1995 honda prelude- jdm h22 swap approximately 25k miles ago.

Heres the scenerio:
I can crank the car up, and it will idle with no check engine light.
Once i drive the car, the light will not come on until i hit a certain mph.
I think it about 35 to 40 mph when it lights up. It will do this every time.
If i cut the car off the light goes off. (ive tried to jump it before since the light just went off and it doesnt work.) I even drove the car until the light came on, pulled back to my house and put the car in 3rd and dumped the clutch so it would die hoping the light would stay on. But, that doesnt work either. I cant pull the code to see what my problem is and I hate staring at the check engine light. Does anyone else have any other ideas on how i can pull this code or what would be throwing a check engine light problem around 35 to 40 mph. The car drives fine and seems to have no power loss. IF there is power loss, its small enough that the butt dyno cant tell.

thanks,
-brad

 

20 views and not one opinion? lol i hope i explained the situation properly. if anyone needs any more of an explanation just let me know.

-brad

 

maybe the timming.

 

You need to try to jump it again because even I pulled a code with a bad knock sensor and that sensor will clear itself too. You can't just guess, you need to pull the code or find someone with a scanner to do it for you.

 

My guess will be an o2 sensor

 

Try it with a code scanner, it might pull something up; most auto stores will scan it for free. Could also be EGR, as that will only trigger once you're up into that mph range.

 

its obd 1- autozones etc... cant scan those to my knowledge. yeah, i didnt wanna guess at the problem either, thats why i was trying to pull the code to see what the deal was. ill look into the egr- thanks.

-brad

 

obd 1 clears when you turn off the car . you have to keep a jumper with you and before you shut the car off jump it . it will them flash you a number .. ususally it test the cat around 45 to 65 mph .. im gonna guess 2nd o2 . jump it when the lights on and pull the number then look it up .. good luck ..

 

idk if prelude has the same codes as eg civic but u need to find u code when it comes on

these r civic codes
1 O2A - Oxygen sensor #1
2 O2B - Oxygen sensor #2
3 MAP - manifold absolute pressure sensor
4 CKP - crank position sensor
5 MAP - manifold absolute pressure sensor
6 ECT - water temperature sensor
7 TPS - throttle position sensor
8 TDC - top dead center sensor
9 CYP - cylinder sensor
10 IAT - intake air temperature sensor
12 EGR - exhaust gas re circulation lift valve
13 BARO - atmospheric pressure sensor
14 IAC (EACV) - idle air control valve
15 Ignition output signal
16 Fuel injectors
17 VSS - speed sensor
19 Automatic transmission lockup control valve
20 Electrical load detector
21 VTEC spool solenoid valve
22 VTEC pressure valve
23 Knock sensor
30 Automatic transmission A signal
31 Automatic transmission B signal
36 traction control found on JDM ecu's
41 Primary oxygen sensor heater
43 Fuel supply system
45 Fuel system too rich or lean
48 LAF - lean air fuel sensor
54 CKF - crank fluctuation sensor
58 TDC sensor #2
61 Primary oxygen sensor
63 Secondary oxygen sensor
65 Secondary oxygen sensor heater
71 random misfire cylinder 1
72 random misfire cylinder 2
73 random misfire cylinder 3
74 random misfire cylinder 4

 

remember 1 faast blink =1
one long blink =10
soooo 3 fast blink and 2 long blinks = 23
which is ur knock sensor etc

 

With Honda OBD 2 the scanners can read the codes while driving real time. Not sure if it is the same with OBD 1 on Honda's though.

 

element600rr- i have pulled codes before. usually i turn car off but dont turn the key all the way back. This saves the codes and allows you to pull it. However, in this situation that doesnt work. I have had car parked for a few months and just now trying to figure out this issue again. I dont remember if i tried to jump it while the car was cranked, but i thought i did. I will try that and see, but i dont think that it'll work. thanks.

-brad

 

huh? no! either obd1 or obd2... there are two kinds of faults, hard fault an soft fault. A hard fault will stay on after you cycle the key, and a soft fault will erase ech time you cycle the key. otherwise known as a two trip monitor.
Sounds to me like its a transmission related code. I would look at your vss. but before you do that pull the code, just leave the car running if you have too.

 

Is your car a 5spd or auto?

 

its a 5 speed. ok the 2 types of codes makes sense. every other code i have pulled stayed on when then key was turned off. i will try to pull the code with the car running this weekend and see if that works. thanks

-brad

 

the ecu will store the codes until a number of key cycles or you pull the power to it. So you shouldn't have a problem jumpering the connection to get it to blink with the engine off.

 

prelude_h22 -normally i dont have a problem pulling the codes, but this situation is different. Everytime i turn the key off, the check engine light goes off. it does not stay on like it usually does when i have used the jumper method in the past. i'm going try to do the jumper to pull the code while the car is running this weekend and see if that will work.

-brad

 

You could even try the auto parts store, even though they use a generic scanner they might have the 3 pin adapter for OBD1, the 3 pin plug is blue like the 2 pin jumper and is in the same place.

 

not with obd1. some obd2 ECU’s will store a code, but that also depends on what the code is, most Emission codes will store, and many codes take a few starts for the monitors to set before any code is thrown.

Careful with the "I think" advice.