Honda Prelude Forum

So incase you havn't read my introductory thread, I bought my friend's '94 Prelude SI. It's now been sitting at my house since Friday and I just had the clutch replaced yestarday with a new one. The main relay is going bad and the car idles like complete crap. I'm making this thread in hopes of getting help as I go along with fixing this Prelude up and to post info and pictures as I go along. Hopefully you guys can help me out along the way.

It's a '94 SI 5-speed with the H22A1 motor. The chassis has 215K miles on it. The motor supposadly had around 85,xxx miles on it when my friend bought it. If that were true, it should have around 90,xxx miles now.



I'll get started with the clutch. The throwout bearing originally got worn out and lead to the clutch getting stuck and not being able to disengage. I bought a Duralast clutch with a lifetime warranty from AutoZone for $204.99, part no. NU31254. I just had it installed yestarday. The old clutch disc was a six puck bronze clutch with a stock pressure plate. The clutch was FUBAR! The Prelude also has a lightweight flywheel. I'm not sure what brand it is though, but it's of a blue color.

As for the idling, i'm really stuck. I've been searching and searching. But it looks like there are so many things that can cause a bad idle. For now i'm leaning more towards that it may just be a dirty IACV (Idle Air Control Valve).

Heres a video of the Prelude starting up.
The car is really tough to drive like this, it bounces a lot. If I disconnect the sensor that you see was disconnected in the video (TPS?), it idles and drives much smoother, but idles way to high (2,000 - 3,000 RPM's).



Can anyone else agree? I'm also not sure if all the vaccum lines or hoses around the engine are properly connected to the right places. I'll try to snap some pictures of the hoses that i'm not sure about.

even if the IACV is full of carbon, it wont make that type of idling problem.
Are you throwing any CEL codes?

TPS could be your problem, or maybe not...

Duralast clutch, lifetime warranty not bad at all.

Check here for engine vacuum lines and diagrams.
http://preludezone.com/showthread.php?t=2005

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Checked the vaccum hoses today, and I couldn't find anything wrong.
But I still have some questions in mind. I used this diagram to help me:



For one, is the intake control solenoid valve required for normal operations? I'm sure it's used with the stock air intake. I removed it completely and it made no difference at all. I put it back in, in hopes that it would make a difference. But again, it made no difference whatsoever.

Plus there is a vacuum hose that comes out of that small box that leads to nothing. I'm guessing that hose would have connected to the stock air intake.



If I remove the hose the arrow is pointing to below and the intake control solenoid valve above, what am I supposed to do with the open port below? Just leave it there sucking in air? The hose the arrow is pointing to below leads to the intake control solenoid valve (line 8 in diagram):



and what are these below? I have nothing connected to them, hopefully they aren't important.
Probably used with the stock intake.

yes you can completely remove the intake control solenoid including the vaccum hose going to the IM, and just cap the nipple off @ the IM.

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So are you throwin any codes?

Check your idle screw its very common for it to back out and cause surging

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I havn't checked the ECU for codes yet. I also messed around with the idle screw with no luck. I did take off my intake and found the bypass valve for the IACV and covered the hole with my thumb while the car was on and everything connected (IACV connected, etc.) and the car idles almost perfect and smooth as ever (about 1,000 RPM's).



I also found a white wire that was cut off from my o2 sensor. The o2 sensor has 3 wires coming out of it, and the white one was cut. I'll try to get some pictures of this cut wire.

I'm going to put the idle problem and o2 sensor to the side for now and lean towards replacing my front brake rotors and pads because they are really bad! I had cracks pointed out to me a few days ago.

So I bought new Duralast brake rotors ($89.98 for two) and brake pads ($21.99). I knew the front pads and rotors needed replacing, but not this bad. I wanted to get some Brembo blanks or something. But I was left with no choice as I couldn't wait a week or so to order Brembo rotors and some good rep. pads like the Hawk's. The Duralast pads also come with no shims, but the service manual shows three shims being used for each pad. So I went back to the store and double checked and they don't come with shims. I guess the shims aren't needed on the '94 Prelude SI? As long as brake noise is tiny to none, i'll be happy.

I'm disapointed at how Honda designed the front brake assembly. They made it so damn complicated just to remove the brake rotor. My 1980's 300ZX is so much simple, remove caliper and the rotor slides right off. I was hoping it would be the same if not easier on a '94 Honda, I guess not.

Heres the longest crack on my front left brake rotor (pretty scary):

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OK, I jumped to conclusions about the front brake rotors. The front brake rotors on my Prelude are not pressed and will not be PITA to replace.

Bad news though, the brake rotors and pads I bought were to small. Two pics of one of the new rotors and pads I bought Vs. one of the front pads and rotors that were all ready on my car:





If this was a true SI chassis, then i'm only left to believe that along with the H22A1 swap, whoever did the swap also converted the front SI brakes to the bigger brakes from the VTEC model. Unless the year of the Prelude plays a factor? I'm really not sure.

