V1 Mikes Extended, Full Frame Goblin - 2009 Cobalt LS with 135k donor

[Ross]

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.

 

[mike_sno]

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.

 

[mike_sno]

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.

Good idea, I have an IR camera.

 

[Rttoys]

Don’t forget the stupid stuff, like vacuum leaks or a mass air flow installed backwards.

 

[mike_sno]

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.

 

[Gtstorey]

Not sure where you are on diagnosing this but I would switch coil first.

 

[mike_sno]

Problem solved. I looked at the not working cylinder and saw that the insulator came out and was stuck on the old injector.

 

[ah.b.normal]

Problem solved. I looked at the not working cylinder and saw that the insulator came out and was stuck on the old injector.

Great it was a simple fix!

 

[mike_sno]

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%.

 

[mike_sno]

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?

 

[Chris_WNC]

How are you getting injector duty cycle? I’ve only been able to find avg pulse width bank 1.

 

[mike_sno]

How are you getting injector duty cycle? I’ve only been able to find avg pulse width bank 1.

It's under the math

 

[Chris_WNC]

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.

 

[mike_sno]

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.

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.

 

[Gtstorey]

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.

 

[mike_sno]

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.

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.

 

[Gtstorey]

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]

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

 

[Gtstorey]

Not sure what I was thinking, but number of Cylinders does not figure into the calculation. Never mind.

 

[G Atsma]

Not sure what I was thinking, but number of Cylinders does not figure into the calculation. Never mind.

I think that works only IF the 4 cyl is the same displacement as the 8 cyl. Easy mistake.