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Misfire under load, any amount of throttle

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Misfire under load, any amount of throttle

Postby raccoonjoe » Mon Oct 01, 2012 7:01 pm

91 CRX dx, 1.5l with manual. Idles well, with a slight erratic misfire that's hard to hear sometimes. While driving, the car misses hard, generally when under 3k rpm. Sometimes it's a single cylinder, sometimes its 2 or more. If I power through the miss, between 2500-3000 rpm, the car will suddenly start runnin great, like someone flipped a switch. Sometimes I can get it to not miss, but only by feathering the throttle *very* gently.

Replaced plugs/wires, cap/rotor, and fuel filter. Car holds 36 psi fuel pressure while running.

Any ideas?
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Re: Misfire under load, any amount of throttle

Postby daveb91 » Mon Oct 01, 2012 7:26 pm

Have you put a timing light on it?
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Re: Misfire under load, any amount of throttle

Postby raccoonjoe » Mon Oct 01, 2012 9:44 pm

Timing light will be borrowed on Wednesday, I'll officially adjust it then. As of right now, it's adjusted by ear....usually I'm not too far off.

A couple of bits of additional info: this car ran great for a long time, 45 mpg +. This issue popped up all of a sudden one day, out of the blue.

Also....fuel pressure at idle is 36psi. While I rev the throttle from under the hood, pressure jumps to 41 psi. The misfire still occurs under throttle with zero load, just not nearly as pronounced.
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Re: Misfire under load, any amount of throttle

Postby jpciii » Wed Oct 03, 2012 9:35 pm

sounds like spark

check the coil, plugs, wires, cap&rotor, etc
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Misfire under load, any amount of throttle

Postby TheLukeMartinez » Thu Oct 04, 2012 10:49 pm

CEL?
1989 Honda CRX Si B16A -Peppy DD-
1990 Honda Wagovan DX -Low N' Slow-
2000 Honda Odyssey EX -The Wife's-
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Re: Misfire under load, any amount of throttle

Postby archon » Mon Jan 16, 2017 1:02 pm

Did this issue ever get resolved? This is the closest thread I've found to the symptoms I'm having, doing some research before I attack it. Very similar:
- low throttle, runs OK
- over 20%ish throttle, misfires. Associated engine-speed vibration that goes away as RPMs increase.
- Worst under 2500 RPM and high throttle.
- Power loss, poor fuel economy.
- Seems smooth at >3000 RPM, but that might just be things rotating fast enough that it gets dampened out.

Other notes:
Just hit 295,000 miles. Car is recently new to me.

Anyway, did this issue get resolved? Anything in particular I should focus on first?

Thanks!
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Re: Misfire under load, any amount of throttle

Postby Myriad » Tue Jan 17, 2017 3:00 am

:closed:

Make a new thread, don't revive and old one.
I got a new shell, just need to stop driving the DX so I can work on it.

I've got a filter for my mouth, it just isn't a good one.
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Re: Misfire under load, any amount of throttle

Postby archon » Tue Jan 17, 2017 3:08 pm

Myriad wrote::closed:

Make a new thread, don't revive and old one.


This doesn't seem like best practice. In every automotive forum I've been a part of, people who had the same problem were strongly discouraged from making new threads for every issue. Instead, we search and add on to existing threads so that the knowledge about a certain problem is isolated in one place, and everything is searchable and easier to find. The RX8 forums will go as far as to delete a new thread and tell the poster to use the search function for a duplicate problem. Having used such fora, I've come to the conclusion that this is best practice.

Can any moderators chime in on how it's done here? As you can tell, I'm new. I have no aversion to thread necromancy; this is why we keep the old threads around in the first place.

Back on topic, I have plugs, wires, cap, rotor, upstream O2, valve cover gasket set (including tower and plug hole rings), air filter, fuel filter all on the way. We'll see what develops this weekend. No particular reason on the fuel filter. It was cheap, and I was paying for shipping anyway.

Lots and lots of threads exist where people's misfire issues evaporate after replacing ignition components. Example: http://www.d-series.org/forums/engine-management/170473-d15b7-misfire.html
O2s thread: http://crxcommunity.com/viewtopic.php?f=3&t=174673
Valve cover thread (also I have a leak, was going to do anyway): http://honda-tech.com/forums/honda-civic-del-sol-1992-2000-1/95-lx-w-d15b7-misfire-bogging-oil-spark-plug-wires-3188721/
If problem persists, will check EGR valve: http://www.clubintegra.com/board/showthread.php?t=61766

EDIT: forgot to note air filter. Shouldn't matter anyway.
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Re: Misfire under load, any amount of throttle

Postby Myriad » Wed Jan 18, 2017 12:22 am

For a thread ~5 years old without any closure of the issue, do you seriously think the OP will hop on and say "Oh, my bad, I forgot to post that this-and-that fixed my problem." He hasn't even logged on since the end of 2012.

You look up old threads to see how they solved the problems, not so you can play Jesus and raise it from its grave.
I got a new shell, just need to stop driving the DX so I can work on it.

