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The vacuum line on my EVP (sensor on back of EGR valve) comes from the EVR solenoid, the vacuum line going to the EVR solenoid comes from somewhere under the intake by the 10 pin connectors. When I had a code 34 (EGR) I checked the vacuum going to the EVP sensor and it was showing no vacuum until I rev'd the motor and then it would jump to about 3in.HG vacuum and then drop to 0 again. I checked where the vacuum was coming from and I had steady vacuum (stock motor) of 20in.HG

I could never see where that vacuum source actually comes from because it is like impossible to see under the intake in that location. I was gonna try to prop a mirror behind it so I could see what was back there but I fixed the code 34 so I never really looked.

When testing the EGR valve and sensor, the manual says to apply 10in.HG vacuum and check the resistance of the EVP sensor. I noticed that when I applied as little as 5in.HG vacuum the EGR valve would fully open so I know that the vacuum I was getting was sufficient to open it when their actually was vacuum getting to it.

I would check the vacuum lines thoroughly and try to verify that the hose coming from under the intake isn't popped off or bad.


Hope this helps.


Bill
 

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90' Cobra, try this with the vacuum pump,gauge.

Disconnect the vacuum hose from the solenoid that feeds vacuum to the EGR valve and put your vacuum pump on the stock factory hose and pull atleast 5in.HG and watch if the EGR valve holds the vacuum for atleast 1-2 minutes. If the vacuum drops as soon as you try to pump it up then you either have one of 3 things wrong there.

1. bad vacuum hose
2. bad EGR valve (rubber inside is torn)
3. bad seal between the EGR valve body and the EVP sensor ( there is a little rubber gasket between the 2)

Next I would check the vacuum from the source going to the EVR solenoid. Again you would check using the stock vacuum line, disconnect the stock hose from the EVR solenoid (should actually be sort of connected to the other hose going to the EGR valve) and monitor it at idle. On my stock cam'd engine I was getting atleast 20in.HG vacuum at idle and then would drop to zero at W.O.T. If you get vacuum, then depending on what type of cam you have in there would determine the amount of vacuum.

If no vacuum present then I would suspect the following

1. bad hose going to EVR solenoid
2. spot where vacuum comes from block is bad (metal/rubber plastic tee under upper intake?)

If you do have good vacuum present on one side of the EVR solenoid then put vacuum line back on EVR solenoid and then monitor the vacuum from the EVR solenoid. Place your vacuum gauge on the end of the vacuum line just before it attaches to the EGR valve. At idle you should get 0 in.HG of vacuum and if you rev the car up you should see a momentary vacuum of between 3-4in.HG coming from the EVR solenoid. If not then, I would suspect the EVR solenoid is acting up.

Do these quick things and post what you have found. I will try to get a mirror down below my upper intake to see what actually is behind there that the vacuum comes from and I'll post as well.


Bill
 

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If you pull vacuum on the EGR valve itself and it doesn't hold the vacuum then refer to my previous post about what could be wrong. I've found that if you use the stock vacuum line from the EVR to the EGR valve and connect the vacuum pump on this it makes a better seal than the vacuum hose that came with my vacuum pump.

The EVR solenoid get's information to open up from the EEC. When it opens up, it allows vacuum to activate the EGR valve to open and then the EVP sensor on the back of the EGR valve senses this and reports back to the EEC that it has opened. There is a small plastic cap on the top of the EVR solenoid and underneath the cap is a small air filter. If you remove the air cleaner you'll see a small orifice, if you put your finger on it, that will cause the car to stall since your allowing all the vacuum coming from the intake to fully extend the EGR valve and open it up.

I'm a little confused on what you mean by the lines coming off the intake won't "hold" a vacuum. Are you checking vacuum on these lines with a gauge while the car is running or are you trying to pull vacuum with a vacuum pump and then watching a gauge and see that the vacuum drops off?


Bill
 

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The codes 44 & 94 are telling you that your secondary air system is having problems. The TAB/TAD solenoid directs secondary air to either the exhaust manifold or catalytic convertor. I will have to do more research on where the secondary air comes from. I would not count out the fact that you have neither the smog pump connected or the cats for the TAB/TAD to direct the air to. If someone who has removed their cats and smog pump connection would post to tell you that's the normal codes to get, that would help.


Bill
 

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No problem helping you at all :) I was wondering if you were able to verify if the little gasket (looks like a rubber band) was properly on the EVP sensor? If it's not seated right than it would cause you to loose vacuum at the EGR valve.

As for the other codes I'm at a loss but I think by asking in other posts is the way to go. Someone else has to have the same and probably just ignores them because they know what causes it.


Bill
 
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