Over the years, I've read many good experiences on this site with the Magnacharger kit, so I decided to try one on my 2003 5.3 Silvy. I was quite impressed with the hardware and the installation went smoothly. The throttle response is more than I expected and daily driveability is fine. However, I am having a problem with significant detonation at partial throttle. At WOT, it pulls hard and there is no detonation. At any throttle position below where boost begins, or at very low boost, there is no detonation. But at throttle positions just above low boost in a range of 1800-2200 rpms, there is constant detonation. Unfortunately, that's right in the normal 4th gear (4L60) every day driving range. It's just like a lean condition, but only at a narrow boost level. It is also taking much longer to start than ever before. I've owned this truck since new and it has always started on the first revolution of the starter. Now it takes 7-10 starter revs.

I contacted Drew, the calibration tech at Magnacharger, and told him of my problem. He first suggested that it was the noise from the supercharger at no or low load conditions. But I had a detonation problem once before when I had a performance tune for regular gasoline and which caused detonation at WOT, so I know what it sounds like. Changing to premium fuel solved that problem and I've used Chevron premium ever since. Drew said he thought he could solve it with a tune update which he sent me and I installed, but there was no change. He tried another update and still no change. He said there was nothing else he could do. Out of desperation, I added a can of NOS octane booster to my tank and that didn't help.

My engine temp runs between 185-200 with electric fans, the intercooler system is ciculating properly, and I can hear the booster fuel pump operating momentarily when I turn the key to the ON position. I can find nothing else that might contribute to this problem. I'm not going to be able to drive with detonation much longer now that things are heating up here in Florida. Anyone have any suggestions?

 

You don't want to be just getting into boost in 4th with the converter locked. Are you talking about constantly being into boost when cruising or just when you try to accelerate gradually? Are you towing something? What size blower pulley? Is the bypass functioning properly- is it closed when the engine is not running and does it open (watch the actuator) when the engine is started? Is the vac line connected to it and to the nipple on the intake tube?

 

I had the same exact problem as you, i could not get it to stop pinging, i tryed tr6 plugs, i checked my intercooler pump circulation, installed a 160 t-stat, checked all my engine grounds, checked for vacuum leaks, i installed long tube headers, had superchips send me a new tune that they said might help, and it still pinged around 1800-2200 rpms just crusing under light excelleration, finally i had a local tuning shop (Dyno-Comp) dyno tune my truck, belive it or not my truck was running alittle lean causing it to ping, from what i here the maggie tune is a really safe tune, but it just was not for my application, after having it tuned i gained 25 hp and 35 tq and no ping any more, i couldnt be any happier. they set my fan temps to match my colder thermo stat, raised my speed limiter, adjusted my speedo to match my gear and tire ratio, and more. hope this helps you.

 

DrX, it's just my daily driving and when gradually accelerating in the moving traffic. It's a new Magacharger, so everything appears to be funtioning properly.

Silverado11, thanks. Good to hear that someone else had the same problem under the same conditions. I felt all along that it's too lean and I would have thought that the two updates would remedy that, but you're probably right...a little too conservative on the tune. We have a good local speed shop and I think I'll let them see what they can do with it. I don't know anything else to do.

 

It definitely needs to be checked out for FP, AFR, air leaks, etc. Sounds like it is going lean. Tunewise, you might need some tweaking of the PE, trans and converter tables if you are getting into boost with the converter locked in 4th and the pedal is not down far enough to trigger enrichment (PE). The engine will not be able to increase RPM fast enough to accommodate the extra air being jammed into the cylinders and a lean condition will result = knock. When I had a similar setup, I had to decrease the pedal position at which the converter would unlock and/or the trans downshifted to 3rd to prevent it loading up.

 

my toyota used to do that also, maybe with a tune It would clean it up. It never caused me any problems.

 

When accelerating but not WOT, there's still vacuum in the manifold right? Even a relatively small amount of vacuum should cause the bypass to open.

 

when i had my truck on the dyno at Dyno-Comp they hooked a boost gauge, air fuel gauge, fuel presure gauge up during the all the pulls while tunning, you cant beat that lets you see whats all goiing on, and the tuner let me sit next to him and work woth him, he showed me why it was pinging (lean) i learned alot of cool stuff. he said that me adding the coolder intake, long tube headers, just mad it run leaner. good luck!

 

If it is functioning properly and the engine is not lugging. He says he is seeing boost.

 

I have not seen anyone suggest checking the fuel pressure..........have you done that yet?

Dont harp too hard on Drew, it is hard to diagnose issues over the phone