SD 5.3 Turbo RPM hanging and underpowered

I've been reading and trying to learn as much as possible from the forum for quite some time already and since then I've slowly been working on my car and tuning it. Aside from it hanging on the upper RPMS for a few seconds after revving the engine, it idles pretty good.

Thus far I have already read as much info on tuning Speed Density on a Gen3 with boost. I've also already seen the Greg Banish DVD's and may need to view them again as this was about 4 months ago.

However, now I feel like I'm ready to get to the WOT pulls so I can start having fun with it at the track. I took the car out for a ride today so I could get some data for tuning.

Two things I noticed from the start.

1)The car hangs on the upper RPMs for a few second after revving the engine. (I suspect some additional idle tuning is still needed)
2)I tried to launch the car today on the transbrake and it felt seriously underpowered.
3)I got on the heavy foot on an empty street today and the car felt like it had no power!

I suppose its best that I not get on WOT anymore until i get the bigger fuel pump as I dont think the Wally 255 will be good past 7psi even then I may be pushing it with out any meth injection. I plan to switch to E-85 once I tune on 93 octane first and once I get the bigger pump.

I will try to provide as much info as possible on my combination along with logs and tune. I do appreciate everyone's input.

Here is a bit on info on my combo

1979 Camaro
5.3 (from an 02 Tahoe)
2002 PCM from Tahoe

Tuned using HP Tuners non pro version.
LM1 using the A/C input

Howard rollercamshaft (190325-12)
Duration at 050 inch Lift: 226 int./232 exh.
Advertised Duration: 281 int./284 exh.
Valve Lift with Factory Rocker Arm Ratio: 0.578 int./0.587 exh.
Lobe Separation (degrees): 112

Brian Tooley springs and gear

Twin 0n3 76 mm turbo chargers
Wastegates set with 7psi springs
4.5” a2w intercooler
Heat exchanger for a2w intercooler

Siemens Deka 80lb injectors
Adjustable Fuel Pressure Regulator 1:1 set at about 58psi
Walbro 255 fuel pump (upgrading to MagnaFuel ProTuner
EFI 3-Bar Map sensor

TH350
3series carrier with 4:10 gears(have 342 ready to swap)
Cal trac bars
TCI reverse manual valve body/tranny brake
Derale tranny cooler with fan
Cheetah shifter

I want to add that when I took the datalog this afternoon it was about 88 degrees outside. Also the tune is the one I loaded before the datalog.

As I said before all input is greatly appreciated.

Something wrong with Bank 1. In other parts of the log it looks like misfires.

Attachment 50478

I'm wondering if it could be a manifold leak on bank 1? I will recheck that to make sure

It may be why I only got about 3psi at 3500 rpm...

*Looked at the log again and it looks like the issue goes and comes at different points..I'm wondering if the O2 is on its way out..the connection may not be tight or maybe the wiring is faulty..


I'll also check the spark plugs, spark plug wires, coils and coil connections to see if that is why it is misfiring.

Does the tune look like I'm headed in the right direction though?

I see that I have a bit of KR on some points when I'm letting off the gas, could it be that I don't have enough timing or perhaps I am over fueling at those points?

I never saw 100% tps in the log either. What I looked at in the tune looked reasonable. You have to correct any mechanical/electrical issues before you start blaming the tune. The tune wouldn't effect one bank only.

Might want to double check fuel pressure too durring or while getting into wot. Just cause you got new good parts, doesn't mean they're working correctly ;) I haven't checked the tune either, but like 2xLS1 said, get the electrical and mechanicals fixed first.

Since it's turbo, make sure you atleast retarded your injection timing somewhere around 15 degrees. You can add 15 to your boundary for this. AND plugs are gapped to no more than a larger gap of .032"... You'll want air fuel ratio under boost somewhere around 11.5ish if it's not. Thing is with turbos they can operate richer to around 10 or even mid 9's then start sputtering then they can operate leaner to about 16 to 17ish before they start sputtering, but obviously you don't want it that lean or kaboom she'll go... In fact nothing leaner than 11.8 or 11.9 would be best or richer than 10.5. You also need timing to build boost, added in the 80 to 100 g/cyl range of your timing charts.

