12 replies to this topic

[icelandic]

My 1994 850 NA engine is knocking below 2000 rpm. Spark plugs, distributor cap and rotor are new. It has a new Cat. Before replacing the Cat which was bad, I kept getting 436, 435 and 315 codes. After cat replacement, I get 435 and 315. I have checked all vaccum lines and all appears to be OK. Is there a relationship between the 315 ( evap malfunction) and the fact that the original cat melted?

My next steps will be:

1- Take the evap cannister out and see if it is not cracked. Check the vaccum lines to it and see if there is any leak in there. There is a valve connected to it close to the radiator. Any way I can check it?

2-Replace the front O2 sensor

3-Remove the intake manifold and check if the knock sensors are properly torked and connected, even though I have not gotten any codes related to them. In the process I will have the injectors ultrasonically cleaned.

Any other ideas? Am I missing anything?

Thaks

There are no leaks in the exhaust manifold, engine runs OK, starts Ok and performance is OK. But the knocking is there. PreIgnition. No valve tapping or mechanical noise.

[theunderlord]

what octane gas you running?

[icelandic]

what octane gas you running?

I am using 89, the same I always used.

[MrWinkey]

Ok knocking like at speed say 50mph at 2000 rpm with converter lock-up?
It may possibly be lean...(vacuum leak....look a little harder maybe?)

[icelandic]

Ok knocking like at speed say 50mph at 2000 rpm with converter lock-up?
It may possibly be lean...(vacuum leak....look a little harder maybe?)

Usually the knocking is heard when going uphill, particularly in first or second gear. When it comes, if I give it more gas the knocking disapears as soon as RPM gets above 2000. It never happens with a cold engine. Gets worse when it is very hot outside. And gets a lot worse in traffic jams.

[MrWinkey]

Where does the temp gauge read ?? Is it possibly to hot ??..or once again it sounds lean to me.....there are many other factors as well...has it just been happening on this ank of fuel...have you tried a fresh tank of 91 or better??...yadayada

[icelandic]

Where does the temp gauge read ?? Is it possibly to hot ??..or once again it sounds lean to me.....there are many other factors as well...has it just been happening on this ank of fuel...have you tried a fresh tank of 91 or better??...yadayada

Temperature is normal, with guauge at the exact middle of the range.

[MrWinkey]

Once again...have you tried a fresh tank of fuel?....How long has this problem been going on?.....It is probably lean

[jens94850]

Once again...have you tried a fresh tank of fuel?....How long has this problem been going on?.....It is probably lean

Have you recently replaced your timing belt??? Its a long shot, but it may be off a tooth on one of the cams or stretched too far....

[icelandic]

This problem has been going on for sometime (a couple of months) I am sure it is not related to gas quality. Yes my timing belt was replaced one month ago. The problem was there before the change and continued exactly the same after the change. If there is a lean condition, what would the causes be besides a vacumm leak? The car has 150K on it, has always been well maintained, but has never had the injectors pulled out and cleaned. I have ocasionally used fuel injector cleaner on the gas, but I can't be sure of how effective this is.

[Bay13]

My 1994 850 NA engine is knocking below 2000 rpm. Spark plugs, distributor cap and rotor are new. It has a new Cat. Before replacing the Cat which was bad, I kept getting 436, 435 and 315 codes. After cat replacement, I get 435 and 315. I have checked all vaccum lines and all appears to be OK. Is there a relationship between the 315 ( evap malfunction) and the fact that the original cat melted?

The 435 code is for the front HO2S. Slow to respond. You more than likely need to replace the front O2 sensor.

The 315 code is the EVAP system. 99% of the time it's because you need a new canister purge Valve, also know as the EVAP valve. When you go to get one you will need a kit that comes with a wiring harness adapter and a new hose with a check valve in it.

[icelandic]

But do you think the bad O2 sensor plus the canister purge valve could be the cause for the knocking?

[Bay13]

The O2 sensor might cause the knocking. The 315 I'm not sure. Either way both those items need to be fixed. A bad O2 sensor could have caused the cat to go bad.