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Discussion Starter · #1 ·
I have a 1998 Jetta TDI.

My #1 injector is running zero at idle, lean at half throttle and then rich after that. My mechanic switched out that injector with another one and it is doing the same thing.

This problem came up after I replaced head, although it may be unrelated. My mechanic says that should not make any difference.

Someone suggested the pressures are not balanced, if that is the case could someone please explain how to diagnose and fix this.

I have been using Stanadyn additive religiously.

Thanks in advance.

John
 

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Discussion Starter · #4 ·
This is what my mechanic is thinking, any additional insight would be greatly appreciated.


I'm leaning toward a control (pump,ECM, adaptation?) issue since the substituted injector is producing the same results as your original injector. If it's a delivery (injector) issue then the presumption is that injector #s 2,3,4 have all failed in the same way and the probability of that is unlikely.

I think the big question is how does the ECM come up with the mg/stroke figure that is displayed on the laptop. Is it the amount of fuel that is being requested? Or is it the actual amount of fuel that is being delivered? Requested fuel may be adjustable thru the ECM adaptations. Delivered fuel is probably related to the pump or the pop off valve for #1.

On boost they give you both, requested & delivered so you can fine tune the wastegate.
 
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