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Old 11-28-2017, 12:38 PM   #1
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Location: Kingsville, MD
Default 1989 745t lh2.2 fuel questions

In light of my desire to begin turning the boost up on my 1989 745, I would like to proactivley add some fuel into the equation. It is my understanding that LH2.2 has a resistor pack due to the low (high?) impedance injectors that need to be bypassed in order to run high (low?) impedance injectors from another Volvo, browntops, etc.

Also, I have read about installing a 4bar FPR. From what I understand, my stock injectors are rated for 300cc/min @ 3bar. Would the stock 3bar with browntops be a good combination for a mild performance increase, or is a 4bar FPR really worth it?

As much as I dislike the idea of doing what sounds like major electrical surgery, does anyone have any pictures of said modification? Does anyone have a picture of the DIY tool to set the idle after the modifications are done? All of the pictures in older posts have broken links.
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Old 11-28-2017, 01:04 PM   #2
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In stock form, the LH turbo cars run low-Z injectors + the resistor pack.
To change to high-Z injectors (like those from a newer Volvo) you simply need to remove the resistor pack.

You can turn up the boost a bit (from ~7 to ~12psi) without changing to bigger injectors or a higher rated FPR. (I have orange-top injectors from an 850T5, similar to stock green-top low-Z turbo injectors, and a 3bar FPR and have not had any lean conditions with small boost increases as mentioned above).

However, I HIGHLY recommend getting a wideband O2 sensor before you start down this path b/c otherwise you are just guessing at how the engine is responding to your mods.
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Old 11-28-2017, 01:08 PM   #3
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Injectors come in low and high impedance, brown tops are low impedance like the stock injectors. They provide more fuel and you can get them to idle and cruise properly but you have to adjust the screw on the AMM considerably. Lh2.2 does not adjust automatically to larger injectors so you can't just throw some 72cc injectors in there and expect it to work. I have a set of reman brown tops that I'd like to sell, I put about 3-4k miles on them. I wouldn't fool around with the FPR, it will just make it harder to dial things in
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Old 11-28-2017, 01:27 PM   #4
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Installing higher flow injectors when running LH 2.2 will have you pulling your hair out. I installed Bosch 0 280 150 934 (same spec as Ford Racing 0 280 150 945). I've ended up running a 2.5 Bar BMW fuel pressure regulator to prevent fuel washing the cylinder walls resulting in oil/fuel on the end of the tail pipe.
Trying to understand stupid people is like trying to pick up a turd by the clean end.
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Old 11-29-2017, 12:19 PM   #5
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Pm'ed on the brown tops
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Old 11-29-2017, 12:22 PM   #6
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So I found a wideband setup that I can actually afford.

Does anyone have any pictures of the DIY idle adjustment tool/board?
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Old 11-30-2017, 06:08 AM   #7
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I've had two 745's. Those should have TD05-12B'S, which too me aren't bad turbos. Not going to make earth shattering power, but they respond nicely to increased boost.

Anyway, I ran 15psi with an RSI Stage 1 on the OE injectors (green tops)! That said, how far do you want to go?

And wide bands are really only a must if you are running stand alones (Megasquirt, Motec, etc...) and particularly during tuning. If OTOH you are just turning up the boost on a
stock turbo and you are reasonable (don't turn that puny turbo up beyond 1 bar), you'll be fine with a narrow band.
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Knuth also cites a letter sent to him by Dijkstra, in which the latter adds some nuance to this earlier statements: "Please don't fall into the trap of believing that I am terribly dogmatical about [the go to statement]. I have the uncomfortable feeling that others are making a religion out of it, as if the conceptual problems of programming could be solved by a single trick, by a simple form of coding discipline!"
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Old 12-02-2017, 01:54 PM   #8
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2.2 has no learning capability. You can adjust the base mixture to compensate slightly. I could not get stock 940t injectors running properly on my old car and they only flow 10% more than 2.2 squirters. This was monitored with a wide band.
I did dyno the car at 205whp at 12 psi on a big turbo with many other mods, but stock injectors. Until you're past that power level, there's not much point upgrading injectors.
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