Running problems with Lucas L (flapper 4CU) injection system
Discussion
wooly350i said:
is it possible that the cold start injector if still connected would be stuck open?
Minor weeping perhaps, but stuck open? No! If that were to happen, a grossly over-rich mixture would be non-combustible and the smell of fuel overpowering. Because this engine runs (after a fashion) one really needs to observe the spark plug condition to move forward with a meaningful diagnosis.
Looking back over the thread, the loss of power as the revs increase suggests a possible uncontrolled weaker mixture with resulting loss of torque as a result of a rogue air leak into the plenum chamber.
They can be a bitzh to find, and because the engine is capable of running reasonably well at idle speed, so a dynamic test program is the best approach.
Testing for Air Leaks
• If during the process of fault finding its is established that all the ignition, fuel and sensor components are working correctly but engine performance is still not up to standard, then obviously there remains a fault as yet undiscovered.
• With so many pipe connections to the plenum affecting what happens at the inlet manifold there is a high probability of rogue air leaks into the system.
• The following mode of diagnosing the location of any air leaks will also prove if the extra air valve and the air-con anti-stall valve (if fitted) are working correctly
• Run the engine until it attains normal working temperature and “try” to set the idle speed to somewhere near its normal level. Now attach a suitable external tachometer, connected as per the manufacturer’s instructions, to a spark plug lead, the negative side of the coil or an injector, as appropriate, and stop the engine.
• Begin by disconnecting the vacuum pipe (‘A’ in fig.1) to the fuel pressure regulator and suck on the open pipe to check the integrity of the regulator and the pipe. If the vacuum generated by sucking does not hold, check the pipe. If the vacuum still won’t hold, the regulator is definitely faulty. This test can also be performed using a vacuum pump working at no more than 15 inches of mercury.
• Thoroughly check the inlet hose(s) between the air flow meter and the throttle butterfly housing to ensure the laminations have not separated, there are no holes in the hose(s) and the hose clips are secure.
• Restart the engine and allow it to come up to operating temperature again. Reset the idle speed with the help of the external tachometer to an easily remembered level (say 800 rpm) and make a note for future reference. Stop the engine.
Fig.1. Plenum Air Connections
• Disconnect all air/vacuum related systems joined to the plenum which can affect performance and seal off all the inlets marked X with patches of self-adhesive tape (badge tape is good) as follows:
1 Disconnect the brake servo, and seal the union connection at the plenum
2 Disconnect the pipe to the ventilation system reservoir and seal the port
3 Disconnect the extra air valve “U” shaped hose and seal the port
4 Disconnect the air rail hose from the pipe next to the throttle and seal the port
5 Disconnect the breather from its pipe near the throttle pot and seal the port
6 If fitted, disconnect the air-con valve hose from its stub pipe and seal the port
7 Disconnect the air supply to the overrun valve and seal the input to the valve
8 If fitted, disconnect the vacuum pipe to the automatic transmission and seal the port.
• With the exception of the pressure regulator connection, all the air/vacuum connections at the plenum have now been sealed off, as illustrated in Fig.1.
• Start the engine (if necessary depress the throttle to raise the engine rpm), run it to attain normal operating temperature then allow it to idle. Check and record the idle speed, and compare with that recorded earlier.
• If there is no change in idle speed, this proves that all the disconnected systems are sound as far as air leaks are concerned. On the other hand if the engine speed has altered significantly (say 100 rpm or more), this indicates one or more of those systems is faulty and must be found by a process of elimination.
• Air leaking into the vacuum connections or blockage of a permanent air feed into the inlet system can cause the engine speed to increase or decrease by as much as 200 rpm or as little as 10 rpm if, for example, the crankcase ventilation oil separator is blocked.
• Faults which cause small changes in idle speed are often overlooked or are erroneously rectified by readjustment of the idle screw. Over time these minor faults can build up and interact so they should not be disregarded when they can be detected and analysed by the following tests.
