surging engine

[Christ]

So just today, i've switched from the 91 Si ECU to the 89 Si ECU... and on the way home from work, the engine started surging everytime I stop and let it idle... it will idle like it's cold, for a sec, then start surging from 800rpm to 1600 rpm, die off, and rev back up, die off, rev back up... I know I have a bad O2 sensor, I've already reset the ECU, and I'm pretty sure my ignition/cam timing is off, but this JUST started today @ around midnight.

Any ideas?

Everything still works fine, no problems driving, revs up fine, except it feels like the throttle is sticking when I go to shift, or just let off it, it takes about one second for the engine to lose power and start decelerating, but only when it's warmed up to op-temp.

[Christ]

and in a recent surge of sudden intelligence, I think I'll just take the TB and IAT off and clean them, to see if that helps... while I"m at it, I'll adjust the timing.

With the A6 cam on a B2 head, should the cam be timed according to the Si spec or the LX spec? they're 6* different, but the timing cover has the mark for the Si timing anyway... I'm guessing I should time it to that, since it's the Si cam, instead of leveling the two marks on the cam gear w/ the head.... although I'm going to have to degree it anyway, so I can mark my new cam gear... so I guess I'll have to figure that one out on my own.

[MrWrongsalive]

The only difference between an A6 cam and a B2 cam is the 6 degrees of timing. Lobe height is identical. There are no other differences unless you are running an automatic.
1989 Civic/Crx service manual courtesy of Honda Motor Co., LTD. Standards and Service Limits page 3-2.
I would use the A6 timing mark.

[Christ]

yeah, thought so... everyone else locally told me to time it to the head, which i figured was COMPLETELY wrong... since the head is stationary and all...

[Christ]

Fixed.. turns out it was the IACV plugged beyond belief... can't believe it didn't start this up earlier..

Took it off, flooded it out w/ carb cleaner 3 or 4 times, until the black/brown/gray shit stopped coming out of it, then reinstalled it, just have to re-set the idle now, it's warm @ 1k rpm... should be 575 or so.

[turtlecrxsi]

You should still redo your timing to a6 cam specs. Also, Your idle should really be around 700-900. If you hopped up your engine at all then 1000rpms warm wouldn't sound so strange...

[Christ]

That's the thing, there aren't THAT many mods done to it... I can see that it's idling high, b/c of the cam being slightly off... but everything I've seen that's even close to reputable actually points at the A6 and B2 cams being either the same, or ever so slightly off from each other (besides the 6 deg diff, approx) I'm actually going to change it back to the B2 cam, and "butt-dyno" it.

[turtlecrxsi]

I would stick with the A6 cam. Which year did you get the cam from? ClubCRXSi used to claim that the 88-89 Si had 105hp and the 90-91 Si had 108hp due to the cam.

Not really sure what you're looking for though. I mean, mpfi and an si cam is a significant difference than a dpfi b2 set up. Even so, I've heard of stock b series engines idling at 800-900rpms but they were stock.

My a6 idled at 1200 rpms (but the gauge was slightly off so I figured about 950-1000rpms) warm. Cold starts showed 1500-2000rpms on the tach. Then again, my engine was far from stock...

[Christ]

I'm going for more low-end... seriously, it's a pain in the ass that I don't start making serious power until I get to 4250, then it just cuts out @ 6k... I mean, literally cuts out... like there's not even as much power as there is @ idle.

I don't know what's up w/ that.. it could be b/c of the cam/dizzy being off, but it's been like that since we did the swap

Have no idea what year the cam came out of, but the replacement pn's are the same from Honda, afaik for 88-91.

other than that, I still can't find specs for the B2 cams... and the specs I've seen so far have either said that it's the same lift/duration/overlap, or the B2 is slightly "hotter"... which I REALLY don't believe.

If you could help w/ that, that'd be great... I called Gude, they were more interested in selling me a head package than even attempting to answer my question.

[MrWrongsalive]

When I was working at a Honda Dealer we always set the idle on those by unplugging the idle air control valve and turning the idle set screw down until the motor started to bog. Then plug the valve back up and that should have it set properly. Atleast that is the service manual's procedure. I have the service manuals from 89 and 91 for the CRX/civic. I'll look up the cam specs and see if Honda did change the lift or duration to squeeze out a little more power. The B2 cam specs up till 89 I know only changed when you run an automatic transmission. The exhaust lobes were larger, but not by much. Other than automatics, 88 and 89 civics with an A6 and a B2 share the exact same lobe sizes. I'll check my manuals when I get home this weekend.

[MrWrongsalive]

When I was working at a Honda Dealer we always set the idle on those by unplugging the idle air control valve and turning the idle set screw down until the motor started to bog. Then plug the valve back up and that should have it set properly. Atleast that is the service manual's procedure. I have the service manuals from 89 and 91 for the CRX/civic. I'll look up the cam specs and see if Honda did change the lift or duration to squeeze out a little more power. The B2 cam specs up till 89 I know only changed when you run an automatic transmission. The exhaust lobes were larger, but not by much. Other than automatics, 88 and 89 civics with an A6 and a B2 share the exact same lobe sizes. I'll check my manuals when I get home this weekend.

[Christ]

I'm not concerned w/ lift so much, rather the duration and timings...

i'm still putting the B2 cam back in, if for nothing else than to get the cam timing straight up again, which will put my ignition timing back to normal.