2008 H2 with Magnacharger preignition issues while towing
 

Let me start by saying, my 2008 runs just fine everyday driving and even when driving it hard. Recently I’ve done some towing. My family and I towed a can am x3 max on a trailer. The whole thing probably weighs 4500-5000lbs.
Earlier this summer when it was about 90 degrees outside, we drove it up the mountains and had horrible spark knock issues. We figured out that the intercooler had ran out of fluid from not being properly bled. After filling it up, we had no issues, but by that time we were going down the mountain.

Today it was 85 degrees and we were towing up the same mountain. The load may have been slightly less but not very much. There was not consistent pinging when going up the hill like before, but in a couple of spots I noticed a little bit of knock for a second or two. The intercooler is full and flowing properly. I really am not sure what to do, because I don’t want to be throwing a whole bunch of money at the thing after just getting brakes done all around and a new transmission.

From what I have read online here are some of the possible things it could be.

-undersized intercooler heat exchanger: the one included for the hummer kit is way smaller than the one included on the Escalade and other trucks with the exact same engine and supercharger kit.

-bad knock sensor: I’m not sure about this one. Wouldn’t that throw a code? And would that even correct for a lot of knock?

-thermostat: I’ve seen people put new lower temperature thermostats in, but is this necessary?

-carbon buildup: I really would not know how to solve this issue or even identify it but I have heard it is an issue on these engines.

-poor tuning: this just has the canned Magnuson tune they sent me. I’ve heard people say it’s pretty good actually and they couldn’t do better themselves. Magnuson says the tune and supercharger are great for towing.

-exhaust leak: I know I have a pretty decent exhaust leak on the manifold. And I highly doubt it would make any sense though I have seen people talk about it before. The knock does sound like it is coming from all cylinders.

The truck has 97k miles on it. Other than this it runs great. I’m a broke 16 year old with not a lot of money to spend on this, so I need some advice on what to start with. Should I contact Magnuson about this? Or is it just an absolute waste of time.

You need to get the exhaust leak done first, before you burn a valve. Are you using 93 octane fuel?

Carbon can certainly cause your issue and a good cleaning can definitely help. GM top engine cleaner and BG products are two of the best. Go to BG products and search find a shop, in your area. After those two items are done then you can see about a retune.

If you continue to pull that mountain while pinging. You will need a BIG wallet soon.

Ok so I should address the exhaust leak and carbon buildup before going further. Carbon buildup seems likely. Could the exhaust leak cause pinging? That's what doesn't make sense to me.

Like stated Run High Octane fuel. the extra Octane is to keep the knocking at bay. are you running regular to save on fuel prices? if the engine was stock that's what is recommended but ram forced air down it's throat and your going to need the extra high octane just to keep the engine from blowing at idle let alone hauling weight up down grades.

Agreed..... as far as I'm aware the timing tables used with a SC are optimized for, and require running premium only. Otherwise there is a potential for spark knock, which if bad enough can cause engine damage. If already running premium, then I'd suggest getting a Diablosport Intune, then get Monte from http://diablewtune.com/ to make you a new tune based on the current installed tune with the timing pulled back some. Then you could switch it to your "towing" tune when needed and switch it back when not. If you explain to him what your goals are he could even make other optimizations in a tune specific for towing like changing some of the shift points and pressures. There might be other brands of handheald tuners where you can have someone make a custom tune as well (I've personally used Monte for remote custom tunes before) or spend a good bit more on EFILive or HPTuners and do your own tunes as well for other options.

I run premium 93 all the time. Last time it had regular was 40k miles ago before the supercharger.

I will consider that once I run out of options. I think I am also going to contact Magnuson to see if they have updated the tune. It was installed quite a while ago.

today a check engine light came on for p0030 for the drivers side secondary o2 heater circuit on my way to school this morning. When doing the trans, the dealer broke the wiring for the o2 sensor and did a hack job to fix it. The code has only appeared once before and went away, but maybe an intermittent o2 sensor is throwing of air/fuel mixture causing a knock. That combined with the leak might be the cause.