450SE wont run

[witty]

Will not run on all 8 cylinders, was sitting for a while and started ok, I decided to check timing with a good timing light.

Set it at 10 degrees before TDC. All good and idled great, then I turned it off. The damn thing now doesnt want to start and when it does it sounds like it has 5 cylinders.

Ive just about had it with this thing, nothing but trouble since I bought it.

Help please or it is going to the graveyard.

Thanks Allen

[daantjie]

I would not go messing around with the timing until you have determined what your issue is (I do not think it is timing related).

First determine if your distributor cap and rotor are in good shape.  Also change to all new spark plugs, they are dirt cheap and can be the source of many little niggles.  Cannot hurt to change to new spark plug wires, if they are still the original wires, by now they will be toast anyways.  Also, a new coil would not hurt matters, also not too expensive.

Good spark is the key, then you move to fuel delivery.  If it has sat for a long time, then you have to drain the fuel out of the fuel tank, and put in fresh fuel and change the fuel filter.

As always start simple, i.e  establish you have nice spark, then go to more complex issues.

Cheers

[witty]

thanks for reply

All replaced so far

coil
plugs
points
leads
dist cap
condenser
rotor
fuel pump
fuel filter

Have spark, 12 v at points, spark at number 1 plug, fires up first turn of key but then chugs away like only on one bank, shakes badly.

Dwell angle is okay, timing now set on TDC with vac on. Compression test all cylinders good except for no 4, down a little, but should still idle and run okay.

I believe it has to be in the injector system, last week was running ok. just decided to shit itself for no apparent reason.

Has new fuel pump and fresh fuel, 98 octane. Drained the tank when i got it as it was sitting for a few years.

Love the car, but it is becoming an albatross.

Cheers
Allen

[daantjie]

Might be worthwhile to pull the injectors and test them flow and spray pattern. New set not too dear and you will see increase in fuel economy as well.

[kastad]

Is it the d jet version? If it is you should check that the trigger points are working

[witty]

thanks kastad

Has the D jet system.

have cleaned the trigger points and they seem to be in good condition, but that doesnt mean I did it right.

What is the best way to verify if they are working correctly ?

cheers

[kastad]

You can check the plugs and see if only four of themhave deposits showinf they are firing. The trigger points operates four and four cylinders, so if four are foulinf the trigger points would be to blame.

It can also be done by measuring electrically. The points should shift between zero ohms and open circuit when turning the engine.

[witty]

I just saw an interesting post re trigger points, this guy had same problem and it turned out to be the trigger point assembly
wasnt seating on the dizzy body neatly, so he had a gap between the outer shell of the trigger assy and the body of dizzy.

I checked mine and i have a 2-3  mm gap in the center of the curve, will adjust this and see what it does.

Have no idea what would cause this change in alignment.

Will post later on results

[Aluminum]

Trigger Contacts

The trigger contacts are housed in the lower section of the ignition distributor underneath the mechanical centrifugal advance plates. On a V-8 engine the trigger contacts have a set of four points. The trigger contacts signal the "start" of injection while the "duration" of injection, which is how long the injectors remain open, is determined by the inputs of the pressure sensor, engine speed, and the various other engine sensors to the electronic time switch of the ECU.

If your engine is misfiring badly, barring an ignition problem, the most common culprit is the trigger contacts. Since the points do not have current flowing through them, unlike ignition points, the point contact surfaces last for quite a long time and are not subject to the pitting that occurs on ignition points. However, the rubbing blocks wear out, just as ignition points, because of lack of lubrication and from normal wear. This will result in the failure of the ECU to receive the signal to fire a pair of injectors, thus the bad miss. Another problem is the point contact surface corrodes causing the same scenario.
   

We have mentioned that you must check the connectors before replacing the parts; this is one area that we have seen frequent connection problems. There are two different types of trigger contacts. The pigtail type has a short wiring harness that is connected to the trigger contacts and the other type has no wiring attached just the male ends. Make sure you check the pigtail connector for any reason that could cause a poor connection. It does not take much to cause a really bad misfire making it seem that the engine is running on four cylinders. The truth is, it probably is.


You can tell that injectors are not receiving the signal to fire it by testing with a 12-volt test light. Connect the alligator clip to ground, pull back the connector boot and so you can touch each wire connector of the injector with the probe. When the engine is running one wire will have a solid light and the other wire will flash or pulse. When this is occurring the injectors have the proper electrical signal to fire.


If both wires have a steady light the injector is not receiving the ground from the control unit. You need a hot and a ground to pulse the injector. Two positives don't make a negative in this case. The most common cause of the above scenario is the failure of the ECU to receive a signal from the trigger points either due to a wiring problem or a mechanical failure. Other causes may be a series resistor, extremely rare, or a control unit failure.


Removing the two screws and sliding the trigger contact set out of the distributor will easily remove the trigger contacts. Make sure you grease the rubbing blocks of the points when you reinstall them.


One final note on trigger contacts; although you can test the trigger points with an analog meter to see if each set of points is working, we have found that there is a big difference with the results by bench testing versus driving conditions. We have seen many contact sets check out good on the bench, when they are only subject to very slow RPM, but fail miserably under driving conditions. My personal rule of thumb is that if the car is an everyday driver and the contact points are decades old, I am changing them for reliability sake.