Hey I just purchased a 00 SI with a JDM type R swap (B18C). Not too sure on the history and it was running a bit rough so I started going through the car. I changed the distributor cap and rotor which was toast. I also changed the spark plugs and a few other things that were wrong and some cheezy things done with the swap.

The car runs strong now and pulls hard but below 2500 (im guessing closed loop) the car will hesitate between gears. Its hard to explaing but the car will also pop between gears. It makes it tricky starting off from a light because it kind of loses power for a second and then kicking in.

This is only when you take your foot off the gas and then apply it again. Other than that the car runs fine and accelerates smoothly. Idle is perfect at 850rpm and no surging either.

One thing retarted I found and wanted to confirm with you guys was for some reason the secondary O2 sensor was put before the cat? I thought this may be contributing to my problem because its sending a rich signal to the computer when it should be alot cleaner with the cat...therefore leaning out my partial throttle mix?

Has anyone had a similar stupid problem?

Sorry for the long post but any help would be greatly appreciated.

 

The second o2 sensor doesn't affect the air/fuel ratio, it just confirms that the cat is working or not, only the first o2 sensor actually changes anything

 

Sounds like your timing is off.. Check it I had the same problem and my intake side was off by a tooth.

Gl

 

check the primary o2 the second one doesnt change anything as he said before

 

Tried swapping the primary O2 sensor with another one and still had the exact same probelm. The car runs perfectly when its cold and runs great at higher rpm just down low it kind of pops and hesitates briefly when shifting between gears. It accelerates smoothly...?

Would my car still run fine at high rpm if the timing skipped a tooth?

 

hmm good question my guess would be no, if it skipped a tooth it wouldnt run good at any rpm. but its worth a shot, maybe you might fix something you didnt even know was broken lol

 

hmm would the secondary o2 sensor being mounted before the cat have anything to do with my problem though?

 

no it would not, there's a chance the cat could be clogged though.

Get a digital multimeter and test your TPS, it should be a 5 volt reference seeing nearly 5 volts at WOT and obviously the reverse at closed throttle. also make sure the plugs for the TPS and the MAP are not switched, as that can be a common mistake for first time swappers.

 

alright ill try that in a few minutes to see if that works. One more question...The guy who had the car before has a jumper harness between the ecu and the oem harness. Is this necessary? The jumper harness utilizes the smallest plug on the ecu and the oem harness does not have the small plug. I'll take a picture in a bit but do I need this additional jumper harness? Or can I just plug my oem SI harness into the jdm p73 ecu?

 

Dunno, but worth checking. Got adjustable gears? Make sure they're set right along with ignition timing.

 

checked cam gears and they are both properly alighned. I dont have a timing light to check ignition timing though. I tried swapping the map and tps sensor wires and the car ran like crap so I switched them back and it ran alright again.

 

checked throttle positions sensor and its reading .5v with closed throttle and 4.xxv at wot. any other suggestions?

 

i would take it to your local tuner and have them change the base map for ya and see if that works. every engine is different and with the jumper harness you need that. but make sure the dizzy is in the right pos. first.

 

the more i think about it you mentioned the exhaust popping, i assume a backfire. drop the exhaust down and take a look at the cat, hopefully it isn't too rusted to get apart.

when you hold the cat up to the light and look through it you should see about a nickel sized circle of light no matter which end you look through, if you don't see the light then this could very well be your problem. whether you get a hammer and prybar and hollow it out or replace it is up to you at that point.

 

OP: how does your car idle when your first start it up? I was having the same exact problem with my B18 swap, turned out to be a clogged cat.