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No acceleration to pass (LY6)

jdot2004

jdot2004

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Not sure if I'm posting in the right place but I don't know that it is an injection problem.

So, I swapped an ly6 and 4l70e in my k5 it seems to idle fine and run fine but when I open up the throttle to pass it just dogs and won't accelerate. I've checked my fuel pressure, it was high due to return pressure, but I was able to correct that and now have 58-60 ish psi. I recently cleaned my injectors so I don't think they are the issue. Plugs and wires are new. Transmission is new. What else would cause this issue? Also, If I back off on the gas I can get it to accelerate slowly but not enough to pass and I'm not getting any codes.
 
Is this a gen3 or a gen4 set up? Is the throttle pedal and linkage all from the donor vehicle?
 
@Bent77
gen4 (08 ly6 from a 2500 hd) pedal is not from the donor but the pedal I put in was noted for the harness and tune from psi conversions. No linkage, drive by wire. Unless you mean shift linkage which I use a lokar kit,not from donor.
 
jdot2004 said:
@Bent77
gen4 (08 ly6 from a 2500 hd) pedal is not from the donor but the pedal I put in was noted for the harness and tune from psi conversions. No linkage, drive by wire. Unless you mean shift linkage which I use a lokar kit,not from donor.
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I was curious about the drive by wire and if it was reading/functioning correctly

Any idea on fuel pressure?
 
Key on its at about 52-54. Running at idle 58-60. Revved while running maintains 58-60
 
Fastereddie said:
Maf backwards?
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Arrow goes toward the engine right? (Not meant to sound sarcastic I just want to be sure since I am not a mechanic and have never taken on this type of project before)IMG_20190713_103239214.jpg
 
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I’m not a LS expert by any means, but I thought I read something about the maf not supposed to be right in front of the tb. Not sure though. You say no cats but you do have the primary/forward O2’s installed correct?
 
Fastereddie said:
I’m not a LS expert by any means, but I thought I read something about the maf not supposed to be right in front of the tb. Not sure though. You say no cats but you do have the primary/forward O2’s installed correct?
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Needs to be at least 6" from throttle body. I'd move it to the filter end of the intake tube
 
Fastereddie said:
I’m not a LS expert by any means, but I thought I read something about the maf not supposed to be right in front of the tb. Not sure though. You say no cats but you do have the primary/forward O2’s installed correct?
Click to expand...


Yes for the o2. And I'll move the Maf and see what happens. Out of curiosity, why the distance from intake? Would my bad location cause this symptom of lack of acceleration? And should I clean the sensor because it was so close to the intake?
 
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Being so close to the throttle body it doesn't read the air flow correctly. Too much turbulence. Can cause all sorts of poor performance issues.
Shouldn't need to clean it.
 
Is this a new problem or has it been doing this since first drive?

Definitely move the maf sensor away from the throttle body.
 
How much volume of fuel are you getting? Because you can have plenty of pressure and little volume. I would als be curious about TPS voltages, or a timing issue.
 
Chevy305 said:
Is this a new problem or has it been doing this since first drive?

Definitely move the maf sensor away from the throttle body.
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I think it's a new problem but I babied it the first few drives then the transmission failed.

I moved the sensor but am waiting on a 4" coupler to complete the relocation. No local stores carry 4" so I had to order one.
 
INChubbs29 said:
How much volume of fuel are you getting? Because you can have plenty of pressure and little volume. I would als be curious about TPS voltages, or a timing issue.
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Not sure how to check fuel volume. What should the tps voltage be?
 
You know anyone local with hptuners that could log it for you? Doesn't cost credits to log it, maybe someone can help you out. Having a log of what's actually going on in the pcm will probably make figuring the issue out alot easier.
 
Tweekls1 said:
You know anyone local with hptuners that could log it for you? Doesn't cost credits to log it, maybe someone can help you out. Having a log of what's actually going on in the pcm will probably make figuring the issue out alot easier.[/QUOTEn
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No I don't. I did find a somewhat local shop that does tuning that told me to bring it by. He wanted to take it for a ride to see if he thinks it's in the tune or what it may be. Just need to replace the power steering pump, that just went, and put the air intake back together first.
 
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