kcpaz

My 85 is still having a pinging/knocking problem. Here is a list of what I've tried.


-New plugs, wires, cap, and rotor
-New Fuel, and air filters
-New knock sensor
-New ESC module
-Checked the timing, and adjusted to 6* BTC...it was at 2*BTC (I think someone tried to fix it the "cheap way")



I don't have a scanner yet so I can't pull any codes, but I will get one soon. I am out of ideas though. The plug for the fan switch was sitting on top of the header, but someone had installed a new switch/sensor with a 2 wire plug so I guess the old plug wasn't needed. I thought that this might be the knock sensor plug but there was already a plug on the knock sensor (The wire on the knock sensor is blue, can anyone confirm that this is the right wire?) The fans work fine. And another thing. When I pulled the old knock sensor out, no coolant came out. What Gives!? I thought I remembered someone saying that the sensor screwed into the water jacket. Anyone have any suggestions???

Spawn22

If the car is running rough and little warm in the winter time, it is very possible that your cat converter is pluged, is there a lose of power?

kcpaz

no the converter isn't plugged. I just passed emissions, and the car has plenty of power. BTW, I forgot to mention, the ping only happens under heavy load like downshifting to 3rd on the highway, and it will go away once I get over 3500 RPM or so.

redwing76

My guess would be a carbon build up?

kcpaz

carbon build-up in the intake?? or in the combustion chamber?? It doesn't do it all the time, just under heavy load. Like when I am going down the freeway, and I floor it. It will downshift to 3rd, and it will ping like hell until I get to 3500RPM's or higher. From a stand still, I can floore it and it will pull hard in 1st. and 2nd. with no ping

mikey whipreck

seafoam would kick carbon buildup ***

Midnite 88

What grade of fuel are you using? What is the heat range of the plugs you installed? Have you verified TDC on your engine? Did you change the knock module on the heater/AC box? Does it appear that the harmonic balancer is undisturbed?

parafrog

if you've got no coolant in the block, and you're pinging; it could be as simple as a seized thermostat causing the head to overheat and cause detonation. maybe.

frog

HeeHaw89

Having some pinging issues myself....I know its not carbon buildup because my engine is almost new.

Muffin

The Knock Sensor is Circuit 496 and the wire from the KS to the ESC is dark blue. Are you setting any codes? That is; is the Service Engine Soon light coming on while you drive?

HeeHaw89

Any news on this kcpaz?

kcpaz

Yeah, the news is that I'm frusterated as hell. I have tried everything I can think of. I'm almost 100% sure that it's not an electrical problem. I have no stored codes, and the check engine light doesn't come on ever. I have replaced both the knock sensor, and the ESC mod. with no change. I have tried probably 6 SeaFoam treatments and have no consistant results. Sometimes it seems like it helps, and sometimes it seems like it makes it worse. I would take the heads off and check out the combustion chambers, but at that point, I would rather throw in a new ZZ4...wich I'm actually seriously considering. . I have changed the base timing from 8*BTC to 0*BTC with no real change. Either way I still get the ping. ANYONE HAVE ANY MORE IDEAS???? I love the car, but hate the sounds it makes when I get on her Could it just be that there is so much carbon buildup from the car sitting so long??? Should I keep using the SeaFoam to try to clean things up???

HeeHaw89

Have you checked your fuel pressure to see if it holds under acceleration?

kcpaz

Not yet, what should the preasures be at idle and under acceleration??? Also, wouldn't a Lean Burn show up with a code??? Oh wait, is that only on the OBD2 stuff??? Anyway, I will try to check tonight.

85 500 horse

Just a thought, but have you ensured that you have the correct spark plugs in use? The wrong plug with the wrong heat range can cause all sorts of problems, including pinging. And also make sure you're running super unleaded. Running regular can cause pinging.

kcpaz

I used some Bosch Platinum plugs. I don't know the heat range. I asked the guy at the AutoZone counter for plugs for an 85' Vette and those are what he gave me. Granted those guys aren't the brightest (no offense to any AutoZone guys that may be on the list) but I doubt that that could be the problem. I would think that if that were the case, that the problem would have gone away with the timing adjustment. and BTW, I use Chevron Super Unleaded, It's the nicest stuff we get here in AZ. I also tried some Race gas (101 octane) and it didn't really help. I mixed it 1:1 with the chevron super stuff.

HeeHaw89

Somewhere around 38-40 psi, vacuum line off. You will need to get a gauge that will be long enough to stick out of your hood and lay up on the windshield. It should not drop at all when you are accelerating. You may want to get someone to ride with you to watch the fuel pressure gauge...I tried this alone and trying to read it while going 75-80 mph after a good squish on the go pedal wasn't the smartest thing to do

kcpaz

Vacum line off??? U mean at idle, or leave it off while I'm driving too??? Sorry, I can't say I've ever had to check the fuel preasure on any of my cars in all my years of wrenching on stuff

ocrick

Check your EGR valve

kcpaz

okay, I just checked the fuel preasure. Everything checked out fine. 35PSI at Idle, 39PSI when I get on it. I have heared a few people suggest the EGR Valve, and that's one of the things that I haven't checked...I figured that I would get a code if there was something really wrong, but I guess that might not always be the case. SO... How do I go about checking the EGR Valve function??? Thanks for all your help.