Ignition miss

ashills

Active Member
so far we have had upto 1.65 bar on stock ecu and stock ignition system and cheapest plugs you can imagine, so be interesting to see where we hit problems
 

stevepudney

GTiROC CHAIRMAN
Staff member
Just thought I'd let you know, I changed my plugs from the Denso IK27's to the NGK 9's and the misfire has gone :-D
 

ashills

Active Member
all these misfires u fellas have must just be the cars dont like u as mines fine at 1.6 bar lol or it might be because im on special £5 a set plugs
 

turblio

New Member
Right my missfire has gone!, after playing with all the connecters under the bonnet it has gone and runs raher well!!
 

gtirx2

Member
Just an update,have posted this else where but now that i think i have found out the reason for the set revs miss/burble i thought i would post it here to.
Originaly posted by campellju...

Aftermarket capacitive discharge systems: Better for high boost high rev applications than OE. Will not give more power on their own but will allow more accurate tuning of the ignition map so in "theory" more power (At high boost/rpm)

However, their short duration is why they have to fire many times at low rpm with lean mixtures. Without this "feature", CD systems will misfire. Inductive OE systems with longer durations don't have this problem. However, running small plug gaps on an OE system would give similar problems.

And when i had a fiddle it seems that this maybe the reason.

I have just tryed upping the fueling and its seems to have done the trick with my set revs miss:-D I had to raise it a fair bit [like 40% on the afc2] but the burble defintaly got better/if not went altogether[with the msd connected] so i am pretty sure it is was what campellju was on about with the duration of the spark on these cdi units with lean mixtures at low revs.I am just guessing that when i hold the revs at set revs in netural it is obviosly not running that rich and is proberly running more on the lean side with no load on the engine so the cdi ignition unit is not igniting it as well as the standard inductive system with a longer spark duration would?
This would also explain why the only way i could get rid of the set revs miss/burble was to gap the plugs wide on the standard inductive system.
My only worrie now is that my R is running a bit lean under no load/light load situations which is causing the miss as no one else seems to get this burble like i do?
Anyway i am pretty happy as this has been a mystrey for me for a long time and tbh now i think i know what the problem is i don't think its much to worrie about under light load conditions.
My next wonder is if i was to get it remapped in the future would you benifit from mapping the car rich under light load conditions so that the short duration muti sparks of the msd system have a better chance of igniting the fuel/air mix better?
 
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