Transitional rattle or pinging - Need some advice (1 Viewer)

[John E Davies]

My '96 LX450 has been suffering some faint "transitional rattle" for the last year and it is getting worse. It only happens for a second or two max, and only under zero engine load in an off-idle throttle position. It is most noticeble at low speeds, such as when slowing and then accelerating around a turn. I can also duplicate the noise at any speed by playing with the throttle. It sounds just like pinging, but it the engine does NOT ping under moderate or heavy load, and is well tuned. It only occurs at about 1/8 throttle, never at wider throttle.

I have an OBDII pgorgam with data logging, but I am not sure what parameters to check. I'm new at this stuff.

Any advice for troubleshooting? Am I looking at a bad knock sensor or ????

Thanks.

John Davies
Spokane WA

 

[Scamper]

Have you checked the exhaust shields forward of the cat? Mine had a similar rattle which was just a loose shield.

 

[tarbe]

I have the exact same issue...a number of us here do.

Premium makes mine go away. I have not been able to isolate a cause....yet.

 

[psfpilot]

I think I'm going to try some Redline Diesel Water Wetter to help alleviate the pinging.
I'm also going to try running some BG44K and Redline Fuel System Cleaner to hopefully clean out any carbon deposits that could be creating hot spots for pre-ignition.

Ping Reduction threads:
---No.1 --- No.2 --- No.3

 

[CJF]

I have a question for you guys, and maybe an answer:

At what point did the intake system change from using an Air Flow Meter (AFM) to a Mass Air Flow (MAF) sensor, or am I confused and they're the same thing?

Here's why I ask:

Over on the 3FE list, it's pretty much settled that the best cure (and it really does seem to be a good, permanent, performance enhancing one) for light load pinging on a vehicle known to otherwise be in good tune is to loosen the spring in the AFM a few notches. This makes the ECU "think" more air is coming in, so it richens up the fuel mixture. Tada! Nore more ping.

Several listers are so fond of this trick that they dial in their mixture seasonally to account for things like wintertime oxy/ethanol fuels, heat in the summer, etc.

So, I've always wondered if a similar trick can be pulled off on later model years; anyone know?

Curtis
91FJ80 (3FE)

 

[John E Davies]

Thanks for the replies. Those links indicate that this pinging is common, but I can't see it being related to octane. It sure sounds like a temporary lean mixture condition rather than carbon glowing. If it were carbon, it would be worse under heavy loads as the combustion chamber temps wwould be much higher. I've tried retarding the ignition with no noticeable effect.

I am wondering if there is an easy way to log the air/fuel ratio while driving, using my laptop. I am not up to speed on the OBDII stuff and am not sure how to go about it. The documentation that came with my software is pretty vague.

Any practical tips would be greatly appreciated.

Thanks.

John Davies
Spokane WA

 

[landtank]

Talk with "Tools R US", he recently reported that his off idle pinging was resolved.

 

[lockd-97]

I've had my 97 FZJ since it had 80k miles on it. It didn't take long to develope the same problem yall are talking about. I have run bottle after bottle of BG44k, Redline, Techron, Seafoam, etc. through it. Never made a difference. I use to have an 85 4runner that did the same thing, it never went away untill I rebuilt the engine and scrapped the carbon off the pistons.

 

[psfpilot]

John-
FWIW, switching from 87 to 89 octane did cut about 40% of the noise.
-Jon

 

[lockd-97]

Forgot to note....I've always used premium too.

 

[alia176]

This pinging can be a combination of:
-carbon deposit (intake, piston, combustion area, etc)
-aging injectors not spraying the proper amount of fuel

I have the same issue too and thought about cleaning the injectors as a matter of high mileage PM.

 

[whodat]

My pinging occurs when the outside temp is over 92 degrees, or when using octane below 93.

 

[tarbe]

I get 16.5mgp (corrected) on the highway with a lifted, ARB'b slidered, 295/75 shod vehicle. I have also done all the BG44K, seafoam/MMO in the tank tricks...but I have not tried seafoam or water into a vac hose.

Might try that next.

I really don't think it is anything that would otherwise negatively affect fuel economy...I wouldn't be doing as well as I am.

 

[RavenTai]

I do not know if this is a sure thing yet but mine used to get ocational transitioal ping with regular, recently it had started pinging even with premium, especialy on hot days in traffic, not long after I got a P0401, insufficient EGR flow,

recycled eachuast gasses are an inert combustion chamber filler containg neither oxygen nor fuel so it has a tendancy to lower cylinder temperatures.

I am hoping that fixing the EGR and gettign the temps down will cure the pinging,

 

[Rookie2]

I am wondering if there is an easy way to log the air/fuel ratio while driving, using my laptop.

You're probably aware you can buy data loggers pretty cheap and download the info onto you PC.

 

[tarbe]

I sucked half a can of Seafoam up my brake booster hose last night, let it sit for a couple hours, then drove it 10 miles until it stopped smoking.

No light throttle/transition pinging this morning. Better test may be when it is 98 degrees on the way home...

 

[Tools R Us]

Talk with "Tools R US", he recently reported that his off idle pinging was resolved.

Mine was slightly different, so the fix that worked for me may not apply?

I only noticed it on the trail on hot days, when the truck was hot it would ping just off idle under big loads. Putting thicker fluid in the fan clutch solved it, along with making all of the temps that I have measured much more stable.

It may of happened on the street also, but when it's hot I have the windows up, A/C on and stereo on, so may not of noticed?

 

[tarbe]

I didn't hear any ping on the way home. Decided to suck the other half of the can up the PCV hose while my son held her at 2k rpm. I let it sit for an hour, then took her out to clear the smoke and try to make it rattle/ping.

Observations: Off-throttle response was notably smoother (even after the first treatment) and I could not make it ping no matter what I did. This was on 89 octane, which normally will ping, especially when it is hot (it was still in the low 90's when I went out tonight. It was 99 according to Yahoo! weather when I left the office.

As you all know, we get awfully familiar with our vehicles, to where we notice the least little thing different. This Seafoam up the vac hose really did make a difference. I will add this to my maintenance list if this improvement is more than just short-lived.

 

[tarbe]

I wanted to wait for an additional data poiint (actually two) prior to documenting one additional observation.

My cold start-up rpm has dropped by 300 since the Seafoam treatment. It was 1,500 - now 1,200.

 

[CodyRx7]

I have a mystery noise now that I am wondering if thats what "pinging" is...

At first I thought it might be a clogged cat. It sounds like the car is gonna hock up a loogie... Thats the closest noise I can compare it to.

I would hear it every now and then, like if I was in a drive-thru and stopped...or just as I touched the gas...but seemed to disappear at higher rpms.

Today, just for the hell of it, I pulled over and put the truck in neutral and couldn't duplicate the noise. At idle, and any RPM the noise was gone...

So its only there under load...

Does this "hocking up a loogie" noise sound familiar to anyone?