Thread: ZD30 - Limp.
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Old 11-07-2019, 14:20   #1
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Join Date: Jul 2016
Location: Northumberland
Vehicle: Patrol GU3 (Y61) 3.0 SVE
Posts: 1,285
Default ZD30 - Limp.

I feel like the heading to this thread is more of a statement!

But I have a query/issue that I just don't know the answer too.... And I haven't been able to solve the issue with my Dawes Valve.

Let me set the scene:

In the morning I get in the truck to head of to work. I drive down my road which is a mile long 1st at 20mph, then it turns to 30mph, then to for the last 200 yards leading up to a T-Junction it's national speed limit. (I achieve around 50mph before I have to slow for a bend and then the junction right after.)

I wait at the junction for my time to pull out and when I do, this is where the problem happens.

The Truck is Auto, so it takes care of the gears. As it builds up speed and gets to about 40-45mph and the revs get to about 2500rpm up I'm at around 16psi of boost (Limited by the Dawes to 17psi) all of a sudden progression is halted!

I can keep my foot where it is and I will maintain the exact speed, like its hit a limiter or I can briefly ease off the accelerator, let the revs drop away put my foot back down and carry on gaining speed. (Every now and again, when I ease off and back on again, it might repeat the limiting process... But never more than twice in a row!)

If this is 'Limp Mode' then I thought setting the Dawes to 17psi would eliminate this? As I understand, the ZD30 usually creates 18psi and sometime spikes which causes the Limp Mode to kick in?

So this has me baffled... Any help would be appreciated.
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