classic 3.5 v8 issues

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Gandi69

New Member
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12
Hi Folks

Got a 1987 classic v8 (100k miles on the engine) with a bit of a niggling issue thats driving me mad.
When the car is started cold it runs fine and is fine for local driving, however after an extended period of time I lose 80% of the power from the engine and struggle to get above 25 mph. I have found it does this just on the cusp of ticking over 30 miles when driving from a cold start up.
I've changed the fuel pump, fuel filter dizzy, dizzy module, leads, rotor arm and cap, coolant temperature sensor. All thats left really are the ecu and air flow meter and I think these are original.
Any one have any advice for me?
also the auto box and transfer box are nearly from ashcroft transmissions and have done maybe 5000 miles.

Andy
 
check your petrol cap (fuel tank prob cant breath),try it without the cap closed or if you dare remove cap completely but take it steady & beware of possible fuel spillage ,the fuel tank is prob presurising starving it of fuel,had it happen to me before 30 miles and it dies give it 15 mins & all good again for another 30
 
Last edited:
wil2813 said:
check your petrol cap (fuel tank prob cant breath),try it without the cap closed or if you dare remove cap completely but take it steady & beware of possible fuel spillage ,the fuel tank is prob presurising starving it of fuel,had it happen to me before 30 miles and it dies give it 15 mins & all good again for another 30
Click to expand...

Sometimes the power will come back and it gets moving again (as much as a big old bus can atleast!) but very rarely.
 
naki said:
hmm, curious.
long shot, have you checked for any air leaks on the intake?
does it run rough at idle when at all?
Click to expand...

No air leaks on the inlet as far as I can tell, it idles lovely and revs up when stationary just fine.

Whats the bi metal valve look like at all? I can check if its got one but I'm not too sure if it has in all honesty - the seem to have swapped the management and control system on these engines a hell of a lot over the production run
 
As below....

ERC3617.jpg



Part Number ERC3617....

Should be found sitting towards the front of the Plenum chamber ontop of the Drivers Side (UK) rocker cover IIRC....
 
would there be a hiss of pressure released when I undo the cap if it was pressurised? if so I havent had that symptom unfortuntely, cap comes off just perfect nice and easily with no noise
 
Gandi69 said:
would there be a hiss of pressure released when I undo the cap if it was pressurised? if so I havent had that symptom unfortuntely, cap comes off just perfect nice and easily with no noise
Click to expand...
you wont when first started but try relasing cap when it starts dying and losing power.as data suggests try drilling a small hole in cap to eliminate vacuuming
 
Drilled the fuel cap and put a 2mm hole in it, so far I havent had the huge power loss when warm yet.
However I still dont feel that the engine is giving the right amount of power.
Had a look at the ECU and tried to swap it out for a known good one from a mate however it wouldnt start with the new ECU on (the original ECU was numbered as 87744D and the new one 87744B). Is this normal?
Also does anyone think it could be the air flow meter - seems that the top has been opened before as there is silicone sealant over the casing as if someone has been fiddling with it?
 
Gandi69 said:
Drilled the fuel cap and put a 2mm hole in it, so far I havent had the huge power loss when warm yet.
However I still dont feel that the engine is giving the right amount of power.
Had a look at the ECU and tried to swap it out for a known good one from a mate however it wouldnt start with the new ECU on (the original ECU was numbered as 87744D and the new one 87744B). Is this normal?
Also does anyone think it could be the air flow meter - seems that the top has been opened before as there is silicone sealant over the casing as if someone has been fiddling with it?
Click to expand...
On a P38, you need diagnostics to fit a new engine ECU as it has to be coded/synced. I don't know if this applies to a classic but it might.:)
MAF's are a fairly common fail item.
 
I dont think it applies as this thing is before the days of immobilisers I guess. Either way we think the ECU is good as it appears to be very shiny and we think its recon unit, no way has it been under the seat for 26 years.
Shame finding the Air flow meters isnt so easy mind you unless someone can help us out?
 
You can't tell if an ECU is good or not by looking at it. It may be clean on the outside but inside the board could have damaged components, corroded tracks etc that you just won't see unless you open it up.You should also get it plugged in to see if there are any gremlins.

I assume you have the flapper system; ECU's are now a common fail but they are getting harder to find. Air flow meters are another common failure, if the AFM has silicon on the top then it has been opened and "adjusted" indicating it may be a problem. I would suggest step one, remove and clean plenum and ram housing. Disconnect start injector, you won't be likely to ever need it. Test your air flow meter or if you can get a good one, swap it out. Check your ignition system, make sure timing is correct then check/set base idle and hopefully all will be well.

HTH
 
I'm only going on a next logical step basis by saying the ECU looks new, I mean it could be damaged internally but I feel there are other my suspect parts namely the AFM that I should pay attention to first. Also Are there are diagnostics that you can use on these early ECUs? its obviously pre odbII etc
The inside of the plenum is all clean, i've had it all off and cleaned it out and the cold start injector is disconnected too.
I've checked the timing too and set the idle to the correct specs as well but i'm still having issues.
Considering the shortages of ECUs is the only option going to an aftermarket kit such as emerald or megasquirt?
 
I don't know much about the flapper system but would have thought it would be possible to diagnose individual components with a good DVM same as you can on hotwire systems.

You might consider sticking a hotwire injection system on it. Find somebody breaking a later RRC or early Disco 1 V8, get the loom 14CUX ECU and pretty much away you go although you would need to have the plenum and stepper motor and also the speed transducer but apart from that it wouldn't be too difficult to swap.

I don't know about megasquirt - Mr.Noisy is yer man for that, do a search for "megasquirt" I know he posted a bit about his experience with it, works well.
 
if thats the only option then we might have to run with it however I would prefer to keep it factory if possible. It amazes me the lack of flapper parts around these days considering the amount of cars the efi v8 were put into
 
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