My 90 Civic Runs like a charm, and takes off like a raped ape. It has a b20b engine, and when downshifting or upshifting when I let off the gas to press the clutch, the car backfires sometimes. It does not happen all the time, but it does occur a lot. Sometimes, just letting off the gas while in gear, to drift slower, it backfires as well.

Friend said I should try some "hotter" plugs because it may not be burning all of the fuel in the cyl. Not sure wha is in there already so this could be mute.

I found the ECU and I have NO idea what kind it is or what its for originally, but it does have a red LED light and a few wires are just sitting (ill have to get pictures when it stops raining)

Any places I should look first?

 

It should not have an ECU that's OBD0 unless that ECU has been chipped and the car has been tuned. More than likely, it's a stock Integra ECU. That would probably cause the motor to run lean as it's not compensating for the B20B's larger displacement. If you want the most from your car, convert to OBD1 and get properly tuned.

 

How do I tell what ECU it is, I didnt see a number on it, and how do I tell if its OBD1?

 

red led light is a dead givaway that it is obd0. another indicator is the color of the ecu plugs. two black and one clearish plugs are obd0, obd1/2 have gray plugs. the wires just chillin are probably left over from an mpfi swap

 

Here is links to the Images of the ECU.

They are too big to post here,

https://dl.dropboxusercontent.com/u/...2017.59.31.jpg

https://dl.dropboxusercontent.com/u/...2017.58.44.jpg

https://dl.dropboxusercontent.com/u/...2017.58.58.jpg

 

yup you are obd0. looks like the wires you are talking about are for the extra injectors and the crank angle sensor that has to be added when doing a dpfi-mpfi swap.

as far as your question goes, i would buy just stock ngk coppers for a b20. also, when was the last time a tune up was done? and is your exhaust in good condition? exhaust leaks can cause popping under decel.

 

My Exhaust is new, everything from Header back, The Air Filter is new, I have not done a tune up because the guy said it had new plugs in it and I took his word for it. I have been doing some reading and looking online and saw the new E3 plugs for the Hondas and reviews and claims, Seems EVERY sparkplug has some kind of claim for difference and more power, better fuel economy, better combustion, etc. This is a daily driver, that I have fun with sometimes. I am thinking I am going to get the NGK standard, and one step hotter, and try the normal ones, and then if it still does it, then try hotter. I have no idea how this car was tuned but I am assuming it was for just getting it.......

 

if u get too hot of a plug u will burn a whole in the top of ur piston

 

Yep, that's an OBD0 PR4 ecu for an Integra LS. If you pull the screws from the top, I'm sure you'll find that it hasn't been chipped. Now the question is, what injectors were used for the swap? And is a resistor box in use? If obd0 LS injectors were used, you need the resistor box. If the B20 injectors were used, the resistor box isn't needed. Unfortunately, not much is available tuning wise for OBD0. Again, I'll suggest you convert to OBD1 and get properly tuned so you can enjoy the car fully.

 

Ok, Ill check that out. My valves are beginning to rattle and I believe it may have something to do with it, So maybe I may just look into a new Valvetrain, or even a new Head completely.
Spark plugs helped but it is still popping some. I need to double check for a leak int he exhaust as well, I dont see one or feel one at Idle, but these are not happening at idle, so maybe there is a pressure leak somewhere. I have an idea that if it is a leak it may be at the bottom of the header where it goes to the cat.