After nine years of construction, the completed Prelude-powered, carbon shell, mid-engine Mini was taken out for a very short drive. As some of you may recall I had VTEC issues about a year ago, and many here helped diagnose it. The symptom back then was the engine would fall flat on its face at 5200rpm, backfiring, and sounding very sad. That is fixed, appearing to be excessive exhaust back pressure.

I assumed this drive would be uneventful but that's not how it went. Decided to drive around the neighborhood to warm everything up. Everything seemed fine so I ventured out onto a real street for only one block, getting up to perhaps 45mph When I turned back into the neighborhood side streets, heading back home, engine issues surfaced again... "Now what", I thought. The engine acts like it's running on 2-3 cylinders, but only between approximately 3000 - 4500rpm. It idled okay, but not with any kind of load on it. However if I pushed it through that region it pops out the high side pulling strong. The stock P13 ECU says I have problems with the EGR and electrical load detection, which is expected since I have neither. I've been assured neither cause any runnability issues. Plus, the car ran fine up to that point, my guess is the ECU switched modes once coolant temp came up. Other engine mods are a blocked off IACV and... whatever the other inlet valve is.

It was too late to do any more testing today but I'm annoyed and perplexed I'm not out of the woods yet. Any suggestions? I'll put up a video tomorrow showing the problem.

 

sorry don't have an answer for your question but this is the first time i am seeing your car - pretty sick

 

I was beginning to wonder how your project was going.

I really don't know what to say it could be any # of things (probably fuel, do you have a wideband or even a narrowband O2 gauge?), but I would suggest driving it some more, so that if it resurfaces we can better diagnose it. It may just be some little bug that will work itself out after some use. My first Prelude did something similar a couple times after I did my first swap, but it was very random & went away.

 

Yeah that's what I'm hoping too... I know I haven't given you guys much to go on, I guess it's my frustration showing through. So close to being really done and now this. I'm not even sure where to start. Like you said, I'll drive it some more and "hope" it goes away...

 

Hmm, that sounds like an electrical/sensor problem. The ECU does run a little rich until the ECT sensor shows a warm engine. You have the O2 sensor hooked up, right? I think the engine might run open loop until things are warm, and if the sensor is bad or wired wrong it could be trying to adjust the mixture based on bad data. The easiest way I've found to diagnose these kinds of problems is to datalog the ECU. This lets you see all the values the sensors are putting out so you can quickly tell if one of them is bad. If you don't have this ability or can't borrow it, then I would suggest checking/swapping sensors, or maybe the ECU itself (you have a chipped P28/72 somewhere, right?). I would start with MAP, TPS, and ECT. The real problem is if the sensor is only intermittently bad, then you can go in circles checking things. This is why datalogging is handy, because you can catch things in the act. We spent a lot of time puling our hair out trying to diagnose my uncle's intermittently stalling dodge (french pronunciation) until we finally hooked a volt meter up to different sensors and drove around. It turned out the crank position sensor would flake out once in a while. Anyway, if the problem persists, try resetting the ECU. If this fixes it temporarily, then I would look into the O2 sensor.

Hopefully it was just a little water in the fuel or something. Good luck.

 

Oh, one more thought... Your crank position signal wires are shielded, right?

 

Thanks flyrod.
Yes the signals are shielded, but if that was the cause it should have the problem all the time I'd expect.

I do not have the ability to log sensors. I do have a multimeter and can have it display readings while driving. One big perk of having all the signals spread out on terminal blocks! http://www.kimini.com/Diaries/...d.jpg

I do have a P72 but haven't used it. The idea is/was, to make baby steps, one change at a time, that sort of thing.

Yes I have the O2 sensor hooked up. I have a cheezy O2 meter connected and I see the mix sweeping back and forth.

I plan to drive it more today. I'll start with the engine cold and see if it runs normally (no missing.) Then after it warms up see if the missing comes back, just to see if the issue is stable and repeatable. If and when the problem returns I'll reset the ECU and see if it "forgets" the problem for a while.

This is the longest I've driven it, maybe 15 minutes, so these problems I'm finding may have been around a long time...

Since this is the longest it's been running, it's the first time I've seen the (expected) EGR MIL error. I want to reconfirm with you guys that this error does *not* cause a limp-home mode. BTW, does that even exist in the P13? Come to think of it I don't think I've ever read of a H22A1 Prelude ever being in limp-mode. Is this just an urban legend?

Anyhow, thanks for the help, this is really frustrating to be so close...

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by kb58 &raquo;</TD></TR><TR><TD CLASS="quote"> I want to reconfirm with you guys that this error does *not* cause a limp-home mode. BTW, does that even exist in the P13? Come to think of it I don't think I've ever read of a H22A1 Prelude ever being in limp-mode. Is this just an urban legend?</TD></TR></TABLE>

I can't go check for you right now (I ditched the P13 years ago), but I'm 95% sure that removing the EGR will only give you a light. The P13 does have a limp mode. Most OBD1 honda ECUs have 2 processors. You can physically remove the ROM for the primary processor and the engine will still run on the backup processor (but probably not very well, hence "limp"). Limp mode is usually caused by using an invalid ROM or removing a critical sensor, which will cause the ECU to use its backup processor.

