I have been battling a idle / surge problem for sometime and finally it threw a code....P0400.

Since the SES light came on for it I haven't had an issue, is this coincidence or is it because the PCM is no longer trying to operate the egr due to the code?

Any advise? I should be able to replace the egr valve and check vacuum hoses and be good right? Anything else I should check? Thanks

 

I have been playing with it and reading up on Shoebox's site and this is what I have..

Manually tested the egr valve with a vacuum pump while off and it seemed to move freely.

With the engine running I pressed it (diaphragm) with my fingers and the rmp's decreased almost killing it and increased when I let it go. So it appears the valve is functioning properly.

I pulled the vacuum hose off the solenoid to check for vacuum and it was good. I don't have a gauge but it grabbed on my finger pretty good. Also removed the other hoses and blew through them to insure the was no blockage, also good..

Right now I'm thinking its the solenoid causing the idle/surge/dtcP0400 but I have no gauge to test it as Shoebox explains on his site. With everything I have done would you think its safe to say the solenoid is bad? Would that cause the issues mentioned?


Part# ?
Price$ ? ...................Thanks again

 

Headers can cause that problem.

 

Yep. Best way to defeat it is to turn that code off in the PCM. Low backpressure in the exhaust causes insufficient flow through the EGR valve.

 

The solenoid has its own code for the electrical circuit - P0403. If the solenoid was electrically defective, you would have that code. You can check to make sure the solenoid is working by pulling the vacuum line off the EGR, putting 12V to the solenoid, and feeling for vacuum at the end of the hose.

The P0400 code sets when the PCM doesn't see enough of a change in MAP pressure when it cycles the EGR valve. That indicates inadequate EGR flow into the manifold. Could be carbon on the EGR valve pintle, or carbon in the hole in the manifold, both of which can be checked and cleaned.

Or it could simply be too little back pressure in the exhaust due to the headers, cat delete, etc.

 

I also have this problem on my SS. I have BBK headers and no cats. My SES light comes and goes and is always the EGR P0400 error code.

Those that are experienced with EGR removal, is it worth removing the EGR and trying to trick the PCM to think the EGR is working correctly? I am concerned that I will get used to seeing the SES light on, so when something is really wrong, I will disregard it as an EGR malfunction and neglect to make the necessary repair.

Jordan

 

It's been known that in some cases, where the lack of back pressure causes the P0400 code to be set, that if the car is an auto, changing the EGR valve to the M6 version cures the problem. Your mileage may vary.

 

No recent mods to cause it, been over a year. I took the egr valve off and it wasn't that dirty but cleaned it anyway and reinstalled it. will see what happens.

Below is the freeze frame when the ses set.

P0400 EGR System
*Fuel system status bank 1:CL-1
*Calculated engine load 13.3%
*Coolant temp 185
*short term B1 2.3%*
*Long term B1 -8.6%*
*short term B2 1.6%*
*Long term B2 -11.7%* What do you think of these fuel trims?
*MAP in Hg 13.6
*engine speed 2104rpm
*speed 61mph
*Maf 4.426 lb/min
*TPS 11.0%

 

Although the old valve seemed to work while off with a vacuum pump it was still faulty. I was messing around and started shacking it and it sounded as if it was full of carbon.

I think when vacuum was applied while running that junk was getting sucked to the vacuum port and was clogging it preventing the valve to operate. The only reason I think that is because both of them feel the same when pressing it by hand....

after testing the solenoid, vacuum hoses, taking stuff of and putting it back on i am now a emissions tech.. lol