Something isn't right w/ my engine

[Schmieder]

Maybe having the MAF right at the front of the TB is not a good idea after all?

Good point, I forgot about that as well.

To answer some of the questions. Wideband, tried old coils and no change, wideband is 32" from turbo downstream, LTFT are tuned now and no more p0171, stock MAF and no changes to MAF tables, stock 43.5 FPR, the 36# inj I was told to set at 32.44 for my vehicle, only tuning I did was VE tables and not drastic and it worked out because the LTFT/STFT are balanced now (hitting 0's and a few +/- 1-2 in all cells at lower rpm's I'll explain in a minute, the exposed area of the spark plug wire is wrapped in many layers of electrical tape and I can notice the difference clearly so that is resolved but the cable will be replaced anyways.

One thing I noticed once the fuel trims are dialed in. When I try to give it fuel above a certain point, it goes lean quick and I have to back off. It only happens under load and is pretty consistent per throttle location. So that leads me to believe the fuel pressure is dropping once the fuel flow required reaches a certain point.

Also, when the condition arises I shut off the vehicle and examined the fuel pressure from the schrader valve. There is a lot of vapor instead of steady fuel. This also leads me to believe there is a lack of fuel pressure since pressure prevents vapor lock. So, there is a vapor lock condition after heat soak. Releasing the vapors and recharging the pressure from key to run several times helps the hard start but doesn't resolve it.

The fuel filter is new. So there definately seems to be a fuel pressure issue. I tried swapping the fuse like block in the engine bay for the fuel pump and no changes.

Wednesday I will take it to my local shop and ask for a fuel pressure test after I warm it up good. I really do think it is fuel pressure related now after witnessing several symptoms. Especially the p0300 and p0171 codes.

btw, I never let it run beyond 17 AFR. If it hits near there I back off the gas immediately.

Now, the idle is a bit high at 1200 rpm with the IAC step at 0. The IAC works and is clean. I tried commanding the IAC and the responses are accurate in relation to step/rpm swings. When I remove the vac line to the FPR, the idle drops to about 900 rpm. Though I can not smell any fuel in the vac line. Strange because I would think an induced vac leak would cause a rise in idle.

Anyways, I'm getting the fuel pressure checked soon. How can I determine if it is the fuel pump check valve or the pump itself? If it is the pump, there is my excuse to get a walbro 255 high flow

Thanks for all the effort guys.

btw, I haven't raped my tune and I will not. I may seem like a novice in many ways and yes, I am. But I am no dummy. I won't ever change a setting unless I am sure of the reasons why and the results I am after. Plus, I always keep a back up of the file before any changes so I can easily revert back if something isn't working out. I have about 15 pcm files now. Each one is a step I took so I can go back and see all my moves.

Here are the log files during the drive when acting up. The O2 readings clearly show a lean condition when the TPS is high enough. I included a zip of the actual hpt scanner log file and an exported version.

Thanks guys!

PS - The fuel trims are dialed in but they bounce around when it is acting up. Well, dialed in the rpm ranges I can safely drive it for now

[Schmieder]

Ok, backed the MAF about 10 inches (was 2 inches) so total of 1 foot from the throttle body.

But it dawned on me the issue was still present during Speed Density mode. So the MAF is ruled out.

And the nature of the hard start increases as time goes by when warm. So it seems fuel pressure is bleeding off. Along with the lean out at higher rpm/load seems like the pump itself is dying. I ams till going to get the fuel pressure checked out though, just can't do that until tomorrow.

I'm going to have the pump replaced with a Walbro 255 high flow. It is something I needed to do soon anyways.

In the mean time, can anyone suggest a method to test the FPR and Oil Pressure Switch?

[Weatheralls Auto]

Fuel pressure gauge, quite cheap, you could also install a fuel pressure gauge permanently into the rail since you now have turbo and custom tune.

Do you have an adjustable FPR?

[Schmieder]

Fuel pressure gauge, quite cheap, you could also install a fuel pressure gauge permanently into the rail since you now have turbo and custom tune.

Do you have an adjustable FPR?

Yeah, but it all adds up $$$

But, I see it is becoming a must. Stock FPR (non-adj).

Looks like I need to buy another gauge (fuel pressure) or rent one and tape it to the windshield.

Adj FPR would be nice.

Why does my idle return to normal when I pull the vac line to the FPR? In my experience, it should increase idle speed. Could that indicate a leaking FPR?

When I command the IAC to 0 steps, it idles at 1100 rpm. I can not find a vac leak anywhere. I am pinching hoses, using brake cleaner to test for leaks. At one point, it was idling at 800 rpm as it should, so I want to rule out a vac leak as they tend to not fix themselves, lol. Besides, I am confident in my work. Preventing a vac leak was obviously a big concern putting the engine together and i secured all areas well.

