Detonation 1bar!

[Ben V]

Does anybody have any ideas?

I have a 964 turbo with full custom exhaust system no cat, Turbosmart 48mm wastegate, KN air filter, K27 7200 hi flow, hi/lo boost control ie standard .7bar and 1 bar.

I think the engine is detonating under boost, very very mildly on low boost .7bar if non at all, but at 1bar high boost distintive tinkle (like coins rattling in the ashtray)
I am pretty sure it is detonation so needless to say I am not allowing it to boost until I reslove the problem!

My thoughts are possible injector problems (semi blocked) or ignition system retard?

[911st]

If you suspect it is on the fuel side, check your control pressures. Also make sure the connection between the manifold and WUR is in good shape. If you do not get a boost signal you would stay lean.

On the ignition side there is not much that can go wrong without a total failure I suspect. You might check that the inputs to the 69EZ are at spec. If you are not getting correct temp and manifold pressure info there it could be keeping the ignition advanced.

It is surprising how often fuel filters effect all car's drivability.

It is always good to have your injectors cleaned and checked for balance once in a while. Some diesel shops have the ability to do this.

Good luck.

[WERK-I]

Originally Posted by Ben V

Does anybody have any ideas?

I have a 964 turbo with full custom exhaust system no cat, Turbosmart 48mm wastegate, KN air filter, K27 7200 hi flow, hi/lo boost control ie standard .7bar and 1 bar.

I think the engine is detonating under boost, very very mildly on low boost .7bar if non at all, but at 1bar high boost distintive tinkle (like coins rattling in the ashtray)
I am pretty sure it is detonation so needless to say I am not allowing it to boost until I reslove the problem!

My thoughts are possible injector problems (semi blocked) or ignition system retard?

Ben,
It very well could be an ignition problem. Check your static, total advance and advance under boost.

[Ben V]

Thanks for your pointers guys, I've got to do some more testing. A/F ratio and ignition timing.

Can you adjust the static timing on a 964 turbo? It's set by the fly wheel sensor isn't it?

The 964 turbo has lambda to adjust fuel pressure against boost, can this fail does it resort to a base map if the air temp or boost sensor fails?

Thanks again

[911st]

No, you can not set it, it is a sealed digital system. There is a provision for an octane jumper but never seen it used.

It is not anything like a 930. You might be able to put a timing light on it and try to check idle and hight rpm timing (apx -40 deg w no load). On a dyno you could check timing on boost. Not sure if you could put a hand pump on the 69EZ if you are thinking of running it up in your driveway to make it think it is under boost to check boost-retard or not.

On a C2Turbo that is modified having an AFR read out and a boost read out are good ideas.

I would check the vac-connection to the WUR first. If this cam off you would have exactly the situation you are noting.

Next I would check the system pressure at the head and the control pressure at the WUR as these are the heart of a CIS system and the first thing one checks when there is a drivability issue. I actually installed a fixed gage at my fuel head so I could check my CP anytime.

Also might want to just put a vac-gage on the intake to check that you do not have any leaks or other issues.


Goog luck.

[WERK-I]

Before going to much into the electronics, system/control fuel pressures.......
Have you recently filled your gas tank and mistakenly got low octane(less than 91) fuel?

[Ben V]

I was looking at pressurizing the 69 EZ then checking the timing to see if the ignition retards.

I'm thinking there might be a vac leak somewhere as the revs hang but only intermittently. In fact I had to adjust the idle the other day as it was reving 1350 idle, later that day I returned it back to where it was, strange!

Fuel I am using shell v power 99 Uk. I even mixed in some toulene to see if that made a difference. Still had det if it is det. (plug show signs of det). This has lead me to think it is a fuel supply issue, like injectors because Toulene should stop det dead, unless there is not enough fuel?

Ben

[WERK-I]

Originally Posted by Ben V

I was looking at pressurizing the 69 EZ then checking the timing to see if the ignition retards.

I'm thinking there might be a vac leak somewhere as the revs hang but only intermittently. In fact I had to adjust the idle the other day as it was reving 1350 idle, later that day I returned it back to where it was, strange!

