PO 400 egr malfunction...
Thread Starter
Registered User
Joined: May 2003
Posts: 724
From: Regina,Sask,Canada
PO 400 egr malfunction...
I just found out that I have this code..PO400.Was there a recall on the lt1s egr valves can't remember..or new part number or something?
Did they make the car run funny like boggy or something when they screwed up..??
I would just block it or disconnect it but have a 96 and will get the codes and don't feel like getting custom programming just to take them out.
Did they make the car run funny like boggy or something when they screwed up..??
I would just block it or disconnect it but have a 96 and will get the codes and don't feel like getting custom programming just to take them out.
remove it
Registered User
Joined: Dec 1999
Posts: 825
From: Houston, TX
I'm pretty sure there was a recall on the EGR for '96 Z28's. Whether or not it makes the car run bad depends whether the valve is open or closed. If it's open at random times then yes, it will make the car run bad, but if it's stuck closed it won't effect performance at all.
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Registered User
Joined: May 2003
Posts: 724
From: Regina,Sask,Canada
Can I get a madwolf tune to delete air and egr and still use my hypertech also when I change gears next year and to make some small changes to things like rev limites shift points or does the hpp not work with a mafwolf tune and how long does he keep your ecm..what is his website /email.
So this code could make the car kinda stumble down low like someone said.I assume just disconnecting the vacuum hose for now to the egr solenoid won't work or it will still stop it from sticking open if the line is disconected.
I don't seem to have a check engine light staying on but the code still shows up on the scantool.
So this code could make the car kinda stumble down low like someone said.I assume just disconnecting the vacuum hose for now to the egr solenoid won't work or it will still stop it from sticking open if the line is disconected.
I don't seem to have a check engine light staying on but the code still shows up on the scantool.
Registered User
Joined: Feb 2001
Posts: 253
From: NJ, USA
Re: PO 400 egr malfunction...
Originally posted by 80TA
I just found out that I have this code..PO400.Was there a recall on the lt1s egr valves can't remember..or new part number or something?
Did they make the car run funny like boggy or something when they screwed up..??
I would just block it or disconnect it but have a 96 and will get the codes and don't feel like getting custom programming just to take them out.
I just found out that I have this code..PO400.Was there a recall on the lt1s egr valves can't remember..or new part number or something?
Did they make the car run funny like boggy or something when they screwed up..??
I would just block it or disconnect it but have a 96 and will get the codes and don't feel like getting custom programming just to take them out.
If you dont have headers...there was a recall on this at one point...try to get it fixed for free at your local dealership.
Registered User
Joined: Apr 2000
Posts: 31
From: Washington, DC, USA
The diaphragm on the faulty EGR valve develops small pinhole leaks from all of the heat. I just replaced the EGR valve with the newer design and my SES went out. Disconnect vacuum hose and two small bolts on the back of the intake manifold and you are done. Bit of a PITA to reach, and make sure the car has cooled off for a few hours. The dealer can run your VIN and see if the recall comes up for you.
Registered User
Joined: Jul 2001
Posts: 4,577
From: DeKalb, IL
Originally posted by 80TA
Can I get a madwolf tune to delete air and egr and still use my hypertech also when I change gears next year and to make some small changes to things like rev limites shift points or does the hpp not work with a mafwolf tune and how long does he keep your ecm..what is his website /email.
So this code could make the car kinda stumble down low like someone said.I assume just disconnecting the vacuum hose for now to the egr solenoid won't work or it will still stop it from sticking open if the line is disconected.
I don't seem to have a check engine light staying on but the code still shows up on the scantool.
Can I get a madwolf tune to delete air and egr and still use my hypertech also when I change gears next year and to make some small changes to things like rev limites shift points or does the hpp not work with a mafwolf tune and how long does he keep your ecm..what is his website /email.
So this code could make the car kinda stumble down low like someone said.I assume just disconnecting the vacuum hose for now to the egr solenoid won't work or it will still stop it from sticking open if the line is disconected.
I don't seem to have a check engine light staying on but the code still shows up on the scantool.