Isaac, I am not sure what application the injectors were from, but they were sold as an upgrade for the 3x00 and came with rail mounts to compensate the height difference. I was told setting them at 32.44 would be a good starting point for tuning. Adjusting them to 34.5 had no noticable effect on AFR. They are at 32.44 as of now. AFR at cold start up is around 12 but it runs great cold and into closed loop. The first drive of the day is fine except for a lean out when given enough throttle. That tells me fuel supply, but I may be wrong there. During Idle, all rpm ranges run great during the first run of the day (from cold to cl)

[robertisaar]

Why does my idle return to normal when I pull the vac line to the FPR? In my experience, it should increase idle speed. Could that indicate a leaking FPR?

computer intervention...

pulling the line to the FPR will make the motor run rich momentarily, until the O2 intervenes and tells the PCM to correct for the inecreased flow.

i'm not sure what this could indicate however... it is odd that the idle drops with more fuel.

EDIT: SUPPOSEDLY more fuel anyways... if the FPR is FUBAR, then it is possible that it's actually having a different effect.

and i don't know who told you to lie to the PCM, but that will only cause headaches later.

[Schmieder]

computer intervention...

pulling the line to the FPR will make the motor run rich momentarily, until the O2 intervenes and tells the PCM to correct for the inecreased flow.

i'm not sure what this could indicate however... it is odd that the idle drops with more fuel.

EDIT: SUPPOSEDLY more fuel anyways... if the FPR is FUBAR, then it is possible that it's actually having a different effect.

and i don't know who told you to lie to the PCM, but that will only cause headaches later.

The AFR shot to 10 (lowest reading) when the FPR line was pulled. I had my wife watch it while I pulled it.

When I get my fuel pressure tested, as long as it is ok or when it is ok, I will set the injectors accordingly.

Thanks for the tip.

edit:

Tell me what you guys think of this scenario possibility...

I guess it is possible the diaphram is busted and will not change fuel pressure under vac or atmospheric pressures and the leaking fuel would richen the mixture. Removing the vac line makes no changes to FP but reduces the amount of fuel being feed to the cylinders. Thus, reduction in idle.

But then the AFR shouldn't shoot to 10 when vac line is pulled, I think.



I think I'll take the easy way out and just upgrade the fuel system. New pump, adj FPR, FP gauge, ect. But if that doesn't fix it, I'm gonna rip some hair out....lol

[DefEddie]

I'm just gonna make some quick observations.
Taping a plug wire to resolve/check an issue is not a correct procedure,take basic electrical. That is high voltage,and black tape will not cause it to not leak.
How much you got into this project? throw out another $5 for a new plug wire.

There is no reason whatsoever that you should have a wideband and all these expensive parts but not have a fuel pressure guage or multimeter to test wires.
You are missing alot of basic auto knowledge like diagnosis that you need to do a project like this.
Stop buying "Upgraded" parts your not even sure you need and invest in some tools so we can walk you through diagnosis.
You shouldn't be tuning a computer without at least a basic understanding of how all the seperate sensors function and correlate and basic tools (fuel pressure guage,multimeter etc..-those are basic tools for auto diagnosis)

I outlined how to check the pump check valve on page 1 or 2.
Also,what's the reasoning behind putting the wideband so far from the turbo?
Mine is in the crossover IIRC,I would put it before turbo personally.
And are you using a narrowband or emulating with your wideband?
I've had issue's emulatintg a narrowband to some PCM's.

[robertisaar]

Also,what's the reasoning behind putting the wideband so far from the turbo?
Mine is in the crossover IIRC,I would put it before turbo personally.

i believe in maximum boost, corkey bell advises against it due to O2s not liking the pressure that would be forced against it because of it being between the turbo and the port, and it will almost always see more pressure than what is actually being pushed into the engine...

as far as being that far away, maybe the idea of turbulence???

i can't remember where the O2 is on a TGP, but i believe it's pretty close to the turbo outlet and it works pretty well...

[DefEddie]

I was referring to my TGP,it's in the hot side turbo housing inlet.

Corky wrote a great book 13 years ago,but OBDII was still new then so I doubt everything is perfectly accurate when it comes to the 02 sensor stuff.
Alot of technological advance's since then,it's still a great primer on turbo's but SAE is where I would look for definitives.
Alot more scientific data in there,those guys have a lot more capital to work with.

[Schmieder]

I'm just gonna make some quick observations.
Taping a plug wire to resolve/check an issue is not a correct procedure,take basic electrical. That is high voltage,and black tape will not cause it to not leak.
How much you got into this project? throw out another $5 for a new plug wire.

