Honda Prelude Forum - PreludeDriver.com

Hi Gang,

New here. I have been reading and researching for a while trying to figure this out but I am out of ideas now.

I bought this 1991 Prelude 2.0l S, 5 speed this past month, 340,000kms, runs great, smokes a touch on start up but that's it. Lots of power, however, it pings like crazy, from just off idle all the way to 3500rpm. First, I'm not sure what gas these beasts need, I have tried 91 and 94, which makes it better, but still there. Here is what I have tried:

Replaced, plugs, wires, cap, rotor, no change. I have tried retarding the timing, within the slot allowed range on the dist. housing. This fixes it but then the computer complains and turns on the check engine light. Car still has lots of power with the timing set here but I think it may be in "limp home" mode and don't want to leave it like this. I haven't read the codes but am going out to do that today.

BTW, when it is cold, it has almost no ping at all, it gets much worse as it warms up which may be sensor??

So, what am I missing here? I have been working on cars for over 25 years and this one has me stumped. EGR? Blocked hoses?

Thanks guys,

Paul

That's quite a problem; definitely something you need to get all fixed up soon.

I'm going to suggest a few things.

First, start by setting your timing back to stock so that you can rule out any timing problems. I know you may have improved things by retarding the timing, but let's try to get things back to factory spec.

Second, and this is likely more important, take a serious look at your fuel system. Detonation (pinging) can occur from an engine that is running too lean. Your O2 sensor may be shot, or perhaps your injectors are clogged up, or worse still, you're not getting good fuel pressure from the fuel pump. Make sure the fuel system is running well. This may explain why it doesn't do it as badly when cold, because the engine will be putting more fuel in the cylinders during warm up.

Let us know what you find.

Hi SpiffyG,

Thanks for the reply.

Two things discovered and fixed today. 1st, I found the CYL sensor had a flakey connection to the ECU, that stopped the code 9 on the ECU, then I discovered that I couldn't get the timing mark to appear in the window on the bell housing. It was way up past 25-30 deg advanced. No wonder it was pinging. I could get the timing back to about 20 DEG but that's it, I ran out of slot on the DIST housing. I dropped all the bolts out and turned it back to about 15 DEG and stuffed a towel to keep the distributor in its hole, and got the timing right on 15 DEG. So, now I know what the problem is...how did the timing get so wacked? The timing belt was changed 100K KM ago, so that is due for a change. Could it have jumped and will that change the timing of spark? The spark gets the timing signal from the DIST so if the DIST is driven from the cam, and the cam is out a notch, then the timing will be off. Did I figure this right?

Feeling better about this already...just need to finalize the fix.

Cheers
Paul..near Vernon BC

Yeah, you've got it right.

Sounds like your cams are off for sure. Take off the valve cover so that you can see the marks on your cam gears. Rotate the engine so that the timing mark is lined up on the flywheel, and I bet you'll find that your cam gears are off. This for sure will need to be fixed before you have any hope of getting the timing bang on.

Let me know what you find.

Hi Guys,

Thanks! Well, the check engine light came on again yesterday as soon as I started it in the morning. I guess I'm going to have to check the CYL sensor and maybe take it apart and rebuild it or replace it. ECU shows the same code 9. Will also pick up a timing belt today and change that, check the timing and see if i can get this all setup and running properly.

I will search other posts to se if there are any tricks or things to watch out for when changing the belt.

Cheers

Paul

Uh oh, I just read the procedure for changing the timing belt. Arg! The whole drivers side of the engine has to be removed.

Is there any way to move the cam shaft one notch on the belt without removing the timing cover? Is there enough give in the spring tensioner to allow this?

Thanks.....otherwise need to pick a weekend and find the special tools to do the job.

Paul

Removing the plastic covers isn't too terrible a task if it comes to that.

You may be able to loosen the tensioner enough to slip the belt anyway. Hard to say for sure as I've never done it that way. Be careful with the belt, and all should go well.

Well I got the covers off easliy, found that the front cam was off by one notch, but there wasn't enough slack to move the cam one notch so I had the idea to pull the cam pulley out a little, move the belt/pulley combo while keeping tension on the belt, that worked great...except I dropped the bloody cam key into oblivion...maybe in the timing cover, maybe somewhere down under the engine. Damn! I fished around with a magnet for a while but couldn't find it before it got dark out so I'll go fishin in the morning. If I can't find it I can get another no prob., just concerned that it may have fallen onto a pulley and may get stuck between the timing belt and a pulley. May not do any damage and if it makes it to the bottom of the pan, I'll get it out when I do the belt.

On the way to finally getting it done...just a few more hours fo work.

Cheers

Paul

Nice work on getting the timing back to where it should be.

