I started a post almost a year back because there was some kind of idle surge on my truck. This issue passed by but the truck developed another issue; I had to give it some throttle to keep it idling otherwise it would die. I researched the issue and Cosmic 88 helped a lot but everything I tested seemed to be good. The truck was properly tuned. I ended up replacing the IACV which cured the problem the first time I started the truck but then the same issue reappeared. Which had me guess that it wasn't getting any signal to close it. I'm starting a new thread because I feel my old one is not relevant.

Back in August I had to park the truck because there was a broken fuel line I was waiting for parts.

My brother repaired the fuel line which was broken right on top of the sending unit, and I got the parts. The truck sat for maybe a month or so but once everything was replaced, it was very hard to start. The truck is firing but not enough to keep it running.

Back in october, I managed to get it running I went for a ride. Upon acceleration it doesn't sputters, it accelerates well, it drives well there is no issue while driving only at idle. I took fuel pressure readings which were 38 PSI while cranking and around 30 PSI while driving. There are still CEL codes ; p1508 IACV open circuit, the B2S2 O2 sensor is bad. I also noticed that when in park, if I put my foot down it hesitates before revving up.

Yesterday I worked on it with my brother and we've never been able to get it running. We double checked his repair and it's good the is absolutely no leaks. Spark is good (i heard it spark from inside the truck). It's getting fuel. When it fires it sounds like it's not getting enough fuel to run but we took 2 plugs out and they were black, sooty and wet. The oil also smells like gas. Which means it's probably flooding and it's been running rich for god knows how long. I opened the ECU there was no corrosion or apparent damage to it. When priming the fuel system I heard a hissing sound, but there was no apparent leaks under the truck.

But the truck was properly tuned-up:

-Spark plugs were done at the end of 2010 but the truck wasn't driven that much since
-O2 are less than 2 years old
-Wires are 3 years old
- IACV is new and the throttle body is clean
- Good air filter
- Cleaned MAF

I'm completely lost with that one, and I got a mechanic puzzled with it.

 

If code says IACV open circuit, it may be clean but not moving. Would suggest removing it, don't move by hand, and turn on key, should see plunger move about as it hunts. Could be a wire or connector issue.

The IACV is a stepper motor with two coils. One coil is across the red/green and green/white wires, the other is fed by the Blue/slate and Orange wire. See attached page from the free RAVE download.

 

Forgot to mention we checked it. I put the ignition on and then off and the plunger was moving properly, closing then opening when the ignition was put on and then fully opening after the ignition was turned off. I almost lost the plunger because it opened all the way and the spring sent it flying.

Continuity in the wires between the ECU and the IACV tested good.

 

Some people have found that after replacing an IAV and cleaning out the manifold opening that they have had to go have the IAC programmed to run with the engine. yours, even though new, may need to be reset.

 

Does that mean a trip to the Dealership? Or is there another way to reset the IACV?

 

What puzzles me is that, even though the truck wasn't idling properly it was easy to start it before I parked it. A little throttle did the trick.

Unfortunately Danny I think it does. But the problem is that the truck doesn't run and the closest dealer is 50 km away. Unless the scanner where my brother works does the trick, his boss just got it and it's pretty complete.

 

see Land Rover Discovery MPI stepper motor - YouTube, works for an earlier version of the control.

see this one https://landroverforums.com/forum/di...63/#post145438

Could also try leaving battery cable off for several hours. Once battery cable is off, turn on headlights and leave on (they won't light) to drain any stored charge in strange places. When doing this have door unlocked, alarm not on, and a window rolled down if possible.

 

The truck has been sitting since September. I took the battery off to charge it. I'll try that for the IACV although on that Disco the IACV is on the throttle plate.

 

You got any video of the one on ours? GEM version.

 

I actually went a more difficult path, could not get mine to drop idle, changed IACV three times, all the tricks I could find at the time, had not found this site or the RAVE, and went to junk yard and bought ECU and IACV from same truck. $40. That problem saved. Hoping one of the factory level techs will divulge the back up re-set the adaptive values method.