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low rev missfire mystery, help please

wizz87ep3

wizz87ep3

Messages
27
hi guys I'm new to the forum so go easy lol, basically I've got a misfire low in the rev range around 2-3k it only happens for a split second then clears. also with a light or heavy foot it doesn't happen but somewhere in-between it does :confused:, the top end was rebuilt last week after the cam chain snapped :mad: and everything was replaced using genuine Honda. new ngk laser iridium plugs were fitted but ive still got the misfire, theres no fault codes showing on the diagnostics and im abit baffled, 1 of the coils was slightly brown so have bought a replacement denso coilto bang in there when I get 5mins but im doubtful this is the issue. any help guys would be gratefully recieved . ep3 ctr
 
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Possibly throttle position sensor as I've got the same kind of symptoms on mine and was recommended it's probably the sensor so I've bought a new once to replace it and see if that sorts it. The thing with mine is it will play up for a while the. Work fine for weeks then come back again.
 
Yeah I have also read this can be the cause but mine does it basically all the time, I have picked up a tps so will get it fitted When I've found time. But hears what's weird, I chucked some injection cleaner in today ( more than suggested) and it seemed to solve the problem until I turned it off and then back on again. I've gota go on a long run tomoz so I'm **** give it a blast and see if that helps, starting to think it may be a injector issue
 
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I've also ran injector cleaner and octane booster in before and thought that helped untill a week later when it came back. I've also fully cleaned the rheottle body inside and out along with the idle control calve but the problem still comes and goes randomly. I'm fitting a new 70mm theottle body and the new sensor soon so will see if that solves the problem.
 
Well took it for a 100mile round trip and it was better after the car had bin running for a ** hour but the issue still remained. Let me no how you get on bud and vise versa
 
I've had the same problem for months. Mine has just started to cut out now. I investigated it today and it was the earth wire on the injectors that bolts to the inlet manifold. The 10mm bolt had come loose so I cleaned it and tightened it up and it's fine now. Also taken up the slack on the throttle cable.
 
I've had the same problem with mine for a few years now. Sometimes drives perfect but most days hesitates slightly around 2-3k. No codes and replaced all sorts. Very annoying and seems to be quite a common problem. If you search hesitation you'll find a few threads but no one ever seems to find a fix.

However! Recently noticed the car drives better immediately after filling with petrol and when removing the petrol cap get a large hiss of air escaping. Now anytime I remove the cap and restart the car it drives great until the next day when I start the car!
Sounds like you have the same issue.

So far I've replaced the fuel cap as thought if this was faulty it wouldn't be venting any excess air/pressure built up in the fuel tank. This made no difference though and I'm now thinking the cap vents air in rather than out?

Next things to try are:

- Fuel breather filter (fuel filter already changed),
- Fuel pressure regulator,
- Fuel pump,
- Carbon canister and two way valve

Hoping I'm finally close to sorting this! I'll keep you updated. Try removing the petrol cap next time it hesitates and see if it helps!
 
Cheers for the info guys I'll give all your suggestions a try and see how I get on! and if I do solve the issue by another means I'll obviously update the post
 
also check your tappets, i have seen it on a few k20s where the tappets that are on the exhaust side get tighter for reason and cause misfire that starts to get worse and eventually pits the exhaust valve seats
 
Can be an electrical issue with plugs, earths etc but all cars do it with a stock ecu. Some its more pronounced than others especially if modified and is accentuates the feeling.
I can get round it with a remap though if it really bothers you. Its something called "throttle tip in" to make the car smoother to drive at low speeds by pulling ignition when it detects a throttle input
 
Right I have some Info but won't know if it's the cause till I try it. Basically when I changed the sparks 1 of them along with the coil was slightly brown and I remember it smelling hot like it was burning, apparently this is due to that cylinder running lean and by running lean it will get hot, which explains the colour/smell. Now the reason this is happening ( so I'm told) is that the injector is failing (not failed) which is causing that cylinder to run lean and so on and so on. So apparently change the failing injector and it should solve the issue! I'm wondering Kirbymeister if this also could be your issue
 
L1r3a this is information I found out for you, bit long winded but may help.
The volume in your fuel tank needs to remain constant, so as you use fuel air will be pulled in to replace the volume of fuel being used ( for every 1 litre of fuel used 1 litre has to replace it.
If this doesn't happen you will get negative pressure in your tank, this means that your fuel pump will have to work harder to maintain fuel pressure at the injector rail, this will cause fuel starvation/misfire. When you remove the fuel cap that hissing is air being pulled into the tank not air escaping, this is happening to equalise the pressure in the tank. Air is drawn in by a non return valve which is fitted to the fuel cap or on some cars on a pipe from the fuel tank.
Was the fuel cap u brought genuine honda? If you've still got the old one drill a hole in it and put it back in the car to see if this solves the problem ( no more than a half tank:D). If it works then your non return valve isn't working. Hope this helps bud
 
Cheers for the info wizz :smt023. I'll do some experimenting and let you know how I get on. Keep us updated on the injectors.
 
No worries bud hope this helps! Will obviously update as and when I've done mine, but unfortunately after just having it rebuilt I don't have a wod of cash flying g around
 
Mine also does this aswell, only owned the car a little while and it's done it the whole time, it seems at certain cruising speeds your foot is hovering right in that rev range and if it's over a prolonged time it'll through a catalytic code and also a oxygen sensor on bank one code
I changed the oxygen sensor today and didn't fix it, will be good to see how it's fixed
I reckon it's tps sensor but after checking on a live data obd meter it holds voltage fine around 2-3k revs
 
I think my o2 sensor has also died as the fuel return has bin woeful, next month I'm changing o2 sensor, tps, injectors and putting a dc5 mani and cat on rather than the toyosports mani im currently running with. I'm hoping this solves it and will update once I've found out. Whatever the cause is its getting worse
 
Hi guys sorry for jumping in here, is your petrol cap not meant to make a hissing noise when you unscrew? I'm new to cars like this and just guessed it was some made Honda thing haha!
 
Wizz I have the same problem, Whether it's cold or warm does it no matter what. I have changed my plugs twice, new tegiwa TPS and calibrated to 0.45 closed and 4.5 open. I've also changed coils, both o2 sensors still doing it, On the 15th I'm ordering a CPL reflash ecu and thinking it might be my mods as it started doing it since I changed to a 2.5" cat back
 
I've been too busy with work to try and sought anything but I'm hoping to have next week off to rattle out a few bits. Has anyone tried replacing the wiring loom? A friend off mine had a similar issue with a vauxhall and it turned out to be that. Also I had no choice the otherday but to fill up with regular unleaded and it actually drove better?? Miffed
 
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