Civic VX miss under load - Page 2 - Fuelly Forums
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Old 05-11-2007, 08:35 PM   #11
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sounds simaler to what I had when I had a faulty o2 sensor, lucky for me the parts store that I got it from remembered me, so I didn't even need my recepte to get a new one, after that it ran perfectly.

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Old 05-13-2007, 12:56 PM   #12
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> Does that thing have an EGR valve?

It does. I pulled the vacuum hose off the EGR and plugged it to see if that made any difference. It didn't. I suppose that's not 100% definitive, though, as it's possible that the valve itself is leaking.

> sounds simaler to what I had when I had a faulty o2 sensor ...

I bought this O2S 6 weeks ago through Ebay, so I'd have to deal with a vendor in (IIRC) Detroit.

I hate to claim it's defective without any proof. Problem is, the only really good way I know of to test it is to substitute a known-good one. There's a test that involves voltages. I tried that on the old one and it passed even though it was junk. The voltage test is go/no go, but it won't identify an oxygen sensor that's out of calibration.

> The fuel injector timing is controlled by the ECM based on the 20 inputs
> it receives from the various sensors ... it is possible that the ECM is
> trying to control fuel injection and ignition with bogus inputs. If so
> you will have to troubleshoot them one by one.

Twenty of them! I had no idea.

This raises the same problem as above - the only way I know of to troubleshoot all those sensors this is to replace each sensor (and control) until the engine runs right. That could get pretty darn expensive. Too bad I don't have a spare VX for parts-swapping.

I just remembered something that makes me suspicious. I recall now that the problems with the poor running 6 weeks ago seemed to get worse right after the ICM and coil were replaced. Before, she'd run lousy at steady speeds and smoothed out when I accelerated. After the new ICM and coil, she missed ALL the time, including under acceleration.

Still, she ran well for a few weeks after I put in the new O2S. Puzzling.

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Old 05-13-2007, 01:54 PM   #13
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It could be that it ran fine with the new O2 sensor until it got "fouled" with something in the exhaust gas that isn't supposed to be there. That's the most likely reason. Do you have the Helm manual in pdf form? You can download it if you search for 92 honda civic helm pdf. I don't remember the exact hit but it works. You don't get a table of contents with chapters separated into tabs though. Makes it hard to find stuff. Anyway, if you get the Helm manual it will guide you through the troubleshooting procedures without replacing sensors unnecessarily. Some procedures require a test jumper to test the input output circuits of the ECM. I don't know what this costs or where to get it. It is listed in the parts section of the fuel chapter. Your comment about the distributor work raises one remote possibility. The TDC/Crank/Cyl sensor may have been damaged or just isn't working right which could cause the problem. The CRANK sensor determines timing for fuel injection and ignition of each cylinder and also detects engine RPM. The TDC sensor determines ignition timing at start-up (cranking) and when crank angle is abnormal. The CYL sensor detects the position of No. 1 cylinder for sequential fuel injection to each cylinder. You will need to locate another TD-42U distributor to find out if this sensor is bad since cannot be replaced except with a rebuilt dizzy or new one. I have heard this sensor has caused problems in other VTEC civics. Keep trying and we'll keep helping. It sucks when the car you enjoy driving is sick.
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Old 05-13-2007, 02:11 PM   #14
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Thanks for the ideas. I have the Helms on pdf, but its troubleshooting seems to only deal with problems that set CEL codes. That's never yet happened! On board diagnostics don't seem to be of much help here.

I see dozens of allegedly new and rebuilt TD-42U distributors for sale on Ebay, prices from $100 to $200. Some of them are no doubt cheap junk. Probably some are fine, and with unknown correlation between price and quality.

However, it really annoys me to think about just throwing new parts at this until something works. Not so much that it's expensive (which it is), but that there just HAS to be a better way.

One thing I have to somehow double-check is - this sounds stupid - basic timing. The crank pulley on this old girl is so rusty that I can't find the TDC and advance notches. I timed her by finding TDC with a dowel in cylinder #1, then using a piece of cardboard cut into a 16 degree angle with a protractor. Still can't find any of those notches. Can anybody think of a better (more accurate) way?
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Old 05-14-2007, 04:31 PM   #15
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Originally Posted by thisisntjared View Post
50/50 shot its the fuel filter or dirty plugs.
don't waste your time or time will waste you
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Old 05-15-2007, 08:48 AM   #16
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OH95vx: I would suggest a couple of things.

First, I'd get another new set of plugs and try that. I have an 87 DX that has the lean burn carburator on it and I have one plug that gets chewed up a bit, for some reason. I think it's related to the lean burn mode, but I've finally gotten to a point where if the engine starts to idle a little rough, or i detect a slight miss, I pull that plug and replace it and then it's fine for awhile.