• So if idle speed changed, record the readings at this and each subsequent stage as they are required for ongoing comparison to pinpoint which of the disconnected pipes or components is at fault during the remainder of the tests:
o No.1. Unseal and reconnect the brake servo pipe. Restart the engine and compare with the idle speed just recorded. If it has changed a fault lies in the brake servo hose, the non return valves (Normally, there are two on Efi cars!) or the brake servo itself which must be investigated and resolved.
o No.2. If fitted, set air-con controls to “on” then unseal and reconnect the pipe to the ventilation system vacuum reservoir. Restart the engine and measure the idle speed. Any change from the previous figure indicates an air leak into the vacuum control system. To isolate a fault, first move the controls to “off” and recheck the idle speed. If still affected the fault is in the vacuum reservoir or connecting pipes. If the idle speed is restored the fault lays in the vacuum distribution unit, one of its associated vacuum servo units that operate the flaps or their associated pipes. Investigate and resolve.
o No.3. Unseal and reconnect the extra air valve hose at the plenum. Restart the engine and check if there is a change in the idle speed. Assuming that the “U” shaped hose itself is sound, and remember, the inlet hose is open at the throttle end, any change indicates that air is leaking through the extra air valve mechanism into the plenum and therefore the fault lies in the extra air valve itself. If when the hose is reconnected there is no change in the engine speed then the extra air valve is proved to be sound with respect to air leaks.
o No.7. Unseal the input pipe to the overrun valve and restart the engine. If the idle speed is unchanged the valve is not leaking. If the idle speed changes there is a fault in the valve that must be corrected. A common cause is debris between the valve head and the valve disc preventing it from closing properly.
o Nos. 4 & 6. Unseal and reconnect both the air-con air valve connection at the plenum (if fitted) and the air hose at the throttle butterfly. Restart the engine and measure the idle speed. If no change is detected this proves that the air hoses and the air-con air valve are sound. If the idle speed has changed, air is entering the plenum either through a faulty air conditioning air valve or the associated pipes. Investigate and resolve.
o No. 5. Unseal and reconnect the crankcase breather pipe and check the idle speed. Any change in engine speed indicates a possible air leak in or around the oil separator or the pipe itself which can be easily checked by visual inspection. However, the crankcase ventilation system is complex and interactive with several seals and gaskets which should be carefully inspected if problems are indicated. It may be that there is a problem with the engine itself regarding how much gas is able to bypass badly worn pistons into the crankcase and subsequently affect the idle speed. If such a condition exists then chasing non existent air leaks will be a fruitless exercise.
o No. 8. Unseal and reconnect the vacuum control pipe to the automatic transmission modulator valve (if fitted). Restart the engine and check the idle speed. Any change will indicate a leak in the rubber connecting elbows at each end of the metal pipe or the transmission modulator valve itself. If the modulator valve is faulty then manifold vacuum is able to suck transmission fluid into the plenum where it enters the engine and burns with a dense white smoke. Such a fault would surely have been previously observed?
• Having checked all the connections and components mentioned there remain a number of other ways in which rogue air can enter the system. It can leak past the plenum/trumpet housing joint, the trumpet housing/inlet manifold joint, the cold start injector seal, any of the injector seals or even the inlet manifold gasket.
• The plenum to trumpet housing joint is particularly vulnerable to poor sealing because the metal to metal face is only 1/4” wide over an aggregate length of 30”.
• To check for leaks in any of these inaccessible areas, restart the engine and squirt very thin oil, WD40 or Plus-Gas around the mentioned joints and gasket locations in turn. Any ingress of fluid into the manifold can usually be heard or seen.
• Repeat the test around all the injectors to ensure each has an airtight seal. Fluid gaining access to the inlet manifold may also be indicated by a change in engine rpm and/or by changing colour of the exhaust gasses.
• If leaks are found they might be temporarily sealed using a brand of Damp Start Lacquer (i.e. Holts). Use it when an area to be sealed is dry and free of grease. Sprayed from an aerosol around the suspect area of leakage, it forms a plastic latex film which can seal the most inaccessible of leaks into the air inlet system.
• This type of sealant should be only used when the engine is switched off as during application, it gives off a flammable propellant. Bear in mind that such a cause temporarily cured by this method would still need to be permanently corrected.
• After fixing any air leaks idle speed and CO level must be reset as per the manual.
I commend its elegance to the house!
honestjohntoo said:
s1v8esprit said:
The problem now is it just does not rev cleanly, missing, and feels like its a carb with the choke full on when it should be off...... Will look into getting a new rotor arm and distributor cap, it would be great to try parts that are known to work
Your first observation seems to indicate a fuelling problem so it could be a distraction, swapping out ignition parts, without any evidence either way.You might consider some very basic diagnosis such as checking the spark plug condition for over or under fuelling - a massive boost in diagnosis of fuelling versus ignition.
As mentioned you'll follow a shed load of random component replacement suggestions and perhaps never uncover a root cause. Case in point, swapping out the AFM brought about a small change in behaviour, not proving that the AFM was faulty but that it may simply have had a maladjusted CO screw. But what if the adjustment on the replacement AFM is still wrong? Better, but wrong!!! A review of the previously referenced AFM and Hunting documents will help you regarding the affect of an over-rich idle mixture on the Efi hunting symptom.
