Rover V8 starting problems

[gav-]

Hello,

I have done a number of searches on here and on google in answer to a problem with starting on a Rover v8, but have not been able to find anything. I would like to fit megasquirt, in fact i have started to collect the parts to start the build, but i need to get the car running well so that i can get it IVA'd.

Engine is a 3.5 Hotwire EFI running a PRC 8702 ECU without cats or lambda sensors (as far as i know this ECU worked closed loop all the time)

The engine hasnt been ran since April this year and i ran it to get in onto a trailer, it hasnt been run for an length of time as i have no way to test the engine properly hence the IVA.

The problem is that the engine doesnt start every go. Infact i can crank it for a number of times and then it starts, once started and run for a while i turn it off and it fails to start for a while. If i come back (the engine doesnt have to be cold) in 10mins or so it will occasionally start.

I have a long spark (tested by removing the plug and testing against the cylinder head), The new parts include new plugs, new dizzy, new leads (8mm silicone) new coil, it runs a RPI power amp as well(which is a few years old). I have fuel on the rail and can smell it on the plugs when i remove them when it has failed to start. The plugs do get sooted up whilst idling, and i have had to clean them a number of times to aid starting.

I have checked the Air flow meter settings for CO, the stepper motor, the coolant sensor and fuel sensor. All are within the right range according to the EFI manual.

When the engine runs (its sounds like its difficult to start- then fires up beautifully) it sounds beautiful no miss fire, it idles nicely at approx 800-900rpm, and opening the throttle whilst its stationary the engine sounds really good.

I am not sure what the problem is hence why i am asking if anyone has any opinions, One thing i did wonder was the ignition timing(when try again at the weekend i will take a timing gun with me and hope it starts from memory i did set it up close to TDC. (but cant remember what)). I also wondered whether the advance /retard function on the dizzy had failed, i tried to suck on the pipe which connects to the dizzy actuator but nothing moved, the actuator in the dizzy was stiff to move. (is this used when on start up??))

how can the dizzy advance/retard be tested?

your advice please.

[Aragorn]

On mine, sucking on the pipe made the RPM's increase. Had to suck bloody hard mind! Sucking on the pipe with the dizzy cap off resulted in the little arm moving.

If the advance springs are working, you should be able to twist the rotor arm about 10degrees clockwise, and it should spring back when let go.

You say the plugs are getting sooted up, are you leaving it idling a lot and not let it run properly? If your firing it up from cold, not letting it warm up and then shutting it off again, the plugs will soot up very quickly...

[gav-]

Aragorn, Thanks for the reply, I havent sucked on mine whilst running, but when the cap was off and i sucked really hard nothing moved at all, the little arm would move by hand (it was stiff) The Rotor springs back no problem.

I think the plugs are getting sooted as its not getting a good run, i allow it to get to temperature and then shut it down. However the plugs seem sooted up quite badly after just running for 5-10mins.

I am starting to think that the timing might not be correct and that the vacuum advance unit doesnt work whilst on startup (from what i have read today the vacuum advance is used at low revs)

what do you rthink?

[steve_d]

Some people do have trouble sucking hard enough to move a dizzy, me included, so I use a syringe which works very well.

You need to find the correct timing setting for your engine because there is quite a range of settings for different engines.

Steve

[Aragorn]

If you can tell me what the engine came from, i'll be able to look up the correct timing settings for you on autodata.

3.5 Hotwire EFI probably means its a disco motor? I'm sure the Rangey went to 3.9 before the hotwire came in? If it IS a disco motor i think from memory it should be running about 5-7 degrees BTDC at idle without the vac fitted.

The engine code should be enough to work out what it came from.

A syringe would work better as has been said.

I also found my Carbed V8 did not pull enough vacuum at idle to actually move the linkage. Presumably its more aimed at light throttle driving at higher RPM's than idle.

[lansalot]

"I havent sucked on mine whilst running"

Me neither !

[SteveRK]

I experienced similar problems with mine whereby it would start then stall and wouldn't start again. The fault was only really cured when i fitted new Lambda sensors.

As per a similar post on the International forum if the Lambda sesors are disconnected then the engine will have to adopt a fixed fuel map.

The only adjustment the ECU has is on fuel injector pulse duration and without it working in closed loop mode adjusting the air flow meter cannot have any affect if no feedback is being monitored by the ECU and it has adopted open loop fixed fuel map mode? the same would apply to changing any of the temperature sensors i suspect.

[Ally V8]

Two things spring to mind here,first is you need to change the tune resistor to a non Cat one,so the ecu wont look for an oxygen sensor input.Second is the fuel temp and coolant temp sensor plugs are easy to get mixed up and lead to very rich running.

[gav-]

So further work today, the tune resistor is a green type which is correct for the ecu without lambdas.

I check and adjusted the timing today, i had set it to 8deg btdc, but when tightening the retaining bolt for the dizzy the bolt pulled itself straight out of the timing cover leaving a nice whole about 25mm square!!!

I think i can temporaily fix it tomorrow so i can get it running again.

Before this happened though it was still playing up and interestingly once i got it to run and got it warm, i could only get it to run by removing no2 spark plug which blew some vapour out of the hole, reinserting the plug and the engine would start everytime i tried it! The spark plug didnt look to sooted up at all, a lot less than previously.

I am using champion spark plugs, should i get some ngk ones

Is it possible that the dizzy hasnt been earthing very well since the retaining bolt may have been broken for a while??

[V8david]

Any luck with this one yet Gavlar?

No surprise you managed to pull the bolt through the timing cover!!! Haaa!! You're too big for your own good mate...

Get some NGK spark plugs. May as well. I've got them.

Anyway, sorry I can't help mate. Hope all is well (apart from this). At least me not helping will get this topic back to the top of the list for a bit!

Speak to you soon mate.