Could someone please tell me where this vacuum is supposed to go?

TIA

George

A more overall photo of your engine bay with the part circled would be far more useful here. I've got an Iron Duke and yet I have no idea what or where that is.

ok

likely nowhere... It is common on many engines to have spare ports.

It may have gone to cruise if you have that option. Otherwise it's capped.

------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurasic Park)

The Ogre's Fiero Cave (It's also at the top of every forum page...)

On my '87 Duke, that fitting is capped.

Thus if you dont have cruise control, you should likely put a rubber cap over that to stop the vacuum leak that's resulting now.
Also, is it me or does your air filter lid have a pair of holes it shouldnt?

Thanks guys. I plugged the vacuum port and the car ran well until it warmed up. I am getting codes 25 and 35. It is also backfiring at low rpms and it got to be barely drivable. Any ideas?

Error 25 on a V6 is the MAT, but I have no idea on a 'duke. Error 35 is idle speed too high/low.

I would start by disconnecting the battery, to clear out the ECM's memory. Wipe the slate clean. After the ECM re-learns the idle, fuel mixture, etc, see if the problems return.

On that note, after clearing the ECM you should take the car for a several mile drive, taking it up to highway speeds for part of it so the ECM can properly re-learn.

Thanks for all of the replies. I cleared the codes and took the car for a drive to relearn. The backfiring has stopped but I still have a lack of power in acceleration. This car has been wonderful to drive up untilthe last few weeks. I guess it is time ro start trying to diagnose.

read the DIS and 700 series TBI articles in my cave...

I changed the Map and Mat sensors and disconnected the battery. Took the car for a drive to learn and it still has no power. I pulled the plugs and they all look very good. The funny thing is now the idle is ROCK solid at 800 rpms but if I try to hold the rpms at anything over 1000 it stumbles. Is it time to check fuel delivery?
I am open to any suggestions.
Thanks,

Geo

Stumbling exactly how?

When there is an ignition problem on DIS you most often backfire like mad thru the intake. If you aren't doing that I'd think the ignition is fairly sound. Tho if you pull the brick for any reason you'll want to throw a new crank sensor on it at the least. Cheap insurance. New set of plug wires, even if they look good to you isn't a bad idea either. Especially if the current ones are unkown age or more than a couple years old.

Allot of backfiring may have damaged/stuck the EGR which can do weird things depending on just what is wrong with it. Idle is even so it's probably not sticking open but it could be opening when it should not just above idle.

Are you certain the MAP EGR etc is on the correct TBI port. It matters. Should be shown on the deck lid. It also in my cave someplace.

Backfiring may have killed the catalyst and partly blocked the exhaust. read the emmissions articles in my cave. You can test for back pressure fairly easy but you'll have to find a low pressure gauge and make some stuff to connect it into the O2 sensor fitting. (Just leave the O2 sensor out for this test.) To avoid burning the guage... have a couple feet of metal tubing between the manifold and gauge. No exhaust actually flows up the tube so it will keep the gauge cool enough long enough to do the test w/o damage. You need a gauge with 0-5 PSI maybe 0-10 in a pinch. No higher. You should only be reading a couple PSI max and a lager gauge won't be sensitive enough.

And don't forget to check the cable to the gas pedal... If it's not able to open the TBI to WOT, which is very likely, then you've found at least part of your problem.

Thanks Ogre
When I try to hold it at 1000 rpms it will stay ther for about a second then then drop rpms for a second then climb back up. I will replace the plugs and wires tomorrow Just hate to be a parts changer instead of being able to diagnose.

Thanks for all of the help,

Geo

I took the car to the muffler shop to have the cat replaced. He sawed the old one out and it was toast, but the car did not run any better. He seems to remember a Fiero he worked on last year and he seems to think it might be ECM related. Could be corrosion around the connectors or bad ECM? Could anyone give some advice on how to check the ECM without a scanner? What to look for? Voltage?

TIA

Geo