m-nelson

I experiencing a definite pre-ignition under very specific conditions. It occurs at about 1300rpm and part-throttle. It's typically jsut a handful of pings as it goes through this RPM range, but I can often make it do it a few times in a row.

Thoughts?
Mike

SLPRC5

Not enough info about your car i.e year, trans and miles on it.
Lots of causes for engine ping.
1. Grade of gas being used.
2. Carbon buildup.
3. Oil getting into the intake.
4. Tuneup needed.
To name a few...

Sleeper

gpracer1

Fill out your profile.
What year?
Stick or auto?
What gear does it do it in and at what speeds?

Tuner@Straightline

Need to know how much "load" as well, or throttle position.

gpracer1

Im guessing maybe lugging the engine in too high of a gear?

m-nelson

I can get it to do it in 1st, 2nd or 3rd gear if I ge the rpm's to about 1200 & then apply about 1/4 throttle. There is preignition as it goes through 1300rpm.

Car is a stick. '99 About 55Kmiles

m-nelson

always use 93 octane

SLPRC5

Has it had the plugs and wires changed? Try running Sea Foam through it to clean carbon build up.
Put in a Sea Foam search and you'll find out how to use it and how it may help your problem.

m-nelson

I thought bout plug mysel & I have no ideal if they were ever changed. As to wires... How could they be implicated in pre-ignition? I don't see the connection.

Mike

gpracer1

Things it could be:

Bad gas (not enough octane)
Carbon build up on pistons
Aftermarket boltons without tune
Driving in hot weather in too tall of a gear (lugging motor)
Engine running too hot

AJay

This probably has nothing to do with your engine but I thought I'd post it for info only. After I did my mods and got the car tuned the engine sounded like it was experiencing pre-ignition from 4500 - 6000K. This was affected by density altitude. On a cold day, no noise, on a hot humid day it sounded exactly like spark knock while under load. The tuner confirmed there was no pre-ignition / detonation while the car was on the Dyno. It turned out to be Coil Dwell. The ignition was actually sparking / firing out the exhaust due to the combination of compression and valve overlap. This was adjusted and the noise went away with no loss of power. I don't recall ever reading any posts on coil dwell so here it is for what it's worth..

BATM4N

Coil dwell ....hmmmm interesting. I thought I'd heard it all on this forum. I learn something new everyday here.

m-nelson

From this & other threads it seems like there are 3 likely items;

Air Temp Sensor
Plugs
Carbon

I just hooked up an OBD computer & it shows a reasonable reading on the Intake Air Temp, so I think I can rule that one out. My next move it to change plugs since the car has 55K on these plugs anyway.

If that does not cure it, I'll do the Sea Foam trick.

Mike

dgrant3830

My '99 has been pinging for a long while now. I've replaced the IAT sensor, used Seafoam, always use 91 or higher octane, tuned it via a professional tuner, replaced plugs and so on...nothing seems to stop it. I have noticed that it does not ping when the engine starts up cold and not until the oil temp gets up to a normal range and then it will start pinging. One other thing I've noticed is the color of the exhaust pipe outlets. The right side is lighter or leaner than the left side. That makes me contemplate the O2 sensors on the right side may be contaminated with carbon therefore incorrectly telling the pcm to lean it out, therefore pinging. Anyone have thoughts along this line or other?

m-nelson

Well, plug replcement didn't do a thing. The ping still persists.

Mike

Nyvetteguy007

I think there have been some issues with bad knock sensors..others can chime in..they are under the intake manifold..there are two I believe...

dgrant3830

I replaced the knock sensors in my, also the IAT sensor and used Seafoam twice with no change to the pinging....still doing it a lot.

TuffShift

Regardless of the "cause", what I would like to know, is how come the supposed "knock-sensors" do not detect this ping and retard the timing accordingly as it is designed to do?

I read about this pinging problem all the time here....mine even "pings" frequently under such a load as when accelerating up from around 30 mph but not so the tranny backshifts.

Nothing I have ever done has gotten rid of it. The dealers says it's "normal". Pre-igition is considered normal?

Nyvetteguy007

I guess it has to do with the knock sensors kicking in only after its either a more pronounced ping or its for a longer period of time...I have the ping every now and then but its just for a fleeting moment,,mostly when in 6th at highway speeds and stepping on it...quite frankly, I prob should be in 5th gear...when I am at the same speeds it doesnt ping in 5th...but it is quite frustrating...

gpracer1

You guys probably just need to richen it up a little. Thats what I had to do to mine. It would start to ping right at 4000 rpms and up. I got a predator and just custom tuned it with more fuel till it went away.