunatly. Everything I have tried so far ends in the same , no idle. I'm to the point now where I am pulling my hair out. I have a few last things to try and then I'm pulling that carb off so you can send it back because I believe it is no good, no fuel flow for the idle. there are no air leaks what so ever, I even changed the intake manifold gasket and O rings. I have gone as far as to block all vacum lines to the carb and plate off. I have checked the ignition and it appears okay. I'm going to take a fuel pump out of another car that I have and see if that does the trick as well as the carb and all the emissions sensors from that car as he wants a Webber. Things are not looking good for your car at the moment.

And now:

As you know I was trying to resurect your Rx7 but alass I am afraid the conclusion is the engine has gone south. It has compression but not enough which is why there is not enough vacum at idle to keep the engine running. The good news is I have had a few other customers ask about your car and were asking if you would sell it "as is" and for how much.

Okay guys, HELP!!! Does anybody have any other ideas?

Verneuil

there may be a way to try to restore the compression. Or just do a full rebuild.

Kentetsu

Just remember that a flooded motor will show low compression. Make sure you perform your own checks before you take somebody's word for it.