Hello and thank you in advance for any help and thank everyone on here. You can honestly build a car with a Straw, Paperclip and Elastic band with all of the Intelligent people on these forums.

Vehicle - 1988 Honda Prelude 2.0 Si
M/T

Problem:
My car seems to have a rough idle (idles up and down consistently) Massive usage of fuel and stalls when there is half a tank of gas or less and when the gas pedal is not pressed. Also when the problems begin a small whistling sound comes from what seems to be the EFI.

What could this be?

I have change the fuel pump, fuel lines, fuel filter, spark plugs, oil and filter, air filter, and had the gas tank cleaned.

Any help would be appreciated,

Thank you.

 

The whistleing sound could be from a vacuum leak somewhere, just spray some carb cleaner in ur intake and it should be visible if there are any vacuum leaks cause itl spray out the holes. Also, try checking ur IAC( idle air control valve), it could be dirty and need cleaning. Also, does it idle ok cold, or warm. Any cels? Hope this helps a bit.

 

I am going to try everything you said. It does not idle ok cold or hot. I found the whistling sound and it was from the PCV valve gromet, it was a little loose.

I am going to use the carb cleaner first, since that is an excellent idea that could show me any leaks. Then I will try everything else you stated.

Thank you very much and I will let you know if it solves anything.

 

Good luck, hope it works out! Let me know how it turns out.

 

Hey Heres What I've Gathered
Ok, If you have done that "performance improvement" where you take the coolant hose from the EACV "Electronic Air Control Valve" and run it strait to the head of the engine; basically eliminating the heater valve where coolant runs through on underneath the throttle body, than that would be my first guess on a rough idle. That mod can work but not for 4th gen preludes consistently.
If you haven't done that then the next thing to do is check the coolant level from the top of the radiator or check for coolant leaks especially the hoses running to and from the EACV.
Step three if those two were'nt infact the case the other thing that can cause that is your throttle cable and idle adjusting screw. I don't know where you take your car to get fixed but both of those need to be tuned to 100% if you want your Honda to run well. First check to see if you even have your idle adjusting screw; if thats missing then you have probably solved both the high rev'ing problem and the whistle sound. If its there go ahead and try turning it to the right slowly but put pressure on the screw aswell, by turning the screw to the right you are dropping your idle "left is increasing idle". If you have turned it too far to where it wont tighten quicly turn the screw left all the way around about two times that should be pretty close to stock. 2nd after accomplishing nothing there, go ahead and reset your EACV and idle:
1). start your car till it has warmed up to it's driving temperature.
2). pull the grey electric sensor plug from the EACV with your car running, your check engine light will pop up blah, blah, blah; go turn your car off now with your sensor plug still un-plugged.
3). no go to your under-hood fuse box and pull the clock/radio fuse should be a 10-amp. fuse; wait atleast 20 sec. more time is always better for esurance that it really reset the idle and EACV but 20 sec. min.
4). now plug back in the silver sensor plug to the EACV, then plug back in the clock/radio fuse; you might hear a air relief "pfff" sound but it's not real loud so you may not.
5). after you have plugged back in both the fuse and sensor, start the car back up.
6). check your idle once the car is at normal temperature, your idle should be anywhere from 600-1250 rpms. at this point.
7). if your idle is reading high adjust the idle adjusting screw to the right till it reads somewhere around 750-900; if idle reads low turn idle adjusting screw to the left till it reads 750-900.
8). always adjust this screw slowly and check your rpms. all the time in-between.
9). do a quick test drive down the block or something, then stop and check your tachometer to make sure your idle is still holding where you had it. If it's not get out and adjust it, now your done with that procedure.

So say none of that has helped yet?!, now its time to adjust your throttle cable, this is one of those things that is freakin' irritating because you will never get it right the first time maybe not even the 15th time.
1). un-hook the cable from the two hold downs that just keep the cable from shaking and moving when your driving (one is connected to the top of the intake manifold, the other is close to the firewall.
2). now loosen the two nuts that are holding the throttle cable in position, now the cable can be moved left or right.
3). I would say to get close start the right nut at about the 5-7th thread on the cable, after that make sure the cable doesnt turn or move or bend when you go to tighten the left nut so that the cable is locked into position "best way is to take either two 12mm. wrenches and hold the right nut while tightening the left nut, or take some pliers and hold them very tight right behind the right nut but on the cable, hold the pliers snug and steady while you tighten the left nut tightly.
4). If you noticed your idle has stopped hi-revving then you know this is your problem but your not done yet.
5). now go for a drive and make sure your driving needs are fullfilled (power, sound, etc.)
6). adjust this cable the same way you did up-top, by like a 1/4 of a turn either way you decide. every time you do this adjusting step till you are satisfied and trust me, as a hardcore tuner especially on my lude this will take some time; but this is what keeps my all motor lude competing with the corvettes out there, by finding my ludes happy spot.

Now if for some reason your car still is working I would probably be freakin' pissed with all the work and time i've already spent but check your powersteering belt, make sure its adjusted correctly and tight to the mount, push on the belt and if theres some give, re-adjust the belt so that its tight to the pulleys, after tightening the three bolts to the mount now adjust the adjusting bolt "that bolt that sticks up from the power steering pump" tighten that snug with a 10mm. wratchet, then take a 12mm. wrench and tighten the lock-nut really snug to the surface this will keep the pump from possibly moving when driving and hitting bumps and will keep the belt evenly laid on the pulleys.

Ok if none of this worked for you man post another message saying thanks but no thanks and i will try to get a better idea as to what exactly your car is doing but I had the problems your having and this is what I did to get rid of it so i do believe you wont be spending much if anymore money to fix this annoying problem, oh and the hsss! noise you hear could also be coming from your brake reservoir cap those were made cheaply just get one of those cotton wristband things that jocks wear and put it around the top where the cap locks to the reservoir and that will work.

Sorry there was a lot to read but it could be worth it to read! later and goodluck man!

 

I finally get to check the EACV today and will let you know what happens.
I am also going to check the fuel presure and the power steering pump and system (the idle jumps upto 2000 when the wheel is slightly turned to the left and held steady).

Thanks alot.

 

ya if those theories don't work, check your fluid in your radiator and make sure its filled to the neck right before the ravine to your hose for the overflow tank and if that doesn't work, try adjusting your throttle cable because if its running way too lean or way too rich that will make your idle go really high and once your car idles at like 1300-1400 rpms it will start high rev-ving"which is when the idle goes up to 1400rpms and than just drops back to like 700rpms and keeps doing that" trust me I hated stopping at a light it sucked ass; I would just sit there holding the accelerator down a little bit just to keep the idle steady if nothing works than just keep posting back and let me know where your at and I'll try to keep helping you.

Oh and when you said your Idle jumped a lot when you turned your steering wheel, go ahead and tighten your adjusting bolt on your powersteering pump. Its the really long bolt(10mm) that runs from the top of your PSP"power steering pump" straight through, and down to the bracket that the PSP sits on that is connected to the head of your engine. Make sure that bolt is extra tight and just keep pushing on that belt to see if its almost so tight that when you push on it with your index finger it hardly or almost seems it doesnt move. than simple take a (12mm) wrench and tighten the lock nut right underneath the head of that bolt, tighten it down to the mount as well. Don't spend money yet try a few of these things first and you'll get it, goodluck