Moving on! In lieu of swapping out every single component you might consider a full ignition system component review.
TESTNG IGNITION COMPONENTS - BACK TO BASICS
The circuit represents BOTH the system where the amplifier is mounted in an aluminium housing behind the coil AND where it is mounted on the side of the distributor. The effective electrics are the same, just the physical locations of components differ.
Be sure the earths and the wiring from the ignition switch through to the coil, distibutor and amplifier module are pretty much the same as shown.
Getting Started
o Reasons for testing the ignition system are a proven loss of sparks at the spark plugs, or weak/intermittent sparks causing misfiring.
o To proceed, separate the Low and High Tension circuits to find out immediately which circuit is faulty, then persue the fault condition in either circuit according to the results of some logical tests.
o Remove the king lead from the distributor, connect it to a good spark plug and lay the plug on the engine somewhere.
o Switch on the ignition and crank the engine.
o Is there a fat spark at the spark plug.
o If Yes - then the problems are downstream and away from the king lead at the dizzy cap, rotor arm, plug leads, plugs, or ignition timing so that is where to look - see " Other Components" (later) for checking the usual suspects, inspect, clean, substitute and only replace if faulty.
o If No - change the king lead.
o If still No - then the problems are upstream from the king lead and towards the coil, amplifier, distributor innards or their local connections all the way back to the ignition switch.
Testing the Low Tension Side Voltage Feed
o Switch on the ignition and use a multimeter to verify there are 12 volts at coil positive.
o If No - find out why, by checking the circuit between coil positive and the ignition switch and beyond, all the way back to the battery if necessary, for corroded or loose/broken connections.
o If Yes - dont take it for granted, waggle local wiring and toggle the ignition switch a few time to ensure the voltage is reliable, even using a bright lamp to check the wiring can supply a load.
Test the coil independently
o Disconnect the wire from coil negative to the amplifier.
o Turn ignition on, and strike coil negative to earth with a flying lead to see how good is the king lead spark.
o If sparks are absent/poor/weak and +12 volts is still present at coil positive then the coil is prime suspect for inspection/replacement.
o If sparks are fat/healthy then coil must be OK, so look for amplifier/pickup coil problems.
Test the Amplifier and Distributor Pickup Coil Together.
o Remove Distributor Cap.
o Disconnect ECU trigger wire from the 6.8k ohm resistor to prevent spurious signals getting to the ECU.
o Disconnect amplifier wire from coil negative.
o Connect a 12v 21W bulb from the same amplifier wire to coil positive (12 volt supply).
o The 21W bulb acts as a substitute coil load.
o Turn ignition on and rotate distributor rotor arm back and forward against the vacuum/mechanical advance springs.
o As the toothed reluctor wheel triggers the pickup coil, the amplifier should flash the bulb.
o If bulb flashing is positive and consistent the amplifier and pickup coil are working correctly together.
o If lamp does not flash or is inconsistent/weak either the amplifier or pickup coil is faulty.
Check the pickup coil independently
o Remove the amplifier connections to the pick-up coil and measure the resistance of the distributor pickup coil for a steady value between 500 ohms to 1500 ohms on the ohm-meter. Flex the wires at the same time to test their integrity.
o Outside the above range, short or open circuit indicates a croaky pickup coil.
o By process of elimination, if the pickup coil is OK, one might conclude the amplifier is faulty but nothing is ever that simple with electronic components, so to be sure:
Test the Amplifier independently
o What follows is an elegant but slightly complex test process.
o Use a 1.5 volt pen-cell battery connected in series with a (say} 2,700 ohm resistor and two flying leads to simulate the pickup coil.
o With the coil and amplifier connected normally and the distributor pickup coil disconnected from the amplifier, connect one flying lead to one of the amplifier input connectors and touch the other flying lead intermittantly across the second amplifier input connector.
o This emulates a pulsed input thereby activating the amplifier in sympathy to generate sparks from the coil?
o Polarity of this simulation is non-critical as neither flying lead is connected to earth, only to the amplifier input connectors, and the pulsing voltage from the pen-cell via the 2700 ohm resistor acts similar to the pickup coil input without causing stress or damage to the amplifier.
o The above test can be performed with the 21 watt bulb as the coil substitute as previously described, except in that circumstance, the pick-up coil simulation will flash the bulb.
