No EGR CEL - Miata Turbo Forum - Boost cars, acquire cats.

Welcome to Miataturbo.net   Members
 


DIY Turbo Discussion greddy on a 1.8? homebrew kit?

Reply
 
 
 
LinkBack Thread Tools
Old 04-28-2009, 01:38 AM   #1
Junior Member
Thread Starter
iTrader: (7)
 
Join Date: Aug 2006
Location: Binghamton, NY
Posts: 448
Total Cats: 1
Default No EGR CEL

So after a bunch of searching, I haven't come up with any real solutions.

I've got a P300 (I think) no EGR flow CEL. I do have the EGR port on the intake mani blocked off and no intentions of hooking it back up.

So the question is, how does the stock ECU know there is no flow? I'd really love to make it go away without the hassle of adding a EGR bung to the exhaust mani and building a crossover tube.

--Alex
AlexO35 is offline   Reply With Quote
Old 04-28-2009, 09:10 AM   #2
Junior Member
iTrader: (1)
 
Join Date: Mar 2007
Location: South Florida
Posts: 491
Total Cats: -1
Default

If your stock EGR valve has a potentiometer on the top it measures flow by the amount of vertical movement of the valve.

If you EGR doesn't have the potentiometer, then it uses an analog (0-5v) signal from the Map sensor.

If there is EGR flow, there is less negative pressure or vacuum compared to when there is no EGR flow.
mrtonyg is offline   Reply With Quote
Old 04-28-2009, 11:22 AM   #3
y8s
2 Props,3 Dildos,& 1 Cat
iTrader: (8)
 
y8s's Avatar
 
Join Date: Jun 2005
Location: Fake Virginia
Posts: 19,038
Total Cats: 406
Default

EGR is good.
y8s is offline   Reply With Quote
Old 04-28-2009, 11:24 AM   #4
Elite Member
iTrader: (9)
 
Saml01's Avatar
 
Join Date: Jul 2007
Location: NYC
Posts: 5,730
Total Cats: 2
Default

^ Well thats some very useful information.
Saml01 is offline   Reply With Quote
Old 04-28-2009, 11:28 AM   #5
Senior Member
iTrader: (2)
 
SamS's Avatar
 
Join Date: Jun 2006
Location: Wisconsin
Posts: 1,251
Total Cats: 7
Default

I get the P0400 occasionally due to my blocked off EGR as well, though I've passed emissions twice without it I'd like to know if there's an easy-ish way to keep the light from coming on at all, too.
SamS is offline   Reply With Quote
Old 04-28-2009, 11:20 PM   #6
Junior Member
Thread Starter
iTrader: (7)
 
Join Date: Aug 2006
Location: Binghamton, NY
Posts: 448
Total Cats: 1
Default

EGR isn't something that usually bothers me. But, in this case it would be a PITA to connect. Not really in the mood to fab up all the plumbing for no real change in the system.

I'm going to look into our valve a little more this week. Hopefully I can figure something out.

--Alex
AlexO35 is offline   Reply With Quote
Old 04-29-2009, 02:02 PM   #7
Junior Member
Thread Starter
iTrader: (7)
 
Join Date: Aug 2006
Location: Binghamton, NY
Posts: 448
Total Cats: 1
Default

Looks like mrtonyg was right. OBDII cars have a MAP sensor. Didn't know that.

There's a switch in the top portion of the valve itself. This is the only indication on the OBDI EGR valves. (they have one vacuum port) This should let the ECU know that the valve is physically open. On the OBDII valves, there are two ports, one for the opening vacuum source like the OBDI valve and another that feeds a fender mounted MAP sensor.

So I need to check a bit more, but I bet we can just run a false signal to the MAP portion when the EGR valve is engaged.

--Alex
AlexO35 is offline   Reply With Quote
Old 04-29-2009, 04:19 PM   #8
Elite Member
iTrader: (9)
 
Saml01's Avatar
 
Join Date: Jul 2007
Location: NYC
Posts: 5,730
Total Cats: 2
Default

So what difference if theres flow or not though?

