Extended cranking time cold start
Discussion
Hi
any thoughts or suggestions on this.
Standard late 94 Griffith 500, cold start cranking time has gone from 1-2 seconds to at least 5-6 over the last few weeks and seems to be getting worse.
I've done the usual checks, no ECU codes, checked for vac leaks with carb cleaner and blocking of various hoses to the plenum, non found. Checked fuel pressure, 40 psi key on and when cranking all good, keyed on off fuel pump a few times before starting no change. Checked ECU coolant temp on ECUmate all good same readings as ambient and fuel temp sender. Battery fully charged and good cranking speed. What did make a difference was carb cleaner into plenum chamber, fired up almost instantly. So seem to have a lean mixture on cold start up, thinking a fuel enrichment thing going on not an air leak. I assume spark is fine as hot starting and starting with carb cleaner is no issue but have not actually checked spark condition.
Any one had a similar experience? maybe fuel injectors past their best?
Any help appreciated.
Ozstyle
any thoughts or suggestions on this.
Standard late 94 Griffith 500, cold start cranking time has gone from 1-2 seconds to at least 5-6 over the last few weeks and seems to be getting worse.
I've done the usual checks, no ECU codes, checked for vac leaks with carb cleaner and blocking of various hoses to the plenum, non found. Checked fuel pressure, 40 psi key on and when cranking all good, keyed on off fuel pump a few times before starting no change. Checked ECU coolant temp on ECUmate all good same readings as ambient and fuel temp sender. Battery fully charged and good cranking speed. What did make a difference was carb cleaner into plenum chamber, fired up almost instantly. So seem to have a lean mixture on cold start up, thinking a fuel enrichment thing going on not an air leak. I assume spark is fine as hot starting and starting with carb cleaner is no issue but have not actually checked spark condition.
Any one had a similar experience? maybe fuel injectors past their best?
Any help appreciated.
Ozstyle
All,
Haynes/Rover manual states fuel regulator controls fuel pressure at 2.4 - 2.6 bar (about 36 psi) above manifold pressure, so happy with fuel pressure readings. Pump primes and gives 40 psi instantly, when priming stops it drops to 38 psi. 40 psi indicated when cranking and settles at 32 psi when engine idling. Fuel pressure holds when pump turned off, takes several hours to drop to about 20 psi.
Had the car 13 years and never had this issue, serviced my self, spark plugs and leads 6 months ago. The rotor arm, cap, coil, ignition module replaced over recent years with genuine lucas/bosch items.
As I'm in Australia extreme cold weather is not something I have to contend with, a coldest start for me is about 5C, this site has always been a valuable source of info and help when needed.
I only have an ECUmate not a Rovergauge so can't check injector pulse. Will look into a noid light.
thanks
Haynes/Rover manual states fuel regulator controls fuel pressure at 2.4 - 2.6 bar (about 36 psi) above manifold pressure, so happy with fuel pressure readings. Pump primes and gives 40 psi instantly, when priming stops it drops to 38 psi. 40 psi indicated when cranking and settles at 32 psi when engine idling. Fuel pressure holds when pump turned off, takes several hours to drop to about 20 psi.
Had the car 13 years and never had this issue, serviced my self, spark plugs and leads 6 months ago. The rotor arm, cap, coil, ignition module replaced over recent years with genuine lucas/bosch items.
As I'm in Australia extreme cold weather is not something I have to contend with, a coldest start for me is about 5C, this site has always been a valuable source of info and help when needed.
I only have an ECUmate not a Rovergauge so can't check injector pulse. Will look into a noid light.
thanks
Plugged in a noid light and all good, light pulses when engine cranking.
Sprayed a touch of carb cleaner into plenum just to double check and it fired straight away from cold, died after a second or so, started again and it fired up and ran.
At the moment still thinking dirty fuel injectors, I have a spare Rover ECU so may try that to see if there is any difference.
Sprayed a touch of carb cleaner into plenum just to double check and it fired straight away from cold, died after a second or so, started again and it fired up and ran.
At the moment still thinking dirty fuel injectors, I have a spare Rover ECU so may try that to see if there is any difference.
its got me perplexed,
everything points to a lean mixture on cold start,
if it's not poor fuel atomisation, its either insufficient fuel delivery or an air leak,
so back to basics, check again for air leaks into plenum/inlet manifold, coolant temp sensor output and check spark condition on cranking, (already checked fuel pressure 3 times).
any thing else?
everything points to a lean mixture on cold start,
if it's not poor fuel atomisation, its either insufficient fuel delivery or an air leak,
so back to basics, check again for air leaks into plenum/inlet manifold, coolant temp sensor output and check spark condition on cranking, (already checked fuel pressure 3 times).
any thing else?
well checked for air leak again, hot engine at idle and stepper motor connector removed, sprayed starter fluid all over plenum connections, afm to plenum air hose connections, stepper housing, vac hose connections, throttle housing/spindle, throttle heater plate, plenum/air stack joint, air stack/manifold joint, fuel injector seals, manifold inlet valley; absolutely nothing, no air leaks detected.
Checked for spark on cranking, it's there, steady white spark on tester from those ignition leads tested.
