[95ChampagneDevil...]

Hello again all. I have developed a bad knock while in part throttle accelerating and I've narrowed it down to timing. My plugs are fairly new and the wires are about the same. I ALWAYS use 93 octane so it HAS to be timing related. I have an adjustable timing gun and I know that the timing has to be set to 10 degrees BTDC. Where is this ALDL located and are there any tips you have for me?

[Bruce from Caddy...]

For a 95, the ALDL connector is under the dash on the driver's side, or toward the center.

Probably looks like this:

(IMG:http://www.aldlcable.com/uploads/carconnector.jpg)

although it may look like this:

(IMG:http://www.aldlcable.com/uploads/obd2pinout.gif)

Knock at part throttle can be a sign of a bad EGR valve also. See knock/ping diagnostic here: http://caddyinfo.com/knock.htm

[95ChampagneDevil...]

You're awesome Bruce. Thanks. Do you think that simply cleaning the EGR valve would do the trick? When I bought the car it had a SES light and it turned out to be that the TB needed to be cleaned. When I did I put a coat hanger down the EGR tubes and it might have clogged it.

[adallak]

See if you have EGR-related trouble codes. Press warmer and OFF simultaneously for a few seconds and write down the codes from your driver info center.

[95ChampagneDevil...]

My SES light isn't on anymore. The only code I got from the diagnostic check was camshaft position sensor and it only comes on when the engine's cold and then it goes off after about 30 seconds. Also, there are marks on the timing cover and a little viewer. You can't see into the view window so which timing mark do it line it up to? Also is there more than one timing mark on the underdrive pulley?

[davek]

My SES light isn't on anymore. The only code I got from the diagnostic check was camshaft position sensor and it only comes on when the engine's cold and then it goes off after about 30 seconds. Also, there are marks on the timing cover and a little viewer. You can't see into the view window so which timing mark do it line it up to? Also is there more than one timing mark on the underdrive pulley?

I don't remember how, but you'll need to find the procedure for turning off the computer advance while you do the adjustment. That might be why you don't see a timing mark. There's something you'll have to unplug or short together or something. If the car is idling as normal and hooked up, it might not be timed to the mark as the computer might've moved it off. The last car I had with a distributor required unplugging the coolant temp sensor, but that was a Chrysler, so I'm sure the Cadillac is different.

Why my 3800 powered Olds started knocking on regular, I changed the EGR and it was fine afterward. It was also $200, so it's an expensive part to "try."

[adallak]

My SES light isn't on anymore. The only code I got from the diagnostic check was camshaft position sensor and it only comes on when the engine's cold and then it goes off after about 30 seconds. Also, there are marks on the timing cover and a little viewer. You can't see into the view window so which timing mark do it line it up to? Also is there more than one timing mark on the underdrive pulley?

As far as I remember the marks are 6, 8 10, 12. There should be a tooth pointing at a mark. i doubt something wrong with timing if you did not touch distributor.

[Ranger]

Look down the TB. See the two EGR tubes staring back at you? Are they carboned closed? If so, rod them out and your problem will be solved.

[95ChampagneDevil...]

I cleaned those two tubes and the whole TB while I was at it. I'll let you all know how it runs. Would it be beneficial for me to take the EGR valve off the intake manifold and spray it out with carb cleaner?

[Bruce from Caddy...]

Also refer to article here http://www.caddyinfo.com/egrvalvecleaning.htm

[adallak]

I cleaned those two tubes and the whole TB while I was at it. I'll let you all know how it runs. Would it be beneficial for me to take the EGR valve off the intake manifold and spray it out with carb cleaner?

You can do that just make sure you do not hold the valve up side down so that the solvent does not damage the diaphragm. You can make sure the diaphragm holds vacuum bu depressing it completely and closing with finger the vacuum port.
It is recommended to use a new gasket for the valve (it is not expensive).

[Ranger]

I cleaned those two tubes and the whole TB while I was at it. I'll let you all know how it runs. Would it be beneficial for me to take the EGR valve off the intake manifold and spray it out with carb cleaner?

In 125K I never touched the EGR valve on my 4.9 and never had a problem. Actually I never cleaned the tubes either. I didn't know about them back then.

[adallak]

I cleaned those two tubes and the whole TB while I was at it. I'll let you all know how it runs. Would it be beneficial for me to take the EGR valve off the intake manifold and spray it out with carb cleaner?

In 125K I never touched the EGR valve on my 4.9 and never had a problem. Actually I never cleaned the tubes either. I didn't know about them back then.

(IMG:style_emoticons/default/laugh.gif) If not this forum I would not know about them either.