: TPS and/or EGR needed?



Jimbad
01-26-05, 01:40 PM
Thanks, again, Bbob, for your second reply to my earlier post. I'd like to add a couple of details now. About a month ago my '93 ETC started stalling on deceleration so I cleaned the throttle body (I did not know to disconnect the neg cable) and put a new idle speed control motor on it, and as Bbob suggests, did not do the relearn, and the car ran fine until 3 days ago when it again started stalling on deceleration. After checking the Forum I became aware of the fact that the throttle position sensor could be at fault. I've done some searching here but I am still not sure of how to test the TSP. Would someone help?
Also, one of my history codes indicates that the the EGR pintle is "...out of range...".
Could that contribute to my stalling? Should I clean/replace EGR?
By the way, this car has 104000 virtually trouble-free miles on it.

Thanks,
Jim

cadillactech
01-26-05, 08:55 PM
The egr code will definately cause your stalling problem. If the egr pintle is stuck open ( which is usually the case ) it will act like a big vacuum leak inherently causing a decel stall.

BeelzeBob
01-27-05, 12:34 AM
Thanks, again, Bbob, for your second reply to my earlier post. I'd like to add a couple of details now. About a month ago my '93 ETC started stalling on deceleration so I cleaned the throttle body (I did not know to disconnect the neg cable) and put a new idle speed control motor on it, and as Bbob suggests, did not do the relearn, and the car ran fine until 3 days ago when it again started stalling on deceleration. After checking the Forum I became aware of the fact that the throttle position sensor could be at fault. I've done some searching here but I am still not sure of how to test the TSP. Would someone help?
Also, one of my history codes indicates that the the EGR pintle is "...out of range...".
Could that contribute to my stalling? Should I clean/replace EGR?
By the way, this car has 104000 virtually trouble-free miles on it.

Thanks,
Jim

Yes, the EGR can cause the problem you are looking at now. The code indicates the EGR is sticking. If it sticks open it could likely caue a stall on decel. Take the EGR valve off and clean the pintle and pintle shaft up inside the cast passage in the base. Carbon builds up on the shaft inside the passage and causes the pintle shaft to stick. Clean the shaft and work the pintle back and forth to free it. Use some carb cleaner to spray the shaft up inside the passage (you'll see it in there with the valve off) Make SURE to NOT let any solvent run down the shaft into the can of the valve or it will ruin the valve completely as the solvent will eat the insulation off the wires in the can and short the valve out. Hold the EGR right side up when spraying any solvent into the passage.

Jimbad
01-27-05, 09:03 PM
Thanks Bbobynski and CadillacTech. I cleaned the EGR, put on a new gasket and the car ran fine, no stalling; however, time will be the real judge. BTW the EGR on the '93 ETC comes off with no problem. Undo the electrical connector, remove 2 10mm bolts and lift. From other posts that I have read EGR removal can be a pain.

I do have another question. Some posts say to clean the pintle using a toothbrush. There is no way that I can expose the pintle. The black "can" is attached to an aluminum mounting block (?) and the pintle is inside of the can. No way, short of drilling the thing apart, could I get to the pintle shaft.
Am I right about this?

cadillactech
01-27-05, 09:23 PM
Yeah, just clean, soak, scrub, repeat. Luckily they are easy to get off. The 4.9 engine and it's closely related counterparts are a bit more difficult to remove. I have had good luck just spraying cleaner in the plunger opening and working it up and down to free it up. Congrats on the cheap repair!

BeelzeBob
01-28-05, 12:26 AM
The "pintle" is the center part of the valve that you see opening when you move the shaft up and down. It is readily visible when you hold the valve upside downwards.... The only part of the pintle shaft that you need to clean is the part inside the passage in the cast base of the valve. The part inside the can and between the can and the base does not need to be cleaned.

GM does not recommend using any solvent in cleaning the EGR valve because solvent will quickly destroy the wire windings inside the can of the valve. That is why you need to hold the valve rightside up when cleaning with solvent and be careful not to spray solvent into the can or spray solvent so that it will bounce off the shaft and go into the can.

It is best to take it off and soak just the base in solvent while the valve is right side up and then work the shaft up and down to clean the pintle valve and shaft inside the seal at the base.

Jimbad
01-28-05, 04:37 PM
Bbobynski, I hope that your last bit of advice did not come to late. I did hold the EGR upright but I did have to spray into the the cavity aside of the pintle.to stop the pintle form sticking in the "up" position. Oh, well, as I said earlier, time will tell.
Thanks all. Jim