O2 Sensor/ Turbo Setup - - Honda Prelude Forum

FOXxX · 08-30-2011, 07:11 PM

Ok so I am completely new to the world of boosting and have been doing some searching on the topic of O2 sensors and turbo's but nothing has been coming up. I understand how it is supposed to work but I cannot find a significant answer on the question. Here is the story.

I've come across a 2000 prelude That WAS well built - I think. It was pushing 415whp's on the dyno and then the OG driver popped the top on the motor. Since, the motor has been replaced with a JDM h22a (which was the original motor that was built previously) and has kept the turbo setup but no internal mods (I think) have been done to this motor. The ecu was kept from the old motor setup and has been replaced with a stock ecu to crank and move from one spot to another. This setup has me all confused.

I know O2 sensors are to be installed on the exhaust. Without them the ecu knows nothing of AFR's or how to even regulate the fuel. The exhaust is the same exhaust used on the recent motor and has no O2 sensors on it - and I think this may be the cause of the original motor pop.

Where do the O2 sensors go or should there be any on the system at all?

FOXxX · 09-01-2011, 01:50 PM

Ok so I think I've got it - after hours of digging... yes you do need O2 sensors. If you dont have O2 sensors in line... The computer shows 0 Volts and thinks you are running lean so it saturates the cylinders. Now digging through the repair manual... Does this thing require two O2's?

usmcmarc · 09-01-2011, 02:26 PM

Yes...One pre-cat and one post-cat.

FOXxX · 09-01-2011, 03:28 PM

Soo.. this lude has no cat. Since there is a turbo setup - how far down should the Cat be located?

bouckarooo · 09-01-2011, 03:58 PM

hold on hold on, so this engine has no internal mods done to block? and is going to be boosted? or jsut used for point a to point b kinda of thing?

if you are boosting you might want to consider installing wideband......

FOXxX · 09-01-2011, 04:49 PM

I've read that boosting up to 6 to 7 lbs on an un-modified jdm H22 is ok - am I missing something here? I want this to be a dd of some sort with mild gains. I'll have the block out this weekend and inspect it for any internal mods but I dont want to dig into this project and sink money I dont have. I did that in the jeep world already.

I already had my eye on a wb O2 but how is this incorporated in the ecu? I can use the standalone AEM wb but that doesn't do the engine any good. I want to get another ecu but haven't decided which one is for me...

bouckarooo · 09-01-2011, 06:40 PM

dear goodness, how are you going totuen the car if you ar not using an ecu that can utilyze a wideband? like your not goign o get far with a boosted engine and a stock ecu???

FOXxX · 09-01-2011, 09:29 PM

I'm def not saying I dont want to run stock ecu, im just saying I dont know which one I want to run... But until I do decide and have the cash... I just wanted to know why this turbo setup had no O2 sensors.

If I can't run a turbo on the setup I currently have then I will have to go NA until I can properly do it right.

wrathofshampoo · 09-07-2011, 06:41 AM

you need a chipped ecu to tune it anyway. no tune is more dangerous than not built motor. i run hondata 300 with a p28 ecu, wideband, no cat, you only need the 1 o2 sensor cause hondata is obd1.

FOXxX · 10-09-2011, 01:19 AM

Update - based upon recomendation - Engine was sleeved, new pistons, and rods installed. Picked up AEM ECU. Going to start putting it back together again and back to the original question... O2 sensor placement - How far down the exhaust should the O2 sensor be? I've read that if it is too close to the Manifold then its life span is short. I'm installing a WB for the AEM. Any suggestions?

This post may be better suited in the Forced Induction area if someone wants to move it...