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Old 05-19-2002, 04:22 PM
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help with EGR and ALDA, please...

A small phillips screw became lodged in my EGR tubing today, completely by accident Anyway, I didn't notice a difference in my acceleration. I'm wondering if I have to adjust the ALDA as previously suggested- can I get some detailed instructions on locating it and how exactly to adjust it?

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Old 05-19-2002, 05:07 PM
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When the EGR system is operating as it is supposed to, you will not notice an obvious change in performance when it is totally disabled.

Most of the time, there is not enough documentation on the EGR system OR people simply don't want to bother fixing it, therefore the systems end up getting disabled.

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Old 05-19-2002, 09:08 PM
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The purpose of the EGR disconnect is not to affect acceleration.

Rather, when you disconnect the EGR you are eliminating a recycling of exhaust back through the intake manifold. The Exhaust that is directed back into the engine contains SOOT. The soot builds up on the interior of the intake manifold and decreases the efficiency of the system. Eventually, this will result in too little air (dirty, soot filled air) making it through into the cyliders. Part of this soot buildup problem is that the air hose leading from the back of the intake manifold (via the banjo valve) to the Injection Pump gets packed with soot, and the Injection Pump is never signalled that the Turbo is increasing the airflow to the cylinders. No signal means no increased fuel flow means the turbo can provide boost but the car performs as if no turbo was present.

So, the EGR disconnect is a long-term preventative health measure - namely soot reduction. To maximize positive effects of the EGR disconnect, clean out the air line that runs from the back of the intake manifold. Clean out the banjo valve that connects this line to the manifold. Make sure that the overboost control unit is clear (far end of air line), and then make sure the line from overboost control to the Injection Pump is clear (see archives). This is the step that can really make a severe and immediate difference in performance.

The final step is cleaning out the inside of the intake manifold. You can probably count the number of us that have gone that far on about two fingers.
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Old 05-19-2002, 11:07 PM
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Location: Holly Springs, GA
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mccan: Excellent summary of the whole EGR, turbo, banjo, soot ordeal. You brought it all together nicely.

I've pretty much done all that now except pull the intake manifold to clean....BUT, judging from the condition of the intake banjo bolt I'd guess that the intake is in great shape. When I pulled the banjo bolt the other day, it was spotless.

Only had the car about 5-6 weeks now but just found that the EGR had already been idea how long it had been that way but the longer, the better.
1985 300SD - 'Grace' (198K mi.)
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Old 05-20-2002, 12:59 AM
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EGR - Exhaust Gases Recircluator - so what does it do besides recirculate the gases - mainly what the one guy explained, So why did they put it on there, partly to reduce smog polution, But it's main reason was to stop spark knocking. Yes, a Diesel will spark knock just like a gas engine will! Partly due to low cetane or low octance for gas car.

When all of this polution stuff came about, spark knocking was a real problem and so to try and stop this from happening, they came up with the bright idea to recirculate the exhaust gases in hopes of stopping that horrible sound. Try to reburn the excess gas. For the most part, it did work.

But it only worked part of the time and on only some cars and pickups. So early on, people found that the valve was also Clogging things up! Like the intake getting clogged (yes a gas engine will get terribly clogged). I had to change an intake manifold once to get a clean open intake! So they found they could block it off and the car ran fine without it. You can disable it. It you car spark knocks, just use premuim diesel.

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