Hopefully you'll just find a vacuum leak and that'll be all it is, but I'm kinda thinking it might be a touch more towards fuel...

Hope this helps.

I will go back and check my peddle and TPS. First time I took the car out it would only go to 60% because I had installed dynamat under the carpet. But after fixing that I remember it showing 88% at WOT.

If it matters I do have truck coils on the car and just recently installed the deka 80s. I will pull the plugs to make sure they were not fouled during initial idle tuning.

Also on the gap I remember gapping them at .028"

I will check my afpr i have the vacuum hose for it hooked up to a distribution block about 3 feet away, that may also be a problem.

I did not use a check valve on the vacuum hose of the afpr. Is this OK or do I need to put one on it. I've heard mixed opinions on it.

I need to go over my timing again but i do beleive i had set the final timing to 12* while in boost, 22* at idle. I need to recheck what I set it at 80-100 g/cyl range. What timing would you recommend on this area?

Perhaps I need to add a bit more timing?

My A/F is set at about 11.48

Thanks again for all the help.

I switched from SBC to LS and I know they are a very different beast so I am trying to pick up as much as I can. For one the timing on the engines are very diiferent.

Attachment 50593 Idle Datalog

OK so still no luck with finding the issue thus far.

I swapped the O2 sensors from Bank 1 to Bank 2 to make sure the sensor was not the culprit and Bank 1 still comes up lean at idle. I also checked all the connections on the coil packs and the harness and they look to be fine.

However, I did notice that when I stab the throttle on the car Bank 1 seems to come to life and register just fine until it comes back down to idle. Would this perhaps mean that there is a leak somewhere on the manifold area? Maybe manifold gasket? I've read they tend to leak.

Also, I pulled the plugs (BR7EF) and they were all black from running rich. I suspect that I may have fouled them when I was tuning the Deka 80's at idle. The plugs (BR7EF) probably have about 20miles on them and maybe about 10 idle tuning sessions. Should I go to a hotter plug?

A/F's look good at idle though.

Are O2's post or pre turbos? They should be post. Yes, sounds like you have an air leak on the exhaust side allowing air to be sucked in. This will show durring idle or any constant throttle light load situations.

Turbos like advanced timing, just make sure your not getting knock and not losing power. Seems like you have to walk a finer line with turbos when it comes to timing.

Did you ever retard your injection timing? Your boundary should wind up somewhere around 6.8 to 7.2ish or maybe even a touch higher with your cam combo setup.

Quote:

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Originally Posted by GHuggins

Are O2's post or pre turbos? They should be post. Yes, sounds like you have an air leak on the exhaust side allowing air to be sucked in. This will show durring idle or any constant throttle light load situations.

Turbos like advanced timing, just make sure your not getting knock and not losing power. Seems like you have to walk a finer line with turbos when it comes to timing.

Did you ever retard your injection timing? Your boundary should wind up somewhere around 6.8 to 7.2ish or maybe even a touch higher with your cam combo setup.

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The O2s are pre turbo. I am using truck manifolds flipped, kept the O2s on the stock locations.

Wideband LM1 is on post turbo Bank2 passenger side.

Here is how I have the timing map set up right now which may be a bit too conservative? Attachment 50599

I saw only light knocking 2-5 counts when I would let off the throttle, but at the same time the idle would hang for about 4 seconds when I let off the throttle. Perhaps the knocking was due to it going rich when the idle hangs?

The car does feel like it has no power though, so maybe too much or not enough timing on some areas.

I have not touched the injection timing. I'm not sure where that table is at but after some research I believe this is the one? If so its set at 6.50. Attachment 50600

Should I change this number to 7.2? Would this also help with my idle hanging after letting off the throttle?

O2's must be post turbo so backpressure doesn't screw with them... They have to be moved... Then you'll need to dial in your O2 switch points. With the backpressure keeping the fuel mix in the manifolds from the turbos, it's going to cause the ecm to take fuel away causing lean issues.

