Pinging (I think) with 87 octane

[Schurkey]

I’ve been running 93 octane, seems to get rid of a ping (sounds like cricket chirp) when under load accelerating, and gets way better fuel mileage. I’ve read this could be egr (which I know nothing about),

I would not have described "ping" or "detonation" as sounding like a cricket chirp. But if more octane makes the noise go away, that's probably what it is.

Detonation ("pinging") and a malfunctioning EGR system go hand-in-hand. If the V-6 EGR valve is like the one on my '88 5.7L (Negative backpressure sensing, has an "N" near the part number stamped into the top) it should hold vacuum when tested. If it leaks vacuum, it's defective. If it's seized, it's defective. Sometimes they can be cleaned, sometimes they have to be replaced. If you manually lift the diaphram/pintle at idle, the engine should stumble. Let go of the diaphragm/pintle, and the engine idle should recover and become smooth. If the idle doesn't degrade with the pintle lifted, the exhaust passages in the intake manifold are plugged with carbon, which will have to be chipped- or solvented-out

The EGR vacuum system needs to be checked as well.

or it could be wrong spark plug?? I’m running e3 diamond fire just to try.

I'm no fan of "gimmick" spark plugs, but scrapping them is not the first thing I'd do.

Verify EGR as already discussed.
Connect a scan tool, verify ALL the sensors and computer outputs, in particular the knock sensor and ignition advance/retard. If you tap on the cylinder head with a small hammer to simulate detonation, the timing should retard which you'll notice as a reduction--and then recovery--of the idle speed. Initial timing is not adjustable, but if the knock sensor, sensor wiring, or the electronic spark advance/retard isn't working right, the ignition timing could be way "off".

I filled up with 87 lately to try and save some money but I don’t want to keep doing this if causing issues. Any guidance in troubleshooting would help a ton!

87 octane should run just fine in that engine.

Consider fully-warming the engine, then directing a "urine stream" of water into the throttle body at FAST idle (~2000 rpm or so.) When it's me, I over-do it by using about a gallon of water; and then I have to change oil afterward to get rid of crankcase moisture/contamination. This should "steam-clean" your combustion chambers to eliminate excess carbon that might raise compression or cause combustion-chamber hot spots leading to detonation. Costs almost nothing to try; and using water doesn't make the neighbors call the fire department due to the smoke from products like Seafoam or GM Top Engine Cleaner dumped down the throttle body.

Get rid of the gimmicky plugs. Either go with AC Delco R44LTS6 or NGK 3951 spark plugs.

If nothing else is helping, it may be a matter of replacing the plugs with non-gimmick sparkers.

I'm thinking that GM recommends R44LTS6 plugs; but I'd install (C)R44LT instead, to get away from the .060 gap. I have grown to dislike the gigantic plug gaps in any application, but even moreso in high-performance use, or on Vortec applications that seem to commonly have distributor cap failures. But like I said...I think the LTS6 .060 gap is recommended by GM.

 

[L31MaxExpress]

I would not have described "ping" or "detonation" as sounding like a cricket chirp. But if more octane makes the noise go away, that's probably what it is.

Detonation ("pinging") and a malfunctioning EGR system go hand-in-hand. If the V-6 EGR valve is like the one on my '88 5.7L (Negative backpressure sensing, has an "N" near the part number stamped into the top) it should hold vacuum when tested. If it leaks vacuum, it's defective. If it's seized, it's defective. Sometimes they can be cleaned, sometimes they have to be replaced. If you manually lift the diaphram/pintle at idle, the engine should stumble. Let go of the diaphragm/pintle, and the engine idle should recover and become smooth. If the idle doesn't degrade with the pintle lifted, the exhaust passages in the intake manifold are plugged with carbon, which will have to be chipped- or solvented-out

The EGR vacuum system needs to be checked as well.



I'm no fan of "gimmick" spark plugs, but scrapping them is not the first thing I'd do.

