Frankenstein is back ! - an update

[The Poond]

It's The Poond here, reporting on progress with sorting Frankenstein !

Original symptoms - stalling when cold and mostly while out of gear, hesitation, slight misfire, CEL on.

Action taken - removed throttle boddy and cleaned it and cleaned the IAC valve. Also ran a can of BG 44K engine cleaner through about 48 litres of Petrol.

Current observations - stalling issue is virtually gone, needs much less warm up. Hesitation is gone but is now slightly apparent when on the LPG, on the petrol it is fine. Misfire is still there. CEL is now off.

Planned action - replace spark plugs with NGK (as manual spec). Get LPG specific service carried out (is due anyway).

Questions - When I cleaned the IAC valve I did not remove the black plastic part of it and just sprayed and cleaned the main body of it. The black bit has "8 point star" headed screws which I was not sure whether I should remove. I realise that the actual rotary solenoid is inside this though I did not think this would be subject to carbon build up.
Should I take this off and clean ?? Also if the new sparks do not cure any misfire what would the next diagnostic test be ?

I loosened the bolt through her neck too !

[Honda Tech]

If the Malfunction Indicator Lamp is "OFF" (assuming that the bulb has not burnt out) then there is not a detectable misfire based upon variations in crankshaft speed. What you are feeling may be vibration, or an intermittant misfire that is not present for enough consecutive crankshaft revolutions to fail the misfire monitor.

If you had a 'hard' misfire DTC for a specific cylinder, determining the cause often involves seeing if you can "move" the misfire to another cylinder by shifting coils, then spark plugs, then injectors (obviously this method requires you to have access to a code scanner so you can clear and read codes when they reset). If you cannot move the misfire, then at that point it would be an internal cylinder / valve problem.

The IAC valve has coolant passages in it, and a gasket. If you unbolt the IAC from the throttle body, the gasket would need to be replaced - it might re-seal, but then again it might not. IAC valves do get dirty internally, and can also 'gall' which can make the rotary vane stick - usually end up with an Idle Control System Fault DTC though.

BG also makes an Air Intake System cleaner that would clean the throttle plate, IAC passages, intake manifold and intake valves of deposits - but this chemical is designed to be dispensed using a pressurized atomizer to drive the chemical mixture through a fine spray nozzle at the throttle body inlet. The fact that the BG 44K seems to have had an impact suggests that you may be on the right track with needing injector / intake valve cleaning.

Good luck

JD

[The Poond]

Thanks for the explanation. I'm thinking it may not be a misfire considering the CEL is not on. What I'm experiencing is a rhythmical lurching when you have it in gear and you let it creep on the brake. The power and acceleration seem smooth enough. I can also feel the rhythmical stutttering of the engine if I put my hand on the top of the engine block. It does not sound like an obvioulsy 3 out of 4 firing which is very obvious.

I thought/hoped that it might have simply been a bad spark plug that is delivering a poor or inconsistant spark.

If I get what you say right without a code and a reader it would not matter if I swap the HT leads between the 4 cylinders as I would not know which one was faulty. However if I disconnect one lead in turn this would cause a misfire fault on the CEL. If I take off each cylinder HT lead in turn (always having 3 obviously) I should be able to hear a change in engine sound. ie the best running sound is the 3 best firing cylinders and hence theone in my hand is the duff one. Am I wrong and about to kill my car ??

[Honda Tech]

If you have a dead cylinder, unplugging the ignition coil or the fuel injector for that cylinder would not cause any change in how the engine was running, while killing a good contributing cylinder would cause a noticable change.

Totally dead cylinders are easy to isolate. Weak cylinders can be a bit trickier, and that's where a scan tool or a code reader would be handy. Misfire DTCs won't set as soon as you kill a cylinder - the PCM has to average the variance in crankshaft speed over a period of time before it'll code.

Killing cylinders for diagnosis won't hurt anything - as long as you don't do it for too long and load the catalytic convertor. A few seconds per cylinder, and then purge the cat for 30 seconds at 2000 rpm between tests should be fine.

If you want to try a set of plugs, by all means, have at it. I don't want to start running you around chasing your tail. You're on scene, I'm not. Keep it simple, and do what's easiest and makes the most sense to you.

Good luck

JD

[The Poond]

Firstly, thanks for the advice.

See whole thread for previous problems. I rushed my V to a delearship to get the valve clearances checked and reset. ALL valves had NO clearance so are now set to specification. A number of trouble codes were recorded re misfire in all 4 cylinders, something to do with a purge cannister and also the IAT. I don't have the actual codes but will get the paperwork and get back to you.

It looks like setting the valve clearance has rid me of the symptoms I had and hopefully has avoided any burnt valve problems. This said I have only driven about 10 miles since getting it back so we'll see.

From many threads I have read it seems that getting the valves checked is well worth it even if just for peace of mind. My dealers said it should be done every 25K miles (UK model), Frankenstein had done 35K !. I will definately be getting them done again at 55K to 60K miles especially as I'm on LPG.

By the way I was given the same advice again - don't convert ANY Honda to LPG. I love mine but it will always be a risk.

Thanks all, The Poond