Hi, I have a 92 RS with 108,000 miles on it. For awhile now, my car sounds like its pinging at low rpms and is louder as the temp gets hot in traffic. Doesn't ping or knock at all when engine is cold.

I usually run 89 octane and tried 93 octane gas, no change. It does not knock/ping at idle or in park. Its a stock 305 automatic with open element and aftermarket exhaust. I just did a complete tuneup, ac delco plugs. New wires and distributer cap rotor. No change. Timing is set to 0 btdc in drive,(automatic), as instructed on the sticker under the hood. Has new fuel filter and the fuel pump is only 2 years old. The oxy sensor is only 1 year old. The catalystic converter is 4 years old. I checked for error codes and none come up.

Im lost at this point. I was thinking maybe its running too lean but what would cause that? The exhaust does not smell rich at all. I also thought maybe the EGR valve is defective but wouldn't the engine light come on and throw a code? If its a sensor wouldn't that also throw a code?

If anyone has any advice that would be great.

 

Assuming it is knock, the possible causes of detonation are: plugged/bad egr and/or solenoid, faulty knock module and/or knock sensor preventing the ecm from seeing detonation (although it shouldnt do it in the first place), carbon build up, lean mixture, slipped balancer causing you to set the wrong base timing, to name a few...

The carbon build up one is common. All my old cars and my L03 had that problem. Theyd have audable detonation under load. Does the car noticably loose power when it detonates or makes the noise?

 

I do not notice any power loss as it pings/knocks. The noise seems to go away after 2000 RPM's. I don't think its a slipped balancer because everytime I checked the timing, it was right on 0.

If it was a bad sensor wouldn't the engine light come on?

Thank you, anymore advice would be apreciated.

 

I think demented nailed it, a good tune up would be the first thing to do for it. If it is detenation, the detination ping is pretty distinct, and not easily mistaken for valvetrain noise, or an exaust leak.

 

If he's done a full tune up, and theres no loss of power..then could it be pinging?
wouldn't the knock sensor(damit and the ESC to hell) retard timing and cause the car to run slow?
I would check your header bolts tighness and see if it effects it at all.

We've the same car the same basic mods, and I've tracked it down to my headers not fitting true anymore. Well I hope thats what it is because I've replaced ,cap,rotor,coil,plugs,wires cleaned EGR, replaced the knocksensor, played about with my timing and different gas, ran sea foam and water, octane booster, and fuel system cleaner...but when I checked the header bolts ,some I could get to felt loose and the noise was reduced when I tightend them. Everything else was needed but tighting the bolts and better octane gas helped the most.
good luck.

 

Thanks for the replies, I checked EGR valve, its good and clean. I also changed O2 Sensor again. No change in ping. I don't have headers, just manifolds. Maybe this low rpm ping while in drive is normal on a 108000 mile LO3. I may change the coil yet, not sure if that would cause ping though.

 

My mistake by headers I meant your exhaust manifold. Theres a few bolts that are easily accessible so you can check tightness. I changed my coil to MSD it didn't effect the "ping" but the engine did feel better.
hope that helps.

 

I thought I would let everyone know that I solved the pinging problem. I had a TBIchips performance chip in the car for over a year with no problems until this year. I contacted Brian at TBIchips and he sent me another chip to try. It still pinged. After emailing him a few times and trying a few things he mentioned, it still pinged.

I decided to buy a new stock chip for my car from the dealer and installed it today. My car no longer pings and runs good. So after all this time and headaches it ended up being the performance chip causing the pinging.

Now Im running 87 octane gas with no pings and decent performance.

Im wondering if I should change my 180 degree thermostat out to the stock 195 degree now.

 

I bet if you mentioned in the first post that you had that chip in there, it would have been people's first guess as to what's wrong. This is why we preach not to buy mail order chips.

Glad to hear it worked out for you though; the 180 stat should be fine, just don't go any lower than that. Out of curiosity how much did the tbichips guy charge you for the chip(s)?

 

What would be the problem with going lower than 180?

 

I just don't like the idea of running a 160 stat like some people do. Higher stat will make sure it stays in closed loop and personally my engine runs much better hot. After I added the aftermarket intake manifold it bogs when it's cold, most likely due to the extra plenum volume. It runs best when its closer to 200* (according to the guage).

 

Proof once again that chips cannot be burnt by mail order. He means well but without the car in hand you have no idea of what it needs.

 

Absolutely Shifty. I'm now completely of the opinion that the DIY community takes on the subject of brian. I don't think he means well with his chips. I think it started out with him trying to help a few guys out with some cheaply burned chips. Now he charges big money! He charges almost as much as the big name aftermarket chips like Jet and Hypertech. He keeps bumping the price up on simple chips that cost him next to nothing to burn, and he charges $70! I don't like what he's doing, he's only trying to make a profit now. My $.02

 

Wow I didn;t realized he did that now. I thought he still provided the $30 stab in the dark chips.

 

I know I learned my lesson on buying mail order chips. I think I paid about $60 for it, its was awhile ago. Im sticking with the stock chip for now on. Thanks for the reply about the thermostat. I may just put the stock 195 back in anyway due to winter coming here in PA. It will provide a little more heat than the 180.

 

Looking through the stock bin, 180 seems to be safe in regards to the ecm thinking the car is still not warmed up. The 160 would cause some problems.

 

I looked at a 5-speed TBI bin and it looks like the minimum temperature for BLM's to be enabled is 189. Seems kind of high, but I would want to stay within the block learn thresholds during normal driving.