my V8 need 20 degrees of advance to run!

[morph2006]

Hi

Help please my V8 have a problem, it will not start even bump start on rollers unless it has at least 20' of advance.

With 20' advance it will run cold but as it gets warm it starts to miss fire at randum. On the scope you can see it misses. Then it gets worse and stops, it will re start and always starts from cold.

It has new ...
Coil
Spark plus
HT leads
Dizzy Cap
Rotor Arm
Stepper Motor

The following have been cleaned ...
All injectors
Hot wire Air Flow


The following have been checked with multi metre / scope etc
Hot wire
Injectors
Fuel presure
Coil
Spark plugs
Fuel return
Engine Speed sensor
Stepper motor
Distrbutor and Amp / Swopped out
Engine management Mod / Swopped out
Throttle Pot

Only probelm found is road speed sensor seems to be stuck at 6V but even with this discountected problem remains.

Have run engine with following discounted but still have problem ...
Stepper motor


Help please have no more ideas

[GreenV8S]

Have you checked the TDC reference on the crank against the physical #1 TDC? They can be miles out.

Is the spark strength and timing consistent when the misfire comes in?

Do you see any variations in lambda before the misfire comes in?

[v8 racing]

More than likely the dizzy itself, i have had quite a number of times where the dizzy weights have been semi seized, i see you are near lincoln by all means pop by and we will have a quick look for you

[z_chromozone]

GreenV8S said:

Have you checked the TDC reference on the crank against the physical #1 TDC? They can be miles out. Is the spark strength and timing consistent when the misfire comes in? Do you see any variations in lambda before the misfire comes in?

I think the TDC mark on the flywheel was Rover workers game of pin the tail on the donkey

Z

[morph2006]

Hi

Just testing TDC mark now.

Thank you to all for help I will update result shortly.

[morph2006]

Hi

We have borrowed and temp. replaced the whole Dizzy and Amp module but got the same result, spark plugs, and all HT leads are new and have been bench tested as has Coil.

We do not have lambda sensors on this car.

Will check strength and timing of sparks next.

[morph2006]

Ok, had the engine apart and checked TDC it is correct. Put it all back together and set timing to 8' advanced.

Will start when cold, but then ran out of petrol so on the rolling road in the morning with more petrol !!!

[morph2006]

Well todaymore testing and now car will start on 8' of advance. Not able to test Kv of spark as when hooked up to this machine the car will not run so long enough to get result.

But the errors are as follows ...

We can see the sparks all going and then the odd spark will not fire as the engine gets warm this gets worse until engine stops.

When we open the throttle rapidly the engine stops but if we open it slowly its fine.

HELP - nothing left to try other than bin the new Coil, Amp Mod and HT leads and buy some more.

[ceejay73]

Sounds like you are having all the fun I had with my V6 late last year (checking and rechecking everything). Have you had it connected to a gas analyser? What are the emissions like from cold and as it runs up to temp? Anything untoward?
Just as a point of interest mine showed all the symptoms of an ignition or fuel fault but ended up being a blocked exhaust. Once you have tried everything else and are at a total loss might be worth dropping the zorst off the downpipes to see if it makes any difference. I just took mine off and cut open the box to find baffles collapsed and all the wadding blocking the exit pipes but you have the advantage of being able to run it on rollers, I would have had to take mine on the road with only down pipes!!
Good luck, Carl.

[HarryW]

morph2006 said:

Well todaymore testing and now car will start on 8' of advance. Not able to test Kv of spark as when hooked up to this machine the car will not run so long enough to get result.

This is ashame because this will tell you loads.......

morph2006 said:

But the errors are as follows ... We can see the sparks all going and then the odd spark will not fire as the engine gets warm this gets worse until engine stops.

This sounds possibly like a duff coil, I know you have changed it once, however it is not uncommon to have more than one die, I know Mark Adams swears by Bosch coils only for Tivs.

morph2006 said:

When we open the throttle rapidly the engine stops but if we open it slowly its fine.