Fuel I am using shell v power 99 Uk. I even mixed in some toulene to see if that made a difference. Still had det if it is det. (plug show signs of det). This has lead me to think it is a fuel supply issue, like injectors because Toulene should stop det dead, unless there is not enough fuel?

Ben

Toulene would have raised the octane, depending on the concentration level. Good idea to check all the vacuum and pressure sensor lines. You should never have to adjust the idle screw if all the other control devices(Auxilary Air Valve and Warm Up Regulator) are in working order. You may have a WUR going. Check your control pressure after the engine is up to temp. An intermittent AAV will give you idle problems if it doesn't close all the way when the temp comes up. The fact the idle went up, means you have a slightly rich AF setting(most people set slightly rich) when additional air is added in an area which bypasses the throttle body. Check all the hoses first. You may be in luck.

[beepbeep]

Originally Posted by Ben V

The 964 turbo has lambda to adjust fuel pressure against boost, can this fail does it resort to a base map if the air temp or boost sensor fails?

Thanks again

nope. It's narrow-band sensor and it cannot really detect AFR's. It only trips when passing trough 14.7 region and is used on part-throttle.

On full throttle, system runs open-loop. Check AFR's, check ignition timing. And do the leakdown test as well, in case pistons rings are in pieces.

[Ben V]

So can you adjust the 964 turbo ignition, my understanding is that it times it's self from the timing pin on the flywheel and then maps accordingly. Is there any point checking the timing or can the map sensor fail in the 69 EZ?

I am very sensitive with engine noises and have switched it back to .7bar
although everything seems ok mechaically, it will do a leak down when I sort the problem.

Does the air temp sensor play a big part in the set up?

[Thierry25]

Originally Posted by 911st

If you suspect it is on the fuel side, check your control pressures. Also make sure the connection between the manifold and WUR is in good shape. If you do not get a boost signal you would stay lean.

On the ignition side there is not much that can go wrong without a total failure I suspect. You might check that the inputs to the 69EZ are at spec. If you are not getting correct temp and manifold pressure info there it could be keeping the ignition advanced.

It is surprising how often fuel filters effect all car's drivability.

It is always good to have your injectors cleaned and checked for balance once in a while. Some diesel shops have the ability to do this.

Good luck.

+1 about what have been said by Keith ! All of this must be checked !

I run 1.2 bar on my 964 turbo ( which has SC/X33 cams) and there is absolutely no detonation or knock ...

You should verify that the hose between the intake pipe and the EZ69 is correct.... if this hose is disconnected , the ignition timing is set at 40° ( so in this case, the knock occurs )

If you are not sure with your EZ69, it can be tested with a timing light

[Ben V]

I have checked through the hoses and connections and as far as I can see it all seems OK.
I have changed the fuel filter, also removed 2 of the accessable injectors which seem pretty clean, I sprayed carb cleaner through them first backwards holding the injector open and then secondly the correct way and the pattern doesn't look too bad either.

Another curious thing is another sympton has developed, the engine runs on for a second or so after keyed off?

[911st]

How did you check the vac lines. Did you put a vac gage on them at the EZ and WUR? They should both have a stable vac on them at idle.

I would check the control pressure warm at idle and check it a hand pump hooked up to the WUR pressurized to above .5 bar (7 lbs) to see if it is in spec.

Might check the fuses to the front and rear fuel pumps. Not sure if it will run with just one pump but if it dose, it would probably go lean.

[Thierry25]

Originally Posted by Ben V

Another curious thing is another sympton has developed, the engine runs on for a second or so after keyed off?

This is totally normal. My car do exactly the same... actually when you turn off the key, the engine continue to run in order to absorb the fuel which is in the injector fuel line in order to kill the fuel pressure inside it.... it prevents some unwanted fuell spraying inside the intake manifold while the car is turned off . ( When the car is turned off after a long trip, the heat increase significantly and the intake manifold can becomes very hot )

[JFairman]

Originally Posted by Ben V

I have checked through the hoses and connections and as far as I can see it all seems OK.
I have changed the fuel filter, also removed 2 of the accessable injectors which seem pretty clean, I sprayed carb cleaner through them first backwards holding the injector open and then secondly the correct way and the pattern doesn't look too bad either.