Verify EGR as already discussed.
Connect a scan tool, verify ALL the sensors and computer outputs, in particular the knock sensor and ignition advance/retard. If you tap on the cylinder head with a small hammer to simulate detonation, the timing should retard which you'll notice as a reduction--and then recovery--of the idle speed. Initial timing is not adjustable, but if the knock sensor, sensor wiring, or the electronic spark advance/retard isn't working right, the ignition timing could be way "off".


87 octane should run just fine in that engine.

Consider fully-warming the engine, then directing a "urine stream" of water into the throttle body at FAST idle (~2000 rpm or so.) When it's me, I over-do it by using about a gallon of water; and then I have to change oil afterward to get rid of crankcase moisture/contamination. This should "steam-clean" your combustion chambers to eliminate excess carbon that might raise compression or cause combustion-chamber hot spots leading to detonation. Costs almost nothing to try; and using water doesn't make the neighbors call the fire department due to the smoke from products like Seafoam or GM Top Engine Cleaner dumped down the throttle body.


If nothing else is helping, it may be a matter of replacing the plugs with non-gimmick sparkers.

I'm thinking that GM recommends R44LTS6 plugs; but I'd install (C)R44LT instead, to get away from the .060 gap. I have grown to dislike the gigantic plug gaps in any application, but even moreso in high-performance use, or on Vortec applications that seem to commonly have distributor cap failures. But like I said...I think the LTS6 .060 gap is recommended by GM.

97 US build would be a Vortec and Vortec engines use the linear egr valves with 5 wiring pins. No vacuum in the system and the PCM monitors the position of the pintle inside. While a valve can become defective and not throw a code, they usually will. The EGR passageways could potentially become blocked or partially blocked, but that is not something I have really come across.

I have however found more than a few Vortec engines pinging on 87 octane even when these had lower milage. It is usually not something you can hear, but if the knock sensor fails to provide the correct response to detonation it can become audible. These engines should have never been tuned for 87 octane as they make more power and get much better mileage on 91 octane. At 9.4:1 compression with the early intake valve closing and iron heads GM had to really retard the ignition timing to make them get by on 87 octane. There is 30+ ft/lbs to be gained on 91 octane and about 3-4 MPG. My 97 was cheaper to run on 91 than it was on 87 and the added torque really woke it up. My 99 Tahoe and my brothers 99 Suburban also both reacted the same way.

I am not arguing that GM did not set these up to run on 87 without audible pinging, but rather countering with the argument that without a properly functioning and torqued knock sensor or sensors in the case of the 4.3L or 454 you will hear spark knocking. The factory tune often shows up to 8* of knock retard on a stock truck. Just putting 91 octane in the tank on my 97 stopped all the knock retard and gave it more power and better fuel mileage.

 

[TCBRacer77]

So I changed my plugs to ac Delco, and this thing drives like a different truck. Idk how long it will last because the e3 plugs I took out were nasty. Reeked of gas and black. Idk if that’s a sign of bad injectors or what. I haven’t hooked up a scanner yet either because it’s been running so much better. I’m hoping it’s not like putting a bandaid on a cut that needs stitches lol it will hold for a minute but not stop the problem… any thoughts?

You must be registered for see images attach

 

[L31MaxExpress]

I think you need to connect a scanner up to it and look at the data it provides. Bad coolant temp sensor among other problems like a skewed MAP sensor or even MAP sensor o-ring leaking or failing 02 sensors will cause it to over fuel and carbon foul plugs like that.

Granted these are the washer seat plugs out of the aluminum heads on my 383, this is how a decently burning Vortecs plugs should look.

You must be registered for see images attach

 

[PlayingWithTBI]

So I changed my plugs to ac Delco, and this thing drives like a different truck.

Good to hear it's better. Did you fix your exhaust too?

 

[Komet]

Gotta fix that exhaust because throwing off your o2 will throw off your whole tune. Also definitely Berryman's in the tank and full throttle redline pulls.

 

[TCBRacer77]

Good to hear it's better. Did you fix your exhaust too?

Yes I did, no more leak!

