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Poorly running VFR800 looking for some advice


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Hi all!

 

Hope all is well. I have a longer term issue with my 2001 VFR800, and wondered if I could stir some inspiration or advice on here. 

 

Bike has done 61,000 miles. 

 

It runs very poorly, and seems like 3 and a half cylinders. I did some investigation, and pulled all the plugs and realised that number 2 cylinder is not firing, or firing poorly (luke warm header). 

 

I have checked the following:

 

  1. Spark (checked with tester and moved coils about). Its strong and consistent. New plugs all around as well
  2. Checked compression (110 psi on all cylinders with a cold engine)
  3. checked fuel supply and that there are not any hoses etc disconnected, all present.
  4. Tested fuel pressure regulator and it holds a vacuum and does not leak into the inlet. 
  5. Replaced the fuel injector on no 2 cylinder (Thinking this was it tbh!) with no change at all. 

 

The crankcase is getting filled with petrol that is coming from the non firing cylinder, and it smokes white out of the exhaust. 

 

If you hold it at 3-4000rpm it coughs and sputters like the cylinder is coming on and off but that's it. 

 

I have resigned myself to thinking its a burnt or leaking exhaust valve on number 2, and I have not carried out a leak down test. I have also not tested the injector output from the ECU but unlplugged the injector does put the FI light on with that code. No other codes are present. 

 

Any ideas? I have spent so much time on it and its getting to the point of being broken for spares.

 

Much appreciated. 

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Not likely burnt/leaky ex valve, compression would show it. Has it always run like this or? Maybe a wiring issue between Ecu thingy & injector? Seems you’ve covered other possibilities, maybe big air leak downstream of injector(“insulator”)sleeve to cyl head..

 

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Maybe worth having ALL injectors professionally cleaned, checked and flow balanced. Fuel in oil and white smoke can be caused by an injector not closing off properly.

 

Assume you have good fresh fuel and no condensation issues?

 

Also make sure ALL vacuum hoses are good, no cracks kinks or leaks.

 

Good Luck.

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hey good job troubleshooting!

 

Seems you've narrowed it down to a few possible culprits:

 

1. power to injector #2. Key ON, measure voltage going to each injector.

 

2. trigger signal going to injector #2. Use 'noid light to verify each injector is being fired by ECU

 

3. ECU may be suspect if it's not firing only #2 injector. Test trigger signal at ECU itself. If present at ECU connector but not injector connextor, then wiring in between is suspect.

 

4. I still suspect spark issue. Test with actual plugs. Insert plug into wire and ground case to engine and crank. What colour is spark?  Do test for ALL cylinders

 

5. do compression-test with warmed up engine.

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Thanks all. 

 

tested all coils with the plug grounded to the block, and get a hot blue spark on the tip of the plug. 

 

I will test the injector signal at the injector and the ECU and report back. 

 

I have not done a compression test on the warmed up engine as I don't want to run it with fuel vapours coming out of the exhaust. 

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15 hours ago, Grum said:

Maybe worth having ALL injectors professionally cleaned, checked and flow balanced. Fuel in oil and white smoke can be caused by an injector not closing off properly.

 

Assume you have good fresh fuel and no condensation issues?

 

Also make sure ALL vacuum hoses are good, no cracks kinks or leaks.

 

Good Luck.

Thanks, all fuel has been replaced. I have another set of injectors but only replaced 1x on the cylinder having issues. If I get that cylinder running properly then I will do the others 🙂

 

All the vac lines are ok without any kinks or leaks, tested with a smoke tester. 

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17 hours ago, airwalk said:

Not likely burnt/leaky ex valve, compression would show it. Has it always run like this or? Maybe a wiring issue between Ecu thingy & injector? Seems you’ve covered other possibilities, maybe big air leak downstream of injector(“insulator”)sleeve to cyl head..

 

I put it away 2 years ago as it was doing this intermittently, but it now does it permanently. 

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could be clogged fuel line going to #2? That would collect more dried petrol over time.

 

Easier on autos, I pull fuel-rail with injectors attached. Place little cups under each injector and crank for 10-15 sec. Measure and ensure volume flowed is identical.

