I have a 90 Integra ls, and its throwing a code 43 fuel supply system. Code only comes on somtimes, mostly when car is idle for 5 to 10 minutes. But car idles really low and rough every morning when i start it up, then when it warms up it idles at 1500rpm and somtimes at 2k rpm and somtimes at 1k rpm. idle is not very steady. there was one time where i dropped to 3rd gear in the freeway and pushed it to 6500rpm then as soon as i put it into neutral the idle dropps and car just died. I have searched and changed some things on the motor. I have already changed the o2 sensor,fuel pressure regulater,fuel filter, injectors, checked timing, changed my distributer, spark plugs and wires, Idle air control valve, fitv, changed my pcv valve, also have tried reseting my ecu. but no luck. I have read most the post on here and the only thing i have on mind is either fuel pump, bad ecu, or fuel relay. i have no access to any fuel pressure gauge. im just getting annoyed of changing parts that aren’t solving the issue. if anyone can give me some advice i’d really appreciate it. thanks-
i had a 91 rs that threw that code, the wire to the o2 sensor was pinched and messed up, i was pretty sure that was causing the code but i never fixed it. my friend owns the car now and we will probably fix that sometime soon so i’ll keep u posted
im in the same boat as you, light keeps coming on randomly and i cant figure out why (also replaced all those parts when rebuilding the engine). When the engine was still stock, I kept burning exhaust valves in cylinder 4 and can’t help but think whatever is triggering the light was causing the burnt valves. I just rebuilt the engine and im getting that light every once in a while so i don’t want to drive the car till i get it figured out. If anyone has any ideas please help us both:rockon:
Sounds like a bad injector with your problem.
To the OP. looks like youve got about every base covered. I would do like fastasleep mentions and check for any pinched or frayed wires.
I also replace the map sensor and put on a used throttle body including the tps sensor. i cleaned it out before putting it on also. i guess what i should do next is have someone test my fuel pressure and also do a compression test. thanks for replying guys!
nope, injector was replaced after the first valve burnt
and it still burnt another one. maybe a pinched or grounding wire:think:
IDK
old skool Maybe i missed it on your original post, but i would definatltly to that F/P test, maybe its time a for a new pump.
G/L
Hey there bud,
my teg was throwing the same code.(43)
I immediately changed the fuel filter and still no fix. I changed the injectors and fuel rail and same thing… i upgraded my fuel pump to a 255 lph walbro (bbk) and then the code still came on. I put a different ecu in it and it flashed 02 sensor. I changed it and kept the other pr4 ecu in it and the problem has dissapeared.
hope that helps a bit.
yep in the same boat as you guys… that shiet comes on randomly, like during a 5 min idle or when other codes pop-up… getting annoying… if u guys get a fix lmk…
yeah, i got a extra ecu from a guy i know, he said i can try to install to see if it helps but he said the ecu probably isnt in a good shape. so i plugged it in and as soon as i start up the car, the engine light came on, and the red led light on the ecu stays on, doesnt blank or anything, just stays on. so im assuming the ecu i got from the guy is a faulty ecu. and i still need to find a good one to really test it out. but those obd0 integra ecu are really hard to find. But its so weird, i drove 2 hours on the freeway going up north the other day and the way back. i had no problem at all with the engine light coming on. it sucks that i cant find a ecu locally to test it out first before purchasing. oh yeah, i have one question. can i use any obd0 honda ecu to plugg in my car? will it work?
HEY COOL! i have the same problem too! we should be friends!
so… has anyone found a fix for this problem yet???
GEEZ! i have the same problem on my 93 integra with a JDM B18c. ever since i swaped the engine 
but my check engine light NEVER comes on at idle… only when i am randomly driving… im driving the speed limit, nothing crazy and it comes on sometimes… today i drove quite a bit… even hit vtec a few times… 
but the light did NOT come on! i changed the fuel filter… i dont think my fuel pump is messed up… it worked perfect on my B18a… new O2 sensor… whats up guys? i am a bit worried… what if the engine is not getting enough fuel!? i worked so hard for the money to swap in my engine… not to mention the LONG time it took me to swap it in…
i feel ya. i think it might be a vacume line, or mabe a fuel line, idk. try cleaning your fuel injectors or getting new ones. thats what im about to do.
i think the code 43 is making my car run a little rich.
Yea, i had the same problem with my b17, my gas tank has a leak at the seam, thought maybe thats what it was, but i took it to a local shop and had him look up the code, and from a actuall Honda service manual, he said my o2 was bad. so i went out and got a used good one from my buddy and i put it in my Password test pipe, no light since. But i have had a minor missfire issuse when i try to baby it since that light came on, now with no codes, it still does, gunna change plugs and wires and see if it fixes it, if it does then my bet is all it was, was the o2 gone bad, hope this helps a little bit for the guys that can’t get anything to work.
i had the same problem when i swaped in my b20 code 43 only came on when driving on the highway couldn’t figure it out so i left it as is but now im in the process of rebuilding my teg and when i took the motor out i realized that one of the wires of my 4 wire o2 was not clipped in so i think that was my problem but like i said i took the motor out so i never got a chance to repair the plug and see the outcome but for the most part i think code 43 has to do wit the 02
YEA! my light comes on when im on the free way. im going to have to look at my 02 censor wires. i have a bosch o2 censor, are those good?? i think it might be tost.
yeah, there pretty good, thats what i replaced mine with and seems to be working just fine. My buddy is running one on his b16 turbo and has had it for almost four years w no probs
i think when i put in an additive, it messed up the censor.
What did you put add? octane booster, fuel injector cleaner ect? that shouldnt have messed with you o2. could be wrong but doesnt seam like something like that would cause an o2 to fail…