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D15Z6 - Civic EK3 stock, random power loss under acceleration
Good evening fellas,
New member here but I've been following your forums for a while.
Car in question:
Honda Civic EK3 1.5 iLS from 1997
D15Z6 (vtec-e of sorts) and it's EDM (so you americans don't come shouting that engine doesn't exist like I've read everywhere )
Completely stock
192.000km (around 120k miles) on the clock
So here's my Civic's problem:
About a month ago I had a problem with my main relay where it would randomly cut-off and I'd loose ECU and Fuel pump powa (not weather related as it would do this when hot and when cold, and no stored CEL code, the CEL would simply turn on when the ECU got power again like it normally does), when attempting to crank after this the main relay would just simply click repetitively so I had to wait a while before being able to crank again. After a few days I got a new OEM Main Relay (quite a price for two relays, three diodes and a resistor...) and the problem was gone.
A few hours after I got that fixed another problem showed up. Sometimes when accelerating (uphill, out of an intersection/roundabout, etc.) (I'd say between 20 to 60% throttle) I feel a huge power loss, the tachometer bounces up and down (within a 2k RPM interval from where it was standing before harder acceleration) and the car bogs, then jumps and then bogs again until it either stops rolling (momentum isn't enough sometimes) or gets going again. The work around is to let go of the throttle and apply throttle right after letting it go or combining this with a downshift, this usually stops the car from hesitating and gets it going again.
A couple of details:
This happens both with the engine cold (30 seconds after I get in it in the morning) or with it hot (after driving for 10-15 minutes).
It doesn't necessarily happen only under acceleration at low speeds, sometimes it happens while cruising at 100km/h (60 mph), I can feel a gradual loss of power (maintaining the same throttle) until I need to apply more throttle to compensate, this results in the symptoms I described above. I can usually prevent this by resetting the throttle before I even try to accelerate.
Spark plugs (NGK), fuel filter and oil change done in the last 8.000km (5k miles?)
Happens with fuel tank either "empty" or full (or half for all that matters)
Sometimes it's more violent if I keep insisting I need more throttle, the car will shake when the motor "jumps" (seems like there's a stroke or two of power when it jumps)
The TPS and MAP seem fine to me as I tested it when I had my main relay problem (TPS showing 0.5v idle and 4.5v WOT with smooth progression and I can't recall the MAP sensor values, but they seemed within spec)
There's no apparent problem beyond 4k RPM, it's a smooth sail till redline.
Unfortunately I can't just throw parts at it since buying Honda parts in Portugal requires me to buy them internationally, which takes time to arrive here and I don't have much spare cash as I just gave 150€ for a mother-fluffing relay.
Can you help me with this? Both distributor (possibly Coil/Igniter) and fuel pump/filter seem like a place to look, but I've only been driving for two years and had this Ek3 with me since April so I think a lot of you have way more experience with this than me!
Thanks in advance <3 and a virtual potato for the long post, figured a lot of details is better than none!
Last edited by LucasTheShep; 12-05-2016 at 12:38 PM.
Re: D15Z6 - Civic EK3 stock, random power loss under acceleration
After a few days I got a new OEM Main Relay (quite a price for two relays, three diodes and a resistor...) and the problem was gone.
What tests did you do to confirm that the main relay was indeed the problem on the first repair? How do you know you lost fuel pump power (and ECU) that first time around?
Re: D15Z6 - Civic EK3 stock, random power loss under acceleration
I ran the car just fine with the main relay from a friend's MB Aerodeck, drove with it for around half an hour no problems. Later swapped with my own main relay that I re-soldered and the symptoms appeared again (re-soldering didn't do the trick). Strangely enough the car didn't start the second time I swapped my friend's relay (was testing the old one on the road and it left me hanging, had to really quickly swap them) but only in the first try.
How do you know you lost fuel pump power (and ECU) that first time around?
When I lost power and heard the main relay click I'd also loose all instrumentation, I figured since one of the circuits supplies the ECU a signal to tell it the main relay is on, when it failed the ECU would think the car is off. Also, fuel pump would not come on when the relay failed.
Re: D15Z6 - Civic EK3 stock, random power loss under acceleration
If you have the speedometer and temperature gauge etc drop to zero, and the oil and battery lights don't come on like they should when the key is on but the engine is not turning, those doesn't have any connection to the ECU other than being supplied with power through the same switch and fuse.
Rather common for the ignition switch to have a bad contact where it will sometimes cut out and stall the car.
Re: D15Z6 - Civic EK3 stock, random power loss under acceleration
Originally Posted by mk378
If you have the speedometer and temperature gauge etc drop to zero, and the oil and battery lights don't come on like they should when the key is on but the engine is not turning, those doesn't have any connection to the ECU other than being supplied with power through the same switch and fuse.
Rather common for the ignition switch to have a bad contact where it will sometimes cut out and stall the car.
That does make sense and it didn't occur to me before, I am almost certain neither battery or oil light were on when the main relay would disengage (it could happen while driving or idling), tho since it would then start to click a few times per second the CEL would also blink with the same frequency as the ECU would be powered on/off.
With the new main relay it isn't as serious, only the tachometer bounces around when I loose power (and I wouldn't say all power completely, I still had like 10% power that would let me downshift without it dying) as I can more easily keep driving, still quite annoying and probably not good for the engine
The ignition sounds like something easy to rule out, how would I go about to test it?
Last edited by LucasTheShep; 12-05-2016 at 01:42 PM.
