Classic 3.5 EFI Running Poorly

Hi

I have a 3.5 EFI with Lucas L Injection and a Lucas 35 DLM8 Distributor (I believe the LR Part No. is ETC 5953) and have recently had to have the original distributor replaced. I was told that 35 DLM8's were no longer available and that a suitable after market one was fitted, However, since the distributor was replaced the RR has been sluggish with the occasional backfire and misfire as well as only returning 12 mpg in town driving whereas before over 14 mpg had always been the norm.

I would be grateful for any advice and a recommendation for a garage that can check the distributor and engine and set the engine up correctly, preferably one as close as possible to the London/Essex border.

Thanks

Doug

I would think Since the distributor was replaced it may have to do with the timeing or the distributor may be off a tooth..,

If your good at tinkering with it, get your self a guns on timing strobe light and you can check thd timing yourself or.... À tipex pen mark on the dizzy locking ate and mark it up then make a small adjustment in a clockwise direction or anticlockwise direction and see if it makes a difference. If it gets worse go back and adjust it the other way a touch.. But only a touch.
As said it may not be timed just right. As engines wear the timing marks don't always ring to the gods of timing and a worn camshaft driving gear can add a small àmout of mal-adjustment. My dad used to tune it by ear.

first check all the HT leads are seated properly and in the right order.. if they are and still causing problem the timing is probably out.. when the dizzy goes back in it needs to start about 30 degrees backwards as the gears are curved spline, so it engages with the teeth it will naturally rotate and you need to make sure the timing is correct for the model, they do vary. also the module on the side of the dizzy can give a problem. was that replaced with the dizzy or was the old one reused? reseating needs the compound reapplying.

What was the running issue that required a replacement dizzy?
What have the place that fitted the replacement had to say about the running problem with the new one?

May sound silly but check the firing order
I hope you kept the old dizzy

Notwithstanding the good advice you've had here, the words 'suitable aftermarket' ring alarm bells with me. RV8's are a very simple (read old-fashioned) unit but they definitely do not like sub-standard ignition components.

As Ratae has asked, what was the original fault? If you were having the car serviced at the time I wonder if the garage tried to pull the rotor arm off & pulled the guts out of the original dizzy.
Just a thought.

I don't really know your engine, but on my old carbed V8 110 there was a specific way of routing the HT leads that looked a bit wrong at first.
IIRC number 3 and 5 leads had to cross each other or there would be a chance of miss-fireing.

Thanks for all the responses.

The original problem was extreme lack of power, it would not go over 50 mph and that was a struggle. Two garages identified the problem as the distributor. The second initially fitted a second hand one, which was possibly an original LR, so I could use the car while they ordered a replacement and the car ran well with this but it would hunt when starting from hot.

The engine is low compression and, according to the Handbook, the distributor is a Lucas 35 DLM8 and the Parts Manual quotes is ETC5953 but the only place I can find reference to this is Rimmer Bros and they quote a superseded model which they state is OEM.

Britpart one for sale at island. Not sure if it would work or not.
https://www.island-4x4.co.uk/distributor-britpart-err4754-p-8164.html

Check timing....Check the gap between the pick up and the reluctor ring, check the bob weights are correctly seated and not fallen off, check the ignition amp output, check the vacuum advance system...etc etc

What year?
What mileage & is that on the engine that's fitted?
Manual or automatic?
Are all plenum hoses in good condition & connected?
Has the car always given that level of performance?
What CR figure is stamped next to the engine number? (If you aren't sure where that is then it will be on the flat area next to where the dipstick goes into the engine).
Has a cylinder compression test been carried out & if so what were the figures like?
With the loan dizzy fitted was it still only able to do about 50 & that was a struggle?
If you put your foot down hard does the car struggle or accelerate briskly?
If it struggles at a foot hard down does it accelerate smoothly if you press the accelerator slowly?
Were either of the garages specialist LR indys or just general garages?

It's very easy to get the dizzy a tooth out. Guess how I know. It ran. Badly.
Also easy to mix a couple of leads up.
Been mentioned above but if the rotor arm is pulled off incorrectly it can disengage the auto advance/retard mechanism in the dizzy bowl. Check by turning the rotor arm with your fingers until it stops. When released it should return smartly to its original position.

In your case I would start with a complete reset of the timing.
Remove left hand - as viewed from the driver's seat facing forward - rocker cover, No1 plug - front, left hand bank - & the dizzy cap.
With a rod of suitable length down the plug hole turn the engine until it's on the compression stroke with both No1 valves closed. If you go past TDC then turn the engine back to the bottom of the stroke & then back up on the compression stroke.
Check where the rotor arm is pointing.
See if the metal pointer is aligned with the TDC mark on the crankshaft pulley.
See if the plug leads are fitted in the correct order.
Mine's an 86 3.5EFi flapper with 4CU ecu (as yours) & the factory manual gives dynamic as TDC +/- 1deg at 600rpm. Set by road test mine's best at 6 deg TDC.