 

Is a part throttle issue or a WOT issue? Is your O2 sensor a Wideband one? Becasue of the horribly extensive modifications to your exhaust system (you effectively removed like 10' of cat/resonator/muffler and piping) your A/F could be swinging all over the place. It could be really lean now without all that restriction. Also how restricted is your supertrapp muffler? That could screw with the back pressure too. I ask because I have seen some pretty wild swings in A/F ratio localized to pretty short rpm bands with high performance headers, even with full exhausts.

If you have a chipped P72 with stock fuel tables for the H22 then what could it hurt to spend the 2 minutes to swap it out just for a quick reality check? If you get the same results out of two different computers then you can at least localize the issues to the engine bay and not the computer.

It is nice that you have the car painted, insured, registered and on the road. I hope you figure it out quick.

Pirate

 

It was at part throttle. O2 sensor is stock Honda. You are right about the exhaust, who knows what I've got on my hands, probably about 100x more efficient then stock. Still, it should be consistant, good or bad. I resisted changing the ECU in order to see if thing were the same this morning... and it ran perfectly . You guys can check out the video at: http://www.kimini.com/Video/12...t.wmv. Granted there's no excitement, but that's not what I want right now, I want consistency. So I'll continue with test laps to build confidence.

But you're right about tuning. Once I feel safe to drive further I'll take it to someone who can tune a socketed P72. Anyone in Northern San Diego county do this kind of work?

Oh and FWIW, I haven't even floored it yet

 

Looks like a blast to drive, i hope you get your drivability problem diagnosed.

 

Thanks. What's odd, in a good way, is how far back I sit. If I look out the side, I'm looking though the back side windows. Kinda cool actually.

 

Ah - i would love to own that.

 

That can be arranged...

 

You're going to sell it?!!! How could you?
or are you going to create kits for people to make one themselves?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by kb58 &raquo;</TD></TR><TR><TD CLASS="quote">You guys can check out the video at: http://www.kimini.com/Video/12...t.wmv. </TD></TR></TABLE>

I can't see the video. It is in some proprietary format... (SmallandSoft format? ) I get audio and some error messages. It sounds real good though.

Pirate

 

No, this is the only one. However, I'm not in love with it, it's is an excellent learning experience, but if someone made the $right$ offer, I'd let it go. Why? Because building a car like this gives me ideas about what I'd like to do next but I have neither the room nor money to build another car. For that to happen this one would have to go.

That said, it'll be several years before I'm ready to do another car anyway. In the meantime this will be a blast to drive. Don't get me wrong, I very much enjoy driving it already, but I'm also objective enough to see the big picture.


Modified by kb58 at 5:51 PM 12/27/2005

 

I haven't been able to find it listed on your site. Do you know what it weighs, or have an estimate?

 

It was accurately weighed about a year ago, but didn't include a few items at the time, so it's about 1550lbs empty.

This is the first time I've driven anything this light. The best analogy I can think of is when you guys turbo your cars. Say you double your torque to 300ft-lbs, that's the about same effect I have, by essentially cutting the weight of the car in half.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by PirateMcFred &raquo;</TD></TR><TR><TD CLASS="quote">

I can't see the video. It is in some proprietary format... (SmallandSoft format? ) I get audio and some error messages. It sounds real good though.

Pirate</TD></TR></TABLE>

Works fine for me - I tested it by clicking on your link above and it worked, and it came up in Windows Media Player as a .wmv formated file. Is it working for other people?


Modified by kb58 at 6:21 PM 12/27/2005

 

yep windows media

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by kb58 &raquo;</TD></TR><TR><TD CLASS="quote">it came up in Windows Media Player as a .wmv formated file.</TD></TR></TABLE>

Oh. Yeah, that would explain it. I have a Mac.

Pirate

 

You can download Windows Media Player onto your Mac. I have Quicktime & Media player on mine.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by kb58 &raquo;</TD></TR><TR><TD CLASS="quote">But you're right about tuning. Once I feel safe to drive further I'll take it to someone who can tune a socketed P72. Anyone in Northern San Diego county do this kind of work? </TD></TR></TABLE>

I might know someone

Are the only codes you are getting for EGR and ELD?

Do you have pictures of the header and o2 bung location?

 

Ha! Hi Jim,

Yes, ELD and EGR errors only.

Here's the header:
http://www.kimini.com/Diaries/...r.JPG

And here it is in place with the O2 bung:
http://www.kimini.com/Diaries/...e.JPG

Of course the picture above is looking *through* the engine bulkhead, which is installed now so I can't get to it from the front. While the engine under-tray is removable, it's very involved to get out. That leaves getting at it from above, doable, but not something I want to do everyday. However, for tuning, I'll deal with it.

Also be aware I do not have a passenger seat in place, and even if I did, I won't have belts...

(I sent you an e-mail by the way...)