The V8 Owners Forum -

Ok, hope somone can help as me and Tony (thev8kid) are completely stumped.

I have a 3.5 RV8 engine with 9.75:1 pistons, 3.9 efi cam and late 10 bolt heads, also has a Mallory Unilite Distributor

Have just installed a 3.9 hotwire injection system (non-cat/lambda) and to begin with the engine would start, run for a few seconds then stop, and I couldnt catch it on the throttle either (just stalled).

Now it just cranks and occasionally splutters but wont fire. For some reason the engine just keeps flooding (plugs are really really wet).

Have checked for spark and its v.good on all the plugs.

Initially we thought the fuel pressure regulator/injectors may be at fault so swapped them but made no difference. Now have an adjustable regulator fitted and the pressure is set at 36psi
Anyone got any ideas?

Stuball

Injectors not closing? lambda needs replacing?

Its a non-lambda system.

As for whether or not the injectors are closing i have no idea how would i check that?

Stu

its a non cat/ non lambda set up mate.

stu you have changed the injectors once have you not#@~?
try changing the stepper mate, as im still not 100% that yours is working, due to the problem when testing it with your other ecu.

What are the injector pulse widths when cranking ? ( car based multimeter is handy for that )


Have you tried drying the plugs, or replacing them ?? More often than not, a soaked plug is only fit for the bin. You can sometimes get lucky and they will dry....but it is just luck.


Are you defo getting spark during cranking ? On all plugs ?

Are all the plugs wet, or just a few of them ?

Is the engine getting enough air ?

i thought the hotwire setup has to have a lamba or somthing to trick into thinking it has ...the flapper is the one that dosn't use a lamba

or i could be wrong ...lol

stevieturbo

Have had all the plugs out and connected to the leads, get good spark on all of them when cranking.

All of the plugs are wet. Have tried drying/cleaning them up a couple of times as well as spinning the engine over with fuel pump off and plugs out. Doesnt seem to help much.

Air could be the problem, have a spare stepper motor so will try that.

I have ordered a new set of plugs so will give those a try when they arrive as well.

Still baffled as to why the engine would start on the button, run and then stop when i first tried it though..........

Stu

I remember having a problem like this.

It seemed to be deciding it meeded to be in "Safe GET YOU HOME" mode and was a bugger to get running. Get you home is cancelled by unpowering the ECU for 10 secs)

I was lucky that I had a power cut off switch fitted and killed all the power.

I then got lucky with a quick power on and immediate cranking and she fired and ran to temperature before spewing coolant as it was not bled correctly.

I needed to do this process a dozen times or so and then it seems to have cleared whatever was not working / sending the right signals.

OK it may not work but is certainly worth trying

Ian

Check temperature sensor isn't open circuit (by measuring at the ECU plug). If it is open, the ECU will think the engine temp is -1000000 deg C and over-fuel.

Chris.

I thought you was using VEMs Stuball, what has made you back to a hotwire setup.

Check CTS as suggested by Chris.

AND: Do you have the correct tune resistor fitted in the loom near the ECU? Green for the non-lambda set up. If not, then the ECU will go into the fault fuel map (since you have no lambda's fitted), which makes the mixture ridiculously rich (get home-mode). The values of the different resistors for different tunes can be found by using Google. I do not remember them by heart and I'm too busy/lazy to dig 'em up.

The problem can be a major air leak also, making the mixture too lean to ignite (it will get the plugs wet as well).

he has got Vems Reg,
but had this same problem with the vems,
so he is trying the hot wire to eliminate the vems, which turns out to be the same fault with this ecu,

Aha, must be a sensor then if both ECUs do the same thing.

Can the AFM be tested?

Chris.

the vems does not use an AFM mate, but two different ones were tried as thats was my first thought,
i still dont think the stepper is working if this is stuck shut this also would cause it to fire then stop yeah and then foul the plugs?