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3.5 V8 EFI won't rev and no power


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Hello all,

After a succesfull megasquirt injection installing i decided to go a step further and install the ignition part. When i turned the ignition key back (during installation) the coilpack (VW jetta type) discharged with a lout bang on a not running engine.

The engine starts quickly, idle is smooth, without load it revs up nice, seems to be a little mechanical noice but not that much.

When i put it in Drive (autobox) it starts to run uneven, hearing a puffing, spluttering sound. There's absolutly no power in it, it won't rev to the normal 2000 rpm, but there are no backfires.

Checked:

- Vacuum leaks, nothing

- Changed valley gasket, sealed inlet plenum, nothing

- Connected a mechanical vacuumgauge, stable strong vacuum

- Timing is correct, sparks are there

- Already changed earth straps and 12 V to startermotor / battery, it solved a not starting problem before

- New battery, 14 volt during running on volt gauge in dashboard

- Changed sparkplugs BPR6 ES, nothing

- Checked fuelpressure and flow, steady 2 bar, half bottle in seconds

- Did compression check, lowest 140, highest 170, with little oil all are about 165

- Checked rockerarm, valves seems to follow nicely, blankmetal/brown color no signs of wear

- After i've build the inlet back on, it started good and powerfull, but when i stopped the motor to fill the coolant and started it again it it runs powerless again !.

- Changed the VW jetta coilpacks back to the original 35DML8 distributer, exactly the same results

- Changed the Lucas coil, i could hear the oil splashing in it !. no result

- Checked distributor,, vacuumadvance is working, centrifugal advance looks ok, no cracks

Started thinking about diesel conversion blush.gif

To be honest, i've run out of idears. The loud bang during installation worries me a bit. This winther it started to run badly on lpg when cold (the reason why i want to megasquirt it)

Can anyone put in some advice ? all idears are welkom !.

Thanks in advance, Frederik.

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Hi there,

Out of pure desperation i've decided to connect the old lpg system back to engine and disconnect the petrol part.

And.. it runs smooth even on the new megasquirt controled coilpacks blink.gif the usual power and respons laugh.gif

I'm completely lost now, it did run pretty well on petrol, the car has stand still for a while in my garage, a lot of bolts have corroded, my startermotor feed cable has also corroded so...........

Can it be that the injectors has passed out, maybe because of the backfire ?

Something to do with corrosion on the resistorpack (low impedance injectors) ?.

Something i want to do now is clean the injectors by a specialist.

Is it maybe wise to replace them by high resistor type injectors and ditch the resistorpack ?. And if so can anyone recommend me a supplier and nummers for a 3.5 V8 EFI, are they exchangeable with for example 3.9 types ?.

Thanks, greetings Frederik

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When i turned the ignition key back (during installation) the coilpack (VW jetta type) discharged with a lout bang on a not running engine.

- Changed the VW jetta coilpacks back to the original 35DML8 distributer, exactly the same results

- Changed the Lucas coil, i could hear the oil splashing in it !. no result

Well, from these two it isn't the ignition. In summary - It starts and runs, but won't run under load. The big bang comment isn't good, and could have had an effect on the MS ECU (which is still controlling the fuel injection).

The only other thing you haven't mentioned is valve timing?

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1st think, calm down and stop swearing (Tsk Tsk diesel indeed :lol: )

Next you have to work through things logicaly and give us specific info

1st

What is the ECU and which firmware are you using

where did the spark and fuel map (MSQ) come from and version type (ie 029V ?)

What / how was the wiring done

Are you using EDIS 8 ?

Pictures of installation may help to

How certain are you Trigger wheel is spot on ? post up a description of where it is at engine TDC esp the missing tooth vs the VR sensor etc, even draw a diagram

What is the fuel pressure in the rail ? MEASURE IT

Check earths, particularly sensor earths go BACK TO ECU not to battery / Chassis earth

Have a work through the above, post up and feedback

It will get sorted :) but no more "Deep Fat Fyryer language" :blink: OK ?

