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Discussion Starter · #1 ·
hello, i come here to ask for advice in regards to a problem i've been having for the past 2 months.
d16y7, d15z6 intake manifold;
all of a sudden (like all car problems), car started sputtering/misfiring only between 2500-3000rpm while warmed up. car runs perfectly fine, pulls fine, mpgs are fine, up until i drive it for longer than 20-30 minutes, then it starts misfiring only betwen 2500-3000rpm, after which car wakes up. it also does it near limiter. car is fine cold (runs amazing), car is fine warm, but once i drive it for a while it starts doing it. i changed the whole distributor (broke cap bolts like a dumbass on my own one while trying to clean it), all spark plugs looked fine, wires are good (swapped because very expensive new for some reason);
i found a thread from 2005 with the exact same problem but the solution wasn't provided.
thanks in advance
 

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what ecu is being used, if it is not tuned?

If you want to see if it is ignition timing related, just undo the intake air temp sensor and dangle it near something hot. This will cause the ecu to pull back some timing. If it goes away, then it was actually spark knock and not misfiring.


If you have never done a fuel system cleaner, find a couple small bottles of injector cleaner, and run them at half tank of fuel. Most of them are so diluted they are nearly useless unless you throw 3-4 into the tank at once.
 

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A few other things to check is make sure none of your spark plugs have any cracks on the porcelain and check your cap and rotor
 

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Discussion Starter · #4 ·
what ecu is being used, if it is not tuned?
If you want to see if it is ignition timing related, just undo the intake air temp sensor and dangle it near something hot. This will cause the ecu to pull back some timing. If it goes away, then it was actually spark knock and not misfiring.
If you have never done a fuel system cleaner, find a couple small bottles of injector cleaner, and run them at half tank of fuel. Most of them are so diluted they are nearly useless unless you throw 3-4 into the tank at once.
its just the stock d16y7 ecu, i will do what you advised me and check to see if it goes away. im running pretty agressive ignition timing done by ear as i didn't have access to a timing light, but it's been running fine up until it started doing this. seems like something is getting hot and misbehaving. i'll try the injector cleaner as well, cheers for the advice.

i have a spare d14a4 ecu, but i doubt that it'll run fine on a d16y7, even though they're both non-vtec non-facelift ej ecus.

A few other things to check is make sure none of your spark plugs have any cracks on the porcelain and check your cap and rotor
i'll check the spark plugs once again, i changed the whole distributor with another complete unit so i doubt the dizzy would have the exact same issue. thanks for the advice

i've attached a video of what it sounds like, ignore the fake spoon steering wheel
 

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You advanced the distributor? This adjustment is meant mostly for casting changes in the head and tolerances of each distributor.

Crack the distributor bolts loose enough to rotate firmly by hand, fire up the engine, and let it warm up until the radiator fans turn on and off every 30 seconds or so. This may take 15-30 minutes, so a short drive can help speed this up.


When the car is back at a good idle, turn off radio, turn off blower fan if either are on, let the car settle. Now pull the distributor towards the radiator until it starts to crap out. Then rotate it towards the firewall until it is butter smooth.. Tighten the distributor bolts.

Check timing. Set the timing gun to 0, see if it is on the base timing marks or at least close. I think it is 12 or 14 degrees on the Y7 ecu. You being in a different region than me, this may be slightly different, as some european markets got much more ignition timing at factory ecu level.


During this time, it would be handy to check for proper exhaust flow out the tail pipe.

This is purely a by ear approach, and by no means, will this come with a 100% guarantee of working. But this should get you very close to an optimal, factory smooth setup.
 

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I did listen to the video, it does sound like ignition timing is the culprit, this is assuming spark plugs are firing okay, and fuel injectors are clean and working properly. An extension or long screwdriver touching your ear and the body of the injector, then comparing across all 4, will let you know if one or more is sounding out of whack.
 

