heavy knok under acceleration

[Chris84]

This afternoon I noticed that my car was pinging alot. it started at about light throttle, and got worse the harder I stepped on it. (perhaps it could be a wrong adjusted TV-cable so it shifted to late) I drove it home, but I'm wondering what is casuing this. I've never had it happen before is swapped the engine. The timing is set right at 10 * BTC.


Let me know what you think. Thanks guys.

[91waggin]

Knock as in detonation? Make sure your EGR is functioning properly. Make sure your cats aren't clogged.

[gadget73]

Clogged fuel filter? Bad fuel, or a spun balancer could cause this. If the balancer is spun, the timing might say 10 btdc, but it won't actually be 10 btdc. Also, it was set with the spout connector out, right ?

[Chris84]

yes, the spout connector was out. the balancer is from my old engine, but on this engine everything was o.k.
i replaced the fuel filter at the engine swap 2 months ago. fuel pressure is ok, too.
it knoks like a detonation, if i step on the pedal it becomes stronger, until the car shifts down. sometimes it sounds like a diesel... but only if i step on the pedal (not a kick down)
last night i tried to set the timing on different points (between 0 and 20° btdc) and it made no difference...
when the timing is set on 10° btdc and i put the spout in, the computer anvances only a few degrees (i think only to 15° btdc)
i also checked the car for vacuum leaks, and so i replaced every vacuumhose that comes from the engine or somewhere... and i replaced the pcv vavle and filter... (so perhaps its to much crankcase air flow?)
what do you think? EGR, Carbon depostis, TFI module or shot EEC? (i´ve got a new spare computer at home)

[Tiggie]

I had this problem in my wagon a few months ago. I think I got a bad tank of gas since it stopped after the next fill up. You didn't get a batch of bad gas did you?

Check to make sure that EGR is functioning correctly.

[cld783]

i would also check for exhaust leaks...

[Chris84]

it´s the same gas as in my girlfriends Golf, you can´t buy regular here in germany since january, only premium.

the egr is working, and i cleaned all the stuff, including the whole intake. but the car still knocks.

the exthaust have a very small leak after the mufflers, so small that you can´t hear it blowing.

but i think the problem comes from the cats... these are from a lexus RX 400 h... so originally designed to handle the flow of 3,6 litres... as they where new, nothing knocks, but i think they clogged a bit in the break in period of the new eninge... ugha....

[1987cp]

You have taken a stethoscope and made certain you know the location of this sound, right?

[Chris84]

ehm, no, i don´t.

when the car idles you´ll hear nothing, it only knocks under load and acceleration, if i floor the pedal in "P" o "N" i´ll hear nothing...

[gadget73]

Clogged converters could cause detonation. It will make the engine temperature high, which will make it more inclined to detonate.

[Pirate]

Clogged converters could cause detonation. It will make the engine temperature high, which will make it more inclined to detonate.

I'm thinking more along these lines....you need to verify how hot the engine is running, which the stock gauge cluster will not do....I think the motor is running hot...which can cause pinging.

Install a temp gauge if you have to, and get the injectors cleaned.

[Chris84]

a temp gauge is installed since i bought the car. the temperature in all driving conditions is around 80°C it seems normal.
i´ve put a new set of injectors in the car and it still pings/knocks... perhaps the downshift points are set to late... later i check the TV cable setting.

but i´m thinking about the clogged converters, it sounds possible...

[91waggin]

New cats cured the problem in my car.

[Chris84]

ugha...

I was at the gas station and filled the car up and now the detonation knock is less than before... (and the golf broke down this evening because of bad fuel)

I think it was that bad gas, but it´s not the only thing, that´s wrong with the car.
The thermostat is ok, the engine is at 80°C operating temperature, but it still knocks.

So i think the cats are clogged, OR the PCV Vavle is stuck open, i can hear a loud hiss from the pcv hose when the car idles (i think at idle the vavle should be closed)... could that be the reason?

I took the car to a emission test, and the lambda was at 1.0, the engine runs ok, not to lean and not to rich, and the cats working properly (co was at 0.0)

[Brandon]

Maybe your gas tank has trash in it. I know our old truck did the same thing, and we used premium in it. So we started stoping at a different gas station, and it straightened out. How long has the pinging been going on?