I haven't tried combining a custom tune with Hypertech's tuning on 96 and newer cars, but it works on 94-95 cars. You could give Hypertech a call and ask if they update the whole tune or only the segments that you ask it to update.
Yes, I can delete both EGR and AIR.
I return PCMs usually next day after I receive them. Sometimes even the same day. It takes 2-3 days at most for you to get it back since we ship Priority Mail.
My website is www.madz28.com and email is tuner@madz28.com
Thanks.
Registered User
Joined: Jul 2003
Posts: 700
From: Upstate New York
SlickBlackZ I asked you to email me the schematic you're offering a few weeks ago but you never responded. I dug this up in an older thread and understand how to do this. Was there any particular relay that you used. I have a relay with a harness from an alarm system that I think will work. What kind did you use?
BitCypher has the right idea...the code is set off because the backpressure is not as strong as with the stock manifold, due to the placement of the EGR tube on the single header pipe with longtubes. It seems to be an OBD2 specific problem on cars with headers, probably because the EGR is more sensitive than OBD1.
Here is why the code is set off: the PCM commands the EGR valve to open, then the MAP sensor takes a reading of manifold pressure. It measures this rise in pressure as a low rise in voltage...but if the pressure hasnt risen enough, the voltage reading is too low and a P0400 code is issued.
Here is what I did to trick the computer: Unplug the 2 wire weatherpak going to the EGR solenoid, and splice it onto a relay. From there...off the other side of the relay, one wire gets spliced onto the rear wire of the MAP, and another wire gets spliced onto the center wire of the MAP, with a 75 ohm resistor. The front MAP wire stays as it was. Now when the PCM tells the EGR to open, it is actually energizing the relay, then sending the properly tuned voltage (because of the resistor) onto the MAP circuit and the computer thinks the manifold pressure has risen. The result? No more SES light.
I made all of these connections using weatherpak connectors I got at NAPA...from their AC delco catalog. It just plugged right in. Otherwise...you would have to cut into the wires and it wouldnt be easy to put it back to stock if needed.
And thats the easiest cure for the P0400 code.
can you email me at ilarion655321@hotmail.com ?
Thanks Dan
BitCypher has the right idea...the code is set off because the backpressure is not as strong as with the stock manifold, due to the placement of the EGR tube on the single header pipe with longtubes. It seems to be an OBD2 specific problem on cars with headers, probably because the EGR is more sensitive than OBD1.
Here is why the code is set off: the PCM commands the EGR valve to open, then the MAP sensor takes a reading of manifold pressure. It measures this rise in pressure as a low rise in voltage...but if the pressure hasnt risen enough, the voltage reading is too low and a P0400 code is issued.
Here is what I did to trick the computer: Unplug the 2 wire weatherpak going to the EGR solenoid, and splice it onto a relay. From there...off the other side of the relay, one wire gets spliced onto the rear wire of the MAP, and another wire gets spliced onto the center wire of the MAP, with a 75 ohm resistor. The front MAP wire stays as it was. Now when the PCM tells the EGR to open, it is actually energizing the relay, then sending the properly tuned voltage (because of the resistor) onto the MAP circuit and the computer thinks the manifold pressure has risen. The result? No more SES light.
I made all of these connections using weatherpak connectors I got at NAPA...from their AC delco catalog. It just plugged right in. Otherwise...you would have to cut into the wires and it wouldnt be easy to put it back to stock if needed.
And thats the easiest cure for the P0400 code.
can you email me at ilarion655321@hotmail.com ?
Thanks Dan
Thread Starter
Registered User
Joined: May 2003
Posts: 724
From: Regina,Sask,Canada
Crap just priced out egr valve and unless they made a mistake they want big bucks for it..like over 200 US!!
Would have expected maybe 75 bucks.They said only open recall on my car is the air pump recall.Not sure what that one even does or if should bother.
I really should just block off the egr crap and take off the air crap too.
I really wish madwolf that would know if you can reprogram my ecm and delete that stuff but still let me use my hpp to change a few things on the fly.Wonder if you can find out or mayb someone that you have done their ecm on a 96 to 97 can chime in if they still also have used a hpp to tweak a few things after your tuning was done.