ETA. This is worth a read. Note the comment "ALWAYS REPLACE water temperature sensor. (the one behind the easy one!)"
Worth doing as if it's faulty & telling the ECU the engine is cold when it's hot it will fuel as for a cold engine. Won't help with smooth running OR the fuel consumption.
http://www.carelect.demon.co.uk/rrp1.html
Don't get too hung up on ECU failure, they do have a reputation & I've had several fail but the car has always been totally undrivable.

Ratae, Thanks for the detailed response, here are the answers:
1988.
203K.
Automatic.
All hoses appear good and connected. The non return valve on the vacuum hose has been removed because it was not working.
I have owned it for 28 years and it has always achieved over 14 mpg around town with no performance problems.
The CR figure is 23D03314B.
Cylinder compression's between 110 and 120 (low compression engine).
Ran fine and did not struggle with loan dizzy but idle would often hunt down and stall when starting from hot.
It regularly struggles when trying to accelerate and I have to push the accelerator far enough down so it drops down a gear to get it going especially when pulling away and accelerating above 40.
The garage which did the work is a long standing specialist LR indy.
Leads are fine.
The rotor arm is fine, it turns about 5mm and has a strong spring back.
It starts and idles fine from cold.
At the same time as changing the dizzy the garage adjusted the idle speed by using the idle speed screw because the idle was low.

These documents for testing the EFI system may be helpful.

It's been a while since I had my 3.5 but I seem to remember having a similar problem which I cured by fiddling/cleaning the Throttle Butterfly and the Extra Air Valve.

Good luck!

Pete

"It regularly struggles when trying to accelerate and I have to push the accelerator far enough down so it drops down a gear to get it going especially when pulling away and accelerating above 40."
Has that always been the case in your ownership of the vehicle? If not, did it come on suddenly or over a period of time?

Get them to check the Throttle Position Sensor is working correctly & is not faulty. The information from this to the ECU (along with other sensors signals) determines the amount of fuel being supplied. When sudden acceleration is sigalled - foot down - the ECU will pulse all injectors once simultaneously to increase the fuelling for acceleration.
Is the extra air valve working?

Pete mentions the throttle butterfly. It is worth propping it open & cleaning the area it closes down to. A build up of dirt can restrict the airflow when it is closed.
With the flapper setup with the butterfly closed there MUST be a gap at the six o'clock position between the butterfly & the plenum bore of a maximum of 0.05mm (0.002in). This gap is adjusted by a hex headed grub screw acting on the throttle stop lever which you'll find near to where the butterfly shaft enters the plenum body from the rear.
That gap needs to be set before playing with the TPS position & the idle speed screw. Note the idle speed screw is the one on the plenum, NOT on the air flow meter.

ETA. That's a lot of miles. If they're the originals I do wonder what the camshaft, followers & the drive chain & sprockets are going to be like.

Ratae said:

"It regularly struggles when trying to accelerate and I have to push the accelerator far enough down so it drops down a gear to get it going especially when pulling away and accelerating above 40."
Has that always been the case in your ownership of the vehicle? If not, did it come on suddenly or over a period of time?

Click to expand...

The car had always run fine. This problem only occurred when there was a fault with the original dizzy and continued when the new dizzy was fitted. The car ran fine with the loan dizzy fitted apart from often hunting with low revs when restarting when hot.

Pete The Biker said:

These documents for testing the EFI system may be helpful.

It's been a while since I had my 3.5 but I seem to remember having a similar problem which I cured by fiddling/cleaning the Throttle Butterfly and the Extra Air Valve.

Good luck!

Pete

Click to expand...

Thanks Pete

Possible fault with the new dizzy - either in itself or its installation, hence my suggestion for re-timing, if only to rule that out.
Your original was a 35DLM8.
What was the loan one?
What have they fitted?
With the original dizzy was the amplifier mounted on the side of it & were the loan & new one the same?

Ratae said:

Possible fault with the new dizzy - either in itself or its installation, hence my suggestion for re-timing, if only to rule that out.
Your original was a 35DLM8.
What was the loan one?
What have they fitted?
With the original dizzy was the amplifier mounted on the side of it & were the loan & new one the same?

Click to expand...

Not sure which model the loan one was but it was from a 91 RR.
No idea of the model fitted only that it is what they use.
All 3 dizzy's had side mounted amplifiers.

Rimmer Bros are the only suppliers where I can find any reference to a 35DLMB dizzy and this is no longer available and superseded by a DM8.

I will be taking the car back next week and ask them to investigate as you and Pete suggested.

Thanks again for your help.

This guy should be able to help with any distributor queries..http://www.distributordoctor.com/

Pete