jbuck_atlanta

I have a 1989 305ci v8 with auto trans. I believe tbi if its got the fat round thing in the middle. I was just replacing my fan relay again for the fourth time in the past month (could use help on that too) and so I just looked up what all the relays are supposed to look like. Every page seems to mention 3 relays on the drivers side panel but I only have 2(picture at bottom). My engine will also shut off whenever I put it in drive, reverse, or leave it in park for a couple minutes. I also have a question about underneath the tbi round thing that the air filter is in (please tell me the name so I can say it correctly). There is a vacuum hose plugged into the bottom of it that goes to a blue thing in the air filter labeled “AC” in the inside (picture at bottom) and when i unplug it the car idles higher and when its plugged up it shuts the car off. Ive put in new spark plugs, wires, and fuel filter today.

Drew

iTrader: (58)

The quantity of relays varies based on options the car is built with. On a TBI car, you've got a fan relay and a fuel pump relay, so what's missing?

V6 EFI cars have a third relay to influence the A/C compressor under certain situations. TPI cars typically have dual fans, hence another relay. MAF cars have a couple more relays for powering the MAF and burnoff. So while compared to some other cars, it might seem like something is missing, it's simply that the equipment doesn't require additional relays.

The air cleaner, the round thing with the filter in it, has a temp controlled, vacuum operated valve that allows hot air rising off the driver's side exhaust manifold to flow into the aircleaner inlet when the outside temps are cold to help compensate for colder temps. The little blue 'AC' gizmo is a thermostatic valve. When the temp inside the air cleaner is hot/cold enough the valve opens/closes to open/close the heat riser in the inlet. As mentioned, it's vacuum operated. When that hose is damaged, disconnected, or the valve is unhooked, you have a vacuum leak in the engine. The electronic fuel injection determines how much fuel to add or remove to properly balance the air flowing through the engine. One of the sensors it uses to make calculations of how much air is flowing, monitors the vacuum being generated by the engine. So when you have a vacuum leak, the quality of those calculations are impacted, and conditions become less than ideal. Since the THERMAC system is basically a 40 year old band-aid for cold weather operation, and has minimal effect even under ideal conditions, and is far less important than some other things (such as starting, running, operating), it might be prudent to follow the vacuum line from the THERMAC valve all the way back to where it connects to the engine (at the TBI), disconnect it from that vacuum source. Cap the open nipple on the throttlebody, and see if the symptoms change. If it runs better with it capped, look for where the hoses to and from the THERMAC valves could be leaking, or consider leaving it plugged. If it runs better with the nipple on the TB open to atmosphere, there's something else wrong.