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I installed both new Crankshaft Position Sensors last week. The car has since been running smoothly and all was well until today. I was sitting at a traffic light and noticed that the car was loping. Not major, but just enough to be noticable. My first thought was that I had gotten some bad gas, since I had just filled the tank at an off brand station. So I put a bottle of HEET in it because I thought maybe I had gotten some water in the tank. I had a little under 1/2 a tank 93 octane and topped off wth 87 octane.

On the way home the check engine light came on. I checked the codes when I got home and it pulled:

IRC U1016 History (lost communications with powertrain control module)

This code came up once before as history before the CPS where replaced.

PCM P0171 current (fuel system lean bank one)

PCM P0174 current (fuel system lean bank two)

I reset all codes at time of CPS replacement, so these are recent codes.

I did a little digging in the archives and checked a few things mentioned there:

(1) the gas cap was on tight

(2) the oil dip stick was in all the way (since I had checked the oil at the gas stop)

(3) the air filter is dirty, but I dont think it needs replaced yet

(4) I checked the plenum from the air box to the intake for cracks

(5) I checked all the vacuum hoses that I could see, and removed the vanity cover from the engine and checked the hoses under there as well.

I reset all codes and now it seems to be running fine again. Any suggestions on what to check.


2001 Deville, Sterling Silver exterior with Dark Gray leather, 93k miles

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Between your throttle body and your intake manifold there is a rubber connector, they tend to crack on the bottom from drying out from the heat... That crack leans out the mixture and you get those two codes (P0171 & P0174). Check that rubber collar/connector/plenum closely, the crack occurs on the bottom


Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Between your throttle body and your intake manifold there is a rubber connector, they tend to crack on the bottom from drying out from the heat... That crack leans out the mixture and you get those two codes (P0171 & P0174). Check that rubber collar/connector/plenum closely, the crack occurs on the bottom

I took the rubber collar/connector/plenum completely off so I could inspect it close and did not find any cracks. It is still in very good condition.


2001 Deville, Sterling Silver exterior with Dark Gray leather, 93k miles

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Between your throttle body and your intake manifold there is a rubber connector, they tend to crack on the bottom from drying out from the heat... That crack leans out the mixture and you get those two codes (P0171 & P0174). Check that rubber collar/connector/plenum closely, the crack occurs on the bottom

I took the rubber collar/connector/plenum completely off so I could inspect it close and did not find any cracks. It is still in very good condition.

You are experiencing a vacuum leak that is affecting both banks equally, look for broken or missing vacuum hoses, etc


Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Those two codes, P0171 and P0174, are telling you that unmetered air is getting to the intake manifold and all combusion chambers without passing through the throttle body.

You have a leak somewhere in the manifold itself, the external plumbing, power brake system, PVC plumbing, oil dipstick seal, oil filler seal.

A stethoscope might be a useful troubleshooting tool.


Jim

Drive your car.

Use your cell phone.

CHOOSE ONE !

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IRC U1016 History (lost communications with powertrain control module)

Did you have to remove any electrical connectors to do your most recent job?

I would check electrical connectors around where you worked , and the battery.

then check the fuses & make sure they are all clean. - spray the connectors & fuses with wd-40

I believe this problem is electrical, and not mechanical. your car lost it's PCM for a little bit, & I'm surprised you didn't get even more messages.

BTW, anytime I remove a plug, I spray it down with wd-40 prior to re-inserting it. anyone with experience in these type of connectors knows that just because theplug snaps in, doesn't mean all the connectors are guaranteed at making 100% contact. that little bit of wd-40 provides enough lubrication to make sure the pins don't get stressed, and will provide you with a little water displacement for some time.

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I changed your thread description to be more descriptive, simply saying 'another problem' means nothing at all, forces members to go into the thread to see what you are talking about, and turns ENTHUSIASTS off to general biaching.

Please be descriptive, it helps later with searching and helps catch the eye of members who have had similar problems


Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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I changed your thread description to be more descriptive, simply saying 'another problem' means nothing at all, forces members to go into the thread to see what you are talking about, and turns ENTHUSIASTS off to general biaching.