The map should still change and stuff no?
Saml01 is offline   Reply With Quote
Old 04-29-2009, 04:29 PM   #9
Hittin' Boost & Cones
iTrader: (2)
 
240_to_miata's Avatar
 
Join Date: May 2007
Location: Cromwell, Connecticut
Posts: 2,572
Total Cats: 11
Default

Im gunna check my CEL's this weekend and see if i have been getting one for the EGR. (i know i have one for the front and rear o2 sensors and MAF cause they are all disconnected).

I have everything connected, just have the actual pipe removed and blocked off.
240_to_miata is offline   Reply With Quote
Old 04-29-2009, 06:31 PM   #10
Junior Member
iTrader: (1)
 
Join Date: Mar 2007
Location: South Florida
Posts: 491
Total Cats: -1
Default

Quote:
Originally Posted by AlexO35 View Post

So I need to check a bit more, but I bet we can just run a false signal to the MAP portion when the EGR valve is engaged.

--Alex
Alex, the PCM is looking for a change in the MAP signal at part-throttle cruise. If there is no change from the MAP the PCM determines that there is no EGR flow.

Basically, when the EGR opens it introduces exhaust gas into the intake manifold thus increasing the pressure slightly.
mrtonyg is offline   Reply With Quote
Old 04-29-2009, 08:44 PM   #11
Junior Member
Thread Starter
iTrader: (7)
 
Join Date: Aug 2006
Location: Binghamton, NY
Posts: 448
Total Cats: 1
Default

I guess my assumption was that that sensor read the pressure in the EGR tube. I would have thought to read true MAP they'd connect it to the manifold instead of to the valve and thereby avoid having to make a different valve to accept the sensor port.

I'm going to put a gauge on it tomorrow and see what happens.
--Alex
AlexO35 is offline   Reply With Quote
Old 04-30-2009, 11:54 AM   #12
Junior Member
Thread Starter
iTrader: (7)
 
Join Date: Aug 2006
Location: Binghamton, NY
Posts: 448
Total Cats: 1
Default

So yea, I put a gauge on the line and it does read MAP. Gunna have to play around a bit more. Can't seem to find a datasheet for the sensor. Its a Mitsu P/N BPS1 18 211 if anyone else can find it.
--Alex
AlexO35 is offline   Reply With Quote
Old 05-02-2009, 12:43 AM   #13
Senior Member
iTrader: (2)
 
Join Date: Aug 2007
Location: North Cackalackey
Posts: 716
Total Cats: 2
Default

left my connected on a 2001 just did not tap the manifold. almost 2 years and no EGR code
musanovic is offline   Reply With Quote
Old 05-05-2009, 01:05 AM   #14
Junior Member
iTrader: (1)
 
Join Date: Dec 2006
Location: Toronto, Canada
Posts: 72
Total Cats: 0
Default

On my 97, all I did was remove the egr tube. I didn't block off anything or do anything to the vac side of the system. It never threw a code in the 3 years that I ran it like that...
Starsky is offline   Reply With Quote
Old 05-05-2009, 06:29 PM   #15
Junior Member
Thread Starter
iTrader: (7)
 
Join Date: Aug 2006
Location: Binghamton, NY
Posts: 448
Total Cats: 1
Default

Sounds like I have a few things to try....
--Alex
AlexO35 is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
Another Cast Manifold Corky Bell Prefabbed Turbo Kits 18 11-22-2016 10:01 PM
Got bad Crank Angle Sensor and Random Misfire codes, but runs fine. Greasyman General Miata Chat 2 09-28-2015 11:44 AM
WTB Begi cast manifold & t25 turbo Heyitsryan WTB 0 09-12-2015 09:47 PM
First to get it out of the way main Meet and Greet 2 09-05-2015 02:03 PM
First to get it out of the way main Meet and Greet 1 09-05-2015 01:39 PM


Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -4. The time now is 05:24 PM.