I've got a filter for my mouth, it just isn't a good one.
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Re: Misfire under load, any amount of throttle

Postby mossin_90 » Fri Jan 20, 2017 4:44 pm

Before you buy parts left and right diagnose possible problems. What cell code (s) is the ecu flashing. Look at the red led on the glass sight over the ecu (if equiped) and by i.e I mean take the time to remove the carpet to find out.
If the ecu is not flashing any codes I would start by removing all fuel injectors and have cleaned up. Also have someone follow you while trying to get the car to miss. Does it smokes? If so what color. If no smoke is visible chances are it is running lean. Either dirty fuel system, vacuum leak somewhere or possible bad fuel pressure regulator. Assuming spark plugs, sp cables, dist. Cap and rotor, fuel filter, fuel pump strainer filter fuel injectors filters (if equiped). Are new. Even a bad electrical connector can cause those symptoms. Does the car smells like rotten eggs? If so it's a clogged up catalytic converter.
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Re: Misfire under load, any amount of throttle

Postby archon » Mon Feb 06, 2017 10:05 am

You are right of course, mossin_90. The intent had been to hit one system at a time, take a test drive, see what cleared it up. Thanks for the info on the ECU light, this is my first Honda and I didn't know about it. I had no dash idiot light, but that would be worth checking. However, the strangest thing happened.

I took the car in for state inspection, and had the shop change oil and filter while it was in the air anyway. According to PO the oil had some life left, but it looked pretty bad, so the plan was to run this oil for a couple hundred miles and change it again with the valve cover gasket job, clearing out the engine. Changing the oil and filter totally removed the misfire issue. I had been checking the oil level and maintaining it, but apparently the fresh oil either made it through a passage, or cleaned something away, or the old filter was clogged or some such. I had no expectation that this would fix things. I drove home from the shop trying to figure out what the heck had happened to fix the misfire. I used Rotella 10-30 diesel oil and a Wix wagovan filter.

I've driven it for several hundred miles just to verify that the problem wouldn't immediately return, and it hasn't. Misfire gone; check the state of your oil and filter I guess?

I'm going to install all the tune up parts etc. anyway, but this issue seems to have been oil related somehow. Fuel economy is clocking in in the low 30's, but I have a lead foot, and the engine has almost 296k on the clock.

If anyone knows what the heck could have been caused by poor oil/filter that created a misfire under load condition, I'd love to know what it was.
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Re: Misfire under load, any amount of throttle

Postby mossin_90 » Thu Feb 09, 2017 9:06 am

I really don't know how oil can make the car misfire but its all good now.
but from experience I know tha water inside the tank will cause a misfire under the slightest of load. I have 99 Teggy and when purchased the car sat for some time, it cough and missed pretty bad to the point that ck engine light came on showing a bad catalytic converter. I added B12 chemtool fuel cleaner and now it all cleared up except for the cel. at this point the CC its trashed but fuel efficiency it still at 30mpg.
add one to your tank before fill up. it will help clean up things up.

good day
'90 CRX DX_5sp
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Re: Misfire under load, any amount of throttle

Postby 4drSpankR » Thu Feb 09, 2017 11:04 am

Low oil can cause misfires due to the fact that there's not enough pressure to pump up the lifters, which is common in many GM cars. Oil that is too thin/old or saturated with fuel will lose its viscosity causing the cylinders to get washed down quickly not allowing the compression rings on the pistons to build compression.

Oil causing a misfire is little more of an extreme case, normal maintenance will obviously prevent this. Unless I know the seller personally or the oil looks brand new, I always change the oil ASAP on a newly acquired vehicle.
1991 HF - previously '90 B18A1 now '97 B18C1
1989 Si - running parts car/gone
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Re: Misfire under load, any amount of throttle

Postby Gr8_EE8 » Thu Feb 09, 2017 6:07 pm

... but have you checked your ignition timing? Sounds like a simple case of excessive advance. Knock knock. Sure, other things can cause it, like hot spots or deposits, vacuum leaks even, but none of that is worth discussing until you check your timing.
Keep it real. This is the only Honda forum worth my time. You make it happen.
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Re: Misfire under load, any amount of throttle

Postby Dave_Darling » Thu Feb 09, 2017 7:28 pm

4drSpankR wrote:Low oil can cause misfires due to the fact that there's not enough pressure to pump up the lifters...


I don't think our cars have hydraulic lifters.

Best guess is that there was something else wrong that the shop fixed along the way when they did the oil change and inspection. Possibly something as simple as the oil cap not sealing, or a ground wire being loose, or a connector not being plugged all the way in.

--DD
"Mango Bango", 1990 CRX Si -- Sold on 10/01/11, with over 227,000 miles.

VTEC is Honda's "select a cam profile on the fly" system; VTECH is a crappy phone.
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Re: Misfire under load, any amount of throttle

Postby 4drSpankR » Fri Feb 10, 2017 11:27 am

Dave_Darling wrote:
4drSpankR wrote:Low oil can cause misfires due to the fact that there's not enough pressure to pump up the lifters...


I don't think our cars have hydraulic lifters.



They don't, which is why I said it's common in many GM cars. The answer is more of a general one.
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