'93 Civic VTEC-E skipping
 

Hey guys, just thought I'd pick your brains before I start replacing stuff. My '93 Civic DX has the VX D15Z1 swap. I just got the car so I don't know the whole history of how well the swap was done, the owner claimed he swapped the computer and everything, all the underhood parts look connected (no missing/hanging/cut wires, etc). I get a fairly constant skipping at most any speed, most noticeable when I'm at 55 or so, let off the gas, then re-apply the gas. It almost sputters, then smooths out, with an occasional skip. Compression in all 4 cylinders is 185-190psi, just replaced plugs/wires/cap/rotor and the plugs all look ok, light tan. It did throw a check engine light yesterday, but it went off after 5 or 10 minutes and didn't leave a code. I'm going to check the injectors/fuel system the next few days. Anyone encountered this? It's getting 45mpg so things can't be too bad. Thanks for the help guys.

I'd start off by making sure the right plugs are in there.

Double check the ECU to make sure it's a P07 (located in the passenger side footwell near the door under the carpet).

Is the EGR hooked up with the control box?

There is a normal stuttering that is inherent to the Z1 motor, coming into and leaving lean burn, but it shouldn't horribly noticeable.

Start here: VX Info Thread

This is the same problem as I had the last three times I had a bad o2 sensor in my VX's.

Thanks for the insight guys, I will look into the plugs tomorrow, the local Advance Auto gave me Bosch's... maybe I want the NGKs. I noticed today that the first 5 minutes or so of running are stutter free also, if thats any clue. I didn't get to check the fuel pressure tonight, I did put a new fuel filter in, still stuttering though. Will update as I discover more.

if it runs good for the first 3 to 5 minutes then starts sputtering then I'm sticking with o2 sensor, as the computer is waiting for the engine to warm up in that time and waiting for the o2 sensor to warm up as well.

O2, TPS, or MAP. All three are affected by engine temps, but the O2 is the most likely culprit for a light stumble while cruising.

Thanks for the advice, I'll check the o2 this week also. This morning on my way to work the car did the usual, ran smooth for 5 minutes then started sputtering here and there. For the first time, the check engine light came on and stayed on the rest of the drive, and the car ran smooth the rest of the way. I'm guessing if its o2 the computer just ignored the signal?

NGK V Power are the only plugs that should go into the VX motor, seriously. :thumbup:

Ok, went to Advance Auto last night, the wires I got are the same part # as for the Si, so should be correct for the VX engine. Got NGK plugs, have to install them tonight. I unplugged the O2 sensor last night, and car runs like a top now (check engine light is on obviously). Would that be a sure sign its the O2? (or could it be another sensor, just computer operating in closed loop, ignoring everything). Don't mean to sound clueless, I've always wrenched on carburetor V8s so this is new terrain to me, and haven't had much time to actually dig in and check stuff this week. Thanks again for the help

Yup, the VX plug wires are the same as the Si ones.
And the model of the plugs were NGK V-Power ZFR4F-11 right?

Unplugging the O2 will make the car run smoother, but isn't the best way to determine if the O2 is bad. Best way would be to measure the output of the O2 and see if it's getting "lazy". The info on how to test the O2 was in that VX Info link I posted before.

You'll catch on to the PGMFI world in no time at all with our help :thumbup:

Ok, I've been busy and hadn't gotten back to the O2 til last night. Checked the ecm, its a p07. I pulled the O2, cleaned the deposits off the tip and re-installed. Following the test procedure in my Haynes manual (backprobe the white wire terminal B on the O2 connector for voltage, connect black lead to ground), I get values around 2.4 to like 2.9 while running versus the .4 -.9 its supposed to be. If I'm not screwing it up (checked it several times) is this even a possible voltage that it could be giving?
Higher voltage supposedly tells the ecm its running rich and the ecm leans the mix out to compensate, which would explain the persistent stumbling/skipping.

get a propane torch, heat it up red hot, and dip it in lemon juice a couple times to cool it off.

Do that 5 or 10 times, then reinstall it. If it still doesn't work, no biggie, get a new one.

Cleaning the tip will do nothing, the sensor is under that metal sheath. As long as the holes are open, it's still making a signal.