I went everywhere looking for the bigger brakes, Auto Zone, Advanced Discount, Honda, and NAPA. No one had them in stock and they were a bit more pricey (except at NAPA). Auto Zone and Advanced were going to take to long to order the rotors and pads (1-2 weeks). Honda was going to charge $20 dollars per item to overnight the parts through UPS and NAPA was able to order them and have them in by Tuesday (3 days). So I ordered blank NAPA rotors ($49.98 for two) and ceramic brake pads ($36.49) for the front.

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I just looked up my VIN "JHMBB1171RC000295" and found out some intresting stuff. It looks like I have the VTEC model afterall. This whole time i've played along with my friends and thought it was a regular SI with the VTEC motor swapped in. The motor may just have 200K miles like the cluster saids if it wasn't really swapped. The tranny must have been changed because it has the M2S4 tranny. I just don't understand why someone would get rid of the LSD unless the tranny was broken.

I wish I would have looked up the VIN sooner, I would have been looking for the right brake rotors. I was looking for the regular SI's brakes thinking the motor was swapped in a regular SI chassis.

the top hose is like an egr hose....its a crankcase breather. the bottom is a coolant hose. i disconnected them, but breather filters on the intake piping and valve cover and put a new hose there for the coolant. i removed it all together
that my friend is why you dont get cross drilled only rotors....they heat and crack....u want drilled and slotted

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ok so your friend is a dick for not telling you...but there is really no way of telling how many miles are on your motor. the h22 and the h23 have the same tranny and not all vtec motors came with an lsd tranny....and for future reference...the trim of your car is an si vtec

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I think they used crappy rotors, like eBay rotors or something. Good rotors shouldn't crack like these.

H22's (S VTEC or SI VTEC, whatever you want to call it) came with the M2F4. Correct me if i'm wrong, but that's coming striaght out of the service manual.


Yeah NOW I know that since I looked up the VIN.

My friend didn't own the car for long. He bought it just like that and the person he bought it from told him that. Told him that the H22 was swapped in there and had around 80K miles on it. So we thought it was just a regular SI with the H22 swapped in.

i stand corrected

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So your telling me Honda randomly put the LSD tranny in the S Vtec Preludes? That makes no sense at all.

Anyway, I fixed the idle today! I woke up this morning determined to either fix it by cleaning the IACV or bypassing it. Whatever the case was, I just wanted to remove the IACV out of the possibilities.

Well I removed the throtle body out of the car and took off the IACV. I saw that the valve inside was loose, it wasn't even screwed in. You can clearly see where the vaccum leak was inside the IACV. I cleaned it up with a lot of brake fluid, screwed in and tightened the valve. I cleaned the throtle body too while I was at it.

Once I was done with all that, I put everything back together. The car had a smaller aftermarket throtle rotor over the stock one. Well I removed the aftermarket rotor (just used the stock rotor and left the aftermarket one out).

This was the moment of truth, I wasn't 100% sure if the loose valve was the one and only vaccum leak casuing the fluctuating idle. I start the car and it starts bouncing off the rev limiter and I immediatly turn it back off. Now i'm thinking, what did I do wrong? Later on my friend noticed the butterfly was opened (intake was off) a little in the T.B.

We overlooked the throtle cable! I forgot to adjust it according to the stock throtle rotor. So I adjust the throtle cable according to the stock rotor. I'm ready to turn the car back on, and bam the car idles perfect! Idles just below 1,000 RPM when warm (about 900 RPM). I'm sure I can adjust it a little bit more with the idle screw. I would have taken pictures as I went along but I couldn't find my camera at the moment. I'll record another video of how it idles now after the fixed and cleaned IACV.

The LSD for 4th gens is in the M2B4 trannys, and its JDM, apparently.
OBX and a few otehr companies make LSDs for the USDM trannies.

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They matched up perfectly this time around. The parts I ordered from NAPA were the right ones. I would recommend anyone buying the front brake rotors from NAPA (if your on a low budget). They come with lifetime warranty and the front rotors were only $25 each.

Of course these parts must meet or exceed OEM specs. and quality. So it's just dumb to spend anymore money on rotors and pads from Honda. Some parts should be ordered from Honda, maybe like a timing belt. But things like rotors or pads are just fine from places like NAPA.





I'm going to go to the 1/4 mile track tonight, gonna run the Prelude. I'll get back to you guys with some timeslips.

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Ah yes, looks like everything is turning out just fine.



good job man, let us know those times!

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I ran a total of three times. My 16.4 run was slower because for one I had a passanger and I didn't launch hard (like 1.5K). I plan on running again on Feb. 11th. I need more practice at launching the car. I'm used to RWD. I ran a better 60' in my '89 300ZX, yet the Prelude is way faster. I guess the Z is just able to hook a lot better than the Prelude since it's RWD. The Z still gets wheel spin but not as bad as the 'lude. I used to think my Z had bad traction, the Prelude is worse. Goes to show the difference between FWD and RWD. I just gotta get used to the FWD and shifting at the higher RPM's (still getting used to the car). Anyway here are the time slips.

