Ecky

Hi all! Having an issue.

I noticed about 2 weeks ago I was having slightly uneven acceleration in my 'Sol. That is, it feels like I generally have a little less power, and it "surges" just a little as it climbs through the powerband. Not a huge effect but my butt-dyno was able to detect it. I'd say it feels kinda similar to the AC compressor cycling on and off when accelerating.

I decided to replace my distributor as I was having some issues with moisture getting in the cap and causing it to run wonky, and I was hoping that was the only issue (plus it was the wrong distributor - was running a VTEC dizzy on B18B). I also ordered a timing light. When the dizzy got here I pulled the old one off, noting that the old distributor (from B16A) was all the way advanced. I have no idea how many degrees advanced it was, but I played with the timing on the new distributor a bit - more on that in a moment. I paid a friend to drop the motor in it about 15,000 miles ago since I didn't have a lift and I guess he just bolted the distributor on and called it a day, I never thought to check it.

I don't think I ever heard detonation, however I have a few minor rattles and a very loud exhaust which might have hid it. I'm hoping I didn't f*ck something up driving it like a bat out of hell with too much timing. I'm not sure who I can take it to in order to get a compression test done, but I assume that as long as compression is good, I can rule out most types of physical damage?

Anyway I changed the oil+filter about the same time I put the new (correct) distributor on and added some injector cleaner. I timed the motor properly and I wouldn't be surprised if I had been running at least 22-24 degrees BTDC - dialing it back to +18 makes it feel quite gutless in comparison, it feels like it doesn't develop torque until like 1200-1500rpm, whereas before I could sometimes break the tires free just by flooring it while rolling in 1st (b16 tranny). In third, dropping the clutch would also cause wheelspin even with sticky tires. It feels like a lost half a liter of displacement or something.

My uneven acceleration isn't gone though. The distributor wasn't the cause. I did a valve lash adjustment as I read that this can cause something like this, but while it did reduce chatter a bit (they weren't too bad) it didn't fix my issue. I checked the AC compressor while I was under the hood and it doesn't seem like the clutch is stuck engaged so I doubt it's that. It could be that my power steering pump is on its way out? How could I tell? I should probably try changing the fuel filter next, but I changed it very recently - like last 500-1000 miles. I can try changing or cleaning my air filter (or running without it for a few minutes just to see) too but I have a CAI and it looks like it should be able to breath pretty well even if the filter were to get gummed up. Would a restrictive air filter cause surging in acceleration like that?

What else should I inspect? I mean, let's assume worst case scenario I lost a little bit of compression in one cylinder due to detonation I didn't hear, it would probably result in just decreased power overall rather than causing surging, right? So it's likely I'm just freaking out? More likely it's fuel or air delivery, yeah? I've also noticed a significant reduction in fuel economy, I was getting an average of 29-33mpg driving it like I stole it, and I'm in the low to mid 20's now.

One more thing. At first I suspected I might even have brake binding. I think one of my rotors is ever so slightly warped, as when braking it feels a little vibraty, but it doesn't seem like it decelerates any more quickly when in neutral than it used to so I can probably rule that out too.

Help me out guys!

grumblemarc

iTrader: (4)

Check the timing.

Ecky

Additionally, the issue developed at some point with the original distributor without the timing changing. I suppose it's *possible* I didn't get it quite right, but the symptoms are the same with the corrected timing and with the old timing, I just have less low-end torque after re-timing it.

Ecky

Sorry if I sounded pretentious, I hadn't considered that the mechanical timing might be off, and thought you were asking me to check something I said I checked in my original post.

I checked the mechanical timing and it was seemingly correct, I was really hoping it would be something as simple as fixing a skipped tooth but it lines up right (to my knowledge).

I played with the ignition timing some and advancing the timing moves the "lumpiness" in acceleration up the powerband. When I have the timing correct it's most noticeable in first gear in the 1000-2000 range, advancing timing all the way brings the lumpy acceleration up into the 3000's.

My ignition timing should be close but I couldn't see the marks clearly as they were part obscured by the timing belt cover, but again, playing with the timing results in the lumpy acceleration moving up and down the power band, it doesn't go away.

While I was at it I put a screwdriver to my injectors and all seem to be ticking like clockwork.

What are some other possibilities I haven't covered? Could an o2 sensor cause this?

I checked for vacuum leaks and found none, but I'll do a more thorough check when the engine cools off.



With the cams lined up, the oil pump TDC mark should be lined up too, right?

Ecky

I noticed when I was turning the crank pulley yesterday that it was a little harder than I remember, perhaps one of the belt-driven accessories is going out and dragging down the motor?