help please!!!



#1
My name is Mike, I recently bought a 92 civic cx with the stock d15b7 and I'm having some issues with what I am trying to convince myself isnt the IACV. with the IACV plugged in the RPM's surge up and down, when i unplug it it seems to go away, until I give it a little gas. While driving the problem is almost unnoticeable until I let up on the gas, any possible ideas are greatly appreciated!
 

SGGilmo

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#3
Could also be something as simple as air in the cooling system. Have you or the previous owner changed the thermostat or water pump recently?

Also on a side note. If you have a stock CX then you should have a d16b8 not a b7 lol.
 

emerican

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#5
^ this
 
#6
Could be a number of things like any sensors, tps, map, o2, air change, it could be any of those, also the EGR valve might be dirty.
air change meaning iac? how do i check if its the map tps or egr?

are yo throwing any CEL codes?
check engine light is on but i dont have access to a code reader.

Could also be something as simple as air in the cooling system. Have you or the previous owner changed the thermostat or water pump recently?

Also on a side note. If you have a stock CX then you should have a d16b8 not a b7 lol.
the rad was replaced just before i bought it, and i have bled the coolant system
92 cx came with a d15b7 in canada.
 

SGGilmo

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#7
the rad was replaced just before i bought it, and i have bled the coolant system
92 cx came with a d15b7 in canada.
lol. didn't notice you were in Canada.
 
#8
i was just trying out a few other things and when i unplug the iac it doesnt go away just gets far less noticeable, when i unplug the O2 sensor it goes away completely.and it doesnt happen when the engine is cold, is it safe to say its because the ecu bypasses the O2 sensor during warm up and that is my problem?
 

SGGilmo

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#11
Yea need a code reader to check for problems with sensors, you local auto parts store should check it free & give you the codes so you can research the issues, o2 might be your issue though.
No code reader necessary. The car is obd1. All you have to do is jump the diag wire and turn the ignition to "ON" (don't start the car). The CEL will then flash the codes for you. However since you've unplugged a few things recently while running there will be a few codes saved up so you'll have to clear those by pulling the "back up" fuse under the hood for 30 sec or so. Then check for codes.
 
#12
No code reader necessary. The car is obd1. All you have to do is jump the diag wire and turn the ignition to "ON" (don't start the car). The CEL will then flash the codes for you. However since you've unplugged a few things recently while running there will be a few codes saved up so you'll have to clear those by pulling the "back up" fuse under the hood for 30 sec or so. Then check for codes.
i tried that and it just gave me a steady light that went away when i removed the wire.
 

SGGilmo

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#13
no led. there is a little t-pin plug on the passenger side tucked up next to the glove box. pull it down and then jump in with a paperclip. then turn the ignition to "on" (dont start the car) the cel (check engine light) will flash the codes to you. a long flash is 10 short flash is 1. like...... long-short-short-short would be code 13. ill get a pic of the location for you and a list of codes.
here you go. the arrow points to where the plug will be resting under the dash. there will be two plugs there. a 2-pin (circled) and a 3-pin (crossed out) you need the 2-pin.






Here is the list of codes.


0 Engine Control Module (ECM)
1 Heated Oxygen Sensor (HO2S)
3 Manifold Absolute Pressure (MAP Sensor)
4 Crankshaft Position (CKP Sensor)
6 Engine Coolant Temperature (ECT Sensor)
7 Throttle Position (TP Sensor)
8 Top Dead Center Position (TDC Sensor)
9 No. 1 Cylinder Position (CYP Sensor)
10 Intake Air Temperature (IAT Sensor)
13 Barometric Pressure (BARO Sensor)
14 Idle Air Control (IAC Valve)
15 Ignition Output Signal
16 Fuel Injector
17 Vehicle Speed Sensor (VSS)
20 Electrical Load Detector (ELD)
21 Variable Valve Timing & Valve Lift Electronic Control Solenoid Valve (VTEC Solenoid Valve)
22 Variable Valve Timing & Valve Lift Electronic Control Pressure Switch (VTEC Pressure Switch)
23 Knock Sensor (KS)
30 A/T FI Signal A
31 A/T FI Signal B
41 Heated Oxygen Sensor (HO2S) Heater
43 Fuel Supply System
yeah I quoted myself. What of it lol
 
#15
pulled the negative wire and the fuse for like 5 minutes, put it back on, ran the car til the CEL came on, turned it off and jumped the ecu cable and no change, still a steady light.
 

SGGilmo

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#16
what are you using to jump the wire with? tire different kinds of wire and paperclips. for some reason when i used a cheap paperclip (the ones that break after a couple bends) it wouldnt work. then i tried a better quality metal one and it worked fine. maybe try some speaker wire.
 
#18
finally F***ing figured it out! the guy i bought it off had his "mechanic" friend help him do a rebuild on the motor and apparently he is a retard cuz he had the wiring harness from the PCV going to the IACV and cut away the plastic wire cover things so i didnt notice earlier. now that that is solved and i know 100% it wasnt an improper air to fuel ratio i can put my AEM short ram back on.
thanks for the help everyone, keep an eye out for my build thread in the spring!!!
 

SGGilmo

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#19
Good deal man. Glad it was something simple.
 




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