7MGTE Woes Input Appreciated (Problem Solved you'll never guess how)

[slide86]

this is probably going to sound stupid but.....is the condition of the battery good. i had a car once that would loose spark because the battery was no good and it wouldnt hold any voltage or current.

maybe put a new (or known good one in) and see what happens....???

[TA-022]

is a faulty AFM signal going to affect spark? not sure how the ecu would determine spark intervals but perhaps under load the AFM isnt reporting a high enuf reading hence the spark isnt increased accordingly giving you what looks to be a spark break down.

if it worked this way then you would not get enough spark for a given load, but as far as the ecu is concerened .. going by the AFM signal it thinks its sparking right.

or everything you swapped has minor faults compounding together to give you your issue.
lets just hope its as easy as it being the AFM.

[TheStitt]

Well the results are in and after alot of ideas and alot of testing the problem with the old beast was found.

It turned out to be a lack of earth wires. I put all the earths it was using back on however the car decided it wanted a few more.

When i have more time I'll post up how we found the lack of earths.

Now just one other small thig to fix and I will be 100% at dyno day

[Draven]

oh where's shane?
He'll be thrilled to know we have fixed another problem due to bad earths

[TheStitt]

it was funny how we found it to. Dad i had been checking the whole elec system and gotten no result. So we moved the car back into the garage late in the evening and thru the timing light back on just to make sure that it was losing spark.

Any ways as we were bringing load on the engine would loose spark and regain it again. even time it lost it it bucked around on the mounts. Then dad noticed the prob, he saw sparks (in the darkish conditions) moving from the turbo heat sheild to the chassis. (The turbo heat sheild is a poor fir nad prob does need to be trimmed. Any way we got the jumper leads out and went from the motor to the chassis and low and behold the car ran fine. Took it for a blat up the street and he presto its all good.

So what its turned out as the engine rocked exissivly cause of how poorly it was running it would for a contact good enough for spark for a split second, then once the enigne rotated that little bit the engine would move back the other way, contact would be lost and the cycle would repeat.

[CrUZida]

I'm amazed that the starter worked if your block to battery earth was that poor.

[bansheebuzz]

the block to battery earth would have been fine, the chassis to battery earth would have been the problem, components like ecu and ignitors would of had a poor earth

[CrUZida]

Ahh yes, of course.

Note to people reading this.

4 gauge - battery to chassis.
4 gauge - block to chassis.
8 guage - head to chassis.

Motor is now well earthed.

[bansheebuzz]

Ahh yes, of course.

Note to people reading this.

4 gauge - battery to chassis.
4 gauge - block to chassis.
8 guage - head to chassis.

Motor is now well earthed.

guage is not automotive standard anymore.

Automotive cable is measured in "B+S" and "mm"

I would use
2 b+s from battery to block
8 b+s from block or battery to chassis/body


Note the smaller the b+s number the bigger the cable, but the higher the mm nuber the bigger the cable.

[BlackSupra]

Did you re-attach all the earth straps properly?

Maybe check the alternator voltage too when your riding the clutch.

FTW

So i take it your driveline wasn't locked then?

[Mos]

The ECU earths on the intake manifold (from factory), so once the alternator is running you have full power to the ECU itself. The reason the spark was breaking down is because usually the ignitor is earthed on the body (was it?).

And Stitt dude.. your post brought memories of those fn stuck injectors - if I was around there I'd slap you! (Yes I'm quite upset )

bansheebuzz - what's the B+S equivalent to mm and what do they stand for?

Mos.

[whatthe?]

FTW

So i take it your driveline wasn't locked then?

And i was so sure Elmo had it pegged there....

[bansheebuzz]

i would have to look on the cable roll at work to tell you the cross sectional area in mm