:)

Nige

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The only other thing you haven't mentioned is valve timing?

Woah there neddy! How does what is probably a minor software settings or wiring problem become something major inside the engine? And why the heck would you start dismantling mechanical bits of the engine because of a running problem on one method of fuelling? :blink:

The crack from the coil pack was probably it discharging to the nearest bit of metal when you switch the ignition off, I don't know how you've got it all wired so I can't comment much further.

So, first things first - when you say you're going to coil packs, are you running them with EDIS-8 or are you using drivers built into the MegaSquirt. Do you have a trigger wheel mounted and working VR sensor. How have you wired the coils up, how have you wired the EDIS, if the ECU is modified for EDIS then how are you getting the TACH signal into it when running from dizzy & coil?

I suspect, making some very big assumptions, what's happened here is the ECU is not (properly) set up for EDIS, either in software or hardware, and so the EDIS is running in fixed 10deg limp-home timing mode, a check with a timing light would confirm this.

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Woah there neddy! How does what is probably a minor software settings or wiring problem become something major inside the engine? And why the heck would you start dismantling mechanical bits of the engine because of a running problem on one method of fuelling? blink.gif

I know i know.......blush.gif but

I've checked my own wiring and configuration for days !. Checked compleet fuel system, swapped ignition and found absolutely nothing, driving me up the wall !.

Strangely enough it has driven on petrol pretty good !. Never the less you are absolutely right its got nothing to do with anything mechanicly inside the engine despite of the hard backfire.

I've should have checked the injectors ! Very strange, i've got a good lambda value although at first it was to lean

possible one or more injector not opening and others compensating with extra fuel ?.

Its running good on LPG now, and i'm thinking about swapping the injectors.

Do you reckon its a good idear to get rit of the low ohm injectors and resistorpack ?.

Thanks for all the info guys !.

Frederik.

ps DEEP FAT FRYERS ? is'nt that something good?, still considering a one of Tefal or Delonghi laugh.gif

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I've checked my own wiring and configuration for days!

You still haven't told us what your configuration is so we still can't help - are you running EDIS, if so have you tried the configuration files available from here for MS'n'EDIS?

I've should have checked the injectors ! Very strange, i've got a good lambda value although at first it was to lean

possible one or more injector not opening and others compensating with extra fuel ?.

Injector's can't compensate, they are a dumb item. Again you don't say what is a "good" lambda value. Also be aware if things are not running properly that lambda sensor readings can be false if there is too much unburnt fuel or an air leak in the exhaust.

i'm thinking about swapping the injectors.

Why? If it ran fine on those injectors before then they are 99% certain not to be the problem.

Do you reckon its a good idear to get rit of the low ohm injectors and resistorpack ?.

If you're making the change, yes, but not worth it if it is not the problem.

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You still haven't told us what your configuration is so we still can't help - are you running EDIS, if so have you tried the configuration files available from here for MS'n'EDIS?

Fridge,

I've left the firmware part out because i figured the injectors should be the problem, erm NOT ! blush.gif

I've had some problems with the startermotor caused by (goodlooking) bad wiring from the battery, so i changed the 12 volt feed and earth as well, and removed a very corroded wire from the innerwing to the battery.

And forgot all about some reset problems in the past when i connected the ms earth to the innerwing and thereby to the battery for better results!.

When i reconnected the ms earth back to the engine and cleaned the powerresistor connector it worked fine !.

On short notive, its very important to follow the Megasuirt saga instructions, if its not working there is a problem else where !

Its a bit sad i've been thrown off by the backfire and lambda vallue, the good thing is i've learnt quite a bit more

about my engine, if i should do it all by my self i could'nt drive this car !. smile.gif

Thanks again !.

Frederik.

Although problem solved, this is the configuration;

MS1, 29V

Unfortunataly not Edis8, already bought VW Jetta coilpacks before knowing of this website (its running good though)

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