Ecky

My current issues are:

Rough idle until warmed up

Tachometer is reading funky - jump around madly above ~3k rpm

Engine hesitating around 1500 and 2000rpm with low throttle - clears up if I press the pedal down


The story: This is a '95 Si VTEC, the stock engine was a B16A3. I spun a bearing driving a little too fast (high throttle above vtec engagement for an extended period) and limped it home. The tachometer was jumping around but I attributed that to the spun bearing.

I attempted a rebuild on the B16, and after I got everything back together, it was running smoothly, but the tachometer was still jumping around whenever RPMs got much above 2500 or so. It also had a hesitation under low throttle around 2000rpm, almost like a fuel cutoff. I pulled the idle control off and covered the hole, and the hesitation changed to ~1500rpm. After putting it back on, I drove it a bit (not hard at all!), and the bearing went out on me again. My guess is the block was warped.

I recently picked up a B18A and dropped it in. I reused the distributor from the B16, since the B18A's was OBD0. The ECU is new, a P75. I also reused the IACV and throttle body from the B16.

Question 1: The tachometer is still jumping around - is the sensor for RPM in the dizzy, and how would spinning a bearing damage it? Maybe my tach itself is bad? Or could it be somewhere in between the two? The dizzy and IACV are the only two engine parts I reused, but it's still on the original harness with all of the original electronics. What do you think?


Question 2: I still have the weird throttle hesitation at 2000rpm, and it still changes when I unplug or pull off the IACV, so I figure it's not entirely dead - it's feeding the ECU something. I picked up a B18B IACV from a junkyard and slapped it on, but the problem is still there. Rough idle until warm, weird hesitation at 2000rpm. I suppose it's possible this IACV is broken too, but what are the chances?

Where should I start when trying to diagnose this? Should I try a new throttle body? A new dizzy? A third IACV? I can't imagine how the throttle body might be damaged, or how it might be causing this... maybe it's all electronic? But I have a new ECU.

Thoughts, ideas


One last question: I'm a little concerned about using the B16's tranny on the B18. At 80mph, I'm running near 4krpm. Is this alright on a motor with a redline at 6k? I've been keeping it under 70 on long drives just to be safe. How hard is it to swap a gear out? Better to just get an entire LS tranny, maybe, and sell this one? Also, even with the slightest amount of throttle, in top gear, it slowly creeps up and settles around 50mph. It's really annoying to have to take my foot off the pedal every 30 seconds or so to try and maintain speeds lower than that.

Ecky

Up!

Ecky

Tomorrow I'm going to pull the dizzy apart and check for corrosion and moisture, I guess that could be a possible cause for the tach bouncing around, and the hesitation at 1500-200rpm - it sounds like the fuel/air mixture is bad, now that I think about it.

Most important, immediate issue - is running the B16 tranny going to be safe on an LS engine?

digitally_remastered

if i remember correctly, a vtec dizzy on a nonvtec car causes some pretty significant issues. you would also need a nonvtec ecu. that is unless you have the b16 head on the b18 bottom end for a ls/vtec setup.

Ecky

Oddly, an alignment fixed the tachometer issue. Now what I'd like to fix is the surging/hesitation under light throttle at 1500-2000rpm... and I've found another odd issue. The rear right brake light doesn't work until the car has been running for a few minutes.

Wat?

Former User

CEL codes?

Ecky

Will grab them tomorrow. The hesitation was happening before I did the swap and I think it was only the O2 sensor previously.