need help malfuction light fail when taken to a smog shop

[Roger_cha]

yea i have a 91 240sx with a ka24de.... when i took ti to a smog shop they said that my engine check light didnt turn on when you turn on the car not start then engine but turn on the car..... they said that maybe my bulb is gone but i check it and the bulb is good.... i took out the ecu and try to do a self diagnose but the light wont turn on even on the engine check light or the ecu light...... can it be my ecu that is bad..... can anyone give me any hints..... that will be helpfull.... thanks

[Roger_cha]

and ya 1 more thing the car didnt pass smog because they said that it is gross polluted they said that something is makeing my egr valve open and closing??? can anyone give me any hints thanks....

[jdm_master_X]

i would check with the wiring on your check engine light. perhaps the circuit is open.

and your EGR is vacuum operated, so apply vacuum to it with a vacuum pump and see what it does. i believe its only supposed to open during cruising speeds.

[Roger_cha]

o yea on the light when i turn on the car (not the engine) then check light dont turn on but when i turn the key half way back then the light blink on shortly only so i didnt think that it might be the bulb or any of the wiring but i may be wrong. and as for the egr i check it but i found that the hose that connect under the EGRC-BPT valve was broken... i just replace it... do you think that might be the case that my car wont pass smog....

[180fan]

post numbers or your car never saw the rollers.

if you're failing NOx yeah that hose from the bpt to the egr will cause you much grief.

[Roger_cha]

they said that its gross polluted.... but when i took it to one of the smog shop he said that something in my EGR system is making my EGR valve open and closing so i dont know wats the cause....

[180fan]

if it's stuck open, your car should be idling funny. Post numbers.

[Roger_cha]

well my engine idling fine... one of the guy that i took my car to go smog at said that my EGR valve is fine but something is making it open and closing.... if you want number lets see for the no (PPM) section the max was 799 the GP was 2002 and MEAS was 2739... that was on 15 MPHFor 25 MPH the max was 738 the GP was 1802 and the MEAS was 3320.... its too high thats why it didnt pass...

[Roger_cha]

so can anybody give me a hint on my EGR.... or any hints on y my engine check light wont turn on when i turn on the car not the engine....

[180fan]

it's triggered by a vac source.

[Roger_cha]

so them do you think that the hose that is under the EGRC-BPT valve that broke off my be the problem.... if it is then i dont have to waste 200 buck to go in and fix it... but what about my engine check light issue??? its just like i said when you turn the car on (not the engine) the engine check light wont turn on, they said that the malfuction indicator light failure...

[180fan]

if that hose has a hole between the bpt and the egr, replace the hose. that should not cost $200. Even dealerships will not charge that much for a hose replacement.

does the cel come on in other situations? if not, did you check the bulb?

[Roger_cha]

i know it wont cost 200 buck to replace the hose... i ment it cost 200 buck to replace the EGR valve... but hopfully its just the hose that cause it to fail the smog check... as for the bulb i check its good i even try doing the self-diagnose on the ECU the Light Bulb wont turn on too...

[180fan]

Hmm, 200 to replace the egr does sound like quite the bargain considering how big a pita it is to work around back there...

so your ecu can't get into diagnostic mode...tried a buddies ecu yet?

[Roger_cha]

yea the ECU wont go on diagnose mode but i havent try a nother ECU yet... dont know where to find one check the junk none on dohc 240sx only single cam....

[Roger_cha]

well im not sure if its the ECU... Because the car runs fine... the engine starts up perfect... the reason that my car fail to smog is because its gross polluted, ignition timing is off and the engine check light fail to turn on only.... well correct me if im wrong... it maybe my ECU that its bad or something else.....