There is no reason whatsoever that you should have a wideband and all these expensive parts but not have a fuel pressure guage or multimeter to test wires.
You are missing alot of basic auto knowledge like diagnosis that you need to do a project like this.
Stop buying "Upgraded" parts your not even sure you need and invest in some tools so we can walk you through diagnosis.
You shouldn't be tuning a computer without at least a basic understanding of how all the seperate sensors function and correlate and basic tools (fuel pressure guage,multimeter etc..-those are basic tools for auto diagnosis)

I outlined how to check the pump check valve on page 1 or 2.
Also,what's the reasoning behind putting the wideband so far from the turbo?
Mine is in the crossover IIRC,I would put it before turbo personally.
And are you using a narrowband or emulating with your wideband?
I've had issue's emulatintg a narrowband to some PCM's.

Taping the wire is purely temporary. And at least I used electric tape and wrapped it about 50 times. Maybe overkill but it worked for the time being. The cables are good otherwise.

My tuning is not the problem as I now have my LTFT dialed in correctly as far as I can in the rpm ranges. I only changed my inj flow and the VE tables.

I have a multimeter. I am getting a fuel pressure gauge shortly.

I have enough knowledge to install the turbo so far w/o screwing up. I am generally good with auto diagnosis. This situation is just stumping me.

O2's need to be 32 inches from the turbo downstream. That is the optimal distance. Robert is correct, o2's do not like pressure.

I am using a new narrowband for the PCM and a wideband for a dash gauge. I will be wiring the wideband through the A/C pressure sensor shortly to log through the pcm via HPT. I also have the original narrowband o2 placed before the turbo. Using the wideband and viewing fuel trims, the AFR's are the same in either location w/o boost.

I am not just buying parts I am not sure I need or not. A high flow fuel pump is just common sense for FI. I am only pushing 5 psi now, but I plan to reinforce the block down the road so a high flow pump is prudent, imho.

Just so you understand me a little better, I may come off as dumb due to the questions I ask but I am very detailed and I like to cover all areas before I make a move. Hence why I ask things that I generally already know so I can avoid any assumptions. And I have an IQ of 157, but that doesn't mean I know what I am doing. It does mean I am very capable.

I over looked the check valve procedure in pages 1-2, sorry buddy.

I have a multimeter, all the general tools and a strong will to correct the issue. I will have a fuel pressure gauge shortly. I would have one but I thought a wideband would be enough to indicate a lean condition if one should arise. And now it is, so the FP gauge is on its way before I buy anything else.

So if you don't mind, ease up. I need to learn a lot but I am willing and able.

i am ready for any advice to test what you feel needs tested.

edit: btw, the high idle was caused from the cruise control cable being a little tight. I released it and the idle settled exactly where it is commanded to be. So the high idle is NOT a symptom to consider any longer.

[Schmieder]

I was referring to my TGP,it's in the hot side turbo housing inlet.

Corky wrote a great book 13 years ago,but OBDII was still new then so I doubt everything is perfectly accurate when it comes to the 02 sensor stuff.
Alot of technological advance's since then,it's still a great primer on turbo's but SAE is where I would look for definitives.
Alot more scientific data in there,those guys have a lot more capital to work with.

I'm sure the o2 works in either area just fine. My o2's are reading stable at 14.3-14.5 (stoich set at 14.3)

I confirmed this by using the stock o2 before the turbo as well all the while watching the ltft/stft and the wideband. There were no changes to be seen.

Lets not get aggressive. I have more important issues to deal with.

[DefEddie]

Sorry,don't take anything I said as condescending or coming down on you.
In real life i'm told I lack "Tact" and i'm working on it-unfortunately I totally fail on the interwebz.
If we're throwing out IQ's I'll mention when I was last tested at 16 it was 167.
Considering my age now,I guess I'm at least half dumber though.

Today is a bad day also,I'm a dealer tech and I get to mess with a hackjob all day.
If you ever want to test your automotive prowess,put something back together,diagnose it and then take it back apart for repair AFTER
The customer took it apart down to the lower mani,lost injectors,lost the bolts,lost half the vacuum lines etc...
I've been cussing idiots that think they are gods gift to cars all day.
I've also had bad days diagnosing/tuning crappy cars due to how cheap HPT is and how ignorant some of the info is on unnamed sponser driven "tuning" sites.
Everyone of them seems to be able to tune a car into the 12's but none of them could diagnose a bad spark plug to save their life.
So sorry if I seemed like a dik,sometimes I can just be an azzhole but I don't mean too.

Just always remember,diagnose 5 times before you try to tune anything out.Not trying to be aggressive,I only want to help if I can in any way.