Tester indicated steady spark, at about 25kv from at king lead from coil, about 20kv at ignition leads from distributor cap.
No recent work done on the engine that could have influenced fuel enrichment.
Dizzy cap, rotor arm, module all genuine items and only 5000+ km or so on them, ignition leads new last year.
No air leaks, got spark, got injector pulse, and fires straight up with a little squirt of starter fluid in the plenum.
? fuel flow
Checked for spark on cranking, it's there, steady white spark on tester from those ignition leads tested.
Tester indicated steady spark, at about 25kv from at king lead from coil, about 20kv at ignition leads from distributor cap.
No recent work done on the engine that could have influenced fuel enrichment.
Dizzy cap, rotor arm, module all genuine items and only 5000+ km or so on them, ignition leads new last year.
No air leaks, got spark, got injector pulse, and fires straight up with a little squirt of starter fluid in the plenum.
? fuel flow
All ready used fuel pressure gauge on the fuel rail, getting 40 psi when cranking.
Sure about KV Blitz being too high ?, general comments on internet indicate figures are ok.
Regardless, for this issue, indicates good HT pulse delivered to spark plugs when cranking, so lack of spark not an issue.
As for ECU coolant temp sensor, checked when cold using ECUmate, all good, giving same temp as ambient air temp and same as the fuel temp sensor reading. I checked wiring colours to both sensors and match that of rover wiring diagram.
As said in prior message, fuel pressure holds in line for several hours; so no fuel leaks in line or connections that could be drawing air into system, checked fuel line connections and fuel pump for any leaks also, non found.
I'll check base idle, clean stepper, pull a few spark plugs (fairly new) for further checks. (Still need to check with spare ECU)
Sure about KV Blitz being too high ?, general comments on internet indicate figures are ok.
Regardless, for this issue, indicates good HT pulse delivered to spark plugs when cranking, so lack of spark not an issue.
As for ECU coolant temp sensor, checked when cold using ECUmate, all good, giving same temp as ambient air temp and same as the fuel temp sensor reading. I checked wiring colours to both sensors and match that of rover wiring diagram.
As said in prior message, fuel pressure holds in line for several hours; so no fuel leaks in line or connections that could be drawing air into system, checked fuel line connections and fuel pump for any leaks also, non found.
I'll check base idle, clean stepper, pull a few spark plugs (fairly new) for further checks. (Still need to check with spare ECU)
So checked spark plugs, all good, gap right, no heavy deposits on electrodes, colour fine as expected.
Cleaned stepper motor and housing, but as expected clean anyway.
Checked base idle, little high, adjusted down.
Absolutely no change still extended cranking when fired from cold.
I have not checked compression in recent times, but as it fires with just 1 squirt of starter fluid at present I'm ruling this out.
Car runs absolutely spot on, no stalling, no hesitation or misfire at any speed, accelerating or decelerating, idles fine.
I still have not tried my spare ECU will try this weekend.
I'll also check ohms across each injector bank at ECU plug
Cleaned stepper motor and housing, but as expected clean anyway.
Checked base idle, little high, adjusted down.
Absolutely no change still extended cranking when fired from cold.
I have not checked compression in recent times, but as it fires with just 1 squirt of starter fluid at present I'm ruling this out.
Car runs absolutely spot on, no stalling, no hesitation or misfire at any speed, accelerating or decelerating, idles fine.
I still have not tried my spare ECU will try this weekend.
I'll also check ohms across each injector bank at ECU plug
so,
changed the ECU coolant temp sensor for my spare good one,
reset ECU by disconnecting battery for 5 minutes,
checked ignition timing, bumped up a degree as touch retarded.
gave the battery, which is good, a full trickle charge for 5 hours
engine spins over like a top, but no change still extended cranking time from cold, 6+ seconds before it splutters into life
one thing I have noticed if I turn over for a couple of seconds, stop wait a couple of seconds and turn over again, straight away it splutters into life, just thinking this may be giving time for any fuel droplets in the system to vaporise
still not tried my spare ECU yet
changed the ECU coolant temp sensor for my spare good one,
reset ECU by disconnecting battery for 5 minutes,
checked ignition timing, bumped up a degree as touch retarded.
gave the battery, which is good, a full trickle charge for 5 hours
engine spins over like a top, but no change still extended cranking time from cold, 6+ seconds before it splutters into life
one thing I have noticed if I turn over for a couple of seconds, stop wait a couple of seconds and turn over again, straight away it splutters into life, just thinking this may be giving time for any fuel droplets in the system to vaporise
still not tried my spare ECU yet
just to close this thread off,
the extended cranking has resolved itself,
no idea what the issues was, all that I did since the problem occurred was add a bottle of fuel injector cleaner, a couple of long runs (2+ hours) and a few tanks of fuel . Assumed I just had some crap fuel causing the issue, but who knows. Cranking time back to about 2 seconds before it fires.
the extended cranking has resolved itself,
no idea what the issues was, all that I did since the problem occurred was add a bottle of fuel injector cleaner, a couple of long runs (2+ hours) and a few tanks of fuel . Assumed I just had some crap fuel causing the issue, but who knows. Cranking time back to about 2 seconds before it fires.
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