emissions passing and egr port

[QWIKSTRIKE]

Just a little FYI guys....If you have emissions problems related to the egr or similar I have found that the EGR port gets extremely clogged over the years and must be cleaned. Also the port on the intake that runs along the whole intake tract of my car was so clogged I needed a little bottle brush and carb cleaner to unblock the carbon build up.This blockage keeps egr circualtion from working casuing higher emissions. So if you cant seem to find out why your co2 readings are high that may be your culprit. Who has ever taken the intake and cleaned that tract out ever besides me. I did it one day because I was bored, and never new it was a nescesity until I found how clogged it was from years of carbon build up.:naughty: :biglaugh: :nono:

Clean out those intake tracts, and blow clean grass hopper!:evil2:

 

[lagged]

wouldnt you see higher NOX readings?

 

[QWIKSTRIKE]

wouldnt you see higher NOX readings?

Yes...so get to cleaning Joe call me. I want to organize ameet in 2weeks if weather is fine.:biglaugh:

 

[jetjock]

Lagged, you'd make a good diplomat. EGR is used for NOx and detonation suppression. CO2 is an indicator of combustion efficiency. You want high CO2, the higher the better. A engine running in closed loop at stoichiometric will emit 14-15% CO2. Anything less and something is wrong.

Clogging of EGR passages is common in all cars, especially in engines that have been modified and not tuned correctly or aren't running in closed loop. The easiest and most efficient way of deep cleaning them is to use an old speedo cable or a piece of wire rope from the hardware store. Fray one end, chuck the other in an electric drill, shoot some solvent in the passage, and go at it.

Fwiw on a modern EFI system every time the ECU calls for EGR it compensates for the loss of performance by advancing ignition timing. Because EGR suppresses detonation timing can be more aggressive. Think about that the next time you decide to yank an EGR valve off.

 

[lagged]

Yes...so getto cleaning Joe call me. I want to organize ameet in 2weeks if weather is fine.:biglaugh:

yeah man. i posted in the other thread im down.

where are we gonna go?

 

[lagged]

Fwiw on a modern EFI system every time the ECU calls for EGR it compensates for the loss of performance by advancing ignition timing. Because EGR suppresses detonation timing can be more aggressive. Think about that the next time you decide to yank an EGR valve off.

very true however, and i think ive asked this question before with no real answers coming up, Japanese domestic 7m's come with no EGR valve, so where is the difference that makes those motors run within a safe margin as compared to a USDM 7M running with no EGR vavle?

 

[jetjock]

I said modern EFI systems. I didn't necessarily mean the Supra. Most engines (and all Toyota OBD-II equipped ones) advance timing with EGR. All it would take to change things on JDM ECUs is tweaking of the program.

If I recall correctly EGR on a USDM 7M isn't electronically controlled in the same manner as OBD-II. As I recall the VSV on a USDM is used for EGR cutoff only. It prevents EGR at cold coolant temps and when above 4000 rpm. Idle cut off is done by throttle valve porting. That said I don't recall if the ECU calls for EGR above 4000 during times of high engine load. I'm going to guess it doesn't but I'd have to test it to be sure. I'll do so if you'd like. Based on what I've read many here had better hope it doesn't. Course, there are other benefits to leaving EGR intact on any engine and the knock control system is still active wheather EGR is there or not.

My point was one needs to be careful when dealing with EFI because it's more sophisticated than many people think. Especially true when dealing with Toyota's stuff and OBD II in general.

 

[lagged]

i absolutely agree

i asked because in the past some have said that on a 7M specifically you risk damaging the motor due to a lean condition if you remove the EGR which i would tend to believe is not true for the reason i stated in my previous post.

personally i have no EGR simply because my motor never came with one.

 

[jetjock]

Well, I'm not saying people shouldn't be concerned. The EGR on the Supra is built to be fail safe ie; if the VSV fails EGR will always be active except at idle where it's vacuum source is removed by the ported throttle body. That sort of implies the USDM ECU has an ESA EGR algorithm. If so an engine sans EGR with a failure that wouldn't permit the system to operate and pulling a high load under boost, such climbing a hill without downshifting, would be a bad thing. Knock control would step in but only after detonation has already begun.

Also keep in mind the ECU on later Cali cars monitors EGR operation. Whether this monitoring is used only for diagnostic/emissions or more is something I've never checked. The only way to know for sure would be to monitor timing and see but based on everything else I know about the ESA system I wouldn't be surprised.

Have to keep in mind I stopped studying this thing years ago. There's a lot of minute detail I don't remember. In fact I had to dig up the books when I came here. I'd have to repeat much of the testing I did back then but I'm not really motivated. It's an old car and I'm looking at getting something else in the next year or so.

 

[miekedmr]

Japanese domestic 7m's come with no EGR valve, so where is the difference that makes those motors run within a safe margin as compared to a USDM 7M running with no EGR vavle?

All it would take to change things on JDM ECUs is tweaking of the program.

^right there

Since the JDM engines were designed without EGR, it's likely they have different fuel and/or timing maps which take that into consideration. That would mean that removing EGR only causes a problem with the USDM ECU, where the engine came with it. Swapping a JDM ECU may alleviate the high combustion temps and NOx that would result.

personally i have no EGR simply because my motor never came with one.

Very good reason.

 

[jdub]

Swapping a JDM ECU may alleviate the high combustion temps and NOx that would result.

Nope...tried this a few months ago trying to pass AZ emissions. The JDM ECU had a minor effect on NOx and no effect on EGT. The car failed emissions for NOx...I had to install an EGR in order to pass.