A second thought is you might try running dual point platinum plugs in the car. I used to have a Datsun pickup that idled lean and it ran like garbage, at idle. However when I put in dual point platinum plugs, it would idle like glass.

Third, if you swapped the ignitor and the coil out and it started running rougher, I'd suggest trying swapping the old coil back in.

Fourth, on Honda engines, the distributor ignitor was a weak link, at least in the year of my car. Their is supposed to be a Honda recall where they will replace the ignitor at no cost. I don't know if this is still in effect or not.

However, if your looking for a replacement, King Distributor sells a new, manufactured distributor, with the fix for the ignitor as a part of the distributor. The price is not much more than what any of the used or rebuilt distributors run, anyway and it comes with a lifetime warranty, so you shouldn't be having to fiddle with it anymore.

Fifth, on the car, with the setup you currently have, if you put a screwdriver into one of the plug wires, hold it close to the engine and have someone turn over the engine, how much of a gap will the spark jump. If it's working properly, you should be able to get a 1/4" to 3/8" gap between the screwdriver and the engine. On my car it had gotten to where I was only getting about 1/16" or less, to the point where it wasn't working right, but it was still working. If it's short, which is what I suspect, then the ignitor, or the ignition coil is marginal and needs to be replaced.

It could always be something else, but the fact it was running Ok, for a period of time, I would recommend checking these things first, before you go after any other possibilities.
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Old 05-15-2007, 09:20 AM   #17
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Here is a pretty good ignition troubleshooting guide. It is for Integras, but I would imagine that the distributers are similar enough to use it.
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Old 05-15-2007, 04:03 PM   #18
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excessive oil in the exhaust will foul things up pretty good. could also be a clogged cat. does the exhaust smell like sulfer?(fireworks) so do a compression test (easy thing to do) will tell you if rings are leaking or valves are sticky/carbon build up will tell you if the headgaskets shot. have ya checked the oil level recently? too much will end up in the exhaust or if its mixed with coolant(ie blown headgasket) that can do unimaginable wonders.
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Old 05-16-2007, 05:12 AM   #19
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I think I should do a compression test on mine, to check the valves. I can hear some valve noise (i think) when engine is cold under light to moderate load at lower rpms. It goes away once the engine is warm.
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Old 05-17-2007, 07:25 AM   #20
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Originally Posted by oh95vx View Post
I'm back again with more VX problems - sorry to say.

Right after I changed the L1H1 oxygen sensor about 6 weeks ago, she ran great - for a while. A couple weeks ago, I started to feel a bit of initial stumbling on acceleration. That's worsened to where it's a persistent miss.

Under even moderate acceleration I can feel frequent misfiring. The little girl just ain't got much go. Even in neutral, I can hear the miss in the exhaust note when I punch her throttle.

I have no CEL codes.

The exhaust smells odd. I'm not sure how to describe it.

Plugs (also ~6 weeks old) have some loose black carbon on the bases, just above the threads, but not much on the tips.

O2S also has a bit of carbon at its base, but the tip looks good (I think).

Ordinarily I'd suspect fuel delivery problems, and to be honest I don't recall when I last changed the fuel filter. However, the missing happens only after she's warmed up. When cold (and in open loop), she seems to run fine, suggesting something in the engine sensors or control is at fault. (Or am I wrong about that?)

ICM and coil were new a couple of months ago, just before the O2S. I didn't install them, however, so who knows what went in there?

New cap and rotor just after that.

TPS is smooth over its entire travel, no bumps or jumps, with resistance ranging from something like 2-3k to about 4.5k.

I just changed the MAP sensor. That was $75 for nothing.

Timing light seems to show the distributor advance working, though I haven't tested it in gear with the wheels off the ground yet.

Could the replacement ICM be causing this? Any other possible culprits you can think of?

I appreciate the coaching. Thanks guys.
This is EXACTLY what mine is doing too. I just R&R'd the dizzy, the O2 sensor and put in the CORRECT plugs. 175Kmiles.

Runs like a champ at 70mph...and when cold runs great thru the gears. When it warms up however, it bogs down just before 3rd & 4th & 5th gear indicator lite lites, and tends to have a very noted 'stutter' in power under load.

And on that note....the gear shift indicator lite seems to lite at diff. rpms & mph ... This is while driving under the same type of load & acceleration scenarios. What's up with that?

Thanks guys!!!

'92 Civic VX h/b 5spd 302K
'97 Civic DX Sedan-auto 125K
'01 Civic LX Coupe 5spd 112K
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