So I own a 90 crx si with a b16a swapped in. All swap work was done before I acquired the car. While driving one day in the rain, my CAI sucked in a bit of water from a puddle and my headgasket blew. After sitting for a few months while I was out of town, I finally got the gasket changed. However, I now have to rev the car for a while after starting to get it to stay idled and not die out, and the car now idles really rough and low (around 300 RPM, if at all) and dies alot while driving. If I keep the RPM high, the car stays running. I am getting codes 1 (O2 SENSOR) and 3 (MAP SENSOR) from my ECU, and my VTEC no longer kicks on. I also get a Knock Sensor code when the engine starts running a bit, but that was a preexisting, known problem and didnt prevent idle or VTEC prior to the gasket blowing.

What could be happening here? Is my MAP sensor blown and causing my car to idle irradically? Did I bend a rod and am now reaping the consequences? Or is everything fine and my cams and distributor are poorly timed?

ANY help will be greatly appreciated. I am completely at a loss and don't want to resort to putting it over to a performance shop to get charged thousands of dollars.

Thank you.

 

Get a new map sensor.

Are you running OBD-0? If so, do you have both O2 sensors?

 

I'm browsing Atlanta craigslist as we speak looking for a new map sensor. Autozone has them for around 140 but that is out of my price range today. If I go to a pull apart what car's map sensor would fit the b16a? Any firewall mounted b series map sensor?

Also, I do have 2 o2 sensors, pre- and post-cat. However, I do not know if they are both working. Is there an easy way to test them?

 

And sorry, yes it is obd0 pr3

 

Another note I forgot to add, my vss might be dead. My speedo does not work (wobbles around 10-20mph) and I'm not sure if the cable pulled out or if the sensor died. Its a ys1 short gear transmission. From what I gather, that might be the reason for lack of vtec.

 

Any firewall mounted map sensor will work.

Yes, you do need 2 O2 sensors, but they do not go pre and post cat. 1 is for cylinders 1&4 and the other is for cylinders 2&3.

http://www.team-integra.net/forum/12...o2-sensor.html

 

Thank you immensely for the help. I'll be visiting the pull a part in a bit to find a map sensor and vss.

I looked at my headers. Theyre 4 2 1 DC Sports headers, and the only o2 sensor slot is right before the cat, after the last merge. Will I need new headers? Or is there a way to chip my ecu to disregard this and run open loop. I noticed even before the gasket blow that my car would have trouble in low end getting power until about 3k, when it would seem to overcome some sort of barrier and lurch forward, then vtec would hit around 3600.

 

Vtec should engage around 4800-5000. And yes, sluggish low end is usually O2 sensor problems. Or bad distributor timing.

Are your headers ceramic coated? If not, then you can just get new O2 bungs welded on where the 4 pipes go into 2.

 

You're probably right about the vtec rpm. It's been about 4 months since I drove it working.

I'm not sure what they are made of. They look ceramic coated though, so I'll certainly have that checked out.

As for the speedo problem, would that be causing my vtec problem, or is it the map sensor? I might make another post in the transmissions section and link it to here. I know I have a gsr ys1 transmission, but I'm not sure how the vss in these cars works. I have thus far been unable to locate the exact position of the sensor or speedo cable. I've found 3 connections on my transmission; the clutch cable, a sensor hookup towards the front of the transmission(aka radiator side), and something directly above the differential that looks as if theres 3 vacuum hose connections, only one of which is hooked up.

Edit: Just made the trans post: https://honda-tech.com/forums/showth...3#post49123253

 

all 3 of your issues are causing limp mode and vtec not working: vss, o2, map.

why wouldn't you be able to weld o2 bungs on a ceramic coated header (singular, not plural, you do not have multiple headers on your car, you have one single header)? its a coating, its not a solid ceramic pipe. you would treat it like paint; wire-brush the coating off where you want to weld the bung, and just weld it on.

 

Sorry motoxxxman, I'm still new to this. I've always heard it called "headers" so that's what I've called them. Probably because before this I owned 2 3rd generation Camaros, so I had two "header" 's.

Where would I take it to have bungs welded and would it be cheaper to find a used header on craigslist?

 

You could weld them on, but you risk further damage to the ceramic coating.


And any exhaust shop should be able to do it easily.

 

Excellent. Thanks for the help everyone. I'll be back with an update soon.

 

Purchased a used map sensor and am still getting a code 3 and having idle problems. What else could cause a b16a with a pr3 to show a code 3?

Edit: Further googling has shown that the cel code 3 on obd0 can be caused by improper ignition or cam timing. I'm going to try to contact someone who knows a lot more about timing than I do in my area. (ATL)

 

There are two map codes there's 3 and 5.

3 is in my experience (limited) electrical (sensor or wiring) and 5 which is bad vacuum line plumbing or something.

You've checked the wiring?

 

Check if you have a dead cyl maybe bent a valve just a little bit start car and pull plug wires one by one and it should change the idle until u pull a plug and if the idle doesn't change there's your dead cyl. If so you have to pull head off again and fix that cyl.. I've bench bent a valve before while installing cams

 

yeah i agree...dead cylinder or map sensor vacuum hose off the firewall not plugged into intake manifold. another quick way to check for dead cyl is to get a spry bottle of water after reving engine up while its still hot, one at a time spray some water on each header primary, the cold one is the dead one...or if its warm compared to the super hot cylinders then thats your dead one.

single wire o2 sensor needs heat from the exhaust so weld a bing high up on one of the primaries on header closer to the head.

the dead cylinder could also be from a bent valve after sucking up water...assume you dont have any rod knock?