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Tom109
12-08-2011, 12:19 PM
Looking for insight to solve an idle/stalling issue on our 1996 D1. It runs excellent under power, but once warmed-up and closed throttle the RPMs drop to zero. I replaced the IACV but problem persists. I've checked/replaced vacuum lines, but have not entirely ruled-out a vacuum leak. I'm told the following could be potential causes:
A. Faulty MAF idle bypass
B. Clogged flame trap
C. Throttle position sensor
D. Crank Position Sensor

Since the truck runs great, aside from stalling, I'm hesitant to believe it's C or D, but open to be proved wrong. Any suggestions for the next step? Anyone have a functional MAF they are willing to loan (for a possible sale)?

Need to get this thing back to safe driver status ASAP!!!

Regards,
Tom P.

Frank84
12-08-2011, 06:13 PM
Try simply unhooking the wires from the MAF and see what that does (assuming you have a code reader to clear the code it will likely throw).

I'm not as familiar with the 1996-1999 DI, but a DII will go into a default program and often run much better with the the MAF disconnected if it is faulty.

parovertech
12-08-2011, 07:25 PM
If you replace tha iac, you need to set the base idle with a T4 to have it run correctly.

Tom109
12-09-2011, 09:29 AM
Frank - I'll try a test drive or two with/with-out the MAF connected.

Parvotech - Anyone in the club have access to T4?

Tom P.

parovertech
12-09-2011, 10:21 AM
I have one, i am in kennett square.

Tom109
12-09-2011, 11:13 AM
Does this sound like a case of T4 base idle adjustment and I'm good to go? How involved is the process? Have any time available this month?

Tom P.

parovertech
12-09-2011, 11:30 AM
To me it does, but without seeing the car its hard to tell. I could make time this month,

rvrsrvc
12-12-2011, 06:15 PM
Tom, on the top of throttle body housing, there is a approximately 1/2" circular plug that covers the base idle adjustment screw. (Sometimes, the plug gets removed for adjustment but doesnt get refit, so it may just be a port now.)
If the seal is still there, you could drill a hole, run a self-tapper into it and work it out with a pair of pliers on the screw. (I have a small slide hammer that does the trick, but not something everybody has in their tool kit!)
The adjustment screw requires a 3/16" allen key to turn it.
I would recommend spraying some sort of lube, WD 40 will work, into the opening as the adjustment screw is sealed with an o-ring. Keep track of how far you turn it. Counterclock wise allows more air into the by-pass, raising RPM. I would limit my exploratory to no more than a full turn. After that, something else needs attention.

This is relatively temporary- it should be adjusted to a spec that is available through a scan tool like Jon's T4 or my Autologic.

Tom109
12-14-2011, 11:03 AM
Thanks for all the input. I have not, and do not want to mess with the idle adjustment screw. I'll manually fine tune the IACV this weekend. I think I can solve this way...

Tom P.

Tom109
01-24-2012, 10:04 AM
Anyone have a known "good" MAF (to fit a 1996 D1) that I can borrow to troubleshoot my Disco?

I'm about 90% sure it's down to the MAF, but hesitant to throw $200 at it unless I'm sure...

Tom P.

rvrsrvc
01-24-2012, 06:10 PM
Tom, I've got a 96 D1 that I appear to be unable to sell. I can hold off on posting it on Craig's list for a week or so if you want to try it. This Rover runs very well.
PM or EM your address and I'll get it out in Wednesday's UPS. trevor b4x4s com

Tom109
01-25-2012, 09:28 AM
Trevor, you're awesome thanks a million! However, I was able to rob one off a running but derelict D1 locally. At least this will give me a comparison point.

I found new aftermarket MAF's online in the $100 range. Funny, considering the genuine MAF runs close to $1800 :confused:

Tom P.