Team Integra Forums banner
1 - 9 of 9 Posts

·
Registered
Joined
·
73 Posts
Discussion Starter · #1 ·
Im kinda stumped on this one. at 1500 rpm's my b18c1 surges no matter the condition. hot, cold, in neutral parked, and in every single gear. I have spent $25 on brake clean from autozone looking for a vacuum leak plus a DIY smoker. I have brand new sensors as far as AFR would be related. Im kinda stumped. This is on a 2000 gs-r thats all stock except short ram, headers, exhaust, and its got a OBD1 P72 instead of the OBD2.
 

·
Registered
Joined
·
73 Posts
Discussion Starter · #3 ·
Did you check your IACV for cleaning or check the TPS to make sure it has correct voltage?
I replaced the TPS a while before this started happening. It reads .48 at idle and 4.5 at WoT with the 5v on red wire i believe. I even went and swapped the TPS with a new one and it still does it. The IACV is also a brand new autozone unit, i had some idle hunting so i replaced it and that went away with the IACV. I have used a pressure bleeder and also bled the coolant from cold to hot with the heater on max twice as well. I learned a lot with the idle hunting issue but this is crazy. I have also searched high and low about this issue and seen numerous posts but none of them have a answer besides something i have already checked. The engine literally has entirely new sensors, full ignition system from plugs to distributor and even the ignition switch wiring which powers the dizzy. I forgot to mention that it started a bit after i put the OBD1 ecu in but i cant say its the ecu because the TPS had a huge dead spot around 1500 and i replaced it after the ecu. My obd2 ecu is burnt up and wont allow the car to really drive but when i plugged it up to check if it would rpm hunt at 1500 it still did. Im literally stumped which doesnt happen hardly ever.
 

·
Registered
Joined
·
73 Posts
Discussion Starter · #4 ·
Incase someone finds this and has the same issue. It ended up being IACV transistor in the ecu had failed. replaced it with a used one out of another obd1 ecu and now the issue is gone. the location differs depending on ecu
 

·
Registered
Joined
·
73 Posts
Discussion Starter · #6 ·
It was easy in my situation, the transistor was visibly burnt up. I read somewhere that it can happen from switching the IAT, Power steering pressure switch, and/or the IACV plugs with each other. Considering it was a obd1 p72 that i got for $150 im sure the previous owner did something and damaged it. nowadays a decent obd1 p72 goes for a minimum of $400 and i have seen some units being sold for $700+.
 

·
Registered
Joined
·
73 Posts
Discussion Starter · #8 ·
How did you narrow it down to that component?
right before i figured it out i had tested every wire involved in the circuit and tried 3 different IACV's. Somewhere i came across a list of IACV components within a obd1 p72 ecu. in my case there was visible discoloration around that transistor. it was a little luck but i cannibalized a old p05 and swapped them out which fixed it. are you having a issue similar to mine?
 

·
Registered
Joined
·
2 Posts
right before i figured it out i had tested every wire involved in the circuit and tried 3 different IACV's. Somewhere i came across a list of IACV components within a obd1 p72 ecu. in my case there was visible discoloration around that transistor. it was a little luck but i cannibalized a old p05 and swapped them out which fixed it. are you having a issue similar to mine?
sorry for the late reply, but not any more. My unusual rpm surge was due to a bad (new out of the box) distributor and some old spark plugs. Now I'm dealing with a p0170 and p0171 code with misfiring when the engine is cold (not started for a couple of hours).
 
1 - 9 of 9 Posts
Top