Codes P0171, P0174, P0430, P0300

Hi and thanks for using 2CarPros.com.

As far as a vacuum leak is concerned, yes to all of your questions. They can cause a lean mixture as well as a random misfire. What I need you to do is use a vacuum gauge to check for leaks. Here is a link that shows how it is done. Also, behind the throttle body, there is a vacuum hose connected near the bottom. If you follow it, you will find a 90 degree elbow. These elbows are known to dry-rot and leak. So, make sure to look for that.

Here is the link:

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Check these things and let me know what you find. Also, if you have other questions, let me know.

Take care,
Joe

The elbow behind the throttle body that you are talking about, goes to the PCV valve, right? Also, I look into the vacuum thing. Thanks

Oh, and when using the vacuum source at the engine, where is the source exactly?

All you need to do is fine a vacuum port on the intake or a vacuum line. Any intake vacuum port will work.

As far as the PCV, that should be a much bigger hose. You will be looking for a smaller one. However, the PCV can leak just as well.

So bank 1 and 2 is lean. Insufficient something to catalytic converter is p0430 and p0300 is random cylinder misfire.

All plugs and packs have just been changed. I have been told that the bank 1 and 2 being lean is usually caused by a vacuum leak. I have checked I can see under the hood. Is there any vacuum lines elsewhere that is tough to get to that I need to he looking at? Could vacuum lines cause the random misfire? Anyway, thanks!

Good afternoon.

The 430 is for catalytic converter bank 2. That is the drivers side

171,174 is for long term trim reading high which is lean.

Check

Fuel pressure. Would also cause the 300 code.

Mass air flow sensor. Make sure the connector is clean and tight. Check the hose that goes to the throttle body and see if it is ripped open anywhere.

PCV make sure the valve is not stuck open.

Intake manifold. Common for the intake manifold to warp and leak vacuum. You can verify by a smoke test to see if it is leaking.

Roy

The 430 is interesting to me because the catalytic converters were gutted. But there still seem to be less exhaust coming out of the driver side than passenger side. Could a clog issue this code? If so, how can I find it?

What is the easiest way to check fuel pressure?

Can I use electrical cleaner of the MAF sensor? Is the hose on the TB a vacuum line?

I just replaced the PCV.

If you gutted it then that is why the code is set. There is no cleaning of the gases. It needs to be replaced to turn out the light.

You can rent a fuel pressure tester. You get it at a parts store. There should be a schraeder valve on the fuel rail.

There is no such thing as cleaning a mass air flow sensor. The carbon is burned on the sensor and there is no cleaner that can get it off.

Roy

I got a fuel pressure tester from Harbor Freight. It has a gauge but doesn't have a pump. I put the gauge on the Schrader valve and turn the key on and it never even moved on the gauge.. I haven't had any problems with it not starting. It's only when the motor is cold and on the first crank in the morning it idles like crap. As soon as I give it gas or put it in drive to take off then everything Smooths out until I put it in park and it idles in. I remind you this is just when the motor is cold

After the motor is good and warm then there is no issue with idle. I also did a vacuum test. I just simply put it on a vacuum line and the needle was jumping everywhere but that's because of the idle. It bogs down like it's fixing to quit and then it catches back up and then bogs back down again. It keeps doing that until I give it gas or go to take off

As for the Schrader valve. I probably didn't get a reading bc my cheap ass harbor freight tester doesnt have any fitting that would release the valve stem to get a reading. I just plugged up the hose that it came with. Is there another way to do a pressure test?

Fuel pressure needs tested at the schrader. The only other way is to disconnect the fuel supply and place a T in it. Then you would still need a pressure gauge to check it.

Okay, so the fuel pressure checked out as normal. The boot on the back if the throttle body is fine, no holes or anything. I am also getting a p1131 and p1151. This is oxygen sensor problems that are tied into this problem I believe. I also checked manifold and all other vacuum lines with starting fluid. Is there anything else that would cause this? Give me all you got because this completely stumps me

Hi again.

The 1131 indicates a lean mixture and the computer has maxed it ability to compensate. See pics 1 and 2 for possible causes. The 1151 is the same thing for the opposite bank.

Take a look through the two pics I attached. See if anything clicks with a possible issue.

Also, these engine often times have exhaust manifold leaks. It will sound like a ticking oftentimes. Is that happening?

Let me know.

Joe

What is a VPWR? I know I have an exhaust leak on one side because it is where the doughnut gasket is that bolts the exhaust on to another piece that is kind of near the upstream o2 on the passenger side. How do I find out in the EGR is stuck? What about cam timing? I know I sprayed everything with carburetor cleaner and I have not found anything.

My theory is that when the truck rough idles and stalls from a cold crank, the leak is from the intake manifold. As the truck warms up, it reseals itself. The only thing is the p0171 and p0174 codes stay present.

I am not sure about a ticking sound. Where and when would I hear it?

If the exhaust manifold is leaking, it would be most obvious when starting it and when the engine is cold. The easiest place to hear it from would be the front wheel openings.

But just one side leaking would not cause both banks lean I would not think. I am going to attempt to pull off a vacuum line and blow cigar smoke in it to see what happens.

If unmetered air is getting into the system, anything is possible.

I like the idea of cigar smoke. I have never heard of anyone doing that, but If you can get enough in there, I do not see why it would not work. Ha. I learn something new every day.

