Detonation
09-25-2017, 04:00 PM
#1
Rennlist Member
Thread Starter
Detonation
No, not Korea.
Has anyone experienced detonation with no loss of power? Going up a hill or loafing around town the car detonates, a firm blast of throttle eliminates that but there is definitely a pinging, yet the car pulls hard, doesn't fall on its face.
We have pretty suspect gas here in SoCal, I try and get it from the same place but you never know. I am all stock, no chip, plugs and wires are good.
The car is looked after by NARW, an excellent Indie here in LA and they have tried everything; just wondering if anyone here has been through this before and can advise.
Many thanks in advance
Has anyone experienced detonation with no loss of power? Going up a hill or loafing around town the car detonates, a firm blast of throttle eliminates that but there is definitely a pinging, yet the car pulls hard, doesn't fall on its face.
We have pretty suspect gas here in SoCal, I try and get it from the same place but you never know. I am all stock, no chip, plugs and wires are good.
The car is looked after by NARW, an excellent Indie here in LA and they have tried everything; just wondering if anyone here has been through this before and can advise.
Many thanks in advance
09-26-2017, 02:37 PM
#3
IHI KING!
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Have you checked your distributor belt? I had pinging when my belt failed. The engine ran ok under light loads but pinged under heavy load. Remove the secondary distributor cap and see of the rotor turns with your hand. It shouldn't.
09-26-2017, 09:42 PM
#6
RL Technical Advisor
Excellent advice here.
Its also possible that you may have inadvertently gotten 80 or 89 octane fuel and that happens more than you think when the delivery drivers puts the wrong product into the wrong underground tank. The only way you'll know is to have the gas in your tank tested by a professional laboratory.
Let me add that you should NOT drive the car until this is resolved, otherwise you could spend a LOT of money.
Its also possible that you may have inadvertently gotten 80 or 89 octane fuel and that happens more than you think when the delivery drivers puts the wrong product into the wrong underground tank. The only way you'll know is to have the gas in your tank tested by a professional laboratory.
Let me add that you should NOT drive the car until this is resolved, otherwise you could spend a LOT of money.
09-26-2017, 11:46 PM
#7
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Thread Starter
Thanks all, distributor belt is fine. Indie wrench thinks I am nuts, detonation comes with fall off in power which is not the case, power is awesome as usual.
Steve is right though, here in LA octane is a crapshoot, you never know what you are really pumping. Steve, do you think the gas tank in the car could be bad? Sucking up crap from the tank?
Steve is right though, here in LA octane is a crapshoot, you never know what you are really pumping. Steve, do you think the gas tank in the car could be bad? Sucking up crap from the tank?
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09-27-2017, 01:19 PM
#11
RL Technical Advisor
Thanks all, distributor belt is fine. Indie wrench thinks I am nuts, detonation comes with fall off in power which is not the case, power is awesome as usual.
Steve is right though, here in LA octane is a crapshoot, you never know what you are really pumping. Steve, do you think the gas tank in the car could be bad? Sucking up crap from the tank?
Steve is right though, here in LA octane is a crapshoot, you never know what you are really pumping. Steve, do you think the gas tank in the car could be bad? Sucking up crap from the tank?
Assuming you don't have a bad chip in your car's ECU, I would followup with some troubleshooting. Old plug wires for example, can cause similar issues.
I've seen enough misfueling occurrences not to ever discount that.
I think if there was sufficient debris in the tank to cause detonation due to fuel starvation, you'd experience some major driveability issues as well. I would suggest you remove the fuel filter and cut it open to see what you have. I would also replace the tank filter if you suspect contamination.
09-27-2017, 02:55 PM
#12
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Thread Starter
09-27-2017, 02:57 PM
#13
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Thread Starter
The ECU will always attempt to maximize performance unless something is drastically wrong and sends the car into 'limp mode'.
Assuming you don't have a bad chip in your car's ECU, I would followup with some troubleshooting. Old plug wires for example, can cause similar issues.
I've seen enough misfueling occurrences not to ever discount that.
I think if there was sufficient debris in the tank to cause detonation due to fuel starvation, you'd experience some major driveability issues as well. I would suggest you remove the fuel filter and cut it open to see what you have. I would also replace the tank filter if you suspect contamination.
Assuming you don't have a bad chip in your car's ECU, I would followup with some troubleshooting. Old plug wires for example, can cause similar issues.
I've seen enough misfueling occurrences not to ever discount that.
I think if there was sufficient debris in the tank to cause detonation due to fuel starvation, you'd experience some major driveability issues as well. I would suggest you remove the fuel filter and cut it open to see what you have. I would also replace the tank filter if you suspect contamination.
Car goes in next week, I will try the fuel filters as you suggest.
Thank you very much for your advice.
09-27-2017, 05:01 PM
#14
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Take a look at this thread here.
Distributor can be off by 1 tooth and still run (supposedly), however under some conditions spark may jump from rotor to wrong post firing the wrong plug.
I looked at advance curve in Adrian's book. Low load dials in lowest advance (in most cases). Plus knock sensors can put 9 degrees of retard into timing. So if your sensors are working and dissies are aligned correctly, hard to blame timing.
Other causes of detonation is too lean a burn. The plugs get too hot. If Air Flow Meter is reporting low airflow, fuel mixture will be leaned out. Same goes for high temp. But DME can still retard timing to compensate. Maybe not enough. Many times the low range on AFM get worn.
One last WAG is wrong temp plugs, or plugs have gotten fouled and have hot spots. In early days of of lean burn engines, I would put a colder range of plugs in the car to inhibit pinging.
One last thing you can try is running one set of spark plugs by disconnecting igniter. You can then swap coil/igniter pair to see if that changes things.
good luck,
Dan
Distributor can be off by 1 tooth and still run (supposedly), however under some conditions spark may jump from rotor to wrong post firing the wrong plug.
I looked at advance curve in Adrian's book. Low load dials in lowest advance (in most cases). Plus knock sensors can put 9 degrees of retard into timing. So if your sensors are working and dissies are aligned correctly, hard to blame timing.
Other causes of detonation is too lean a burn. The plugs get too hot. If Air Flow Meter is reporting low airflow, fuel mixture will be leaned out. Same goes for high temp. But DME can still retard timing to compensate. Maybe not enough. Many times the low range on AFM get worn.
One last WAG is wrong temp plugs, or plugs have gotten fouled and have hot spots. In early days of of lean burn engines, I would put a colder range of plugs in the car to inhibit pinging.
One last thing you can try is running one set of spark plugs by disconnecting igniter. You can then swap coil/igniter pair to see if that changes things.
good luck,
Dan