Run 1, 15.985 @ 89.84 MPH

Run 2, 16.449 @ 88.83 MPH

Run 3, 15.675 @ 91.23 MPH

By the way, my R/T in my first two runs are crap because I was originally not worried about getting good R/T's. I just wanted to get an idea of what the car ran in the 1/4 mile. So I stood at the line 'till I was ready to launch. In my last run, I took it more seriously because I was asked to race a CB7 H22 for fun. I also lowered my front tire pressure to 30 PSI for the last run.

Edit (3/5/07): I just want to make it clear that I had a lot of junk in my car that night. I had everything from a bunch of clothes in my back seats to my old front brake rotors/pads, old clutch disc/PP, OEM donut, and tools in my trunk.

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What's up with all these Prelude's leaking a lot of oil? Mines leaks a little oil, and I think it may be the seals for the cam gears. Whatever it is, it always leave a drop of oil when I park it. I just don't want it to end up like these other Prelude's i'm reading about where it leaks like 3 quarts of oil in less than a day.

So I put a full tank in the car last week. $27 dollars of 93 last Sunday (1/27) and it lasted me roughly 320 miles. Today I checked the oil and noticed that I was little low on oil. Maybe I could have had better gas mileage? I wasn't that low though because my VTEC was still working.

By the way, I throw a CEL sometimes. It usually comes on during driving, when I get on the brakes while in gear. I'm thinking it's a combination of the exhaust leak (missing header gasket) before the catalytic converter and a cut wire from my o2 sensor. It probably explains why the car hesitates sometimes too.

I also cleaned the wheels, they were dirty as hell:





The car's not as low as it used to be. Got it raised and evened out a little.

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well if u have an h22a4 then u burn oil hitting vtec...if its the h22a1 then ur not burning nearly as much...same with the jdm h22a. the h22a4 is open deck compared to the h22a1 and jdm h22a being closed deck

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My friend's dad saids the car has a bad valve. He can hear it because the car misfires sometimes when it's idling. It might burn oil from that bad valve. Plus it leaks a few drops of oil everywhere I park it. By the way, it's the H22A1. Hopefully the oil leak is an easy and cheap fix. =(

So I started getting a lot of brake nosie from my rear left brakes. I knew it was my rear brake rotors because they are FUBAR. So I bought new rear rotors and pads from NAPA.

I had a lot of trouble putting one of the rear calipers back on after installing a new rotor and pad (rear right). I later find out that my (rear right) caliper bracket is frozen (thanks to my friends dad)! So I kept the new rotor on and I had to put the old pads on. Now i'm stuck with brake noise for who knows how long. Most likely the other caliper bracket is frozen too. I'm going to get some good ones from the junk yard tomorrow after school.

That sucks bro. Let us know how it turns out.
4,000 posts! w00t!

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well first and foremost....NAPA FTMFL!!! and second...the caliper bracket doesnt freeze...the caliper freezes. auto zone sells pairs of calipers for 100-250 with core charge or something like that. get some new calipers, install them and the new pads, if u have to cut the rotors then do it, and bleed the brakes. should be good as new

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all type s jdm prelude's came with lsd. u had to do that many things to fix a problem lol wow u could of just got the code and know wat was wrong w/ it. saves a lot of time but good job fixing the problem.

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Nothing wrong with NAPA.

The two holes where the caliper bolts onto the bracket won't slide in because they're siezed up. Hence, it's not allowing me to install the caliper back on properly with the new pads and rotor. I'm just going to try and find good rear calipers and brackets from the junk yard.

Does the '94-'95 Accord share the same rear brakes? Do any other car's share the same rear brakes as the Prelude?

Many things? I didn't do many things and I got it fixed soon after getting the car anyway. I'm sorry if I don't have a scan tool at home. Plus I wasn't throwing a CEL before I had the idle fixed for some odd reason, and I didn't know how to run codes then w/out a scan tool on this car.

see if there is a way that u can grease the slides. if not then u may have to replace the calipers

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I found rear calipers (w/ brackets) at the junk yard for $30. They work great too. So I officially have new brake rotors and pads all around. =) No more brake noise, and the brakes are working great. All I have to do now is tighten my e-brake. It's hella loose.

I finally got this gasket for the header I ordered like a month ago. The old gasket was torn apart and caused a huge exhaust leak. If you watch the video I posted at the begining of this thread you can hear the horrible exhaust leak at the header.

Anyway, I have a aftermarket header so I had to order a gasket that would fit the header. I put the gasket in today and had trouble screwing in a bolt on the bottom flange. So there would be a little gap at the corner of the flange. I wasn't sure if the flange was bent or what. It's a small leak though and the new gasket still made a night and day difference compared to before. The car hesitates much less, drives a little smoother, and is quieter. I'm thinking i'll either take it to a shop to see if they can fix the header somehow or save up for a new Megan Racing header.