 

[TCBRacer77]

I think you need to connect a scanner up to it and look at the data it provides. Bad coolant temp sensor among other problems like a skewed MAP sensor or even MAP sensor o-ring leaking or failing 02 sensors will cause it to over fuel and carbon foul plugs like that.

Granted these are the washer seat plugs out of the aluminum heads on my 383, this is how a decently burning Vortecs plugs should look.

You must be registered for see images attach

I agree, that’s what a healthy heart looks like! What exactly should I be looking for on a scanner? Never really done that. It’s one thing to hook it up but it won’t do me much good if I don’t know what I’m looking for. Might as well be reading binary lol all 1’s and 0’s

 

[L31MaxExpress]

I agree, that’s what a healthy heart looks like! What exactly should I be looking for on a scanner? Never really done that. It’s one thing to hook it up but it won’t do me much good if I don’t know what I’m looking for. Might as well be reading binary lol all 1’s and 0’s

First check for trouble codes, stored, pending or current. Then look at live data on a cold engine that is not running.. Make sure the coolant temp is near ambient. Make sure the MAP is reading close to the barometric pressure. TPS should read Zero. Then start the engine. The MAP sensor should read around 20 in/hg vacuum, some scanners read it as absolute pressure. Baro being 30 in/hg or so and 20 in/hg vacuum being around 10 in/hg absolute pressure. As the engine starts to warm up the CTS should rise and the short term fuel trims will become active. A range of -10 to +10 with some fluctuation is pretty common during initial warm up before the long terms become active. The front 02 sensors (Bank 1 & Bank 2, Sensor 1) voltage should have a nice swing to them from around 0.100 to 0.800 volts or so and be switching steadily. As the engine warms up beyond 140F, the long term fuel trim will enable and the long terms should start to follow the short terms. I would expect to see them in the -10 to +10 range as well with Zero being ideal. Realiatically these engines were calibrated when fuel was 100% gasoline and E10 ethanol fuel will usually drive the numbers higher. If you are looking at short or long terms much over 10 in either direction, something is off. If you see 02 sensor voltage sitting at 0.450 and not moving, the sensor most likely is bad or has a wiring problem. If a coolant temp reading is -40 there is a sensor/wiring problem. At idle the MAF should read around 1 gm/sec for every liter of engine displacement. As you accelerate the engine the MAF reading should smoothly increase. If you snap the throttle it should rise sharply.

I am more in depth with datalogs from tuning software, more than generic scanners. @Shurkey may have more to offer on this.

 

[TCBRacer77]

First check for trouble codes, stored, pending or current. Then look at live data on a cold engine that is not running.. Make sure the coolant temp is near ambient. Make sure the MAP is reading close to the barometric pressure. TPS should read Zero. Then start the engine. The MAP sensor should read around 20 in/hg vacuum, some scanners read it as absolute pressure. Baro being 30 in/hg or so and 20 in/hg vacuum being around 10 in/hg absolute pressure. As the engine starts to warm up the CTS should rise and the short term fuel trims will become active. A range of -10 to +10 with some fluctuation is pretty common during initial warm up before the long terms become active. The front 02 sensors (Bank 1 & Bank 2, Sensor 1) voltage should have a nice swing to them from around 0.100 to 0.800 volts or so and be switching steadily. As the engine warms up beyond 140F, the long term fuel trim will enable and the long terms should start to follow the short terms. I would expect to see them in the -10 to +10 range as well with Zero being ideal. Realiatically these engines were calibrated when fuel was 100% gasoline and E10 ethanol fuel will usually drive the numbers higher. If you are looking at short or long terms much over 10 in either direction, something is off. If you see 02 sensor voltage sitting at 0.450 and not moving, the sensor most likely is bad or has a wiring problem. If a coolant temp reading is -40 there is a sensor/wiring problem. At idle the MAF should read around 1 gm/sec for every liter of engine displacement. As you accelerate the engine the MAF reading should smoothly increase. If you snap the throttle it should rise sharply.

I am more in depth with datalogs from tuning software, more than generic scanners. @Shurkey may have more to offer on this.

Thank you I’ll give this a go