TOPIC: 1998 Honda CR-V

The trouble code I got was PID02 1457. On troublecodes.net the note I found was:
P1457 Unable To Pull Vacuum In Tank

This seems reasonable as I disco'd the vac hose from the charcoal cartridge and capped it for now. I can reconnect to the passive side later.

I cleared the code using my brand new Scan Gauge II, and the check-engine light went off.

After my first full tank of gas, I got 22.3 mpg - not a breakthrough, but Ron says in the Vacuum Sytems PDF

gadgetmangroove.com/media/kunena/attachm...%20with%20tweaks.pdf

that Honda's often need a couple of tanks to show results. I think I will try that. And my exhaust temps are high, maybe higher than pre-mod (476 up to 560 or so).

This suggests to me that I need to research my vacuum leaks, maybe the TB gasket, or the Idle Air passages (two big ports, see above).

That said, I swear this car has more power and runs smoother. It seems I barely need to squeak the gas pedal to get all over town really easy, and it pulls great on the hills when I need it. We have a lot of these out here.

I got 24 1/2 mpg on my latest fill-up. 3rd one since I grooved it. Lots of city driving and traffic jambs on this tank. EPA mileage for this 2wd version is 19 city, 23 highway. Ron says Hondas can take a few tanks to show results.

I am so jazzed - something is working here. And I know there is a lot more I can do to ratchet this up.

Way cool.

I covered up one of the idle-air ports on my CR-V a week ago, and have run about a tank and a half.
I covered the port that is regulated only by water temp - probably closed when cold, like an automatic choke, and open when warm. The other port is governed by a combo of water temp and an electrical signal as far as I can tell. Ron - you suggested I leave this open and I did.

At the moment, economy is down - to about 22.5 mpg from 24.5 previous. This is still 5 or 10% better but not a breakthrough yet. Halfway thru my second tank I might be getting a little better - I hope the ECU is learning.

If this doesn't get a lot better I am going to plug my IA port in a different way. I pasted a piece of soda can over it last week with RTV silicone. But maybe this is introducing undesirable turbulence upstream of the TB and groove.
I will also regroove, and try to do better than my virgin run, and wire in the Mapster when I get it.

Two questions - how do check my intake manifold gasket for leaks? I notice that this car has a new one, so someone has been in there already.

Second - has anyone tried putting ball-bearings into the hoses to block them? then they could be reconnect to the intake manifold, but be non-functional. A cleaner and more professional look at the very least, we just need to make sure the balls can't get sucked into the engine - be bigger than the nipples that we stick the hoses onto.

You are almost correct about the function of the valve, but reversed. It opens on cold.

One thing the MFR may be forced to do by our friends at the EPA is to mandate temperature of the Cat be higher. We are about to release a $5.00 solution and are waiting on the parts to check out its viability.

We'll keep you posted. Until then, just keep Groovin'!

Ron

Thanks for the clarification - opens on cold, OK.

I might poke a little hole in the cover I pasted on to let a little air thru. On starting, cold, the ECU seems to hate being so starved for air, and idles very poorly until the water temp is up to about 125.

I would recommend first seeing if the ECU will adapt. More accurately, that the IAC valve will accommodate the changes. You may choose to clean it first, soaking it overnight in a gasoline bath. This sometimes restores some of the functionality of the valve. (That's the electrically powered one)

If that fails to help, I would consider replacing the IAC valve itself.

The second valve (that we've been discussing) shouldn't be necessary at all once the IAC can achieve full range of motion.

I hope this helps, Mark.

And you are doing great!

Ron

Just filled up again (at the 1/2 tank down) and mileage continues to go steadily up.

This car - CR-V - is EPA rated at 19 and 23, with 21mpg combined. I am now getting 25 1/2 mpg in mixed driving (maybe a little heavy on freeway) NICE! This is about 20% better than stock.

My Scan Gauge II seems to be finally calibrated to my engine, so that its instantaneous mpg readout is pretty accurate. I like what I see so far - maybe even 30 mpg on the freeway, at 60 mph.

I got my Mapster in the mail yesterday, and I am thinking of connecting it with small-gauge push-on terminals, so that it is easy to remove from time to time. For experimental reasons of course.