Pinging On Regular Unleaded

[Kodachrome Wolf]

Hey all,
I'm wondering if anyone has had bad pinging under heavy load while using regular gasoline. I filled up with regular (was using mid-grade for a few months) just the other week, and under load, the engine would ping and felt weak when at operating temperature. I put in premium today just to see if it would make a difference, and once it was warmed up, decided to go at WOT. Heard no pinging and the pull felt strong as it moved up to 60 MPH.

I never noticed pinging or weakness on mid-grade either, but regular seems to burn poorly. I also found burning regular used to irritate my downstream O2 sensors when they were going and would often set off an inefficiency code (hasn't happened since they were replaced, however). I've run injector cleaner in it before and it's even been Seafoamed previously, so I'm doubting carbon build up. The car just seems to run properly on mid-grade or higher.

Anyone else experienced something similar?

[Mainemantom]

My 96 CVPI will not run right and ping badly on regular.Using midgrade or super and it runs great. When I was working, the 92-97 CVs had to have midgrade. For some reason the '98s on ran ok on regular.

[Kodachrome Wolf]

My 96 CVPI will not run right and ping badly on regular.Using midgrade or super and it runs great. When I was working, the 92-97 CVs had to have midgrade. For some reason the '98s on ran ok on regular.

Well now that has me wondering about my ECU. I swapped the nanny Grand Marq ECU for a P71 ECU out of a '97. I was looking for slightly firmer shifts (which I got) and the slightly higher shift points. That original 1-2 shift took half a month on the civvy ECU, which is what prompted the swap.

IIRC, the pinging came around after the swap, and not too long afterwords I started running mid-grade and it went away, and the car felt more "there" when I accelerated. If the above is true and for some reason that the P71 tune just behaves better on mid-grade, I'll just continue filling on mid-grade.

[Lincolnmania]

have you tried other brands of 87 octane?

[sxcpotatoes]

Yeah, I know Ohio is a dumping ground for bad gas because we have NO testing standards at all to make sure the crooks are honestly putting 87 into the ground tanks.

My brother hauls tar, sulphur, whathaveyou for/from the refineries and sometimes delivers gas for a certain gas station chain here. He's clued us in on the fact that there is no 87 octane, all the deliveries are 89 at the least. Usually 89 is made by mixing 87 & 91/93 what have you, gas stations only ever have two tanks (low/high) and they blend them at the pump to deliver mid-grade.

[Mainemantom]

I buy the Super at Sam's club. Since they have a fast gas turnover, I am not worried about sand in the gas. Regular I normally buy at a Gulf or other major brand. Much of the gas on one load goes to many stations. You really don't know what you are getting. The police ECU must be the reason for the pinging.

[Kodachrome Wolf]

have you tried other brands of 87 octane?

I've run 87 from a few stations, Shell, Enmark, and Kroger, usually with ping. I have only gotten 89 and 92 from Shell and Enmark, both without any ping.

[miamibob]

Here in South East Florida I have run 87 both in my Dad's '93 GM (when it was alive) and my '95, currently without issues. I gas up where it is the cheapest or most convenient and have never had any pinging. Maybe there is a mechanical issue or the 87 in your area is lower than 87???

[gadget73]

I'm usually not a fan of magic in a bottle, but have you tried running some Seafoam through the PCV valve to de-carbon the engine? I had the same problems for years with my S10, and that stuff fixed it. I did that probably 8 years ago and it still has not returned.

Basically you start the car, and slowly feed about 1/2 the can of Seafoam through the PCV valve. SHut the motor off and dump the rest of the can in the tank. Let it sit 10 minutes or so, then start it back up. Give it a bit of throttle so it runs at a high idle until the smoke clears out. It will either work or it won't. If nothing there, its possible the cop chip is tuned for more advance, and you will just have to run high test to make it happy.

[jaywish]

It could be a timing curve on the p71 module but I don't know one way or the other. Seafoam has worked for some people.

On the other hand I have been carbon cracking for several years now and there is still carbon on the piston tops. I need to run 89 or better to avoid nasty detonation on hard acceleration. Before I started the cleaning process it was worse, so it has improved. I have sea foamed, used the gas additive a number of times, I used other direct intake supplied cleaners and also removed the plugs and soaked the pistons with carbon cleaner overnight a few times.

I have a camera so I look at the pistons. They are maybe 50/60% clean now. I am reasonably certain that it is the carbon that causes the detonation.

[sly]

my 93 would ping like that with the original engine when they started putting ethanol in the gas. Had to run 89 to keep it from pinging. The PI swapped engine doesn't care. It just runs. The 88's 302 would probably run on 85 without issue... it loves 87.

[sidneymratcliff]

The reason you get the ping or labor knock is because of what they call a cleaning agent. Which is water. The bonding agent for watrr to gas is ethanol. Which is unfinished moonshine. In turn is cut with water. Which in turn lowers the octane. So to answer the question yes your computer is doing its job self adjusting for the lower octane. And advancing the ignition timing so far tge it's predetnating. The intake valves are not closed yet. The only way to solve the problem is to do what you have done. Buy plus or mid grade or advance the cam, or modify the lobes to close earlier. I hear stories of the dealer solving the problem by selling you a new car with the retarded timing. Which comes stock along with a note.

[AmuletOfNight]

I've never personally had any issues running the 87 in our area in our '94, the darn thing will take 87 and eat it up all day long. 89 and 93 doesn't make a difference for it.