Alternatively (for even more elegance), going one step further:
o Construct a small test box complete with switch, 21 watt bulb/holder, pen-cell battery, 2700 ohm resistor, 12 volt pos/neg power connections (from a car battery), spade connectors to the amplifier, etc.
o Connect up the 12 volts power and the amplifier to the test box and flick the switch repeatedly to emulate the pulsed input from a pickup coil and see the 21 watt bulb flash in sympathy to show the amplifier is working correctly.
Other Components
o Another possible component failure will be the suppressing condenser breaking down under the back-EMF from the coil.
o Remove condenser from circuit to see if the problem disappears.
o If yes, replace the condenser.
o Almost finally! For all the previous components check the LT wiring is not corroded, broken, dodgy or otherwise failing.
o Because all the components upstream of the king lead now check out OK, if fat sparks emerge from the king lead but not at the spark plugs its time to review the downstream components to see if they are dragging down, or failing to conduct, the Hi-Tension energy.
o Rotor arm - inspect for carbon tracking, clean with WD40, smear with a trace of silicon grease to prevent moisture ingress.
o Distibutor cap - inside and outside - inspect for carbon tracking, clean with WD40, smear with a trace of silicon grease to prevent moisture ingress. Wipe completely clean and shiny, especially between the turrets.
o Plug Leads and Hi-tension connectors - inspect for breaks and contact damage, clean with WD40, smear with a trace of silicon grease to prevent moisture ingress. Wipe completely clean and shiny.
o Spark Plugs - Check for recommended type, clean and gap to correct spec, inspect for insulator damage externally and whiskering/crud between central contact and body. Clean externally to a shine.
o The above four items are "zero cost" actions, yet, many owners replace them all never knowing which of the components may have been faulty.
o Check by swapping S/H or borrowed parts is an easy process before buying replacements.
o Looking for spark tracking on a dark night generally reveals faulty hi-tension parts.
Precisely the reason why I got rid of the Efi and switched to an Edelbrock Carb & Mallory Ignition setup. Unless you have a degree in electical engineering who the f
k is going to understand all that bks unless you're a TVR techie charging £100 an hour plus the VAT to locate and fix an electrical fault....Edited by GV on Monday 13th December 12:23
GV said:
Precisely the reason why I got rid of the Efi and switched to an Edelbrock Carb & Mallory Ignition setup. Unless you have a degree in electical engineering who the fk is going to understand all that bks unless you're a TVR techie charging £100 an hour plus the VAT to locate and fix an electrical fault....
If you cannot follow the above-mentioned procedure you should not be trying, take it to someone who understands.k is going to understand all that bks unless you're a TVR techie charging £100 an hour plus the VAT to locate and fix an electrical fault....However, it's not rocket science!
GV said:
Yeah - but he runs the risk of getting fleeced by someone who does....!!
There are certain types of car which are very appealing despite being very unreliable. Anybody sensible who decides to buy one (oxymoron?) needs to be aware that they will either:-
a) Have to have a bit of knowledge and be prepared to get their hands dirty
or
b) Be prepared to dig deep to pay someone else to do it
Fact of life unfortunately!
s1v8esprit said:
fitted new spark plugs (old ones were a nice tan colour)
changed the HT leads again for some magnecor ones no difference!
changed the power resistor no difference!
changed the ignition module on distributor no difference!
changed the coil yes you guessed it no difference!
But your ignition will be trouble free for some time now! changed the HT leads again for some magnecor ones no difference!
changed the power resistor no difference!
changed the ignition module on distributor no difference!
changed the coil yes you guessed it no difference!
GV said:
Precisely the reason why I got rid of the ---- Unless you have a degree in electical engineering who the fk is going to understand all that bks
How sad that is? So hard is it, to follow those simplified instructions, that you really believe it takes a degree in electrical engineering to follow a procedure thus:k is going to understand all that bks(just for example) Bear with me - STEP by STEP! The bits in BOLD are just for reference! OK?
