[unknown_eyes]

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.

[BodybyFisher]

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

[unknown_eyes]

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.

[BodybyFisher]

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

[JimD]

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.

[winterset]

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.

[BodybyFisher]

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

[unknown_eyes]

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! (IMG:style_emoticons/default/smile.gif)

[unknown_eyes]

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.

This post has been edited by unknown_eyes: Jul 4 2009, 09:43 AM

[JimD]

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.

[Ranger]

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?

[unknown_eyes]

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! (IMG:style_emoticons/default/ohmy.gif)

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.

[BodybyFisher]

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

(IMG:http://i135.photobucket.com/albums/q140/Parallax1/Plenumforintakemanifold_collar.jpg)

[Ranger]

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.

[unknown_eyes]

Thank you very much for the picture BBF! That really helps!! (IMG:style_emoticons/default/smile.gif)

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.