Hesitation!

[DMDRIFTING]

Hi all,

posted this originally and thought problem was resolved after fitting a HKS Twin Spark Amplifier!

But still after driving  normal or flat out for more than 15 mins car becomes hesitant like a break in ignition, coils etc. Changes coils can\'t confirm these are 100%, new plugs fitted, have new leads to go in on the weekend.


Was advised by Clive at mazdarotaryparts that I would need to keep engine cool with a vented bonnet, to lower intake temps, and that the intake temps are the problem, done some research into vented bonnets and cooling efficiency and the results are not to good in comparison to standard bonnet!

Also some regular track attenders and 1/4 mile loons use up to 11.5 plugs in the trailing side of the rotors, and will look at taking mine from the 9\'s up to a 10!

I see a few people have suffered from this on there FD\'s is there something i\'m missing? Is this something that will show as a fault code?

Many thanks

[DMDRIFTING]

Anybody here?

[BenLewisMav]

Might be worth getting in touch with some of the rotary specialists in the UK, it seems as though it could be almost anything as you\'ve changed the obvious stuff;
Guess it could be
-Plugs
-Leads
-Coils
-Wiring/Earthing
-ECU fault
-TPS fault
-Vacuum Leak


Also is it standard?

[BenLewisMav]

Just read you HKS twin spark install post..
What ECU are you running?

[DMDRIFTING]

Just running a standard ecu


Gonna put 10\'s in trailing and new Fujita leads in this week

[DMDRIFTING]

The car was standard when this started!

Now running a cat back exhaust and blitz filters waiting for new ecu, fuel pump, injectors etc. But want to try and solve this problem first.


I can trace it back to running the car into the rev limiter on Quarry Corner @ Castle Combe, been fine for 2 whole open pit lane track days but obviously didn\'t stay on track for longer than 15mins

Once i visited the Nurburgring and jumped straight on for lap 2 thats when hesitation began, let it stand for 20  back on and it would be fine?

I should take it to Geoff but just don\'t have the time or money this month is it something that should come up as a fault code?

[Brett]

Sounds like its going to be a heat issue - visually, are there any signs of heat damage?

[DMDRIFTING]

No immediate signs of heat damage, have replaced a few vacuum pipes that run above the turbos, they were original, and had heat damage, but after taking off the plenum and investigating the rats nest all other vacuum pipes seem fine!
 
Have had a little chat with Tim again at RXmotors and have been pointed in the route of the positive wire that runs to the ignition amplifier, as the light on the HKS Twin Spark is on but not 100% bright!
 
This could be the problem? Fingers crossed!
 
 
List of changes so far:
 
Ignition Amplifier
Coil Packs
Sparks plugs 9\'s Trailing and leading
Added HKS Twin Spark
 
To come:
 
Spark plugs 10\'s trailing
Fujita High Tension leads with grounding cables
New live/positive feed to original Ignition Amplifier
 
 
Slowly but surely going to solve this
 
 
Many thanks for your time

[Brett]

Have you checked the pulsation damper at the end of the fuel rail - these can fail with some odd faults being the symptom.

[DMDRIFTING]

Would be good to add pictures on the install thread as planned but i can\'t add pictures until i become a full club member i think!

[DMDRIFTING]

I will have a search in the workshop manual for the Pulsation Damper, guess its simple to find as its on the fuel rail? Does this act in addition too or in a similar way the \'Fuel Pressure Regulator\'
 
What are the signs on a failed PD unit?

[Brett]

Depending on how bad the failure is you can get a strong petrol smell (more than usual for a rex) - really extreme you get a fire :flamed

But one thats split can let air into the system. (Expansion when hot could make a split worse)  IIRC its not too bad to get at, so give it a clean up and you should be able to tell pretty quickly if its split or not.

[DMDRIFTING]

Now that is very interesting, im yet to smell it but the day before yesterday my missus arrived at work in the Mazda and she could smell petrol she also had a comment from her work collegues of a strong smell of fuel ?
 
The next day I took the car out for a 15min run but did not experience the smell?
 
How much are these?

[DMDRIFTING]

Can you just confirm what IIRC stands for?
 
I understand its part of the intake system is that correct?

[Brett]

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