Please be descriptive, it helps later with searching and helps catch the eye of members who have had similar problems

Thank you very much. I will remember that in future posts! :)


2001 Deville, Sterling Silver exterior with Dark Gray leather, 93k miles

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I spend almost three hours under the hood this morning. As suggested, I checked for vacuum leaks with a stethoscope. I did find a small hose on the engine near the firewall that was not on all the way. But that was the only vacuum leak I could find. I made sure all the hoses where on all the way and also checked for cracks or loose connects.

I also checked the oil dipstick seal and the oil filter is on tight. I checked every electrical connector under the hood I could find, and also checked that all the fuses where seated. The only fuses I pulled where marked for the PCM. I did not spray wd-40 on these as suggested as I felt this would be to big a mess. I also pulled the rear seat and checked the battery terminals and the fuses located there as well.

I drove the car about 30miles this morning with several start/stop cycles, and the problem is gone now. I also re-checked for codes and all is well. So, I'm not sure if I corrected the problem during my tinkering or not. I'll just have to keep a check on it I guess.

Edited by unknown_eyes

2001 Deville, Sterling Silver exterior with Dark Gray leather, 93k miles

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I spend almost three hours under the hood this morning. As suggested, I checked for vacuum leaks with a stethoscope. I did find a small hose on the engine near the firewall that was not on all the way.
Bingo.

And it will be easy enough to duplicate the problem for confirmation.


Jim

Drive your car.

Use your cell phone.

CHOOSE ONE !

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Between your throttle body and your intake manifold there is a rubber connector, they tend to crack on the bottom from drying out from the heat... That crack leans out the mixture and you get those two codes (P0171 & P0174). Check that rubber collar/connector/plenum closely, the crack occurs on the bottom

I took the rubber collar/connector/plenum completely off so I could inspect it close and did not find any cracks. It is still in very good condition.

Did you remove the manifold? That's the only way to get the plenum off. Seems like a lot of work to check it when all you needed to do was spray some Brakleen around it.

Did the vacuum line you found fix the problem?

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Between your throttle body and your intake manifold there is a rubber connector, they tend to crack on the bottom from drying out from the heat... That crack leans out the mixture and you get those two codes (P0171 & P0174). Check that rubber collar/connector/plenum closely, the crack occurs on the bottom

I took the rubber collar/connector/plenum completely off so I could inspect it close and did not find any cracks. It is still in very good condition.

Did you remove the manifold? That's the only way to get the plenum off. Seems like a lot of work to check it when all you needed to do was spray some Brakleen around it.

Did the vacuum line you found fix the problem?

No, I did not remove the manifold. I removed the rubber collar/ connector/ plenum connected to the air filter box! :o

I was thinking of a completely different part than what you were talking about! So I definately need to check it!!

The vacuum line I found did not correct the problem. The engine started to lope again, but it has not tripped any codes or made the check engine lite come on yet.

So my search continues.


2001 Deville, Sterling Silver exterior with Dark Gray leather, 93k miles

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This is what I said above

BETWEEN your throttle body and your intake manifold there is a rubber connector, they tend to crack on the bottom from drying out from the heat...

This has NOTHING to do with the air filter box at all. You are looking for THIS part circled in red

Plenumforintakemanifold_collar.jpg


Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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No, I did not remove the manifold. I removed the rubber collar/ connector/ plenum connected to the air filter box!

That's kind of what I thought and why I asked the question. BBF's picture is worth a thousand words.

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Thank you very much for the picture BBF! That really helps!! :)

As soon as I can get a can of brake cleaner I'll check it out again, probably be saturday before I get a chance.

Again, THANK YOU for the pic.


2001 Deville, Sterling Silver exterior with Dark Gray leather, 93k miles

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I think Body by Fisher is using the pictures from MY engine.

Same problem. 171 and 174. I thought bad gas as I had just put some in. Kind of sudden failure. It was a leak at the bottom of this intake hose.

I think the EGR 'fluids' and other crap settle in this area. And rot the rubber out. Hence the typical failure is at the bottom of the intake hose / coupler.

$30 part for the boot. Intake has to come off to replace. Doable job.

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I think Body by Fisher is using the pictures from MY engine.

Same problem. 171 and 174. I thought bad gas as I had just put some in. Kind of sudden failure. It was a leak at the bottom of this intake hose.