Reason: Question added
Re: D15Z6 - Civic EK3 stock, random power loss under acceleration
Strangely enough the car didn't start the second time I swapped my friend's relay (was testing the old one on the road and it left me hanging, had to really quickly swap them) but only in the first try.
Sometimes swapping a part temporarily suppresses a symptom. One reason is that jiggling and pulling wires during the procedure can either re-seat a flakey connector, or re-seal a frayed line. It looks like the part change did the trick, but the fix actually came from moving the wires.
The fsm for US 96-00 civics gives this test procedure for the main relay:
If you still have the old relay, it might be worth testing it. If it's good, then the relay clearly wasn't the original problem. I suspect it wasn't given that you re-installed your friend's relay and it didn't work that one time.
I'm not sure how this might be related to the symptoms you report after the relay swap, but it seems very unlikely that a completely unrelated problem (power loss) can start up within hours after repairing an unrelated system. So this could all be part of the same problem.
I would begin by testing the old relay if possible.
From there you'll need to choose a direction consistent with everything you're seeing. There are a few, I think, but they're hard to rule out without data. An easy one would be fuel pressure: is it up to spec and does it stay there under load?
Re: D15Z6 - Civic EK3 stock, random power loss under acceleration
I do still have my old relay and I tested it before swaping with a new one. It had continuity where it needed to have. I work with power relays in my field of work and we've had cases of random failures with them sometimes even out of the box.
Since power to the relay coils comes from the same place and the new relay never clicks when it's not supposed to, leads me to think the old relay was giving out and it would be a matter of time before it failed completely.
The auto stores here really suck, they don't have spare parts and they barely have any decent tools, I'd have to order a fuel pressure gauge to test that.
I was thinking about taking out my fuel pump to check its state and overall fuel tank health as well as checking the fuel filter for clog, I've been running a questionable quality gasoline in the car for some months.
Over the weekend I'm also gonna take out my distributor to take a look at its overall health as well as testing the coil (plugs' resistence are within spec as per the 1.6l service manual) -> Doing this because of the tachometer bouncing when the car bogs as the RPMs its showing me at the time don't match the motor's. I think this is as much as I can do with the limited tools I have (ratchets, multi-meter).
Will give it a shot this weekend, Was trying to take out me dist. yesterday at lunch but the damn rotor screw wasn't budging and I didn't wanna risk eating out the screw. What's the point in putting Philips screws on things that don't budge easily?
The only thing I could check was that the dist. cap contacts were a bit eroded and I just scraped them a bit. Some slight brown dust near where the cap meets the body of the distributor (it was not much if barely even noticeable) and a slight discoloration on the side of the coil (couldn't remove the dust cap to take a good look at it)
Not the first time I hear that, but the car has never stalled and when it jerks I can tell I still have just a little bit of power (which also keeps it from stalling if I decide to downshift), when idling I never feel anything out of the ordinary. None of the symptoms of a failing ign switch seem to apply here. That RPM bouncing around when the car jerks makes me believe it's really something in the distributor.
I'll hopefully have some answers this weekend when I get time to check a few things.
Re: D15Z6 - Civic EK3 stock, random power loss under acceleration
Good morning Honda fellas
Was going to test my coil and ICM this weekend, but the rotor screw is giving me a pain in the *** as I couldn't take it out with best fitting Philips screwdriver I had... so to take it off I'll probably brake the rotor in the process.
However my rotor seems like it has seen better days (pictures below) and my cap contacts too. The little I could see of the coil I noticed some discoloring on the side (photo) probably because of heat. So since I have to probably break the rotor off I went ahead and ordered a new rotor, cap and coil, even if these components aren't the problem they will most likely fail not so long down the road. (and also spark plugs b/c why not, spark wires are fine and within spec)
Rotor
Distributor cap Coil
I also re-tested my TPS but I got puzzling values.
Measuring the voltage between the signal wire and battery ground ( - ) I got 1.72 v @ idle and 5.7 v @ WOT which is waaaay above what it should be (smooth transition between idle and WOT).
But then I measured the voltage difference between the TPS ground wire and the battery ground and it's 1.6 volt, the actual voltage between the TPS + and TPS - is a constant 4.95 volt so I'm thinking the ECU is reading the correct values. Isn't the TPS ground supposed to match the chassis ground? Or is it just a separate circuit used by the ECU only? Because I've seen a lot of people testing their TPS's using the battery as reference and not the TPS ground it self...
And since we're on the Christmas cheer, here's a pine tree taking a ride in my trunk (click spoiler)
Re: D15Z6 - Civic EK3 stock, random power loss under acceleration
Hello guys, and a happy new year for all of you.
I'm almost sure I have fixed the problems I had right before 2016 closed.
One day the car got really out of hand (I had to drive with almost no accelerator action, cruising on idle at gears) so the following day I spend most of the night around the car.
I replaced the distributor cap, rotor (a huge pain in the *** to break that rotor screw, I just broke my rotor in half and dremmel'd a flat head screwdriver head deep af in the original screw to take it out), the coil and the sparkplugs.
I also noticed my ground resistance between the battery negative and the DLC connector negative (or any other ECU ground), it was reading a lil' over 11 Ohms so I went ahead and sanded all the ground connections including the famous G101 on the thermostat housing.
The problem was gone, runs perfect now but I'm left in doubt if it was one of the parts I replaced or just those pesky ground connections. I just corrected my timing (it was a few degrees retarded)
TL:DR - Check all your ground's connections you guys before replacing parts (or do it with your routine maintenence)
12-05-2016, 08:42 AM
D15Z6 - Civic EK3 stock, random power loss under acceleration
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Re: D15Z6 - Civic EK3 stock, random power loss under acceleration
