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· Science, bitch!
1992 VR4
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965 Posts
Discussion Starter · #1 ·
I picked up some used injectors recently. They were advertised as 780cc injectors, but I’m pretty sure they’re just Delphi 750cc low impedance injectors like 3SX sells. I can’t seem to find the dead time settings for these online unless they’re the same as RC injectors. Does anyone have a reference setting for these?


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· SDSU Alumnus
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5,167 Posts
Do a search on here. I posted some personally verified settings several years ago. They are still working well on Eddie's 99 VR-4, and that is going on eight years with my flash tune on "chrome" modified rom.

However, I will say that YMMV and you should always consider adjusting latency anyway with sizing to suit the car's needs. Case in point, I used the same 750/780's with AEM EMS Series 2 on Ben's VR-4 last year, and it needed major alteration there.
 

· One fix at a time
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9,760 Posts
No but you realistically don’t want to use off the shelf latencies for these cars unless they are Evo 560s. The manufacturer numbers are wrong for our cars because they are based on injector drivers for standalone ecus not our archaic ecus.

What you need to do is start with the stock injector latencies and then say for example multiply it by .8(takes out 20% fuel), then see how the car runs at idle. This is of course assuming it has warmed up to operating temperature to make sure you don’t have the enrichment tables doing multiple corrections. If your car is too lean and not anywhere close to 14.7 but say 17-18 AFR, then multiply the latency value by 1.2(adds 20% fuel). Rinse and repeat the process until you get to 14.7.

Oh and you really have to disable the 02 feedback trims when you do this meaning in periphery 0 disable bits 1 and 4 I think for the 02 sensors. Otherwise, you will be fighting the ecu making +\- 12.5% corrections that will really skew your injector latency compensation and not give you your true latency values.

I hope all of that makes sense but it’s the first key step on any Chrome ecu tune.
 

· Science, bitch!
1992 VR4
Joined
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965 Posts
Discussion Starter · #4 ·
OK, I was thinking the car wouldn’t even run if the latency was off. Thanks for the info and suggestions, I’ll start there.

Oh, and Alan, I searched a lot for Delphi latency or Delphi dead time but didn’t find much. Do you know which thread you’re talking about?


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· SDSU Alumnus
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5,167 Posts
A car will run albeit like crap heh

The thread is eluding me despite a ton of different searches... bleh so I will just post here for more recent and related searches

These values worked well on both EVO8 MAFS and GM LS6 - both 91/Race and Pump-E85. Again, you will need to adjust based on data; there is no "set it and forget it"

Delphi / PTE 780cc (750 flow-tested)
4.69v..........3.825ms
7.03v..........2.445ms
9.38v..........1.545ms
11.72v.........0.975ms
14.06v.........0.615ms
16.41v.........0.435ms
18.68v.........0.300ms
 
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