Yeah it is an old timers trick. The only things that I am not grasping is what the best vacuum line is to take off to test it and what do I do with the component of the vacuum line that I pulled off? I mean do I have to put a t in it with a hose so everything stays connected or do I just block the whole of the component that I took the vacuum tube off of? I do not see any direct vacuum lines going to the upper intake manifold. What about the PCV tube?

The PCV is your best bet. You could use the brake booster vacuum hose, but then you will not see if there is a leak in the booster.

Okay, so leave the PCV valve in there and just use its hose that goes to the elbow behind the TB. Would I need to cover the top of the PCV valve with something while doing this?

That should work. As far as the PCV, you will need to get a lot of smoke in the combustion chamber for it to come out there, but it won't hurt to plug it.

Please keep in mind, I have never done it this way. lol This is new to me with the cigar smoke.

Haha, well I am glad you learned something from me lol. So this done with the vehicle turned off I assume?

Yes, the engine would have to be off. Otherwise, the engine vacuum will suck the smoke into the combustion chamber with the air. I guess in a way, the vehicle's exhaust could make one believe the car was smoking a cigar. LOL

Yep. LOL

Okay. So I smoked a fat cigar in less than five minutes and not only did I manage to find a couple of air leaks, but I also smell like an old man with good luck at a poker table. LOL. I can vouch for the cigar test but only if you use at least a 3/8 hose, because you cannot push enough through a small 1/4 line if you are trying to test everything. Plus it will give you lockjaw's (which is another problem you do not want).I went through the PCV tube on bank 1 (passenger side). The first leak was found off of the cold air intake. I have two outlets about half way down the intake pipe. The bottom outlet goes to the PCV valve on bank 2. The outlet above it goes to the IAC valve in the back(its against the back firewall right above the notorious boot that dry rots.) Both leaks was on that line. Someone who had the truck before me used a piece of hose as a sleeve between the hose off the intake (1/2 in) to the hose going to the IAC (5/8in). It was not tight so unmetered air can get in. The other leak was actually at the IAC valve. I put this part on about 2 months ago because of this vacuum problem. The smoke was coming out of the bottom of a little metal cap that has made on to it. I believe this metal cap is meant to be designed this way for some reason but when I put a little carburetor cleaner to it while it's running, there is no difference in idle.

I fixed the hose problem and I am not sure if anything needs to he done about the IAC.

This is not my IAC but its the same one for my truck and here is the cap I am talking about. It seems like it is for venting because the cigar smoke came out from under it. It was not excessive smoke but a small amount.

So after further research, I have read that this cap is suppose to do that. It is unmetered air but the PCM compensates for it. The cap is for pressure relief to balance the idle speed and without it, the idle cant be stabilized. That is good to know.

Wow! I cannot believe it worked. Has repairing the vacuum leaks corrected the problem? I think it would be fun has (*&^ to have you working in the shop. However, I do not know how I would explain to customers that smoking a cigar helps fix vacuum leaks. LOL

Well I smoked the cigars but I did not inhale, LOL. I did it again after I repaired it and it worked. The only thing is, I will know more when I crank it in the morning because it idles and runs badly until I drive a few miles. I think the intake manifold gasket is messed up and when the motor gets warm, the gasket seals itself again. I will report back tomorrow with details but I do not expect this issue to be the only one.

I will watch for your reply. If the intake is an issue, you are most likely correct. The metal expands as it gets hot. I hope this does the trick.

Take care,
Joe

So I fired her up this morning and there is still some tough idling going on but it does not seem to be as bad. I will say it has improved by 25% so that hose was a problem. I have sprayed carburetor cleaner all around the intake and never got any changes it in idle. It is so weird but I am never going to give up on this piece of crap because it gives me something to do, lol.

I wonder, what are the odds of the cold rough idle being a ETC sensor?

Can air getting into a small leak hole in the exhaust cause this problem? I like said before, there no driveability problems and no idle problems after the motor is good and warm. Just idle on the first start up of the day or after its sit for about nineteen hours or more.

Well, you are getting there. And yes, the ECT (electronic coolant temperature sensor) can cause problems. It is responsible for telling the computer the coolant temperature. Based on that reading, the computer regulates the air/fuel mixture to the engine. If it thinks it is colder or hotter than the actual temperature outside, the mixture will be off.

If you have a live data scanner, in the morning connect to it and see what temperature the sensor is telling the computer. If it is off by more than 10 degrees F, that could be an issue. Interestingly, even if the sensor is wrong, the computer will not know it is wrong and will not set a code. Ugh! I miss carburetors. lol Actually, points and condenser too. LOL

Right! LOL. I knew it would not necessarily throw a code. I do not have a live reader yet but I will have one by Christmas LOL. I will know a lot more from that probably. I do have a cheap scanner and it shows freeze frame and PIDs but it is not live. I wrote down all of the information from one of the codes. It will not show me the advanced info of multiple codes, just the first one. Here it is:

This was before I fixed the hose yesterday.

P0174
CL
Etc 176
Shrtft1 16.4
Longft1 25.0
Shrtft2 8.6
Longft1 25.0
rpm 1430
Vss 40

Wow, the fuel trims are really high, They should be close to 0. It is over compensating for the lean mixture. Ugh!

What does this mean, a bad PCM? What can cause that?

Basically, the PCM is trying to compensate for what the O2 sensors are telling it (too lean). I do not feel it is there result of a bad PCM.