loss of power

[dub-disaster]

i have been getting a loss in power when changing down gear and planting my foot, after doing so you ca  waot usjaly 2-3 seconds then there will be a loss of power at first i thought it was knocking but after listening to some videos of knocking on you tube sounds nothkng like it. Its not so mucb a sound as it just feels like youve hit the brakes or lifted you foot completley.

At first i thought the fueling was to blame so i did a pressure test and when the fault occured pressure was fine repleated this 3 times and fuel pressure was around 60-65psi solid no fluctuation.Boost was at 15 psi ish and revs usualy aroind 3.5-5k hard to watch all thr dials at once and keep the car on the road as i was doing this testing on my own. fault only occurs after a downshift and then floor it doesnt happen if you slowly build the power.

All the fueling system is new but since the rebuild the car was remapped and ran fine for a few months most of witch it sat in the garage doing nothing. Fuel wise its had new pump uprated sytec one good for 250bhp at 7 or 8 bar cant remember now,new lines throught,new filter,new 330cc orange volvo injectors. AFRs arr good thr fault has occoured at 11.7 once and once at 12.7 again i dont now think its fueling related as it feels very sudden like somone has stapmed the brake very briefly at which point i let of as i dont want to damage anything.

So my next line of i investigation is ignition this is entireley new since the rebuold and has proabbly done 2k total it includes new oem coil new gsf electrospark leads (which arnt the best fit but did run the car no problems for a year with over 1000 miles on it) and bp7evx plugs i pulled the plugs and they look spot on not to hot not oily or sooty gaps range between about 0.6-0.8 i will be restting the gaps to 0.6 in an attempt to fix the fault.

Has anyone ever had a fault where the spark was blown out under load what does it feel like? would it have to lose spark from all cylinders to get the same sort of fault as described?

With regard to the ignition system i know resistors are used for suppression but are they contained in the leads and the rotor arm do they need to be in both which resistances can i remove and which need to stay ?

Any other ideas what this could be the only things i coils think of are:
Fueling related issues

Ignition related issues

Transsmission or maybe clutch although its unlikley as i run a paddle but i wont rule it out

knock sensor could this maybe be giving faulty readings and pulling timing back wouls this feel like an instant loss in power like lifting of quickly?? Can digifant run without a knock sensor? is there a way to effectivley link it out or test it ?

hall sender breaking down maybe but i would imagine this would give a fault that occurs throught the rev and load range but again wont rule it out rotor arm and dizzy are new.

Any thoughts?

[z3i]

http://www.polog40.co.uk/forum/index.php?topic=9225.0

The resistor is in the rotor arm, yoof knows all

[Jezza-7]

I would look/check at hall sender mate.

Few summers back i had a similar problem and then one day it jus died. Gave the hall sender a wiggle and back to life, replaced it and sorted the problem.

This developed since RR day i take it? Cause it felt fine and quick.

P.S still going santa pod?

[Andy]

My money would be on the ignition system breaking down.

Make sure that you're using non-resistor plugs, normal leads (no fancy uber-supression jobbies) and a decent dizzy cap and rotor arm. If you prefer to use resistor plugs, remove the resistor in the rotor arm.

Mine tends to eat rotor arms and has done for ages (used to do it pre-turbo with Digifant), possibly because the GSF ones aren't up to much. My first warning is random misfires under load - usually worse at peak torque. After a while of that there's usually obvious burning damage to the rotor arm.

[dub-disaster]

My money would be on the ignition system breaking down.

Make sure that you're using non-resistor plugs, normal leads (no fancy uber-supression jobbies) and a decent dizzy cap and rotor arm. If you prefer to use resistor plugs, remove the resistor in the rotor arm.

Mine tends to eat rotor arms and has done for ages (used to do it pre-turbo with Digifant), possibly because the GSF ones aren't up to much. My first warning is random misfires under load - usually worse at peak torque. After a while of that there's usually obvious burning damage to the rotor arm.

lol funny you should say this andy i pulled the dizzy of today to remove the resistor from the rotor and the contacts in the cap where pretty well burned (cap is beru and done arou d 2k miles) i cleaned this up along eith the edge of the arm (beru 2k miles aswell) these should make contact on rotation im guessing? The spark isnt ment to jump this gap ? mine dont any more so im going to invest in a new cap and arm which i will remove the resistor from ill also swap the new hal sender over as mines a bit wobly although still in tact.

