Mikes Extended, Full Frame Goblin - 2009 Cobalt LS with 135k donor

Ross

Ross

Goblin Guru
A lazer temperature gun pointed at each exhaust pipe when the engine is running, will tell if you have 1 bad injector, or cylinder.
If you don't have a lazer gun, you can see how long it takes a cold exhaust manifold to get too hot to keep your fingers on.
 
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mike_sno

Goblin Guru
Yes, that was the first things I checked. The fuel rail sits in is place, I would think that means that the injector are also sitting properly.

It could be that the wiring harness is different? I'll check that tomorrow as well.

I just saw that I can reset the fuel trims in vcm scanner and disable the injector individually. That's what I will try tomorrow and see if that feels me narrowing down the failure.
 
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mike_sno

Goblin Guru
Ross said:
A lazer temperature gun pointed at each exhaust pipe when the engine is running, will tell if you have 1 bad injector, or cylinder.
If you don't have a lazer gun, you can see how long it takes a cold exhaust manifold to get too hot to keep your fingers on.
Click to expand...
Good idea, I have an IR camera.
 
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mike_sno

Goblin Guru
Ok, first check with the IR camera. One Cylinder is not running. Checked the wiring harness, it's correct. Will investigate further and maybe switch this injector with another cylinder.
 
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mike_sno

Goblin Guru
Made some tuning today and rented the fuel pressure gauge from Autozone. With 60lbs injectors and full throttle the pressure never dropped below 54psi. Idle is 60psi. Injector Duty Cycle reduced from 125% to 73%.
 
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mike_sno

Goblin Guru
Question regarding the Injector Tuning. I have the ZZP Siemens deka 60lbs injectors. What I found on HP Tuners forum, is that with an injector usually a set of parameters come, which can be copy and paste into HP Tuners. I can not find this information for the injectors I have. The only thing I found are those 2 pictures below. Question 1: Does anyone have the factory data for the Siemens deka 60lbs injector?

Question 2: in the picture 1 it says Minimum Linear PW 1.5ms. In Hp Tuners, I have 0.094 ms for the 43lbs injector. This value should be 1.5ms according to the picture. That is factor 15 higher. It seems to me that this probaly should be 0.15ms. Which would indicate an error in the HP Tuner software. Can someone confirm that?

46487
46488




46489
 
Chris_WNC

Chris_WNC

Well-Known Member
Neat.
So your graph numbers are half values of duty cycle? 31.8 in the graph equals 63.6% duty cycle?

If so...I need to lay off the boost until I get different injectors.
 
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mike_sno

Goblin Guru
Chris_WNC said:
Neat.
So your graph numbers are half values of duty cycle? 31.8 in the graph equals 63.6% duty cycle?

If so...I need to lay off the boost until I get different injectors.
Click to expand...
I don't think so. I think the graph is the actual duty cycle. With the old injectors I was at 125% but only when I was at high rpm and high boost. It was short enough that my wideband sensor never picked up a lean situation.
 
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Gtstorey

Goblin Guru
You need to confirm the injector math is correct for a 4 cylinder, unless HPT labeled a for a 4 cylinder. Since it fires 2x more than an 8 cylinder per revolution the duty cycle is double for a 4 cylinder for the same pulse width.
 
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mike_sno

Goblin Guru
Gtstorey said:
You need to confirm the injector math is correct for a 4 cylinder, unless HPT labeled a for a 4 cylinder. Since it fires 2x more than an 8 cylinder per revolution the duty cycle is double for a 4 cylinder for the same pulse width.
Click to expand...
How would I do that?

I have limited doubt that the math is wrong. The old LSJs came with too small injectors. I had the 43lbs and maxed them out. Just eyeballing, the reading should be correct.
 
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Gtstorey

Goblin Guru
Calculate injector firing time vs time it takes for the engine to run through both strokes on all 4 cylinders. Probably an online calculator if you look. I’m sure you can find a formula if not a calculator.
 
Chris_WNC

Chris_WNC

Well-Known Member
My HP Tuners math for Injector Duty Cycle shows as:
Injector Pulse Width (minute) * Engine Speed (rpm) / 2 * 100
 
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