[maiahsdad]

Hi All - I only use the Unleaded Plus on my 99 STS because the dealer I purchased it from said to do so. Well, I understood from some folk that when using regular, and you need to JUICE it really good to get past traffic, you'll hear a gurgling, valvy-like knocking. Well, I use PLUS and when I need to pass or REALLY get on it, (or if I just want to), it sounds like knocking. This can NOT be good! Any ideas? I've had it for 2 months now, and it has 114000 miles on it, which the reviews indicates that is good!

Thanks for your help...

 

[Submariner409]

Read the entire Cadillac Technical Archive up in the black bar, ^^^^^^, especially the article "Occasional full-throttle operation is good for your engine".

When you say it pings when you "REALLY get on it", that rules out EGR passages: that ping shows up as a part-throttle rattle. Is your fuel gauge or fuel door marked "Use Premium Fuel" ? If so, Plus is not what you want - you're in the 91 - 93 octane Premium crowd.

When was the car's last spark plug/wire change ??? More than 75,000 miles back and you're on the border - read up on the proper plugs and wires. Also, plug wiring diagrams have been posted many, many times lately. Follow them.

 

[maiahsdad]

When you say it pings when you "REALLY get on it", that rules out EGR passages: that ping shows up as a part-throttle rattle. Is your fuel gauge or fuel door marked "Use Premium Fuel" ?

No, it doesn't mention fuel other than "unleaded". I don't know if it's missing or not, but I was told that it should be fine with 87. But I use 89 anyways. I DID put premium in there once and it DIDN'T ping at ALL. So, I've been using PLUS. Also, if I buy two cheap Octane Boost bottles from the auto store, add it to my tank of PLUS, it won't ping.

When was the car's last spark plug/wire change ??? More than 75,000 miles back and you're on the border - read up on the proper plugs and wires. Also, plug wiring diagrams have been posted many, many times lately. Follow them.

Thank you. The dealer PROMISED that the car has been "gone through" from head to toe. But it SOUNDS TERRIBLE to the point that I think it's about to throw a rod or something. But I think it'd still sound that way idling if it were a case like that.... I THINK. I assumed it was tuned up all the way...

 

[Ranger]

Also, if I buy two cheap Octane Boost bottles from the auto store, add it to my tank of PLUS, it won't ping.

Don't waste your money. That stuff only raises the octane rating by .1.

Now, back to your original post. Are you hearing a "gurgle" like water or a spark "knock" (ping) like Sub is talking about?

 

[maiahsdad]

Don't waste your money. That stuff only raises the octane rating by .1.

Now, back to your original post. Are you hearing a "gurgle" like water or a spark "knock" (ping) like Sub is talking about?

It's a KNOCKing sound. Sounds like a rod or something slapping when I use PLUS. When I let off the gas, the sound goes away, or at least I can't hear it. I didn't "notice" it when I filled with PREMIUM the one time. Someone told me that filling with PREMIUM is about $4 more than regular unleaded per tank full, but well worth it. But shouldn't I be able to use regular?

 

[Ranger]

Yes, you should be able to run regular and the knock sensor should retard the timing if a spark knock is detected long before you ever hear it. If the knock sensor is bad, it should set a DTC. Pull them and see what you have. There is a BIG difference between a spark knock (ping) and a rod knock. I'm still not sure what you have.

 

[maiahsdad]

Yes, you should be able to run regular and the knock sensor should retard the timing if a spark knock is detected long before you ever hear it. If the knock sensor is bad, it should set a DTC. Pull them and see what you have. There is a BIG difference between a spark knock (ping) and a rod knock. I'm still not sure what you have.

Thanks Ranger. Now... do I press and hold BOTH round temp knobs while pressing BOTH warmer temp buttons to get the codes? I'll run get them now and report back to you....

Thanks.

PS: I tried to send you a private message earlier but it was blocked and I was delivered a SPAM message. I thought members could send private messages to each other....

 

[Ranger]

Go to the Tech Tips section and see the appropriate sticky for pulling DTC's for your year.

You might not have enough posts to send PM's, but these discussions should be kept public so others can help and benefit.

 

[maiahsdad]

Go to the Tech Tips section and see the appropriate sticky for pulling DTC's for your year.

OK, went out in the HOT weather and got my codes.

NO current codes, but here's what I have that were all followed by "history".

B1652 - Loss of Keep Alive Memory (KAM)
B1983 - Device Power Circuit Low
B1344 - HeaterDefrost/AC Door Movement Fault
U1064 - Loss of Communications with DIM

Doesn't seem like this is indicative to my current situation. There were a LOT of test areas, but they all said NO prior to their symbols as it toggled through.

Suggestions from here?

 

[Ranger]

No, none of those are relative, but I'm still unsure of the sound you are describing.

 

[maiahsdad]

No, none of those are relative, but I'm still unsure of the sound you are describing.

Sorry, don't know what else to say. When I bare down (approaching full throttle), I hear this pinging sound. May be a loud valvy sound, but as I think of it, I don't think it would be a rod, for the rod would be heard hitting at an idle as well I suspect. Maybe I need to pay to have a garage RE-tune the car up. A little discouraging at this point...

 

[Ranger]

When I bare down (approaching full throttle), I hear this pinging sound.

Now THAT sounds like spark knock. Try a tank full of premium and see if it stops.

 

[maiahsdad]

Now THAT sounds like spark knock. Try a tank full of premium and see if it stops.

But doesn't that indicate that something's wrong since I should be able to use regular unleaded? I'll try a tank of 93 on this coming Tuesday when I get paid (hopefully the gas prices will be lower than $2.83 per gallon).

I also hear that these cars are MONSTERS to tune up, so get ready for a HUGE bill from the shop that tunes it up! OMG!

 

[Submariner409]

If you're willing to do a little homework in here and Northstar Performance and/or subscribe your car to www.alldatadiy.com for 3 years, using basic hand tools and a few hours of your time you can do a "tune up" (plugs, wires, coil cleaning, throttlebody cleaning, air filter) for around $200.

www.rockauto.com, your car, ACDelco #41-950 Platinum plugs, AC wire set.

If you're dumping "cheap" octane booster (it doesn't) on top of Plus fuel, you're paying the $2.83 anyway. Google "chevron techron" and "top tier gasoline".

 

[chubbyranger]

Check what kind of plugs are in the car. If they are Bosch (or anything not OEM) then throw them away and get AC Delcos. I made the Bosch mistake and they were junk in under 10,000 miles. I run premium in my 99 and do not have spark knock issues.

 

[Ranger]

But doesn't that indicate that something's wrong since I should be able to use regular unleaded? I'll try a tank of 93 on this coming Tuesday when I get paid (hopefully the gas prices will be lower than $2.83 per gallon).

I also hear that these cars are MONSTERS to tune up, so get ready for a HUGE bill from the shop that tunes it up! OMG!

If it stops it, yes. This will tell us for sure if in fact it is spark knock.