Any one know a decent supplier of ignition parts as gsf are a pain as you never realy know what youre going to get these days!

[Yoof]

Spark will jump from rotor arm to dizzy cap, hence old ones look like they've been spark erroded!

From experience, it's a pain to dig the rotor arm resistor out each time you change it. I'd leave the rotor arm and get a resistorless plug (BP8EVX)

Here's a vid of Robin's G40 blowing the spark out when Andy was mapping it:

http://www.youtube.com/watch?v=sqG1vfR6GeE

It happens at peak torque (highest cylinder pressure- greatest spark energy requirment usually) and we believe it was due to aquamist jetting/boost setting at the time, and probably heatsoak into ingnition components.

The conditions you describe do sound like spark being blown out, rather than a missfire.

[dub-disaster]

trying to source some bp8 evx as we speak but theve gone obsolete now and ngk now recomend there iridium restor plus instead (if ive got my spark plug codes correct) some availible on ebay but i dont realy trust them, may not have a choice now.

It definantly seems to occour at around peak torque around 4-5k ish but i never push past it i always back of if it is the spark being blown out can i just keep acceleration and once the cylinder pressures have gone down a touch the power should come back ?

Ive ordered myself a spark strength tester so im going to give that a go and see what im getting.

If i find the spark to be inadequate im assuming my options are:
Dig out the resitor in the rotor arm and run no resitor in plugs or rotor
close up gaps on the plugs to around 0.6 from the suggested 0.8

Change ht leads for magnecor or similar ( Although i was under the imperssion these arnt much better than normal ones even though trevor from won recommend them, although he does sell them :S)

change coil to something like msd blaster - my current coil is a OEM genuine part and has only done 2k so i cant see it being this to be honest got a mahooosive earth strap on it aswell for good measure along with all the other engine earths

Can the spark be tracking down the metal sheilding around the lead ends and wasting energy?

I have rebuild by dizzy with a brand new OEM hall sensor and cleaned the contacts in the cap and rotor arm i will refit this and close the spark plug gaps up a little, then try my spark strength tester and see how i get on might dig the resistor out the arm aswell just for good measure.

hopefuly this is ignition related and not fuel related as ignition breaking down is less dangerous than h the having fueling problems, i may enlist the help of jezza and do some "testing" getting him to read the guages.

Thanks for the help guys ill let you know how i get on

[Jezza-7]

I'll help you if you help me with my suspension

[Jezza-7]

Have you spoke to yeovil motor factor or that other parts place in lynx industrial estate?

http://www.ebay.co.uk/sch/i.html?_trksid=p5197.m570.l1313&_nkw=bp8evx&_sacat=0&_from=R40

[dub-disaster]

i bought some this morning this morning thanks jezz, local motor factors are crap to be honest.

[Yoof]

You can try closing the plug gap- it does make them more prone to fouling when cold though, but I've run at .6mm with no problems.

[dub-disaster]

Ok so i re-assembled the ignition system with the modded rotor arm and did a spark strength test and found that on all cylinders my spark will jump a maximum of around 11-12mm consistantly is this enough should this cause a problem? all ignition components are new so if this isnt enough then i would have to go for an aftermarket ignition system which i think is overkill as everyone else runs standard polo ignition without major problems with a turbo and the 21psi of boost.

I do intend on running nitrous and the sugessted spark strength for that is a minimum of 15mm recommended 20mm so an upgraded ignition system wouldnt be completley wasted , yoof did you run your 25 shot with standard ht leads and coil and other ignition componenets ?

[dub-disaster]

for any one who has similar problems, this problem was resovled by tweaking the spark plug gaps down to 0.6mm and removing the resistor in the rotor arm i cant guarntee this was what caused it but its running ok now.

I am still considering using an msd ignition though as it will guarntee i never have this problem now or with nitrous. Any one have any experiences of CDI ignition or comments on it ?

[Yoof]

I've got a blaster 2 coil to use with a Golf amp module if/when I ever get round to it...