Ok so I just put on a obx intake manifold I purchased for my 95 civic d15b. I connected everything how it should go but then when I went to start it up the car just kept idling up and down. I replaced all old hoses with new hoses so I wouldn't have any vaccum leaks. Help me out honda-tech members.

 

Can it be that since this new intake manifold is bigger than the stock one, its holding more air therefore something is not reading right or have to adjust something

 

Check your throttle cable adjustment.

 

I did its good

 

maybe a vacum leak or any leak of some sort..check it throughly

 

I would also check and Clean the IACV(Idle Air Control Valve). If its doing it when cold as well I would check and Clean the FITV(Fast Idle Thermo Valve). The IACV is on the back of the Plenum on the Intake Manifold. FITV is on the bottom of the Throttle Body. Any CEL?

 

you have a vacuum leak somewhere. make sure you don't have a leak in the gasket itself. you can check this with a bottle of carb cleaner. spray it around the gasket while the motor is running if it stumbles then you found it. also don't forget your TB gasket as well.

 

ok ill check tomorrow

 

He's right but be careful not to spray your alternater as it could pretty much blow up.

 

thanks for the info, ill be super careful

 

any cels?

 

im a noob so i was wondering what does the throttle cable have anything to do with the idle being rough?

 

i just swapped a y8 intake manifold onto my y7 and im having the same problem, the motor starts an sits as 1500 as usual, then as it warms the idle starts bouncing from 1500 to 750 and back up constantly and wont stop. all hoses are new, i cleaned the thing that bolts to the bottom of the throttle body(dont know name) has two hoses and an electrical connection, what else is there to clean and check?

 

i just finished mine yesterday and had the same prob. the thing on the bottom is the iacv but anyway what happened to me was that the o-ring under the map sensor wasn't sitting correct and also the studs and bolts were leaking for some odd reason so i put a little thread sealer on the studs and bolts and that fixed my idle. i hope this helps you cuz i was almost ready to put my y7 im back on!

 

Nope.

 

hey i also forgot make sure you are using the y7 tb gasket because the y8 tb gasket is too short and doesn't go around the iacv so id say that this is prolly what is wrong in your case.

 

got any pictures?

 

GOT THE SAME PROBLEM AND RESOLVED IT, THE PROBLEM IS IN THE TB GASKET, MAKE SURE TO USE (ON A Y7 TO Y8 SWAP) THE Y7 TB GASKET AND MAKE SURE TO PUT IT IN THE RIGHT PLACE, THERE IS A LITTLE VACUUM LINE THAT REACH THE MAP SENSOR THAT IF NOT RECEIVE THE VACUUM MAKE THE IDLE GOING FROM 1000 TO 2500 UP AND DOWN... THIS WAS MY PROBLEM... IF THE PROBLEM PERSIST IS FOR SURE A VACUUM LEAK SOMEWHERE...
Hope to be helpfull...
Andrea...

 

just use the gasket that came off your car originally and not the one with the new intake

 

If you didn't make sure that gaskets were sitting wrong or the o-Rings are torn or damaged then it will definatley will have a crazy idle. IMO I would take everything back off and inspect all the gaskets and make sure that they are ok. If everything is ok thenu need to adjust your IACV by honda procedures. That new intake has a larger chamber and draws in more air. You need to re calibrate ur ECM to compensate for the new air flow.

 

how do you calibrate the ecm?

 

well after u verify that the gaskets and orings are good. here is step by step
1. start engine. No loads(lights radio ect....)
2. let warm up i.e. fan comes on
3.disconnect IACV
4. adjust idle screw on TB til idle is at 470 rpm (+- 50rpm)
5. shut off engine
6. reconnect IACV
7. remove ECU fuse for 25 seconds
8. re instal fuse
9. start engine let idle no loads for 1 minute
10. turn on hi beams verify idle stabilizes

if it all checks out then your good.. if idle drops low then u will need to raise the idle up a bit.. but u have to start from the begining

 

Ok, this is a fairly common problem when you take the i/m apart. Usually it's nothing more than a vacuum leak. It could be that something didn't line up right or the i/m you put on was warped/bent or even scratched or cracked. Gaskets can look fine somethimes and have a hairline crack and cause this. So to pin point the problem you have two chioces: You can try to clean out the IAC valve or THOROUGHLY spray the whole intake manifold, the throttle body, the iac valve, and all vacuum lines with brake clean or some sort of carb cleaner. If your normally surging idle raises and stays high for a longer period of time than your car normally does you have found your leak. I highly doube this problem would be electronic.

 

u might also want to check ur tps.. make sure i didnt get damaged in the swap.

 

Hello fairly new to site and although i do not have a civic i was running into a similar problem. My problem is that every time i go to give the car gas the engine wants to die on me, whats awkward is that when the car is parked the idle seems to be fine. Can anyone give some insight?