I Have A Tick.....
- Thread starter aladinsane
- Start date
Tim Kay
Lifetime Supporter
Happy to report we diagnosed the "tick". I took Ian and GTRene's suggestion and just fired her up in the dark. Hoping to see some arcing because i was so sure the sound emulated an arc but I was surprise to see the tick is audible at the moment a small flame occurs within the opening throttle body. And not one particular throttle body but on any given blip of the throttle it occurs in all eight. Not all at the same time of course, generally only one but occasional two throttle bodies will light up at slightly different interval.
Now the remedy. Keeping in mind this is a TWM FI, what could be the cause?
Coincidentally I have a dyno appointment in four days so I'll have the tuner see if he can resolve the tick in the mapping or ECU programming.
Stay tuned...
Now the remedy. Keeping in mind this is a TWM FI, what could be the cause?
Coincidentally I have a dyno appointment in four days so I'll have the tuner see if he can resolve the tick in the mapping or ECU programming.
Stay tuned...
Do you have a lot of overlap in your cam.
Does your ECU have sequential inj.
If you do and our ECU allows it changing inj timing maybe a solution.
If it has batch fire it maybe having a little burn of in the intake on overlap.
Just a thought.
Jim
Does your ECU have sequential inj.
If you do and our ECU allows it changing inj timing maybe a solution.
If it has batch fire it maybe having a little burn of in the intake on overlap.
Just a thought.
Jim
Seymour Snerd
Lifetime Supporter
I'm sitting here on the edge of my chair waiting for an explanation like that. Jim or anyone -- have you ever seen this before?
Sounds like a 'lean' backfire, much like you get with a carb when its opened quickly on an engine where its not at operating temp or the carb settings are lean or a dizzy with a retarded advance curve or timing. Could be case of all three plus cam overlap as Jim suggested. With a 4bbl you get a big flame, but with the individual stacks on Tims car you get the 'small' single 'tick' from any one of the eight then nothing til that cyl fires again.
Allan
Yes and it has been related generaly to valve springs, cam timing. ignition system things of that nature.
One thing I would do is pull one plug lead of at a time,put a plug in the end of the lead so as not to hurt the ign system.
I would then see if the ticking come flames in the inlet stop then that will then pin it to 1 cylinder.
If it doesnt then its related to all, it may give you direction.
This would only apply if the inlet runners are linked.
If they are seperate then it is on all cyl by the description.
Jim
Yes and it has been related generaly to valve springs, cam timing. ignition system things of that nature.
One thing I would do is pull one plug lead of at a time,put a plug in the end of the lead so as not to hurt the ign system.
I would then see if the ticking come flames in the inlet stop then that will then pin it to 1 cylinder.
If it doesnt then its related to all, it may give you direction.
This would only apply if the inlet runners are linked.
If they are seperate then it is on all cyl by the description.
Jim
Tim Kay
Lifetime Supporter
It's done, finally got it resolved
Pretty much as Jac Mac points out, the "tick" was prevalent from the closed throttle position to a quick opening of the throttle bodies allowing an immediate large volumn of air to enter. When this lean condition occurred the throttle bodies firing at that moment spit out a small back fire flame. The "tick" did not rear it's head while on the dyno the previous week due to the dyno pulls were from 2K RPM and above.
We resolved the issue by tuning "on the road". The Tuner was amazed at how much fuel was required to balance out the lean condition. Initially he tried increasing the volume of fuel at the "accelerator pump" which didn't help even when taken to the max. Finally he corrected it by adding fuel directly on the fuel map. I'm sure he did some other "massage tuning" as well to iron it all out (I don't fully understand the ECU tuning much beyond the basic mapping) since she runs smooth throughout the whole power band.
She runs like a champ now, pulled 509hp\488tq on the chassis dyno, and with that I am thrilled.
Pretty much as Jac Mac points out, the "tick" was prevalent from the closed throttle position to a quick opening of the throttle bodies allowing an immediate large volumn of air to enter. When this lean condition occurred the throttle bodies firing at that moment spit out a small back fire flame. The "tick" did not rear it's head while on the dyno the previous week due to the dyno pulls were from 2K RPM and above.
We resolved the issue by tuning "on the road". The Tuner was amazed at how much fuel was required to balance out the lean condition. Initially he tried increasing the volume of fuel at the "accelerator pump" which didn't help even when taken to the max. Finally he corrected it by adding fuel directly on the fuel map. I'm sure he did some other "massage tuning" as well to iron it all out (I don't fully understand the ECU tuning much beyond the basic mapping) since she runs smooth throughout the whole power band.
She runs like a champ now, pulled 509hp\488tq on the chassis dyno, and with that I am thrilled.
509 you had better hang onto your hat.
Jim
Jim
