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Discussion Starter · #1 ·
We did the full zzp stage 1 . Northstar throttle body different mass air flow. Exhaust manifolds. Smaller pulley and PCM tune. Now car cuts out after 1/2 throttle and shifts at like 3000. Zzp won't help me. Anyone have this issue or know why and how to fix. Never had issue until throttle was installed. Idk if we got wrong throttle body or wrong mass air flow. Got throttle outta 2001 Northstar . Which worked great with adapter. And used mag from 04 Silverado 5.3.
 

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First things first, the northstar tb doesn't come with zzp's stage 1 setup and seems like overkill for your current setup. Secondly your main issue I believe is the silverado maf. When you change your maf to a different one or upgrade to a much larger tb such as the northstar the tables in the pcm have to be adjusted for it. The programming for the ZZP pcm in the stage 1 kit is probably still for the stock maf & tb. Put back the stock tb & maf I bet your issues go away
 

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Discussion Starter · #3 ·
We did the full zzp stage 1 . Northstar throttle body different mass air flow. Exhaust manifolds. Smaller pulley and PCM tune. Now car cuts out after 1/2 throttle and shifts at like 3000. Zzp won't help me. Anyone have this issue or know why and how to fix
First things first, the northstar tb doesn't come with zzp's stage 1 setup and seems like overkill for your current setup. Secondly your main issue I believe is the silverado maf. When you change your maf to a different one or upgrade to a much larger tb such as the northstar the tables in the pcm have to be adjusted for it. The programming for the ZZP pcm in the stage 1 kit is probably still for the stock maf & tb. Put back the stock tb & maf I bet your issues go away
They told me with the PCM tune that we got and all the modifications we needed to have the lq4 Mass air flow and the North Star throttle body I got a throttle body from a 2001 Cadillac Northstar and I got a mass air flow sensor out of a 2004 Silverado I don't know if they are right and they will not contact me back The car was fine until we put the throttle body on other than that it runs good but it cuts out at half throttle what
 

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Discussion Starter · #4 ·
First things first, the northstar tb doesn't come with zzp's stage 1 setup and seems like overkill for your current setup. Secondly your main issue I believe is the silverado maf. When you change your maf to a different one or upgrade to a much larger tb such as the northstar the tables in the pcm have to be adjusted for it. The programming for the ZZP pcm in the stage 1 kit is probably still for the stock maf & tb. Put back the stock tb & maf I bet your issues go away
I don't know if it's the correct mass airflow sensor or if it's the correct router body that they told me to get because they won't reply to me
 

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Discussion Starter · #5 ·
I just simply tried to do what they told me to do I got the correct throttle body that bolts up to the adapter but I don't know if the mass air flow sensor was right but they did tune it for the LQ4 mass air flow and the North Star throttle body cuz that's what they said we needed to have.
 

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Discussion Starter · #6 ·
I just simply tried to do what they told me to do I got the correct throttle body that bolts up to the adapter but I don't know if the mass air flow sensor was right but they did tune it for the LQ4 mass air flow and the North Star throttle body cuz that's what they said we needed to have.
Whatever stage it is that we got they had to tune the PCM for the throttle body and mass air flow sensor cuz we have the air intake system the cat delete as well. And I forget what size pulley but technically it's one size less than what we're supposed to have for stock internals
 

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Discussion Starter · #7 ·
First things first, the northstar tb doesn't come with zzp's stage 1 setup and seems like overkill for your current setup. Secondly your main issue I believe is the silverado maf. When you change your maf to a different one or upgrade to a much larger tb such as the northstar the tables in the pcm have to be adjusted for it. The programming for the ZZP pcm in the stage 1 kit is probably still for the stock maf & tb. Put back the stock tb & maf I bet your issues go away
Any idea with this more info?
 

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The LQ4 actually refers to the 6.0 liter vortec v8. While being very similar to the 5300 both being LS-based they are still considered different engines. Doing a quick search on rockauto it seems both engines do share the same maf sensor so that eliminates that. Does the MAF sensor still have the screen in it? If not the sensor may not be getting a good reading on the air coming in. There was alot of discussion on this years ago and it was determined you are always better off leaving the screen in and there wouldn't be much if any restriction caused by it. When I got my ported tb from zzp it didn't come with a screen and they claimed at the time you didn't need it with the ported unit. Me like an idiot without thinking sent my core back with the screen. I don't remember exactly what issue I was having, but I ended up finding a new screen. I felt like the car actually ran better after I put the screen back in plus it makes more of that cool sucking noise. One more thing I would check is the throttle position sensor. Are you using a northstar TPS or are you using the 3800 one still? The northstar TPS would need an adaptor harness for it as the plug is round (whereas the 3800 plug is oval shaped). Both look like they would mount up but because the Northstar tb is much bigger it wouldn't get an accurate reading.

Just thinking out loud, but hopefully one of these things fix your issue
 

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Discussion Starter · #9 ·
The LQ4 actually refers to the 6.0 liter vortec v8. While being very similar to the 5300 both being LS-based they are still considered different engines. Doing a quick search on rockauto it seems both engines do share the same maf sensor so that eliminates that. Does the MAF sensor still have the screen in it? If not the sensor may not be getting a good reading on the air coming in. There was alot of discussion on this years ago and it was determined you are always better off leaving the screen in and there wouldn't be much if any restriction caused by it. When I got my ported tb from zzp it didn't come with a screen and they claimed at the time you didn't need it with the ported unit. Me like an idiot without thinking sent my core back with the screen. I don't remember exactly what issue I was having, but I ended up finding a new screen. I felt like the car actually ran better after I put the screen back in plus it makes more of that cool sucking noise. One more thing I would check is the throttle position sensor. Are you using a northstar TPS or are you using the 3800 one still? The northstar TPS would need an adaptor harness for it as the plug is round (whereas the 3800 plug is oval shaped). Both look like they would mount up but because the Northstar tb is much bigger it wouldn't get an accurate reading.

Just thinking out loud, but hopefully one of these things fix your issue
Thank you I will check that and yes I am using the adapter harness
 

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Discussion Starter · #10 ·
Thank you I will check that and yes I am using the adapter harness
All right it is the same mass air flow sensor so I should be good there unless by chance I got a bad one. They also told me that the throttle position sensor might be bad even though I checked it on the scanner and it seemed to be right I did replace it on that North Star throttle body for an actual Cadillac I didn't look it up for the Bonneville but it still got like half throttle and I mean it's like somebody turns the fuel off it just does not rev no more past half throttle It does in park it'll rev up to full RPM but when you're driving it shifts at three grand and doesn't do anything after half If that helps any I mean I've been emailing them like few different times and they won't even respond to me anymore They took the computer back and retuned it again because the first time they didn't tune it for the mass air flow and the throttle body so we sent it back and then they did it and this is the last bug we need to get worked out do you think a bad mass airflow would cause this. I mean I've seen a lot of bad mass air flow sensors on GM's before but I've never seen them do something like this but I've never modded anything before either
 

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1998 GTP coupe. All stock and rust free. That will change soon.
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Can I assume that when you changed out the manifolds you reinstalled new plugs and wires. Did you use dielectric grease in the wire boots at the coils and plugs? Do you have a scan of MAF frequency and throttle position to show the MAF signal is not working properly?
 
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