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Weak Spark on Xflow/Megajolt/EDIS System and MOT booked!
GaryM - 8/3/21 at 05:01 PM

Hi Guys

My cars been off the road for an embarrassingly long time. I've just finished putting it back together after an engine refresh (xflow) and electronic fuel pump upgrade.

It's not starting very well (weak spark) and i'd like to replace the HT leads and coil pack. The car runs a megajolt/EDIS 4 system.

Can anyone help me with the make/model/year of a suitable car that can supply these parts as without these it seems impossible to order parts from my local auto-factors?

If it helps the coil pack is the version where the HT leads have clips securing them to each coil pack terminal, part no. 88SF-12029-A1A. I'll try and post a photo but i'm struggling at the moment.

Many thanks in advance.

Gary

[Edited on 8/3/21 by GaryM]

gremlin1234 - 8/3/21 at 06:40 PM

as always, check the 'earth'/ chassis connections, any rust under the terminals /will/ cause problems

obfripper - 8/3/21 at 09:51 PM

quote:
Originally posted by GaryM
Hi Guys

My cars been off the road for an embarrassingly long time. I've just finished putting it back together after an engine refresh (xflow) and electronic fuel pump upgrade.

It's not starting very well (weak spark) and i'd like to replace the HT leads and coil pack. The car runs a megajolt/EDIS 4 system.

Can anyone help me with the make/model/year of a suitable car that can supply these parts as without these it seems impossible to order parts from my local auto-factors?

If it helps the coil pack is the version where the HT leads have clips securing them to each coil pack terminal, part no. 88SF-12029-A1A. I'll try and post a photo but i'm struggling at the moment.

Many thanks in advance.

Gary

[Edited on 8/3/21 by GaryM]


A 1.3 hcs/valencia fiesta mk3 (89-94) or early ka mk1 (96-03) would be suitable as essentially a xflow anyway, coil is oe mounted on the block (long enough leads to reposition elsewhere) they have short boots at the plug end and so are more suited to 8v layout engines. Either will fit but only as a set, ie fiesta leads and ka coil pack will not work.

The ka and later blacktop mondeo/focus zetec (98-04) coil packs will take universal type leads if you're unable to find a set of the above.


It may be worth checking that the centre pin at the coil remains at battery voltage while cranking/running, if this supply is poor it will cause the spark to be weak and should be supplied direct from your ignition switch/relay..
A meter from here to the battery +ve post will show any difference in voltage while cranking.

The edis units are generally bulletproof, if there is a connection problem between the megajolt and edis, they will default to a 10°btdc spark which is good enough to get you home.


Dave

Mr Whippy - 8/3/21 at 10:00 PM

Another vote for cleaning all the earths. I then coat then in copper slip. Just last week my fiestas lights were going haywire, turned out it was just a single small earthing point were the bolt had rusted. Quick scub and a new stainless bolt and everythings working great. Start with the simple things first.

SteveWalker - 8/3/21 at 10:02 PM

quote:
Originally posted by GaryM
Can anyone help me with the make/model/year of a suitable car that can supply these parts as without these it seems impossible to order parts from my local auto-factors?


It is well worth looking out for an existing car (just a Google image will do) and noting its number for future use. Somewhere I have two numbers recorded - one for a 1983 Sierra 1.6 (the donor) and another for a similar aged 2.0 (engine and gearbox donor) - the donor had the engine and gearbox upgraded before becoming a donor itself.

That also covers me for things like rear brakes (8" 1.6) and front brakes (vented 2.0), etc.

GaryM - 9/3/21 at 03:41 PM

Thanks for all your help. Here is some feedback.......

Double checked all the wiring and it seems ok.

Ran a thick earth wire direct from battery to the EDIS (no better) :-(

Checked the centre pin of the coil pack connector (unplugged) whilst cranking (with no spark plugs fitted)...it drops to 9.6v-9.9v whilst cranking. Also checked across the battery whilst cranking and measured 10.5v ish.


Added a timing strobe to the circuit to plug one and couldn't see a reliable spark as the engine turned over.

The battery is a brand new Odyssey PC545 full charged over night.

The engine is rebuilt so i guess it could be tight but the same battery model had no problems starting and running the car pre-engine rebuild.

Thanks Gary

[Edited on 9/3/21 by GaryM]

[Edited on 9/3/21 by GaryM]

02GF74 - 9/3/21 at 06:37 PM

PC545 may be on the small side.

Generally PC680 is the one that gets a mention, which I had for my 1660 xflow.

150 vs 170 cranking amps doesn't seem much but that could make all the difference.

Are you able to connect another battery with jump leads to see if that makes starting any better ?

obfripper - 9/3/21 at 07:07 PM

The voltage to the coil looks fine, but if you can backprobe the pin and recheck with everything connected&cranking it would give a better picture.

I didn't realise the cranking amps were that low on your battery, definately worth checking with a booster battery for change in cranking speed.

If you're able, check the cranking speed while trying to start using the megajolt tuning software - i would say you want 120rpm at minimum but 200-250 rpm would be preferable for a clean start.
Recheck with no plugs fitted and check the cranking speed shown is consistent with what you can hear ie no deviations or drops.
Check in the megajolt settings that you don't have too much cranking advance (5-10° btdc should be ok) - too much will make the cranking sluggish or kick back which could result in sync issues.
Check that nothing has changed in your toothed wheel/vr sensor setup, basics are you should have a 1mm gap at the sensor, and the missing tooth at 90°btdc (or the 9th tooth back at tdc if it's easier to check)


If there is problems with the reported cranking speeds:

If you have access to an osciliscope, check the signal being fed to the edis unit for a clean waveform (~10v peak to peak, 35 peaks and one tooth gap sine wave) and being the correct polarity as connected to the edis unit (rising edge after the missing tooth) -though if the wires are swapped around you should have no spark.

With no oscilliscope, a meter set to ac should show approx 2.5v rms at the vr sensor wires - this will not tell you the quality of the signal though.

Dave

GaryM - 16/3/21 at 08:53 PM

Sorry for not responding sooner but Locostbuilders.co.uk went offline for me for a few days.

Again thanks for all your comments.

I've ordered a PC680 so will upgrade from the PC545.

I've also discovered that my CTEK trickle charger was not recharging the battery to fully full so have switched to using a battery charger whilst testing this starting problem.

I've changing my MJ map to lower the advance to 8 degrees in the top left cell.

All these things have made a difference. If i remember not to touch the gas pedal the engine fires into life immediately so I call that a result, thanks.

The PC545 still can't manage much cold cranking so if i fluff the above start procedure and (possibly?) flood the engine then the battery runs flat before firing. I guess the bigger PC680 will improve this so not overly worried at the moment.

One more thing i noticed. My ignition light does not distinguish immediately when the engine starts. In fact it takes a good blip of the throttle (possibly >2000rpm) before it goes out and my voltage meter starts reading above battery voltage. Is this normal?

Thanks
Gary

obfripper - 16/3/21 at 09:09 PM

The alternator will have a minimum startup speed, depending on your pulley ratios this can occur anywhere from 500+ engine rpm.
A shorter ratio will make this happen at a higher engine speed, but this can protect the alternator from over-revving.
Once charging, it should still have sufficient output at idle to cover normal running loads.

Dave