What causes high rpm pinging?

[K85 Octane]

My truck runs great through first, second, and most of 3rd. Normally, in the upper range of 3rd, it will begin to ping. When that happens, I let off and it calms down.

Sure as hell sounds like pinging. Like ball bearings rattling around near the bell housing.

Another example. The 5 freeway goes up over my local mountain to about 5,800ft. It gets up there fairly quick. The truck has NO problem lugging 3rd or 4th gear. BUT, if it drops from 4th and into 3rd, BAM.... pinging. At which point I have to pull my foot out of it and run 3rd with less throttle.

Now, I run a FAST EZ efi.
The O2 sensor reads fine at this point. My fuel usage % never reaches 100%, not even close. So it's not the system running out of steam. My total timing is 35* @ 4k rpm. The MSD Pro-Billet dizzy is running the slowest curve springs and the second quickest advance stop. SUPER MILD for a slightly built motor.

Just wondering where I should start. Does it sound like a timing, fuel, or build issue?

Thanks

 

[wetoolowdingbangow]

Thats usually a sign of running lean or carbon build up...

 

[dyeager535]

Does FAST run a wideband O2? Narrowband should be reading rich constantly under heavy load, other than that it's worthless in this case.

 

[Blue85]

As mentioned, the likely causes are dirty (or damaged) motor, not enough fuel or too much timing.

Some troubleshooting:
-drop the T-stat to a colder one and see if the problem goes away
-turn the dizzy back to see if it goes away
-Is there a knock sensor? Can you scan it with your FAST interface?
-Dizzy weights/springs moving freely? vacuum can working right?
-disconnect vacuum advance to see if the problem goes away. You may be getting more from the can than you think or the curves are overlapping too heavily there. Vacuum increases when the truck downshifts.

Injector pulse width won't tell you much (unless you have a very good map of the engines volumetric efficiency, injector characteristics, fuel pressure vs vacuum, etc). What you need to know is AFR. I can't see how FAST could self-tune without a wideband, so AFR is likely close. Can you manually increase the fuel map in that load/rpm region? I hear some FAST guys talk about AFR like the engine has only 3 operating points (idle, cruise, WOT), so I don't know if you can tweak actual map points or if it's just optional.

Unfortunately tuning timing will be all old school and you may want to seek out help from somebody with a dizzy dyno or get recommendations from MSD.

 

[K85 Octane]

Haven't had much time to work on this or even post a decent reply. Work and getting ready for Rubicon takes my time.

I agree, I need to find a dizzy dyno.
I've messed with my cruise and WOT fuel mixtures and it doesn't seem to get better. I've also pulled the vacuum advance off and pulled timing out. I haven't tried to fix this in forever, so I can't even remember what happened when I pulled timing out.

EDIT: I've also tried higher octane fuels like 91, but it doesn't help.

 

[Blue85]

Higher octane not helping makes you wonder if it's really detonation or just something rattling around. Does the engine have a knock sensor?

At what MAP reading and RPM does it happen? You don't want to mess with your WHOLE cruise AFR, just around that specific operating condition.

 

[skunked]

Doesn't the FAST EFI have the ability to control timing? All this vacuum advance spring talk sounds archaic when you have an aftermarket EFI system.

IMO engine tuning is better left to those that do it for a living on a dyno. You're in So Cal, go to Westech and have it tuned properly.

 

[Smokinthehippies]

Doesn't the FAST EFI have the ability to control timing? All this vacuum advance spring talk sounds archaic when you have an aftermarket EFI system.

IMO engine tuning is better left to those that do it for a living on a dyno. You're in So Cal, go to Westech and have it tuned properly.

For that matter. Get ahold of fast. You paid for self tuning. Let them help diagnose.

 

[K85 Octane]

The EZ EFI only controls fuel. I didn't really like the idea of needing a computer to control spark.

I need to call.

 

[Wyomingboy]

So my K-5, 350 is running a FAST EZ EFI also. I have 10.1-1 CR and Iron heads with an MSD standalone dist. I have the medium springs and I was running a total of 40 deg and a 195 thermostat when I was out there in Dec of 2012. While running @ 80mph on the freeway one morning @ 2800 rpm near Oceanside, mine started pinging and I had to back off.
Since then I've backed my timing down to 36 deg total and changed my thermostat to a 180. The truck runs much better with the 180 thermostat. Where you live that would be plenty of temp. for you.

What is your CR and cam setup? I have a lot of overlap, so my cranking compression is only 160psi. If your running closer to 180psi or higher, then you could very well be pinging ? Depends on your engine temp and timing.
Going up in elevation would alleviate the situation due to elevation effects(losing power) unless your getting hot, which I suspect could be part of the problem, cause those long climbs normally cause your 700R4 TCC to unlock and that builds a volcano of heat in the cooling system !

Just some ideas.

 

[folkenheath]

Some people were asking, the fast EZ does have a wideband, it tells you exact A/F ratio. The EZ version does not allow specific parameter tuning though, only WOT, cruise, and idle. It interpolates the rest to populate the fuel tables for you. One would have to get the sportsman version or XFI to allow total parameter tuning with a laptop.

If it were me I would be looking at timing if the A/F ratio looks good. Vacuum can, total timing, etc. Make sure the engine is not rising above your set timing after the RPM you set it at.

The premium fuel not helping the issue makes me wonder if it is something else, like something rubbing it hitting while spinning.

If retarding the timing does not help it, especially if you retard the timing significantly, it is unlikely it is pinging.

 

[Blue85]

The premium fuel not helping the issue makes me wonder if it is something else, like something rubbing it hitting while spinning.

If retarding the timing does not help it, especially if you retard the timing significantly, it is unlikely it is pinging.

This is what I was saying several posts back. Something isn't what it seems.

All this vacuum advance spring talk sounds archaic when you have an aftermarket EFI system.

Just want to point out I'm not the one saying it in THIS thread.

 

[folkenheath]

It's call EZ-EFI for a reason. It's the simplest one they make that is made for people who don't want to deal with the computer controlled timing and the associated installation of it. It works great for what it is. Programmable timing could be added for $300 with an MSD box or with the EZ-EFI 2.0. Or you could get XFI and leave the stock systems in the dust. Or go Holley Dominator or Big Stuff 3 and leave everything else in the dust and make them archaic. Different installation levels and different cost levels as well, they all have their place if you ask me.

 

[Blue85]

They do it so the EZ-EFI is seen as a carb replacement. This logic works assuming you already have a running engine with the timing set well. On a new build you have to set timing one way or another. Getting a default table in the ECU would match some default spring/weight combo in a dizzy and be "EZ-er" to adjust.

 

[folkenheath]

I would agree with that, but not everyone would. And you still have to sync the dizzy timing to the computer timing. For my next build I will convert to DIS and not have to worry about rotor phasing or springs, weights, cans, etc. But many old timers would rather set the distributor timing than mess with a laptop. EZ-EFI 2.0 you can set the timing without a laptop.

I just find it funny how they market a super simple EFI system for simple carb replacement and everyone says it's archaic. Actually, the self tuning feature was quite state of the art when it came out and it actually works. Now others have followed suit. Leaf springs are archaic too, but we still use those.

I think the EZ EFI is great on my truck, and I would buy it again. But I would choose others for other applications. I think it's good we have all the options, there is something for everyone.