CEL P1400 MDP sensor questions?

19BLACKGST98 · 07-05-2012, 10:48 AM

Ok well I hopped in the car this morning to get it inspected but during warm up this Cel came on (p1400). When I purchased the car it had this cel so I purchased a mdp sensor from the forums and installed it. I thought it fixed the problem because the cel was gone but it may have just been gone because ive been disconnecting the batt since the car has been sitting.

I pulled the sensor after I got back from the parts store to see if something was blocking the hole in the manifold. It looked fine but I noticed a small tear in the mdp sensors O ring. I figured that Oring may be the issue so I will swap it with the mdp sensor in my gst since it has link.

My question now is if it turns out that the gst sensor fixes the problem how long will I have to drive the car before it will pass inspection? Will the cel go away on its own? I know if I unhook the battery it will go away but I wont be able to pass inspection for like 50 miles. Also if I unhook the battery will the cell stay off even if it did not fix the problem causing me to wait even longer for inspection?

All of this is for a stock 97 gsx auto.
Any help is appreciated.

EAKEREAK · 07-05-2012, 12:30 PM

Your MDP (Manifold Differential Pressure) Sensor is done. It's not going to effect your drive ability. It's really only there to make sure your EGR valve is working properly (it helps display the readiness code for it) it's just to tell the ECU that the EGR valve is working properly, you'll get a CEL for the sensor being out and your readiness code for the EGR won't show ready. By replacing it it should remove MIL light after driving it for a while

19BLACKGST98 · 07-05-2012, 12:46 PM

Quote:

Originally Posted by EAKEREAK

Your MDP (Manifold Differential Pressure) Sensor is done. It's not going to effect your drive ability. It's really only there to make sure your EGR valve is working properly (it helps display the readiness code for it) it's just to tell the ECU that the EGR valve is working properly, you'll get a CEL for the sensor being out and your readiness code for the EGR won't show ready. By replacing it it should remove MIL light after driving it for a while

I just replaced it when I purchased the car but its really easy so ill change it again. I was more curious how long ill need to drive it before I can get it inspected after I change it. Someone locally told me around 400miles so I was hoping for a shorter answer or a way to speed up the process.

EAKEREAK · 07-05-2012, 01:01 PM

I would drive for at least 50 miles highway

95'RS-T · 07-05-2012, 01:20 PM

I'm not sure how Texas emissions works but, with a 98 I'm pretty sure you can have a max of 2 monitors not ready for emissions to pass. As for the CEL here in PA if the light is on, the machine automatically fails the car. The worst thing you can do for readiness monitors is disconnect the battery, because they all reset everytime you do that. Every time the CEL is turned off with a scan tool the monitors are reset as well. Just something to think about before going, and perhaps paying for the test and not passing. Here in PA you pay for the test pass or fail. Get a mdp sensor and have a autozone or advance shut the light off for you and drive like stated about 50 to 75 miles and you should be good. You could also ask them at zone or advance to tell you how many monitors are ready.

19BLACKGST98 · 07-05-2012, 02:53 PM

Ok ill get on that. Thanks guys.

Edit: the bad thing about driving it 50 miles is that the car has Alabama plates and its out of state registrations out.

NHerron · 07-05-2012, 03:32 PM

Ah ha! I never thought about looking for this before but check it out, the DSM emissions Wiki. Hopefully that gives you more info

OBDII Emissions Testing and the DSM - DsmWiki

Also try this, it's easy enough anyway
http://wiki.answers.com/Q/How_do_you...iness_monitors

And this, from http://www.crxsi.com/info/driveabili...ostic-Tips.htm

Quote:

READINESS ISSUES
One of the EPA's requirements for using a plug-in OBD II check in lieu of a tailpipe test is to make sure the OBD II system has run all of its monitors and that the monitors have all passed. But there's a catch. Some import vehicles have readiness issues when it comes to setting all the OBD II monitors. Consequently, the EPA currently allows up to two readiness monitors not to be set prior to testing 1996 to 2000 model-year vehicles, and one readiness monitor for 2001 to 2003 vehicles.

More confirmation

http://www.aaapa.org/wp-content/uplo...dii_issues.pdf

And this is TSB#00-13-005 mentioned in the link above
http://mitsupartsworld.com/Diamante%...tsb0313005.pdf

Let us know how it turns out for ya!

19BLACKGST98 · 07-05-2012, 04:32 PM

How have I never seen that wiki before? Before I made the thread I did a search for my specific issue and never ran into it.

EAKEREAK · 07-07-2012, 02:41 AM

Nice job NHerron that actually helped me out too thanks

NHerron · 07-07-2012, 02:47 AM

Hey no problem. I hate emissions codes. In fact, I have another thread on emissions codes. Not sure but I might try making something simulation wise to bypass the solenoids. They are a little tricky! I figure if DSMlink can do it I can at least try to figure it out

What to check next ?

19BLACKGST98 · 07-16-2012, 01:19 PM

Does anyone know if the cel will go off after I replace the sensor or do I have to have it reset then drive the car around? Ive currently driven the car about 70 miles since replacing it and still have the cel. Ive only taken it on 2 country road drives during those miles.

NHerron · 07-16-2012, 01:36 PM

Code needs to be reset with any cheapo OBD-II scanner

19BLACKGST98 · 07-16-2012, 03:45 PM

Ok thank you. I read otherwise when I did a google search but it wasnt car specific.

They wouldnt reset it at the parts store so I disconnected the batt and am 25 miles inyo my 50+ mile cruse.

19BLACKGST98 · 07-17-2012, 09:10 PM

65 miles and no check engine light. I will drive it to the NTB about 20 miles away for the inspection tomorrow....will have my fingers crossed the whole way.

NHerron · 07-19-2012, 02:34 AM

I have this code every 3 starts of the car. It doesn't matter the mileage, as I have driven 300 consecutive miles (very recently, we moved across state) without it coming on. But if I start the car x amount of times it pops up, I'd have to look through the FSM again on this code though, I believe it has to meet a few requirements during each start up (ie drive above 40MPH for at least 60 seconds etc)