EGR Elimination

[DeMasi1990]

hey,

I Just Signed up today And I wanted to ask a few questions here on the board, Ive been lookin thru the whole site and Ive already found alot of good Info. I have a 1990 Pontiac trans am I have had for about 2 years now, and Ive Replaced the T-5 5 Speed and clutch Tune up Tires and Brakes.. I have been having Problems with the EGR getting hung up as the mechanic says. I have to Be careful on anything I do with this car because the guy who had it before me did a decent amount of modifications to it that were just.......Sloppy... So, can I Eliminate the EGR and put a plate over it? its a 305 T.P.I Manual Trans.... Thanks

[96slow6]

You can block it off but you will get a ses for it. There is no gain in deleting it. How exactly is it hanging up?

[DeMasi1990]

I have No Idea how its hanging up. My mechanic Put My car on a Graphing Scanner and it came up with a few problems. One was an EGR Problem...Another One was a ESC Modual.. which I replaced... and it still comes up, I replaced the black piece connected to te distributor and the coil.... Its running EXTREAMLY rich. I thought it could be vaccume, But I was told EGR...The car has some bugs to work out, as you can see

[five7kid]

Extremely rich is more often an O2 sensor than anything else. What happens is as the O2 sensor ages, it doesn't put out as much voltage as it should for the actual mixture ratio. The ECM sees a "lean" indication because of the low voltage and richens the mixture more. As long as the O2 sensor puts out enough voltage that the ECM can still richen it up enough to get the voltage the ECM wants, no trouble code (SES light) will be set.

EGR problems would be indicated by a lack of temp sensor feedback when the ECM wants the EGR valve open or closed. That can be caused by a sticking or non-opening valve, or blocked passages (depending upon what the symptoms actually are).

[DeMasi1990]

The O2 Sensor was replaced last year. So was a failing fuel injector. I forgot to mention that this car has a Performace chip in it. which Eliminated the Mass Air Flow Sensor.. I dont know if this makes a difference to how the car runs Rich/Lean. But I am Not sure..The fumes are unbareable. I cant let the car run in idle without getting sufficated by the smell...I cant think of what it could be. I really dont know what this guy did to the car prior to me owning it in 2005 But, Id like to get this accomplsihed, so I can move on to a new interior etc...Summers right around the corner:lol:

[five7kid]

You don't just "eliminate" the MAF in the chip and expect the car to run properly. The '90-'92 TPI system didn't use the MAF, but there were other sensors added and total reprogramming done to accomplish that.

If your "performance" chip really did program out the MAF, and nothing was added to the engine to provide the information needed to compensate for that, you've got something that will never work properly. You need to figure that out without doubt before you do anything else.

[DeMasi1990]

Well, thanks for clarifying that for me... As far as the mass airflow sensor goes. It Did have one At one time. The Wires were cut From its terminal and tucked away in the harness loom. The car is a 1990, however the Paper I found under the back seat Says the car was manufactured in July 1989. maybe that makes a difference?The Car runs rich like I said, but the car is very powerful...It just seems to be this car has been toyed with toooo much.

[five7kid]

I missed that you said in your original post that it is a 1990 model. It still could have been manufactured in July 1989 and be a 1990 model - it would be one of the first ones made for delivery at the start of the model year in late August-early September.

But, if it is a 1990 model year, it isn't MAF, it's speed density, and it never had a MAF. If the chip has been reprogrammed, that's probably your problem, it wasn't done properly.

It could still be the O2 sensor, though. It isn't unheard of for a new one to be bad.

[DeMasi1990]

See, thats the thing....I am sure myself that its got something to do with that chip. The car will run fine for a short amount of time, then it will start with the running rich, shaking, idleing at 1500RPM..It does alot of weird stuff, then just goes away!....The only thing that happens for sure is when I start it, cold it will stay at 1500RPM sometimes, if i nail the gas pedal to the floor for one second then release it will slowly go down... and the the RPM with go Up and down up and down up and down from 1000 to 1400 rpm...Then will stop, then will shake the whole car, then the shake stops, and the car idles perfect......I have a mechanic that told me in the past that he FOUND the mass air wires cut from the terminal and tucked into the wire loom, I have also had 1 fuel injector fail on me, and I replaced it....I cant think of what it could be....I have 2 other cars besides the Trans Am, so I am willing to take the car apart or fix whatevers wrong with it, No matter how much time it takes, because i really dont depend on the car.. Thanks for your help soo far...By the way, the fuel pump has been replaced last year:jif: