Can a loose valve cover screw trigger CEL?

[maxchao]

I'm trying to fix my g/f's '00 LX protege CEL. I went to autozone and got the code of P0106, P0171, and P0507. I was told they are vacuum leak, system lean (bank 1) and idle too high.
I searched around the engine bay for leaks but didn't find anything, then I came to a totally loose screw on the valve cover.(See pic red circle) I found it because I saw it was shaking around in its hole when the engine is running. I tighten it, reset the CEL, but not sure if that was the problem. and I can't think of a way to find out.
So I'm just wondering what a loose screw can do. That was the only loose one on the valve cover, and one above it is a little loose but not too bad.

Josh

 

[njaremka]

i doubt that loose bolt has anything to do with the codes...

P0106 pretty much has to do with the EGR system. this code would make me think the EGR is going bad. (or is shot)

P0171 "Could" be a result of a misfire, which could have been caused by a bad EGR valve. so, i would work to correct code 106 and see if this one comes back or not.

P0507 could also be related to the other two, or it could be the IAC valve.

if this were me, i'd look into replacing the EGR valve, clear all the codes, and see where it takes you. it probably couldnt hurt to do a full tune-up with new plugs and wires and air filter.

 

[maxchao]

The weird thing is that the car runs fine. Unless maybe the EGR is stuck closed, then it will rob the power, but the car is slow anyway(1.6L) so I can't really tell. Idels even better than my P5 w/o CEL.
I guess I will take time to clean it. I checked around PCV and the hose there seems good. I'm trying to find a way to inspect vacuum hoses around the EGR.
I really don't want to spend money on replacing the EGR, it costs too much.

Oh well.

Josh

 

[Shane5425]

iac motor is going out, try taking it off and cleaning the inside, mine crap out on me and gave that code.. as for the other 2, you can try to take the egr valve off and clean it, but most of the time you have to replace it.. once the car is warmed up.. the egr wont make a differance, its only during warm up the egr does most of its work.

 

[njaremka]

the EGR only works during steady state cruising, not warm up and not at idle. also, there are no vacuum hoses that go to the EGR, its all ECU controlled.

yeah, you can try cleaning it, but chances are it will need to be replaced. at about $120 or so, its worth the hassel just to get a new one. the IAC valve on the other hand, will cost a LOT more than that and might be worth a try to clean it.

 

[Shane5425]

[FONT=arial, Arial, Helvetica]"If EGR is on during idle, stumble and even stalling will likely result. If EGR is on during hard acceleration, low power (from reduced air/fuel volume) is the result. At part load, lean mixtures for economy create high combustion chamber temperatures and without EGR, these conditions not only create Nox, they also foster pre-ignition and pinking."

egr valve is prolly stuck somewhat open, that will cause you misfire code , lack of power.. bt yea the iac motor is about 300 bucks if i recall when i replaced mine..
[/FONT]

 

[maxchao]

Actually I did not only tighten that screw, I also found the PCV was a little, like 2mm, out of the gourmet, and the gourmet was a little loose.
I did not check the idle before I did all that, but I remember it was like 800 or something, nothing crazy.
Anyway, it idles well now. I think I will need to drive it around to trigger the CEL and take it right to autozone again to find the major problem. But I can't do that until Saturday.

Josh

 

[maxchao]

Oh and I was talking about the hose from the exhaust to the EGR and from EGR to intake.If the one from the EGR to intake is loose, it can suck in air and alter the manifold pressure and trigger the EGR boost sensor, I guess.
Well, but that hose is like beneath the intake manifold, so hard to find.
Plus there are lots of ants on her car now for some reason I don't know, (only outside), so working in the engine bay is even harder.

Josh

 

[pro2002]

I had code a P0171 and while checking it out the intake tube was cracked causing the P0171 code. Replaced the tube and all is good. Just my two cents.

 

[maxchao]

pro2002, did you mean the black plastic intake tube before the throttle body and after the MAF sensor?

Josh

 

[pro2002]

Yup, that's the one.

 

[maxchao]

Hmm...I guess other than the EGR valve and its line to the intake that would be the other thing that I haven't check. I did check the upside but not the downside of it.
I drove about 10 miles hwy yesterday and 25 miles hwy and 15 miles traffic jam today, the CEL hasn't come back on yet. Hopefully it is just the PCV valve that was loose causing all these troubles. (I push it back, refer to the previous post)
But my g/f said that the CEL won't come back until you drive it for a week, well, we'll see.

Josh

 

[blackshine007]

Hmm...I guess other than the EGR valve and its line to the intake that would be the other thing that I haven't check. I did check the upside but not the downside of it.
I drove about 10 miles hwy yesterday and 25 miles hwy and 15 miles traffic jam today, the CEL hasn't come back on yet. Hopefully it is just the PCV valve that was loose causing all these troubles. (I push it back, refer to the previous post)
But my g/f said that the CEL won't come back until you drive it for a week, well, we'll see.

Josh

So, umm, any updates? I'm having the same problem with a '00 pro 1.6 and I need to know how did you resolve it.

 

[maxchao]

That was it, just the PCV valve leaking air. The previous owner probably live somewhere north and there is a lot of dirt under the hood, and the rubber seal for the PCV is very dried and so not securing the PCV valve on the valve cover well. And as everyone knows our engines vibrates a lot, and probably overtime it push the PCV valve outward like 3-4 mm. (I'm better with metric unit) After I push it back in there, the code never came back on.
It was really that small thing that bothers us for 3 months.

Josh

 

[jdbru]

I had code a P0171 and while checking it out the intake tube was cracked causing the P0171 code. Replaced the tube and all is good. Just my two cents.

Bless you pro2002.

I've been struggling with a P0171 issue for a couple weeks. I was ready to look at buying new coils or injectors.

After reading your post, I checked and the tube is cracked, almost in half.

I guess I was too busy/lazy to notice. Thanks again.

 

[Wingman21]

Actually I did not only tighten that screw, I also found the PCV was a little, like 2mm, out of the gourmet, and the gourmet was a little loose.
I did not check the idle before I did all that, but I remember it was like 800 or something, nothing crazy.
Anyway, it idles well now. I think I will need to drive it around to trigger the CEL and take it right to autozone again to find the major problem. But I can't do that until Saturday.

Josh

Can anyone let me know here exactly is located the PCV and how can I verify that it is not loose like that? I'm also having the lean condition during idle and the P0171 CEL.

Thanks