Another curious thing is another sympton has developed, the engine runs on for a second or so after keyed off?

There is an ignition delay relay on the rear electrical console that keeps the ignition on for about 4 seconds after you turn the key off to burn any possible left over fuel in the intake ports.

Did the run on start after you pulled the pintle up and backflushed the CIS injector?
If so you may have damaged it or it's seat, or the spring that holds it shut and now your injector is leaking down after you shut off the motor rather than shutting and holding something like 30psi against the accumulator spring loaded diaphram and fuel pump check valve like it's supposed to.
If thats happening than the ignition delay relay could cause the run on.

It's best to use a softer metal than steel like a thin strand of copper wire wrapped around the pintle and bent down the side of the injector to hold it up while backflushing them.

[Thierry25]

Originally Posted by Ben V

I have checked through the hoses and connections and as far as I can see it all seems OK.
I have changed the fuel filter, also removed 2 of the accessable injectors which seem pretty clean, I sprayed carb cleaner through them first backwards holding the injector open and then secondly the correct way and the pattern doesn't look too bad either.

Another curious thing is another sympton has developed, the engine runs on for a second or so after keyed off?

If your car run correctly at iddle and off boost rpm, it means that your injectors are not involved in your problem.

As said by Keith, you should verify your fuel system pressure ( min 6.6 bar) and fuel system flow rate ( 1.5 liter per 15 second). Thus, if correct, it will means that your fuels pumps, fuel filter and accumulator are correct !

Then, in the mean time, you should verify your WUR controle pressure in warm ( about 4.5 bar) . Then you have to trigger the WUR with 0.75 bar signal and verify that your your controle pressure drop to 2.9 bar ( about).

I still believe that you have somewhere a problem with a vaccum/boost signal which could false the pressure information which is given to the WUR and to the EZ69

[Ben V]

Correct, the run on problem was due me back flushing the injectors, 1 not seating right. I managed to make it seal again.

Back to my detonation problem, I have checked again the hose from the 69EZ and the WUR they are T'd to the same connection.

I have booked it in for a rolling road next week to clarify whether there is det! We can also check A/F, timing under load and fuel pressures.

[911st]

Do you have proper gages to test control-pressure and vacuum?

If not, it would be a worthy investment.


When you do your dyno tune, have them put there wide band in place of your O2. Also, unplug your O2 so the Lambda-computer will not give you funky AFR's.

This is preferred to sticking a probe up your tail pipe. On the dyno you can set your O2 a little fat if you like and if you do not go to far, when you plug back in the O2 it will bring you back on idle and cruse.

You might even un plug your O2 now as a test to see if it changes anything. It should not unless the throttle switch is not functioning correctly. Many just run without the O2 plugged in.

The best.

[Ben V]

The guy where I am getting it dyno'd is an 80's Porsche specialist and has all the test gear. He has suggest welding some lambda bosses in the manifolds to get a good A/F reading.

A point on the O2 sensor, is this not required to enrichen the mixture especially on full throttle? I thought this was a benefit over the 930 setup?

Thanks again for all your input guys

[Ben V]

Correct! one of the injectors wasn't seating well after the back flush, fortunatelt I have got it seating again. I was pretty careful but the cooper wire idea is good.

The reason I am looking at the fueling is if it was leaning out on boost at 4.5k upwards injectors could be clogged up, I have heard there are some gause filters in the injectors which can block or loose efficiency. The vac system seems in good order and the 69EZ seems by all accounts to be pretty reliable. I still have a slight question over the WUR and warm up valve?

Any way enough guess work time for dyno diagnositics, afterall it may not be detonating at all, it could be a rattle, I suspect no though and it's not worth the risk of serious engine damage.

The guys I am taking to are 80's porsche specialists, so they do have all the test gauges and knowledge, at least I hope. They are going to weld additional Lambda boses in the manifolds to test with wide band lambda sensors and we can check the ignition timing on load. I guess I will also get to know how much over the stock 320bhp it is.

On the point of the O2 sensor control, I thought the sensor was a benefit over the 930 system giving the fuelling the ability to richen the mixture on full throttle by lowering the fuel pressure with the frequency valve.

Thanks again Guys for all your input!