Your prices are great but still like that hpp to change out a few things on the fly.I usually set my fans for 160 in warm months and back to 180 to 195 in colder months also currently have 2.73 but might have 3.42 next year etc.
If I disconnect the vacuum line to the egr will that stop any bad effects of it leaking when its not supposed to.Kind of pain to intall what is it three block off plates when intake is on the car.
And what effect does disconnected egr solenoid due same as disonnecting vac line to it.Maybe if you disconnect vac line it won't throw a code.or just solenoid..???Anyone know.
I can erase and scan my codes at any time as have autotap and
powerscan cart for my hpp and soon might be buying used lt1 scanmaster.In my ls1 I just look up trouble codes as they light is always on from no egr and no air in that car.
Would have expected maybe 75 bucks.They said only open recall on my car is the air pump recall.Not sure what that one even does or if should bother.I really should just block off the egr crap and take off the air crap too.
I really wish madwolf that would know if you can reprogram my ecm and delete that stuff but still let me use my hpp to change a few things on the fly.Wonder if you can find out or mayb someone that you have done their ecm on a 96 to 97 can chime in if they still also have used a hpp to tweak a few things after your tuning was done.
Your prices are great but still like that hpp to change out a few things on the fly.I usually set my fans for 160 in warm months and back to 180 to 195 in colder months also currently have 2.73 but might have 3.42 next year etc.
If I disconnect the vacuum line to the egr will that stop any bad effects of it leaking when its not supposed to.Kind of pain to intall what is it three block off plates when intake is on the car.
And what effect does disconnected egr solenoid due same as disonnecting vac line to it.Maybe if you disconnect vac line it won't throw a code.or just solenoid..???Anyone know.
I can erase and scan my codes at any time as have autotap and
powerscan cart for my hpp and soon might be buying used lt1 scanmaster.In my ls1 I just look up trouble codes as they light is always on from no egr and no air in that car.
Registered User
Joined: Apr 2000
Posts: 31
From: Washington, DC, USA
The new valve I bought was less than $30. That was only for the part, I'm sure they will gouge you on installation. Unplugging the vacuum hose will do nothing for the SES, except keep it on. PO 400 is for insufficient flow, because the sensor is not detecting the pressure change from the valve actuating.
Thread Starter
Registered User
Joined: May 2003
Posts: 724
From: Regina,Sask,Canada
Where do you get an egr valve for less than 30 bucks they are saying its over 200 wonder if gm made a mistake..anyone have the right new part number and is the 30 bucks true or the 200 plus.
Registered User
Joined: Apr 2000
Posts: 31
From: Washington, DC, USA
Found this on GMPartsDirect.com
17113381
Emission Control System Hardware
VALVE
1
$39.91
This is the part # for M6. Different number for AUTO. You should order from Dal or Jason, so you don't get ripped on the shipping. Check out Shoebox's site, that thing is money!
http://shbox.com/1/4th_gen_tech1.html
17113381
Emission Control System Hardware
VALVE
1
$39.91
This is the part # for M6. Different number for AUTO. You should order from Dal or Jason, so you don't get ripped on the shipping. Check out Shoebox's site, that thing is money!
http://shbox.com/1/4th_gen_tech1.html
Registered User
Joined: Apr 2000
Posts: 31
From: Washington, DC, USA
Here you go, for the auto. Almost the same number as the M6, only difference is last number. You should also replace the gasket when you change the valve. Let us know if this does the trick!
17113382
Emission Control System Hardware
VALVE
1
$39.91
Your local stealer will rape you on the price. Use Jason or Dal.
17113382
Emission Control System Hardware
VALVE
1
$39.91
Your local stealer will rape you on the price. Use Jason or Dal.
Thread Starter
Registered User
Joined: May 2003
Posts: 724
From: Regina,Sask,Canada
Thanks guys..will check and see what the parts guy that gave me the price over 200US was smoking that day.
I plan on taking off the egr and air entirely but likely wait to get some programming for that and then not bother with my hpp or see if can use the hpp on top of the program to eliminate the egr and air.
I plan on taking off the egr and air entirely but likely wait to get some programming for that and then not bother with my hpp or see if can use the hpp on top of the program to eliminate the egr and air.