 

 

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Disassemble the spark cap with a screw driver and note any corrosion
at the resistor and spring... unscrew the cap from the plug wire and look for broken wires...

full-45634-36698-sparkplugcapdetails.jpg
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Check your subharness connection that goes from the main harness to the throttle body harness. I had severe corrosion in my connector that led to somewhat similar symptoms. Cleaned the throttle body sub harness connector out with a bunch of contact cleaner and it immediately fixed my problems. Easy to check!

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15 minutes ago, Madfox said:

This is what mine looked like before cleaning.

20200306_102535.jpg

20200306_102529.jpg

Hi Madfox. Just curious, did you note the wire color code for that oxidized pin?

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6 hours ago, Madfox said:

Check your subharness connection that goes from the main harness to the throttle body harness. I had severe corrosion in my connector that led to somewhat similar symptoms. Cleaned the throttle body sub harness connector out with a bunch of contact cleaner and it immediately fixed my problems. Easy to check!

Thank you, good shout, I will give it a go

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11 hours ago, DannoXYZ said:

could be clogged fuel line going to #2? That would collect more dried petrol over time.

 

Easier on autos, I pull fuel-rail with injectors attached. Place little cups under each injector and crank for 10-15 sec. Measure and ensure volume flowed is identical.

 

 

All the injectors are bolted into the rail, and judging by the amount of fuel that came out of the rail port, it seemed pretty unblocked 🙂

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9 hours ago, alexanderfitu said:

All the injectors are bolted into the rail, and judging by the amount of fuel that came out of the rail port, it seemed pretty unblocked 🙂

I suspect this is similar to "fuse looks ok". ;)

 

If you've got good spark and sufficient petrol, why's it not burning in #2 ??? Odd...

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Just now, DannoXYZ said:

If you've got good spark and sufficient petrol, why's it not burning in #2 ??? Odd...

My thought as well. I went down the burned valve route as a partially sealing exhaust valve would show a good compression test on a 5 revolutions on the starter, but not provide enough in 1 for good firing. I have not done a leakdown yet. 

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Burned valve would not reduce combustion though. Just lower power as it leaked, but that cylinder would still be as hot as others.

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2 minutes ago, alexanderfitu said:

It would if it was leaking compression. 

But it's not as you've measured.

There's something we haven't measured yet that would make #2 stand out...

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Looks like only thing you haven't swapped is spark-plug wires?
Maybe switch 2 & 4 ?

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I did a CoP swap on another bike & it worked great for about 5 miles, then lost power & stopped.  Strangely diagnosing the fault, showed good spark, fuel & compression. In frustration I swapped back to the original coils & the fault went away. 
 

The reason I tell this story is to show what appears to be correct may not be. So on the basis that everything else appears normal, I'd be inclined to follow the ignition system/ecu. If all parts tested OK by swapping then the fault must lie in the control signal system. 
 

Intermittent firing stinks of poor electrical connectivity. Check all cables related to cylinder 2 & if they test good then beg borrow or steal an ecu to swap with yours. 
 

The only other thing that may cause no ignition would be a very poor AFR,  possible with a bad air leak. 
 

My money is on faulty cable. I'd also check the earth multiblock in the harness under left side if tail fairing near the reg/rectifier. Mine looked great when I unwrapped it, but when I cut it open half the earth cables were badly corroded. I cut them all out, unsheathed the ends, splayed & cleaned all strands, then intertwined all earths & soldered them together. The strange electrical issues I had experienced went away 😀

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are there issues with aftermarket/countrefeit coils like with autos?

 

Seems unless you buy genuine OEM Denso coil for Toyota from Toyota dealership, you're bound to have ignition issues. Most coils from auto-parts stores are crap right out of box!

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On 5/9/2021 at 5:18 PM, Grum said:

Hi Madfox. Just curious, did you note the wire color code for that oxidized pin?

Had to double check, it was the Black and white wire. So the grounding wire for the injectors and pair valve solenoid. It would do weird things similar to the 3 or 3.5 cylinder power description before eventually getting bad enough that it went into limp mode and threw FI codes at me. All problems disappeared when I cleaned it out 

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