The V8 Owners Forum -

Check the wiring diagram, but if you're not firing on four cylinders, that could be either a resistor pack or ECU fault.

The ECU has two injector outputs, but I can't remember how they are divided up between the cylinders. But basically the two outputs go to the resistor pack, where they each drive four resistors and then four injectors.

If you could prove that the four that weren't firing are all driven from the same ECU output, that might suggest a cause....

Chris.

I think you mis understood my post, it all seems to be okay now, tick over seems great steady at 750rpm, just need to tune it now.

Thanks again for that flapper manual is was dead on for checking out all the wiggly bits!

Well I must have got a bit of a jinxed lemon so to speak as I am still having a few problems.

First though what is the correct way to by pass the idle overun actuator? just disconnect the vac pipe?

My new pressure regulator failed during tuning today, the diaphram broke and pumped the plenum full of fuel, so much so it filled the inlet tracts! had to remove the plugs and de-hydraulic it, drain the oil, remove the plenum base and let the intake pipe dry out. Still in bits got fed up and went in!

I could not believe how quick it happened! Oh well we plod on!

Oh yeah another Q. can injectors from a 3.9 be fitted to a 3.5 flapper or are they a different type of fit?

3.5 flapper & 3.9 hotwire injectors are different and non-interchangeable.

To eliminate the overrun cutoff switch, just disconnect the two wires from the switch and connect them together.

Chris.

Just going back to the original question about the AFM.

If it's a flapper type then it really does ned to be fitted level or else gravity influences the flapper too much.

I sped read the posts so if I'm repeating something just shoot me

Thanks Chris, I'll not bother looking at a set of 3.9s then. Just connect the wires up for the over run, thats easy cheers.

The spring on the flapper is pretty good so can't see it being a problem rotated 90 degrees TBH. i have now got the ol' girl running okay, on and off! It seems a bit flat when you put your foot down, and was a right pain to get emmissions down eventually got 2% CO at idle at thats the best i can do, something is still not right as after 15 mins she ran like a bag of spanners again.

The distance between AFM and plenum is not critical is it? Only I have relocated the AFM on the bulkhead? I can't see why it would cause any problems.

I have to got to Aberdeen Monday and then off back to work so not much else will happen till i get back.

Thanks for all the info and help so far, its been really great.

Yes the spring is good, but you've now introduced an additional force that acts on it.

It wont be reading the aiflow correctly as either depending on which way you have it gravity will cause it to open too much or else will tend to try and hold it shut.

Either way it's not measuring the air flow correctly.

Next chance I get I will refit it the right way and se what happens then, maybe a while though off back to work soon.

Cheers.

Back home now and back to poking.... tried AFM the right way up but no difference, I think am still getting excess ito the engine somewhere.

Can you run the V8 without the extra air valve?

We plod along....

Hello Mike, did you perform any of the actions recommended here?

ramon alban wrote:

mikeinatruck wrote:---- starts great and tickover seems ok, a bit lumpy maybe, but when its warmed up and you blip the throttle it almost dies and back fires a bit or down into the sxhaust.

Hello Mike,

Choice of two mixture control problems, running rich or running lean.

Could be the temp sensor failed or with open circuit connections creating a too rich mixture, but:

Because of the backfiring as you describe it, its more likely to be an uncontrollable weak mixture as a result of a rogue air leaks into the plenum chamber.

You can read all about temp sensor and plenum air leak detection from the essays in the following index:

http://www.vintagemodelairplane.com/pag ... nts01.html

There are several other possibilities, but best to go with the usual suspects first.

Movimg on.

mikeinatruck wrote:tried AFM the right way up but no difference, I think am still getting excess (air?) into the engine somewhere.

Can you run the V8 without the extra air valve?

It would seem you agree with the premise that you have rogue unmetered air. even if you did some tests previously, time to do them all again.

Its possible thet squirting easistart around the plenum pipes will help find some faults but it wont find others such as internal or remote component failures, brake servo, EAV, vaccy advance, transmission vaccy valve, etc.

Re EAV - why would you want to run without it? It has a clearly defined function to keep the engine running as it warms up from a cold-start.

Its an unusual question, given the described symptoms, did it get omitted in the transplant?

Your question exposes the possibility that some study of your system funtions is needed, following this major Efi transplant.

Virtually everything you need (including the AFM) is in the above mentioned link.

Also, do you have access to an Efi Ops Manual to tie everything together?

Hi all

Well we can put this one to bed, after using the workshop manual to fully check out the wiring and after changing the Dizzy which needed done anyway, the water temp sender and TPS I managed to scrounge another ECU and tried that and voila all ok.

It seems the ECU i was using has a fault on the engine tempreture sensing side somewhere so as soon as the engine was up to temp it ran like a bag of spanners.

With the new one it runs great, emmision levels are good idle is good and revs great, So it took a while but we got there in the end. And on the plus side whe the engine is hot I have 35psi oil pressure at tickover, awesome!

Thanks to all that offered advice and information, I am now fully up to speed on how the EFi flapper system works!


Mike

mikeinatruck wrote:I am now fully up to speed on how the EFi flapper system works!

That's worth a lot. Now you should be in a position to enjoy the superior fuel economy / cold starting / etc. compared to carbs.

Chris.

Fuel economy? It does 500 miles a year and most of that is low box up to the gunnels in mud! I once got 4mpg on an off roading weekend! I was proud of that LOL..