low side drop.hplz06 tune rev 3.1.hpt
I have what appears to be a low side pump going out. The vehicle is 7 years old with 62k miles. I would have expected it still to last longer than this. Is there anything I could try to up the low side pressure? Is there anything else I can check before I condemn the pump? The pump is a huge job to do.
I also would like to mention there are no codes being thrown and it runs great otherwise. Its a new purchased vehicle to me so I started logging to get a baseline of where the car is at. Seems to make good power but was having issues with a lot of knock at first.
Low side pump does look unusually low even under wide open throttle runs. That being said, however, it does not seem to be impacting performance to the HPFP (yet). I went ahead and made some changes to your fuel pump system on the low side, and hopefully this helps it out some, no guarantees though. Revise the changes I made on the change comparison log so you can see what I did and give it a whirl. Worst case scenario, you are looking at a low side that is on its way out.Originally Posted by kenand1988
Attachment 125279
Last edited by ZLRob; 10-20-2022 at 03:45 PM.
I also want to try and replace the line with the check valve by the hpfp rail. Its cheap so its wort a shot. thank you for taking a look at my log and tune! it seems like a dirty fuel filter or something.
No problem! I hope it helps you out in a positive way. It should honestly, but the rubber will meet the road once you flash it over and give it a shot.
I hear those lines can be a problem, but given that you are stock (I'm assuming you are right?) I wouldn't condemn the line as the problem and there definitely isn't an excess of fuel demand here necessary if you are stock.
Last edited by ZLRob; 10-20-2022 at 05:16 PM.
Yes it's bone stock which is why I was surprised to see what the low side was doing. I'm putting a different supercharger on it. I already know a low side fuel system is in the future for me but the plan was to see how far the stock system could go. From this it would seem not much further but I will try out your changes and report back.
Yeah normally the Z06 fuel systems are actually more stout than the ZL1's and can handle more fuel demand than the ZL's can so it's a little surprising to see that happening on yours at such low mileage. I'm hoping your knock is contained and handled at this point as well. I didn't track it on your log, as the only thing I was looking at was fuel on the LPFP and HPFP side.
I used a good known spark table for the high octane map, changed some retard settings as well. The knock was all over the place at first. It could be all the way through the pull, the second half of the pull or right at the end. No rhyme or reason. Cold mat or hot mat. I turned off cot too. It was like 5 degrees or less knock. That had me worried I thought maybe the dealer put 87 in it. Octane booster did help too.
If you have cats, it would be in your better interest to turn COT back on. There is a higher chance of burning out your cats if you turn it off. Ideally you want to be within less than .5 degrees of knock range. anything over that and you are pulling timing which equates to good usable power loss. Do you have an AFR sensor on this thing for your tuning purposes?
Where do you live? If you have access to 100 octane fuel, it would be better to use that instead of octane booster because legit octane booster contains MMT and will turn your spark plugs, sensors and exhaust tips orange.
These damn LT4's are so particular man. Lol.
I hear you. Most of what I did was to diagnose the knock and fuel issues. I'd never rely on octane booster and don't plan on buying the 100 or 105 octane stuff we have around here I think it's $9 a gallon. Along with new supercharger I'm going to do some long tubes. I just ordered an aem 30-0334 wideband.
With cot on targetjng . 74 lambda it drops high pressure
You don't need to fill up full with 100 octane, all you need is a few gallons to raise up the octane a few points. It's the cost of owning these cars man, no way around it unless you go flex fuel/ E85.
Your COT features need some dialing down is all, but like I said, if you value your cats and have emissions inspections its in your better interest to keep them. Your tune is probably adjusted pig rich anyways. Something that GM corrected for the ZL1's when they released them. Along with the taller supercharger lid.
Short of having to mix fuel, if you only have 91 available in your area and don't want to use octane booster then you would have to neuter the tune by removing timing under WOT which would in effect lower your overall power output. That is another option that is there for you.
Yeah it'll be great to see what the afr is doing once I get that wideband. I probably will try to run like e30 later on. I don't have emissions where I am. To start though it's getting an ESS centrifugal blower which should drop the iats to just a few over ambient.
Are you referring to the MAT's, not the IAT's? The manifold air temps are the ones which are the prime contributor to pulling timing if they go up too high.
Since you are tuning your car it is really important that you get that wideband on there, because targeted AFR's don't really mean much. Especially if the MAF scaling is incorrect.
Correct. Without the stock blower there will be alot less heat mat should be roughly what iat is on a good Centri blower setup. I haven't touched anything to do with fueling aside from turning off cot. I know I can't tune it withouf a wide and.
I've always been interested in why the values in the ZL1 and the Z06 are so wildly different. Part of me really wonders if it has to do with GM learning from their mistakes in what would be Gen 1 LT4's vs. I guess what could be seen as Gen 2 LT4's. I could send you a stock 2017 ZL tune so you could see the differences if you want to see?
From what I remember Z06's were tuned pig rich by GM from the factory.
I didn't realize they had so many differences between the two. My guess would be the heat problem with gen 1 lt4 is why they wanted things more rich. Sure you can pm me or post it here if you like.
Maybe. I know they definitely did have a heat issue for sure. Most owners abated those issues especially at the track by switching to Water wetter, Engine Ice or similar with their coolants since water has better heat dissipation properties over antifreeze. Are you running any sort of external LTR reservoir for the supercharger? That was one of the first things I did on mine and I also switched out my coolants to water wetter on the engine and supercharger side.
Here is a factory 2017 A10 ZL1 tune
Attachment 125285
I am not. I did add water wetter to the intercooler system but it did basically nothing. Not sure if I also needed to replace the coolant with water to get a big result. The ess blower will be air to air.
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