Test the Amplifier and Distributor Pickup Coil Together
o Remove Distributor Cap. Thats the bit with 9 HT leads coming out of the top..
o Disconnect ECU trigger wire from the 6.8k ohm resistor to prevent spurious signals getting to the ECU. White/Black wire from trigger resistor to pin 1 of the ECU - DISCONNECT means "undo and leave off".
o Disconnect amplifier wire from coil negative. You'll recognise the coil? It has just One H/T lead and two other terminals, one of them is marked "negative" and you find the wire going to the amplifier and just disconnect it.
o Connect a 12v 21W bulb from the same amplifier wire to coil positive (12 volt supply). You may have come across bulbs? They are used in the cars lighting system, glass and metal shaped like - er - Ah yes, a bulb!!!?
o The 21W bulb acts as a substitute coil load. Substitute, means "instead of"
o Turn ignition on and rotate distributor rotor arm back and forward against the vacuum/mechanical advance springs.I know you know where the ignition switch is? Nobody's that stupid! But then again, it could be a close run thing! Own up, if you are having trubble with this bit?
o As the toothed reluctor wheel triggers the pickup coil, the amplifier should flash the bulb. Bulb flashing can be observed using the things in the middle of yer face - Eyes, they are called! You also use them for reading and in my case, crying with laughter!
o If bulb flashing is positive and consistent the amplifier and pickup coil are working correctly together.See below
o If lamp does not flash or is inconsistent/weak either the amplifier or pickup coil is faulty.This is a logical process of deduction, Flashing is good, not flashing is bad.
I'm sure you get the idea now? Degree in Electrical Engineering, my foot. What a load of Trollocks!!!. Marks, 1/10 for knowing where the ignition switch is!! Just. Must try harder!
No-one has specifically mentioned the engine temperature sensor - it's worth taking the plug off and shorting it out, after it's a bit warmed up. If it runs much better then there's your culprit!
Also I was emailing Ramon (HJ2) the other day about the ignition module - he pointed out when changing it you MUST use some thermal paste on the back, or else it will start to overheat and go bad.
Also I was emailing Ramon (HJ2) the other day about the ignition module - he pointed out when changing it you MUST use some thermal paste on the back, or else it will start to overheat and go bad.
No worries Karl.
Glad to help Karl.
I was going to post a sarcastic response about checking facts before making odd claims. But then I remembered that there's probably more than 1 Karl on PH; and posting on this thread.
And I can't be accused of assuming. Now can I Karl?
Anyway - back to sleep for me
Glad to help Karl.
I was going to post a sarcastic response about checking facts before making odd claims. But then I remembered that there's probably more than 1 Karl on PH; and posting on this thread.
And I can't be accused of assuming. Now can I Karl?
Anyway - back to sleep for me
Kinky said:
No worries Karl.
Glad to help Karl.
I was going to post a sarcastic response about checking facts before making odd claims. But then I remembered that there's probably more than 1 Karl on PH; and posting on this thread.
And I can't be accused of assuming. Now can I Karl?
Anyway - back to sleep for me
G'nite Glad to help Karl.
I was going to post a sarcastic response about checking facts before making odd claims. But then I remembered that there's probably more than 1 Karl on PH; and posting on this thread.
And I can't be accused of assuming. Now can I Karl?
Anyway - back to sleep for me
From the only Karl on this thread!
PoleDriver said:
Kinky said:
No worries Karl.
Glad to help Karl.
I was going to post a sarcastic response about checking facts before making odd claims. But then I remembered that there's probably more than 1 Karl on PH; and posting on this thread.
And I can't be accused of assuming. Now can I Karl?
Anyway - back to sleep for me
G'nite Glad to help Karl.
I was going to post a sarcastic response about checking facts before making odd claims. But then I remembered that there's probably more than 1 Karl on PH; and posting on this thread.
And I can't be accused of assuming. Now can I Karl?
Anyway - back to sleep for me
From the only Karl on this thread!
Regards,
adam quantrill said:
No-one has specifically mentioned the engine temperature sensor - it's worth taking the plug off and shorting it out, after it's a bit warmed up. If it runs much better then there's your culprit!
Also I was emailing Ramon (HJ2) the other day about the ignition module - he pointed out when changing it you MUST use some thermal paste on the back, or else it will start to overheat and go bad.
Ok Will give it a go, thanks for the tip about the thermal paste, cheersAlso I was emailing Ramon (HJ2) the other day about the ignition module - he pointed out when changing it you MUST use some thermal paste on the back, or else it will start to overheat and go bad.
changed TPS........... yes you guessed it no difference!
changed the thermal time switch.......yes you guessed it no difference!
changed the temp sender..........yes you guessed it no difference! (looked like a brand new one I took out?)
engine would not run with this disconnected? and ran very poor if I shorted the wires? like Adam suggested?
changed the thermal time switch.......yes you guessed it no difference!
changed the temp sender..........yes you guessed it no difference! (looked like a brand new one I took out?)
engine would not run with this disconnected? and ran very poor if I shorted the wires? like Adam suggested?
Gassing Station | Wedges | Top of Page | What's New | My Stuff