engine cuts out at full throttle

[MontrealRR90]

i did a tune up with wires ,distributor cap,plugs,rotor and it started cutting out at full throttle? when you accelerate half the way it does not do it. i went to the dealer and they checked the distributor and tinkered with the timing and it runs a bit better but it still cuts out at around 50 mph when giving it full throttle. any ideas? range rover 1990 3.9

 

[scrover]

i did a tune up with wires ,distributor cap,plugs,rotor and it started cutting out at full throttle? when you accelerate half the way it does not do it. i went to the dealer and they checked the distributor and tinkered with the timing and it runs a bit better but it still cuts out at around 50 mph when giving it full throttle. any ideas? range rover 1990 3.9

Check the vacuum advance hose for leaks. You might have disturbed it when you did the tune up - it comes off the side of the distributor and goes to the intake plenum. Or, you could try putting back the old rotor and/or cap in turn and testing driving. Did you buy Genuine cap and rotor? Most of the aftermarkets are crap.

When you say 'full throttle' what RPM are you doing?

SC

 

[GregH]

Try checking if one of your centrifugal advance springs came loose.

 

[MontrealRR90]

i got everything except the wires from atlantic british its lucas i think.the mechanick at the dealer told me that it should not be the wires because it would cut off at lower speeds also.
has for full throttle its all the way to the floor has far has it will go its then that it cuts out but only at around like i said at 50mph. i do the same in first,second ,and third gear with rpm to 4,500 and it does not cut out.?
where is the centrigugal spring?
i'll check the vacum today tks

 

[scubaman99]

have you checked your fuel filter?

i had a similar problem... went through all the regular "tune up" steps and it still had no power...

took it to the shop, they replaced the fuel filter and it was like a new truck... acceleration and all

 

[cbrown]

similar problem

My 89 RRC has a similar, but different problem. It only happens from time to time, but when it does, its very annoying. I would describe it as a hiccup in the engine. Everything will seem to be fine, but when I reach a speed I want to sustain, and back off the accelerator, the engine hiccups. It will continue to do this everytime I ease of the pedal. Anyone have any ideas of where to start diagnosing?

Chris

 

[MontrealRR90]

i will change the fuel filter just in case but it was not doing this before the tune up?
and mine looses power when i press on the accelerator at full throttle.when i accelerate easely its no problem.I checked the vacum hoses this afternoon and no problem there.
could it be the stepper motor or the potentionmeter?

 

[tcns]

Check you air flow meter by connecting multimeter to pin 35 and ground on you ecu,
I think from memory it should show from 0.2V - 0.7V for normal outside of that it is broken.

Check the testing procedure as that is off the top of my head - it sounds to me like the
car is not metering the air flow properly


Tom

 

[MontrealRR90]

Tks Guys ! Taking It Ti The Dealer This Morning For A Diagnostic.i Don,t Have The Tools To Check Or The Knowlege Tks Anyway And Will Let You Know What The Hell It Was Tks Again.

 

[MontrealRR90]

dealer spent 7 hours on it and can't find it yet.He did re-do the distributor and timming which now gives it all kinds of power but it cuts out again when flooring it! Engine only has 30,000 miles from a 97RR.all data speaks of a bad rotor can cause misfirring.

 

[cptyarderho]

Mine does a similar thing, but I think it has to be a vacuum leak somewhere, or maybe oil off the valves getting by the crankcase vent. I will be checking on that this weekend.

 

[mmathews]

Throttle Sensor

My 89 RRC did the same thing and it was only when I gave it full throttle, it lost all power.
It ended up being the throttle position sensor.

 

[cptyarderho]

I replaced the crankcase vent tonight, mine runs much better now. $30 or so from Rovers North, mine looked almost solid and you can see through a new one...

 

[MontrealRR90]

tks marc!

 

[MontrealRR90]

dealer changed the coil and spark plugs because i had plugs from a 90 3.9 and the engine that i have is a RR 97 engine so it fixed the cutting out at full throttle but now it cuts out when the engine is hot! but not at full throttle go figure? check engine light has come back on so ill bring it back again on monday to see what it is this time $1,500 and still counting!

 

[MontrealRR90]

forgot also changed the throttle positionner or something!

 

[alia176]

Have them check the Alternator diode circuit. I know, it's in the far left field, but an aging laternator can really mess with your ECU...specially when it's hot and under heavy load.

As a quick test for this "hiccup", try removing the belt from the alternator and drive on the battery alone. Don't drive for more than a hour or two at best in order to preserve the batteryIf your "hiccup" doesn't return, then change the alternator or have it rebuilt.

Ali

 

[Joey]

Sorry I read this so late in the game, but this could be the VSS. When this goes bad it will tell the ECU that the vehicle is exceding the speed that the vehicle should travel and will shut down any acceleration.

Vehicle speed sensor

The vehicle speed sensor is located on the side of the Transfer box adjacent to the parking brake. The sensor provides road speed data to the ECM. The ECM in turn detects vehicle movement from the road speed input and ensures that idle air control mode is
disengaged. Should the vehicle speed sensor fail in service the ECM idle air control would become erratic. The sensor also provides road speed data to the
electric speedometer and cruise control ECU.

 

[MontrealRR90]

tks joey that is a good lead!!!