Show15

I have a 93 civic cx I just bought and it idles sometimes from 1000 rpm to 1500 and back down again. The map sensor has no electrical connector and I can't find the wires. Should I look harder for the wires and try to find a map sensor pigtail or buy a whole new wire harness. Thanks

Mike

msc-k

if the map sensor isnt pluged up i dont see how it is running. is it on the firewall

Jimster480

WHen it starts idling high its usually a vacuum leak or its a IACV issue.

Show15

The map sensor is only plugged into the vaccuum line. And it doesn't idle high when it's started. Usually it'll start about 1000 then after I drive or flip a switch even sometimes it'll start it's up and down idle. Like I have my fan on a switch and sometimes when I turn that on it'll stop the reving up and down. Or if ive been driving with my lights and my fan on it'll idle fine and then I'll turn one or the other off and it'll start the up and down idle. I dunno if this helps but I'd like to fix this problem asap

Jimster480

It might just be a coincidence. Because I dont see how a fan would have anything to do with how the car idles. Now if your driving with AC then thats a different story.

Show15

Dont think it is because when it does that I can keep flipping the switch on and off and it'll change the rev deal. And it's not just the fan I can do it with the headlights too

Jimster480

maybe your alternator or grounds are bad. Because its def a electrical issue.

Show15

I'm thinking it is the alernator now. The other day I left my lights on and it killed the battery. When I got it jumped and running again I tried turning the fan on and it killed the motor. But what grounds could be bad? Sometimes it does actually idle fine but that's usually pretty rare

Show15

But still I'm runnin my car without a plugged in map sensor

92hbfreak

Add a pic if you would. The Map has to be plugged it to work correctly, if you are somehow running it without, you will run the risk blowing that engine.

Jimster480

i dont understand how the car is running without a map sensor...

Show15

heres some pictures of the map sensor. where the t is in the vacuum line leads to the pcv plastic piece. i think its the pcv valve but cant be positive.

Jimster480

wtf crazy map sensor

shawn_crx

Your car is a 93 CX which the Map sensor should be on the T/B... and your engine is a DX engine (DX engine MAP sensor is on the firewall). When I did my swap, I brought an 95 ex T/B and works fine, the 94-95 EX T/B MAP is on the T/B and same size as your DX TB..

Show15

I don't have a dx motor. I have a Canadian cx. The motor is stock so the map is supposed to be on the fire wall but isn't. There's no mount or anything. What should I do? Find a wire harness or find a map pigtail and the wires that are cut off somewhere on my harness?

94EG8

'94 - '95 DX/LXs had a throttle body mounted map sensor as well, all civics and del sols equiped with a D15B7 used a firewall mounted map sensor from '92 - '93 and a throttlebody mounted map sensor from '94 - '95. And before anyone else asks, yes Canadian CXs (the ones sold in Canada) did in fact come with a D15B7, we thankfully never got the 8 valve boat anchor that is the D15B8.

The map sensor harness for a factory firewall map sensor is weird, it comes straight from the ECU out through the firewall, it isn't part of the engine harness at all.

Show15

Where is the vacuum line from the top of the pcv valve supposed to go? If I do fix the map sensor I have to connect it somewhere right?

Jimster480

well on the newer models 96-00 the one that goes from the PCV goes to the intake manifold.

slow96lude

If i were you i would just secure the vacuum hose onto that map sensor you have and find that map sensor plug and plug it in. It will have the same outputs as the firewall mounted sensor to the ecu. Make sure you reset the ecu. because you have to have a code 3 or 5 CEL because of the map sensor missing. Plus it will save you some money on buying a new firewall mounted map. Or you could just go get a TB off a 94-95 b7 and use it. Which in my opinion would look much cleaner. The engine will run without the map, but the ecu use a preset map setting for it. My old b7 just idled really high without the map sensor plugged in.

Jimster480

well you could just plug the map sensor in. Its fine with it running off of a vacuum line. It just needs to be the same vacuum line that goes to the fuel pressure regulator.

slow96lude

I thought the map sensor used the vacuum source off the TB. Ill check some pics in my haynes real fast.

slow96lude

It does. it uses the one he has pictured as the source. It shouldnt be tee'd like it is.

Jimster480

well if your TB has a vacuum source then use it there. I just know on my Y8 mani there is a vacuum source for the FPR and u have to tee that to run a aftermarket MAP.

slow96lude

I see where your coming from. But on the b7 it is just referenced off the TB like the newer ones are. pretty much same spot

Jimster480

ah ok