So the Civic has been down for 2 months for massive repairs. It was leaking oil like a sieve and needed the o2 and a timing belt. After I bought the car I discovered the rpms are too high for the VX/CX tranny gearing, best I can tell its a DX gear ratio. So I also got a CX tranny to swap in (checked the ratios on it before I bought it this time). While out I had the head shaved .030, replaced all the gaskets, timing belt, had a 3 angle valve job done, new valve seals, etc. As I pulled it apart I discovered the intake manifold-to-head bolts were just barely snug, various bolts were stripped or broken off, the motor mount was ripped in two, the oil pan gasket was ripped, and the flywheel and pressure plate surfaces were blued from a serious beating at some point. Great. :mad: Never buy a Civic from anyone under 50. Anyways the fuel intake bolts were also loose, and the injector seals showed signs of debris leaking past them. The combined loose intake/loose injectors may be partly to blame for the skipping, I won't know for sure until I start the car here this week but hopefully its gone. Last couple bolts to install, and trying to remove a CV from the new tranny (another topic) and I'll be ready. Just an update on my progress since I haven't gotten to actually try the new o2 yet.

Thanks TomO, That I didn't know!

Dave:thumbup:

Wow Tim,

You're really into this project. All this because the O2? Dude! How's it going? Is the engine back together? Did you have any burned valves because of the loose manifold bolts?

All the best,
Dave

To my knowledge the valves were ok or the machine shop would've said something. Car was a real lemon but I'd already bought it. The car is back together and running/driving, needs an alignment still. I've got what seems like low power and some skipping at idle, I suspect the timing belt could be off but I checked the marks before assembly. I need to check ignition timing first here, could any of you post or PM me a pic of your Civic VX VECI label for the timing specs? (should be the decal on the underside of the hood, should say 16* BTDC or something similar somewhere on it). It should also list what hoses need to be plugged, rpm, etc. My engine was a swap and the hood decal is missing anyways. My car is a 93, but I'd imagine 92-95 is fine. Thanks guys. My 24mpg '97 Grand Prix 3.8L V6 would have been cheaper to keep driving than this thing has been so far...

Is your VX from the rust belt like mine?

Just remember these cars are getting scarce. Yours had an unfortunate past.
Mine has been in the same family, brother, mother, to younger brother, never hot rodded but on the other hand has not seen a coat of wax since new.:o:o

But basic maintenance was taken care of fairly well.:)

My label is there but is unreadable for the info you requested. I will have to look for my 92-95 Civic book.

Dave

Ask and thou shall receive:
VX Idle Set Procedure
VX Ignition timing Check/Set Procedure

The info will be great for me as well, Thanks TomO!

Dave

Thanks for the specs TomO, just what I needed.

Well after many weeks of late nights in the garage the Civic has returned to normal service! My cousin and I spent an all-nighter in the garage Friday night (with mountain dew and pizza) trying to find electrical issues that would cause a skip. Earlier in the week we found a couple bare/melted/burnt wires in the distributor so I replaced the guts with a junkyard distributor, but no change in the skip. Friday we went through the ecm pins and wiring and replaced a few butt-splices, but didn't really find anything wrong except some contact pins in the harness plugs. Been running like a top since, something must have had a weak connection. Getting 45mpg with new snow tires all around and 20* weather... can't wait for spring. Thanks again for the help everyone. Thanks to TomO for the timing specs too.

Glad I could help out a bit. :thumbup::thumbup:

I know this post is old but I just read through it and was wondering if you've had any problems with it skipping since the all nighter? Sounds like a lot of money to put down up front, but Im sure you'll save more over time. Good luck!

Not one hint of skipping since, mpgfan. Car has been running great.

After the initial fix-up bill (I knew the car would need a little invested, then got the idea to shave the head and redo the other stuff as long as it was apart), the car has been pretty reliable.

Driving the Civic instead of my truck will save me a fortune in gas. And most of the parts will go on the next Civic when this one dies anyways, so it's more a long-term "investment". Just would have been nice to have had a Civic expert with me when I looked at it before buying it.

Great news Tim, glad it's all working out for you!