OBD1

Third Generation Honda Prelude topics

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buckybwhiplash
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OBD1

Post by buckybwhiplash »

Are all B20A5's an OBD0? Looking up parts online I noticed that some 1991 Prelude came B20A5.

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spiffyguido
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Re: OBD1

Post by spiffyguido »

Yes, all B20A5s should be OBD0 and the engine was offered through to the end of the 3rd generation Prelude's run. The OBD1 engine is the B21A1.

Here's a breakdown:

B20A3: OBD0 (PK1)
B20A5: OBD0 (PK2)
B20A7: OBD0
B20A9: OBD1
B21A1: OBD1 (PK3)

buckybwhiplash
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Re: OBD1

Post by buckybwhiplash »

Engine is installed and it immediately threw the check engine light. The idle fluctuates from 600 to 1500 and I double checked to make sure everything was hooked up and it is, and my question spiffy is I used the cyl sensor and distributer from the B20A5 could that be my problem? I haven't retreived the engine codes yet so I'm unclear what the problem is.
Thanks

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spiffyguido
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Re: OBD1

Post by spiffyguido »

Not sure about the cyl sensor. Let's start by seeing what the error codes are.

buckybwhiplash
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Re: OBD1

Post by buckybwhiplash »

It's a code 6 which is the coolant temp sensor. I see one switch and two sensors on the thermostat housing and there was one other at the bottom of the radiator. I looked up there are two and autozone only lists one as available.

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spiffyguido
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Re: OBD1

Post by spiffyguido »

In my experience, a code 6 has always stemmed from the sensor in the thermostat housing. These wear out with age, so I'm not surprised that you are having trouble. It will affect your idle and make the car difficult to start when hot.

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spiffyguido
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Re: OBD1

Post by spiffyguido »

There's some chatter about the ECT sensor in this thread: viewtopic.php?f=4&t=5005

Might help.

buckybwhiplash
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Re: OBD1

Post by buckybwhiplash »

Do you know what the OEM part number is for a VSS and EGR valve w/ a B21A1 engine? I've looked through several online sources and no luck on either and that should cure the rest of my check engine light issues. And last but not least can the IAC vavle be cleaned? I narrowed my idle fluctuaton issue to that.

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spiffyguido
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Re: OBD1

Post by spiffyguido »

The OEM part numbers are easy to find using the parts database at http://www.hondaautomotiveparts.com" rel="nofollow" target="_blank

If your IAC valve is causing a fluctuating idle (and they often do), it may be because the plunger inside the valve has come unscrewed. To fix this, just take the cap off the IAC valve (two screws) and then use a large flathead screwdriver to thread the plunger back down onto its shaft. In many cases this will resolve the problem. If it doesn't the valve often has to be replaced.

buckybwhiplash
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Re: OBD1

Post by buckybwhiplash »

I want to make sure it's the IAC valve before I replace it. I did check it and the screw is tight, and didn't cure anything when I unscrewed it and then bottomed the screw again. What it is doing is, if I'm driving it at low speed and have my engine speed between 1000 & 1500 if i pull my foot off the RPM's jump about 500RPM only for a second and makes the car lunge forward or if I have the clutch in just jumps the RPMs. Now, I do have a VSS & EGR issue and the parts are on order for a check engine light problem, I just not really up to replacing something that isn't the issue because I've never had a code for the IAC valve.
Thanks again
Not too bad for $900, but its the $800 later in parts not including my labor.
Not too bad for $900, but its the $800 later in parts not including my labor.
I guess it's a nice enough car to save from the scrap pile

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spiffyguido
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Re: OBD1

Post by spiffyguido »

Woooahhh! Your 'lude is hot hot hot! Not an original color, but it looks like it is in really good shape. We're definitely going to need to see some more pics.

As for your engine troubles, I think you've taken a wise path by choosing to resolve the issues with the other sensors first. After you get them replaced, we can guide you on how to resolve the idle issue.

buckybwhiplash
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Re: OBD1

Post by buckybwhiplash »

Do you know if someone makes different ring and pinion gears for this trans? I was wanting to lower the ratio for better topend and fuel economy while commuting back and forth to work.

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spiffyguido
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Re: OBD1

Post by spiffyguido »

The B20A5 tranny has longer gears than the B21A1 tranny. Which tranny are you using right now?

buckybwhiplash
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Re: OBD1

Post by buckybwhiplash »

mine is the stock one for the B21A1.

On a differnt note. I'm looking at another prelude minus the engine and trans and I have a 1.6L TDI engine gathering dust. I helped a friend put one in a Toyota pickup a few months ago but we had an abundant of gears we could select from, and we're able to get the engine RPM's down to 1700 @ 75MPH. Now he's getting 32MPG with a 4X4 truck with good useable power! If I could use the using the stock trans it would make life a lot easier. If I didn't hate VW's so much I'd just buy a TDI and be done with it, but my last experience with the electrical, interior (and no problems with the engine), and how could I forget the transaxle issues. Those Germans make a bullet proof motor, but the rest is absolute JUNK. And since I’ve had this 91 up and running for a couple of weeks, I love it. The handling, comfort, lack of road noise, and I would find it absolutely cool to have a prelude that’s getting over 40MPG that is still relatively quick. I could shove a VW transaxle in there but I’d rather not butcher anything to get it to fit and line up right. To use the stock transaxle I would need some super low (300's or 310's) to make this work.

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spiffyguido
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Re: OBD1

Post by spiffyguido »

Given your situation, I would seriously consider slotting a B20A5 tranny in. We can do a splash of research, but as far as I know it should slot right up. The bell housing will mate up for sure. I think the speed sensor will have to be swapped, and that's it. I can't remember the exact ratios (we can look them up) but the gears on the B20A5 are definitely longer. The tranny on the B21A1 was designed for sport driving, so the gears are short to allow for hard acceleration.

I used to drive my car on the highway a lot and thought about doing the same thing many times to save a bit on gas. It never seems right to be doing 4000rpm on the highway.

I agree with you on the VW stuff. My experience has been the same. I don't think the Germans have quite figured out how to work with electrical bits yet.



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