A weak spark will not ignite the enriched mixture from rapidly opening the throtltle

morph2006 said:

HELP - nothing left to try other than bin the new Coil, Amp Mod and HT leads and buy some more.

I'd start with a known good coil from another running car first, do you have access to a fellow Tiv owner near you

All IMHO/E etc

[morph2006]

More new parts added !!!

Added today ...
Bosch Coil
Amp Mod.
new set of Silicone HT Leads

When cold did start better even after just the new coil but then idle was up and down between 500 and 1100 rpm as it got warm so added king HT lead, no differance so added new Amp Mod.

Not a lot of differance but do not try to stall so much under heavey acceleration and does idle although up and down so added the rest of the HT leads.

Does sem beter but needs a tune.

Gas emmisions are good last time we checked but will be checked again during tune up.

Overall it's better but will still not pick up very well when throttle is floored and idle is up and down. Starts when cold and hot. Advance is on about 8'.

Next is tuning I think!

[HarryW]

At times like this an hour with the likes of Mark Adams @ £60ph seems such a good idea.

I assume things like base idle, AFM voltage checks, ECU fault codes/check sum have all been done prior to whipping bits out

[morph2006]

Hi

ECU checks are as follows ...

pin 15 to earch 11.86v
pin 19 to earch 11.4v
pin 7 - 25 2.719 ohms
pin 32 - 25 2.919 ohms
pin 2 to earth 11.9v
pin 2 - 13 0 ohms
pin 2 - 11 0 ohms
pin 39 to ground 12v - engine RPM
pin 35 to earch 425 mV
pin 5 to 27 473 mV
Pin 3 - 25 5.77k ohms TPS (changed smothly when throttle moved)
pin 20 to earch 339mV - 4.87 mV
pin 1 to 26 45 ohms - steper motor
pin 28 - 29 44 ohms - stepper motor
pins 2 - 13 and 2 -11 not in use - no lambda sensors
pin 6 to earch 6.7v - Road speed sensor (would not go to 12v range about 1v - 8v)

Fuel Pump tests
fuel presure with vacuum 28 psi
fuel presure without vacuum 36 psi
return flow ok

Exhaust gas test
Hot idle
CO 2.3
HC 500
O2 12.8
CO2 4.8

Hot Wire Air flow metre
Tested and matched figures in book for different RPM although a bit on high side.

Tests done at ECU but also checked many sensors on sensor as well and checked low tension wiring around Amp Mod and Coil

[morph2006]

Oh yes almost forgot, also replaced stepper motor.

Base idle and tunning was tried first but that's when we ended up with 20' of advance - the only way to get the car to run long enough to get any readings for the emmission tests.

With all new parts it is nearly ok when cold but still stalls if throttle is opened quickly and the idle wonders between 500 and 1100 esp. when hot but this could be down to needing tunning / removal of all the fuel presure sensors and other bits on the car at present.

I have to wait for slot in mechanics time to do turning as I don't have equipment. But still worried that problem has not gone away.

Other initial tests ...

Mass Air 1.4v - 2.4v
Vacuum 450 mm hg
Commpression test 175 lbs

[HarryW]

Is that AFM range of 1.4v to 2.4v on load through the rev range or just idle .
I would have expected to see 1.4-1.8v at steady tick over and up to 4.5+v at full throttle peak power under load. Revving not under load may give you less than 4.5+ but not sure of what figures though.

[morph2006]

Hi

AFM was not under load as rolling road was in use - we compared it to bible and it seemed to be right at the top of the range but consitant.

Thanks for taking the time to help. Any ideas welcome as we have run out.

[HarryW]

OK but if your AFM tops out at 2.4v under load its fecked IMHO

[morph2006]

Hi will check notes on this - it did match the book when we tested it at different RPM so I think I copied the notes down wrong.

[v8 racing]

The throttle pot can cause these kind of symptoms too?

[morph2006]

Hi

We are checking throttle pot next - car now tuned and emmission are spot on.
Car starts and runs fine when cold but still missing at randum when warm.

Thanks for all help, hope I'm nearly there !!!