Rover 3.5 EFI Misfire ?

yankfan101

Torque Junkie
Points
182
Location
Taplow
Car
1987 Range Rover
Hi all, ive got a Range Rover with a factory fitted 3.5 EFI lump, I cant find out where the misfire is coming from, not the dizzy cap or plugs & leads or rotor arm, (replaced).
Im thinking maybe the coil or something under the plastic cove below the rotor arm but I havnt delved that far into it yet, engine just cuts out for a split second & then its ok again, its getting me wound me up. HELP. I'm going bald fast !
 
Possibly injector related as you've done all the ignition stuff. Does t happen at high revs only? This might point to a coil problem.
 
The most disconcerting, that's a big word for me, thing is when it does it at the lights, I feel a right " Del boy " that's said HDi , it does have an ecu, but only on the air intake.
 
You said it is and I quote : "the factory fitted 3.5 EFI lump". You can't have an ECU only on the air intake. That makes no sense. ECU is fed data from all manner of places.
 
Honest HD, its got a label on the air intake but there's no sign of a " brain " , these were the test motor's, 1986- 1987, for the new 3.9 vogue efi , mine runnin' 155 bhp, the 3.9 is 165 bhp & she's running all Lucas stuff, maybe they changed stuff for the 3.9 & the 3.5 is the odd ball !
 
EFi stands for Electronic Fuel injection. It is likely to be a Lucas arrangement using a hot wire anemometer - the Montego 2.0 EFi models used the same metering arrangement. There will be a magnetic reluctance pickup on the flywheel and at least one knock sensor. AR was quite well ahead of its time in some areas.
 
A hot wire anennno... anoometr....anenomy thing? Really? Like one of these?
And is that a forerunner of the MAF or is a MAF just another name for an anemeo.... thing?
Anenometer by Robinson.png
 
It's just a MAF. The hot wire or hot film principle is clever as it automatically accounts for pressure and temperature. This misfire is odd though. Is it all cylinders or just one?
 
What kind of ignition system do you have on the car? Is it old fashioned system distributor with points (contact breakers) or electronic breakerless system? Does your rev counter die when you get the misfire? It's fed off the dizzy so if there's an interruption to the electrics the RPM feed will go dead.
 
Ok, brain scrambled with stuff I know nuffin' about, aneme thing , magnetic reluctance pickup, wassat, mine very reluctant, no points in the dizzy, I think 20-30 years of thecno stuff has passed me by, give a 4 barrel or twin 40's & a dizzy & timing marks & I'm yer man, all this electro stuff is way beyond me HD, this reluctant magnetic thing, is it easy to get to or is it a g/box pull out..
 
HI Gladrags, yes the rpm drops to almost cut out mode but its so quick it comes back in a millisecond but the whole car jumps slightly as if you've stalled it , mine an auto, plugs & leads r all ok but ive got a feeling the coil is 30 years old, Mmmm, think its time for a change.
 
I did actually mention coil a few days ago. They do fail over time. Even modern systems with a plug-top coil per cylinder fail, possibly more often due to their location right on top of the cylinder head and getting baked. It won't be the timing sensor on the FW otherwise you'd have no

As far as hands on goes I am in your camp. (I'm not terribly young, either :( ). I can work on a pair of SU carbs, adjust points gap/dwell angle and set timing with a strobe. Thankfully those days are long gone. Modern systems are infinitely more reliable as well as offering better performance and economy.
 
But Paul, you've forgotten the most important thing, the satisfaction factor,,,who did that,,,me why,,,,wow wish I could remap a car by hand,,, !!!!!
 

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