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Trilogy injectors / crappy idle


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Just wondering if anyone has experienced any rough idle issues?

I'm gonna see if I can get my old stockers to work and tell a difference later today.

Seems to run fine just idling is rough.

 

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Yeah, Delphis seem to be more challenging to get a good idle with, and run the motor a little choppy off throttle. Mine tends to need to idle a little high, like at 900-1000 in order to respond well in the low/mid throttle range even after a TPS / ISC reset. I can lean it out a little bit and drop the idle but the off-idle response suffers. I increased the fuel pressure to 45ish PSI and that helped, by playing with the fuel pressure and fuel mixture I have it idling around 12-13ish AFR's, I'm happy enough with it not to swap stockers back in.
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I just cleaned the old stockers that came with the car . The primary was stuck closed. Had to clean it and flow some cleaner both ways through it to get that nice spray pattern. Gonna put them in and see how it runs.
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The older TT injectors I kept that I almost sent you instead of the newer ones you have now, work great on my project Palermo car. It idles perfectly, better than my quest with good stock injectors. I think every situation is completely unique when it comes to these darn TBI's... :wacko:
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  • 2 weeks later...

The rough idle with Delphi fuel injectors problem until the engine warms up past 1760 F may also be attributable to the TB shaft seals leaking cuz they haven't been replaced since Christ was a kid. ;)

 

I'll bet that at least 80% of the Starquests on the road haven't had the TB shaft seals replaced.

 

For What It's Worth.

 

KEN

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Keep in mind that a fuel injector has an impedance(ohms) for its internal coil mechanism...

The OE injectors have a known impedance(ohms), the aftermarket injectors can/will have a different impedance. The Mitsu CPU sends a certain voltage to the injector to function/fire, if the impedance(ohms) is different the current/voltage to the injector will vary. This impedance difference is not as critical once the accelerator is being pushed but @ idle it is crucial. A mismatched injector impedance to the CPU will cause a rough idle...

Whenever possible, run OE injectors..

 

Just my $0.02... ;)

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The Mitsu CPU sends a certain voltage to the injector to function/fire

 

For the sake of clarity, the factory ECU (and all aftermarket/OEM ones) ground the injectors to fire. Voltage to the injectors is battery voltage somewhat buffered by the factory injector resistors. The biggest problem we face with injector replacement is the factory injectors are true throttle body injectors with a very pronounced dispersion spray pattern where replacement injectors are designed for port injection with a 15 degree cone spray pattern. So they basically shoot a stream of fuel onto the floor of the factory intake, or in the case of idle shoot it onto the closed throttle plate. The Trilogy Delphi injectors are low impedence injectors just like OEM mitsubishi.

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My car wouldent even start with both trilogy injectors installed so i put one of my good stock primary inj back in and used the trilogy secondary.Started right up runs great,i had to add eextra gaskets to make the stock inj taller and took the big bace rubber seal off the trilogy to shorten that one.looking back i may have had too much fuel psi at the time but just havent tried to figure it out,going mpi now.
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My car wouldent even start with both trilogy injectors installed so i put one of my good stock primary inj back in and used the trilogy secondary.Started right up runs great,i had to add eextra gaskets to make the stock inj taller and took the big bace rubber seal off the trilogy to shorten that one.looking back i may have had too much fuel psi at the time but just havent tried to figure it out,going mpi now.

thats a new one, mixing the 2. Desperate times call for desperate measures I guess
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For the sake of clarity, the factory ECU (and all aftermarket/OEM ones) ground the injectors to fire. Voltage to the injectors is battery voltage somewhat buffered by the factory injector resistors. The biggest problem we face with injector replacement is the factory injectors are true throttle body injectors with a very pronounced dispersion spray pattern where replacement injectors are designed for port injection with a 15 degree cone spray pattern. So they basically shoot a stream of fuel onto the floor of the factory intake, or in the case of idle shoot it onto the closed throttle plate. The Trilogy Delphi injectors are low impedence injectors just like OEM mitsubishi.

 

Lets clarify this subject..

The injectors are fired by the CPU, and the battery voltage has to go through certain series resistors to lower the firing voltage/current similar to how a conventional iginition system worked with a ballast resistor. The issue is that just calling an injector low impedance has no guarantee to equal the operation of Mitsu OE injectors. The purpose of the injector resistors is to limit the current to the injectors.

Note that the Mitsu OE injectors are a specific impedance so that their operating voltage/current meets the factory specifications, to function properly with the CPU. Aftermarket injectors are typically 2-4 Ohms..

One can better understand this by recalling Ohm's law a small difference in impedance can/will change how the injector functions due to different operating voltage/current.

 

In my TSi, I was running the Trilogy replacement injectors and even though the engine ran fine during acceleration, @ idle it had a certain uneven twitch making a rough idle. While kleening the garage, I found my original Mitsu OE injectors since we build performance engines and muscle cars I have access to certain specialized equipment including an injector kleening machine. I ran my injectors through the kleening process and swapped these into my TSI replacing the Triology injectors. I was very surprised to find that my idle smoothed out significantly.

 

Thats why in my opinion... :unsure:

It is always best to use OE parts when available such as injectors, temp and oil sensor sending units. Though these parts are getting extremely difficult to source, I am able to get these directly from Japan when I travel abroad.

 

Just my $0.02... ;)

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Ya I noticed my car ran a lot better all the way around the rpm range with stock injectors. But when I parked the car at the auto parts store it wouldn't restart. The primary was stuck open some causing the car to flood. So I swapped the trilogy injectors back in. Again ran ok with a crap idle.

Then I found a Delphi 785 cc that's the same height as the trilogy's of course. Switched in the 785 cc injector and got rid of the 650 cc for a primary.

That cleaned up my bad idle issues pretty well. This is at the stock 36 psi fuel pressure at idle.

On the air fuel guage with the trilogy injectors at idle. It stays lean.

On the air fuel guage with stock injectors it bounces from lean to rich . The ole light show.

I noticed back along time ago with the 1 g mas my cars like to have the primary switched out for a 86 injector.

This time I got a 60 mm bored tb and intake. With 2 added injector setup welded into the intake.

So that probably changes the behavior of my car as well.

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