what are the symptoms of actually running out of fuel pump or injector?

[RealMcCoy]

Why would you think it isn't spark blow out...? Mid 20psi range is where the stock ignition is known to give up. That's precisely why I haven't turned mine up over 22 psi... One of these days I'll step up and buy an ignition amp, and see what it can really do...

[thor'svr4]

maybe im wrong but ive talked with Ray several times about my ignition system and every time hes told me to simply buy a new set of OEM coil packs/wires and the ignition system will take whatever you can throw at it. maybe he was referring to lower boost levels.

but even if i was getting spark blow out, wouldnt the wideband read really rich since there would be a lot of unburnt fuel entering the exhaust?

[RealMcCoy]

Wideband is an oxygen sensor... It measures oxygen, and only oxygen. The mixture ratio is calculated by the how much oxygen is left after combustion. That calculation assumes proper combustion occurred. Misfires send unburned mixture down the pipe, and the only thing the sensor sees is the O2, and skews the calculation lean.

[BaadVR4]

Wideband is an oxygen sensor... It measures oxygen, and only oxygen. The mixture ratio is calculated by the how much oxygen is left after combustion. That calculation assumes proper combustion occurred. Misfires send unburned mixture down the pipe, and the only thing the sensor sees is the O2, and skews the calculation lean.

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This. When a spark plug fails to fire, the unburned air/fuel mixture causes the 02 sensor to "see" a huge amount of Oxygen, and it "reads" the condition as "lean". Very lean.

The first indication of an intermittent misfire, especially at idle, is the wide band 02 gauge bounces around, going lean after a misfire, back normal when there is no misfire.

Spark plug blow out is just another term for "misfire". And even an intermittent, almost un-noticeable misfire will have huge affect on 02 gauge reading. Your symptoms sound exactly like misfire. The misfire could be caused by either ignition system issues or fuel issues. Look at both.

[Roybatty]

This may be helpful to you. Stealth 316 - Injector Duty Cycle Calculation

Depending on your logger, I thought I remember reading the IDCs that MMCD shows is too high.

[GTWHOA]

I found 20psi to be the sweet spot on my 13Ts. Is your knock sensor even plugged in?

[thor'svr4]

A buddy of mine just sold me his MDS DIS-4 HO for dirt cheap so i'll throw that in the car. i'm not sure how the MSD compares to the HKS/AEM/Kenne Bell ignition amplifiers but for the price i paid it cant hurt to try the MSD out. worst case scenario i can sell it.

Also i know my knock sensor is plugged in and working.

also i finally got home from school to pressure test, there weren't any leaks.

[Lugnut]

FWIW I had zero fuel issues on the DR750's with a hotwired Walbro255 and 680 precisions installed .. Went up to 28 on the boost on pump and meth as well .. IIRC I had spark blowout around 22-23 on new coils wires and colder plugs and it seemed like the car was almost sputtering a bit .. breaking up and losing some power .. Added a DLI and the problem went away ..

[GTOJOE]

How cold where your plugs. I have a set waiting that are 2 grades colder than stock but thought maybe it's overkill. Also have a dli to install.

Sent from my GT-I9300 using Tapatalk 2

[Lugnut]

One stage colder .. Check the gap before you install .. They can be all over the place outta the box !!!! ... Below is a post Matt from DR made in a thread about DR750's and plugs ..




There are 3 plugs I would recommend

1 heat range cold

the BCPR7ES, this is a good all around plug, long life and not Expensive
Another very good choice is to go with a NGK R5671A-7 This plug is a non-resister plug so it will be less spark blow out prone then the Resistor BCPR7ES is.

2 Heat range cold

R5671A-8 , This plug is also a non resistor plug and will pull more heat from the chamber. But will foul easier because it's a 8 heat range.


But most importantly get a HKS twin power DLI. This will allow a larger plug gap, better idle, and say byby to spark blow out.


And STAY AWAY FROM ANYTHING iridium! I can not stress that enough.

My DR-750 car had the same set of BCPR7ES's in it for over 2 yrs going back to when the car had 16T's on it. I have a HKS DLI, and was running a 0.030" gap. I ran the boost 20+psi that entire time (and up to 32psi). I just started getting a little blow out a few weeks ago when running over 30psi, I pulled the plugs and thy had so many miles on them that the gap had eroded to over .036", so I went ahead and replaced them with a set of the non-resistor's.