I think the EGR 'fluids' and other crap settle in this area. And rot the rubber out. Hence the typical failure is at the bottom of the intake hose / coupler.

$30 part for the boot. Intake has to come off to replace. Doable job.

:lol: Yes Logan, that is your photo! I keep it on photobucket


Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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HA HA!! :lol::D:P

Thank you so much for the pic BBF! That was exactly the problem! I sprayed Brakleen at the bottom of the plenum with the engine running like Ranger suggested and each time the engine smoothed out.

I just want to make sure I am ordering the right part/parts.

On gmpartsdirect.com they list the intake plenum under: (fuel system/fuel induction/intake/intake plenum), for $17.75, no part number given.

Do I also need to order a new gasket/seal for the intake manifold since it has to come off? Also what about a new gasket/seal for the throttle or does it have to be removed?

I managed to break off one of the little plastic nuts that holds the engine vanity cover on. I was able to get it off, but the nut is not usable. Does anybody know the part # for these plastic nuts or were I might find them. I did not see them listed on gmpartsdirect.

Thanks again for all the comments everybody!


2001 Deville, Sterling Silver exterior with Dark Gray leather, 93k miles

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I managed to break off one of the little plastic nuts that holds the engine vanity cover on. I was able to get it off, but the nut is not usable. Does anybody know the part # for these plastic nuts or were I might find them. I did not see them listed on gmpartsdirect.

Thanks again for all the comments everybody!

Can you post a picture of one of those nuts?

I might have what you need.


Jim

Drive your car.

Use your cell phone.

CHOOSE ONE !

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Hey glad you found the problem! Another satisfied member! :lol:


Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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I managed to break off one of the little plastic nuts that holds the engine vanity cover on. I was able to get it off, but the nut is not usable. Does anybody know the part # for these plastic nuts or were I might find them. I did not see them listed on gmpartsdirect.

Thanks again for all the comments everybody!

Can you post a picture of one of those nuts?

I might have what you need.

Thanks for the offer JimD, but I looked around on gmpartsdirect a little more and found them, they are only .84 cents each.


2001 Deville, Sterling Silver exterior with Dark Gray leather, 93k miles

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I got my parts in saturday and will get them installed sometime during the next week.

Just as a note for future reference, the GM part number for the intake plenum is 12555840.


2001 Deville, Sterling Silver exterior with Dark Gray leather, 93k miles

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This is what I said above

<b>BETWEEN</b> your throttle body and your intake manifold there is a rubber connector, they tend to crack on the bottom from drying out from the heat...

This has NOTHING to do with the air filter box at all. You are looking for THIS part circled in red

<img src="http://i135.photobucket.com/albums/q140/Parallax1/Plenumforintakemanifold_collar.jpg" border="0" class="linked-image" />

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I had the "check engine" light a few days ago and after checking the codes, got the p0171 and p0174 numbers. After looking at the various posts, it appears that the rubber gasket between the throttle body and intake manifold appears to be cracked. The photo that Body by Fisher posted points where the gasket is. I haven't opened the hood to check the location out but my first question is what all is involved in replacing the gasket? Could I do this myself or is it a dealer item?

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<!--quoteo(post=147658:date=Jul 3 2009, 05:17 PM:name=BodybyFisher)--><div class='quotetop'>QUOTE (BodybyFisher @ Jul 3 2009, 05:17 PM) <a href="index.php?act=findpost&pid=147658"><{POST_SNAPBACK}></a></div><div class='quotemain'><!--quotec-->Between your throttle body and your intake manifold there is a rubber connector, they tend to crack on the bottom from drying out from the heat... That crack leans out the mixture and you get those two codes (P0171 & P0174). Check that rubber collar/connector/plenum closely, the crack occurs on the bottom<!--QuoteEnd--></div><!--QuoteEEnd-->

I took the rubber collar/connector/plenum completely off so I could inspect it close and did not find any cracks. It is still in very good condition.

I dont know if this will get any attention. But before staring another stream, how do you get the rubber collar off? I removed the TB but there is a EGR spacer that looks pretty solid. Do I need to remove the fuel lines or do I have to remove the intake.

Newbie,

jeff

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