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Discussion Starter · #7 ·
When the car is back at a good idle, turn off radio, turn off blower fan if either are on, let the car settle. Now pull the distributor towards the radiator until it starts to crap out. Then rotate it towards the firewall until it is butter smooth.. Tighten the distributor bolts.
Check timing. Set the timing gun to 0, see if it is on the base timing marks or at least close. I think it is 12 or 14 degrees on the Y7 ecu. You being in a different region than me, this may be slightly different, as some european markets got much more ignition timing at factory ecu level.
During this time, it would be handy to check for proper exhaust flow out the tail pipe.
that is pretty much how i've done it myself. initially did it because car was bog slow and has pretty high fuel consumption, ran well for some time then started doing this. changed the whole dizzy then warmed up the car and adjusted it by ear again, and the smoothest was pretty advanced towards the firewall. i'll try to get a hold of a timing gun and do it properly, belts are due to be changed anyway so might just do the whole thing. i did the paper test on the exhaust and it seemed to blow out fine, it didnt pull the paper towards the exhaust in any way. i have a spare set of spark plugs as well, i'll change over to those, and luckily i have a spare set of 190cc injectors as well left over from when i switched to the ek3 intake. if anything seems weird with the injectors i'll be able to change those. thank you for the swift response, tommorow i'll tinker with it and see if theres any improvements :)
also a note: car seems to have a SLIGHT loss of power at low rpms when its warm as well, but doesnt start misfiring until i've ran the car through its paces. have a good one :D
 

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advance is towards teh radiator, retarding the timing is towards the firewall.

EDIT whoops, got that backwards. Dammit.

 

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Discussion Starter · #9 ·
advance is towards teh radiator, retarding the timing is towards the firewall.
got another set of oem wires, it seems to have fixed it weirdly, the other set wasn't oem so that must've been it. i drove it for a while and problem seems to be gone, cheers for the help, have a good one!
 

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Discussion Starter · #10 ·
well, problem is not fixed.
misfire came back, except now it does it when it's cold as well, runs on 3 cylinders, pretty bad, but it goes away after 2000-2500 rpm, while still running about rough. changed spark plugs again, no help. im pretty much done on ignition, whole dizzy was changed, the plugs were changed, the spark plugs were changed, any advice on where to go forward from here on out?
 

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Is everything new? Spark plugs, wires, distributor cap and rotor? I know you changed the distributor, but some dont come with new cap or rotor, and if they do they can be cheap/poor quality. If it didnt come with new cap and rotor, you might be transferring problem parts between fixes.

If it got fixed temporarily by installing another set of wires, I'd bet on secondary ignition components being old or worn.

What kind of plugs did you reinstall? Brand? Part number?

Take detailed well lit pictures of all your ignition components, and post them here. Include pictures of the cap and rotor itself, as well as both sides of the wire boots.

Maybe we'll get lucky and can spot an issue, or even see carbon tracking.
 

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Discussion Starter · #12 ·
Is everything new? Spark plugs, wires, distributor cap and rotor? I know you changed the distributor, but some dont come with new cap or rotor, and if they do they can be cheap/poor quality. If it didnt come with new cap and rotor, you might be transferring problem parts between fixes.

If it got fixed temporarily by installing another set of wires, I'd bet on secondary ignition components being old or worn.

What kind of plugs did you reinstall? Brand? Part number?

Take detailed well lit pictures of all your ignition components, and post them here. Include pictures of the cap and rotor itself, as well as both sides of the wire boots.

Maybe we'll get lucky and can spot an issue, or even see carbon tracking.
thank you for the response, i might have found the issue. made the last post after the night shift quite angrily, now i woke up and started poking around some more, messed with some wires i extended from the map sensor when i did the intake manifold conversion. i attached a video. will rectify the wire work and hopefully this will fix the issue.

just as info: plugs i had in the car were ngk ZFR6J-11, i switched them to ngk ZFR5J-11, i've now put the former back in because it ran better. plugs came from running driving car. if the map sensor issue doesnt fix it i will purchase a new cap and rotor as well.

 

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Discussion Starter · #13 ·
thank you for the response, i might have found the issue. made the last post after the night shift quite angrily, now i woke up and started poking around some more, messed with some wires i extended from the map sensor when i did the intake manifold conversion. i attached a video. will rectify the wire work and hopefully this will fix the issue.

just as info: plugs i had in the car were ngk ZFR6J-11, i switched them to ngk ZFR5J-11, i've now put the former back in because it ran better. plugs came from running driving car. if the map sensor issue doesnt fix it i will purchase a new cap and rotor as well.
welp, this wasnt it either. disconnected the IAT as well, problem persisted, altough when disconnected there was no check engine light which was strange. still waiting for suggestions on what parts to throw at it
 
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