Be sure to locate that Woodruff key; the last thing you want is it to get stuck in a belt. That would spell disaster. Comb the underside of your car for it, and knock off any more panels you need to to see where it is.

Hi Gang,

Well, it's been a long and winding road the last few days, no time to spell out the story right now...it's a doozy, suffice it to say, I am now replacing the head. ARG~

Seems the exhaust cam pulley came loose and the woodruff key (yes I found it) rolled, chipped the end of the cam shaft and the cam came loose and WAY out of time and wacked the exhaust valves into the pistons. I am part way through pulling the head, and I don't know if the pistoms are damaged, hope not, but the valves are definately not closing, zero compression. I have a bad back so can only work in 1 hour spurts.

What I would like to know is, what is the standard procedure, just the highlights for pulling the head? I have the manual from the UK site but it seems that they would like a whole lot more stuff removed than seems neccessary. Is it neccessary to pull the exhaust manifold from the pipe? Should be anough play to just pull the whole system ahead 1/2" to clear the studs, but I can't budge mine. Guess the intake mfold comes off with the head, and all the fuel injection stuff too.

Thankfully, I found a complete donor car, a 1990 SR with the B20A engine, whole car not bad but lot's of dents, it's from a wrecker so no reggie. Just going to pull the head and swap them, put in a new belt and get her going again. Then I can start pulling the other parts I need. It's will be nice to have a spare parts car sitting at the ready, if I need anything. It has all the power options, windows, roof, air cond. etc. Not sure how hard it will be to transfer those items...maybe next year.

Wish me luck, and let me know how much crap I have to remove to get the head off.

Cheers

Paul

Hi Paul,

Sorry to hear what happened to your engine. Not to worry though because it sounds like you're on the right track to getting it fixed.

Swapping out a head really isn't that hard, just a few hours on it and you should have the old one off. It'll be easiest for you if you take the intake and exhaust manifolds off as you go. The exhaust manifold is easy enough, as long as the bolts haven't seized too much. The intake manifold is a bit of trick as the bolts to undo it are hard to get to. Start by taking off the intake plenum and throttle body and get any wires and hoses out of the way so that you have a clear view of what's needed. You will also probably need to remove the injector wires and harness to get enough space that you can remove the lower set of intake manifold nuts. One trick with the intake manifold is that it is actually bolted in a few places on the bottom. You'll need to get under the car, or at least have some very flexible arms to get at the (2??) bolts that fasten it on the underside of the intake runners. You'll have some water lines to move about as well. Once this is all done, you should have no trouble removing the intake manifold. After that, it's a simple matter of taking the distributor and thermo housing off to complete the job.

When you take everything off, be EXTRA careful not to lose any of the oil line guides that fit into the block. Also be sure not to harm/lose the oil pisser that is in the middle on the firewall side of the engine block. You'll see it when you get everything apart. In short, take your time. oh, and you'll probably need a new head gasket.

Reassembly is easy enough as well. The only major thing you'll need to pay attention to is that you have the correct torque value and torquing sequence for the head bolts. I believe this is indicated in the manual you have, but if you need help, let me know and I'm sure I have it written down somewhere. If you don't have a torque wrench, now would be a good time to get one.

Make sense?

Hey spffyGuido,

Thanks for all. Yes, I have several torque wrenches and gear wrenches and little doodads for making wrenching a bit easier. Okay on the sequnce of removal on the intake. Thanks. I have all the top nuts off already (easy) it was the bottom nuts I was worried about. All the exhaust manifold nuts came off easy peasy but it's the header to pipe connection I am having a time with. Do you remove the bracket to the block, or the 2 or 3 bolts holding the header to the bracket? Picking up the doner car on Friday or Sat. so should have it running by Monday....(hopefully)

Yup, head gasket for sure, maybe valve seals. I priced out the head set kit at Lordco and OUCH!!! $360 retail, but even with my 50% off it's a stinger. I am going to try to start the doner engine before I dismantle to make sure everything is in order. Getting key made this week for it.

Thanks for all your help. I have a trip to Edmonton to make soon and want to take my Prelude as my F-250 deisel gets 15MPG and the Honda about 30-35 on the highway. Where in Alta are you? May have tome to stop in and show you my ride (not much to look at though).

Cheers

Paul

You can do either, but you'll probably have an easier time detaching the bracket from the block. Not too sure, as las time I did this, I just disconnected the exhaust manifold from the down-pipe and pulled it right out, so I must have left the bracket connected to the block. Do what you can, and even take advantage of the flex in the flex-pipe if you have to.

Post some pictures of your lude up in the Just For Fun forum if you want. There's a Prelude Pictures thread there.