Seems like my disco at complete random decided to start acting funny, maybe she doesn't like the cold. It happened to be running great with the tank above half, then one day I let it run down to just below 1/4 tank and this is when the problem started.

1. Now the idle is extremely, extremely high. Not 1100-1500 like other posts, but its idling between 2500-3000 after startup, so I am afraid of throwing her into gear with the engine running that fast.

2. The idle is high, but when in gear she's sputtering, almost chugging. Tach is bouncing between 0 and 900 in gear. I have to really give her gas to move. I drove it home last night with the intention of driving it to my shop this morning, and alas, the final problem.

3. She won't start. The starters trying, but the engine won't turn over.

Fuel issue? Any input would help.

 

1. Tach bouncing makes one think of alternator dying, which would mean battery would be almost dead. Volts on battery with head lights on should be 12.6 or above, truck not running.

2. Cold may be part of the problem. If you have a scanner, check values of IAT (Incoming Air Temp) and Coolant temp to see if they make sense. On my 97, an unplugged coolant temp sensor = -40F = ECU will dump more fuel, and it will idle high.

3. IACV always comes to mind when idle speed issues pop up.

4. You can check fuel pressure with a gauge on the schrader valve on fuel rail on passenger side, should be 32 - 34 PSI. Truck does not have to crank to get a reading, but if truck is not running pump will time out.

 

Thanks I'm going to try to figure this out if i resolve the issue I will post.

 

You have a vacuum leak.
When cold the injectors dump in as much fuel as they can and with the extra air it is like holding your foot on the gas pedal.
When in gear it is still getting to much air but not enough fuel so it wants to stall.

 

Start by cleaning your t/body and the IAC, idle air control, then get back ti use and let use know how it is running.

 

Well, the vac leak spots (hoses) are such a small number of places. If it is a D1, there is the small hose from the fuel pressure regulator to the intake, but if that was off he would have no fuel pressure. There are the ones associated with the "pcv" functions. The vac system for the cruise control is actually separate from the intake (uses its own pump). But a cracked curved hose from air cleaner to intake could be at fault, or gaskets. One pro tech suggested a technique of removing hose from air cleaner, inserting a clean oil filter, and crank engine, the vac leak will turn into quite a whistle.

 

Cleaned the throttle body and swapped the IACV to no avail, caved and brought it to a tech. Will have the diagnosis today but it seems like Spike is right about the vacuum leak. I will post all the steps up once I hear back from the shop in case anybody has this issue in the future. Thanks a lot guys.

 

Martin, fellow NYC'er (with a 1997 DI) here. I sent you a PM.

 

Alright guys. Finally got it. Culprit: Throttle position sensor in cahoots with the fuel pressure regulator. I feel this probably started after a small issue I had and addressed immediately. Spark plug wire resting on exhaust manifold, melted. I changed the cables and plugs and then the fuel issue/idling issue started. That cause all sorts of ****ed firing to occur, I think in turn messing with the signals the throttle position sensor was sending.