[Schmieder]

Sorry,don't take anything I said as condescending or coming down on you.
In real life i'm told I lack "Tact" and i'm working on it-unfortunately I totally fail on the interwebz.
If we're throwing out IQ's I'll mention when I was last tested at 16 it was 167.
Considering my age now,I guess I'm at least half dumber though.

Today is a bad day also,I'm a dealer tech and I get to mess with a hackjob all day.
If you ever want to test your automotive prowess,put something back together,diagnose it and then take it back apart for repair AFTER
The customer took it apart down to the lower mani,lost injectors,lost the bolts,lost half the vacuum lines etc...
I've been cussing idiots that think they are gods gift to cars all day.
I've also had bad days diagnosing/tuning crappy cars due to how cheap HPT is and how ignorant some of the info is on unnamed sponser driven "tuning" sites.
Everyone of them seems to be able to tune a car into the 12's but none of them could diagnose a bad spark plug to save their life.
So sorry if I seemed like a dik,sometimes I can just be an azzhole but I don't mean too.

Just always remember,diagnose 5 times before you try to tune anything out.Not trying to be aggressive,I only want to help if I can in any way.

I understand, the I-Net is harder to communicate due to the lack of body language/ect. And I know how frustrating the general population can be. 90% of people are idiots but according to the population, ALL of them are smart, lol.

Funny how you say your customers loose pieces and think all should be fine. Isn't that the truth of ignorance?! I have a board where EVERY bolt and screw is placed with a label and generic outline where it goes. When I built this turbo, I can easily say EVERY bolt, screw, nut, pushrod, sparkplug, hose, ect went back in the exact same place. Every wire disconnected was labeled with blue tape. Even if I know the wire well, like the TPS wire. I assume all memory loss, hehe. I even took pics of certain steps to have a referenced source of disassembly just in case I needed to refer to it.

Every bolt was torqued just right w/ appropriate thread lock. Except for the few bolts I couldn't find torque specs for like the throttle cable bracket that bolts to the Throttle Body.

I am insanely methodical. Otherwise I may have goofed by now.

I'm glad we can meet on good terms.

Now, I did a little test of my own. I had to pick up the wife at work so I figured this was a good time to warm up the turbo GP. It ran fine as it should except for it going lean steadily as the rpm and load increases and the PCM can't seem to correct the lean condition. That tells me the fuel pressure is dropping too low.

Also, when I let the car sit for 40 minutes it was hard to start and it actually stalled out after 5-7 seconds running, the problem is getting worse.

This is what I did to help diagnos w/o the use of a fuel pressure gauge atm.

I released pressure from the Schrader valve and I again was getting fuel vapor with fuel (into a rag of course )

I then attempted a start agin and it was a LITTLE better but still stalled out.

So I pulled the vac line to the FPR to see if the added fuel pressure would help the situation under idle. It worked! The car started up rough but it corrected itself after a few seconds.

So this is what I think is happening. The fuel pressure is too low allowing vapor lock in the fuel rails during heat soak. This is the cause for the rough start/idle until it removes the vapors. There is enough fuel pressure to run the car in idle and mild load but once the fuel demand reaches a certain point, the pump can not handle the demand. Which is why the engine is tipping lean as the load increases. Note, I never let it go over 17 AFR. Once it reaches 16.5 I back off the throttle.

I am still going to get a fuel pressure gauge but I am pretty confident the pump is failing. I did swap the relay a day ago or so and it din't do anything different. That is the fuse like item under the hood above the PCM, right?

The pump is also getting initial power as I can hear it prime every time I turn the key. Though, after 30+ minutes, the priming sound is stronger. So there is a bleed off of pressure as well, obviously if there is vapor lock occuring.

[DefEddie]

If not clamped the rubber "pulser" hose on the fuel pump can leak pressure easily.
I was a victim of this crap when I did my pump upgrade a couple weeks ago,just spaced it out and forgot to put on the clamps.

The next week my brother in law's truck was bleeding pressure out also,and when I dropped his tank sure enough it was split down the middle and bleeding pressure off on high load.
Knew what it was before I ever dropped the tank thanks to my handy guage,as output loss isn't a characteristic of those older pumps like it is the newer PWM pumps.
But those are tested a bit differently also.

I like to use sound deadner on the tank when I reinstall.
High performance pumps can get a bit loud.
I lay down mat material and then spraycoat rubber deadener/undercoating.
Of course my gas tank is 18in from my ear underneath my center console,but they are loud even in my yukons.

[Weatheralls Auto]

You keep saying you have Tuned the VE tables (most VE is pointless but not in all cases)
But have not mentioned much about PE?

If you are going lean under load, are you in PE Mode? have you tuned for PE?