You should also remove and reseal the effected manifold that's leaking and verify you see NO cracks in it anywhere.

Would add about 5 or so degrees in the .76 to .96 ranges while blending into their neighboring cells. This is where the extra timing needs to be to get the turbos to spoil. 12 to 14 is good max timing for turbos if your running 8+ pounds boost if you've got newer more efficient heads and decent compression - lower compression built motor = more timing. If it's showing knock, you can always take a little out via making knock tables less sensitive, as long as it's not actual knock.

Yes that's the injection timing number to change. Change it to 7.2 and see how it does. This will actually cause the turbos to spoil anywhere from 300 to 600 rpms sooner if correct.

Just looked at the datalog. Are you only using the wideband for tuning? Only reason I ask is because O2 voltages aren't corresponding to where the A/F should be. Wondering what you would wind up with if you turned your Fuel Trims back ON. Fuel corrections are a must with boost or at the very least a spot on VE tune. After fixing the O2's and your leak, turn these back on, retard your injection timing and start over. Turbos and cams are hard to tune by themselves and can require several reworkings to get that sweet spot. Heck turbos alone in certain cituations can require remapping a lot of your airflow tables for idle quality and so on. Your starting out with both on one of your first tuning jobs from the sound of things.

Not sure if it matters by I am running Open Loop SD 3bar OS. I have the STFT and LTFT disabled.

I thought it was OK to run the narrowband O2 sensors pre turbo and just use them to hunt down leaks or misses. I did not think that they would command any fueling adjustments to the PCM when running Open Loop Speed Density. Do I have the concept wrong?

My LM1 wideband is located post turbo about 12 inches away from turbo on the downpipe.

I will check the exhaust manifold and reaseal it if no cracks are found. Should i stick to the same plugs or are they too cold? Ill be running about 20psi once i switch over to ethanol and upgrade my fuel pump.

For now I'm sticking to about 7-8psi on 93 gas.

I'll also change the injection timing and log the difference. Any idea what would be making my idle hang after I crack the throttle?

Yes I am only using the wideband for tuning the VE table with the copy paste% method.

I have both STFT and LTFT off do in turn them both On or only the LTFT?

This is the first vehicle I have tuned with HPTuners. In the past I've used edelbrock pro flo and Moates. Its a big learning curve on the transition but the learning part is what makes it even more worth while.

Turn them both on after moving o2's. 7 on plugs are hot enough.

Removed and re-installed the driver side exhaust manifold after checking to make sure there were not any cracks on them. I did find two exhaust bolts from the manifold to the turbo loose initially.

Also, looked at all my vacuum lines and intake to make sure there were no leaks or cracks. I changed the O-rings on my distribution block as well, they looked brittle and cracked from the heat I think.

I did find that the boost reference hose going to my AFPR was pinched so this is one problem found and fixed. (This is why my fuel pressure would stay at 59psi at idle when it should have been going lower due to the vacuum)

I also had another two questions.

1) I am going to add a second inline 255 Walbro and was told to lower the fuel pressure lower than 59 so I can have enough flow from both pumps when transitioning into boost. Do I have to adjust my injector data if I lower my base fuel pressure? Right now I have the Injector flow rate vs KPA VAC set at 81.4 all across the flow chart (0-80)

2) I'm now wondering if perhaps my injector data might be wrong as I was comparing my tune to another tune and saw that we were running different setups but the same injectors and the data did not match.

Sorry if these questions may seem a bit too ignorant on my part.. Just trying to learn more on HPTuners and get my car running decent.

Attachment 51830Attachment 51831

Coming back to this.

I've made the following changes to the car.

1)MagnaFuel 4303 Pump
2)E-85
3)Switched to Lamda on the scanner.

I am running the LM1 through the A/C sensor. I used the equations found on these forums to convert over to Lambda. Also I set my Stoic to 9.7756

STFT and LTFT are disabled. I was told by a few people that since I am running SD and a 3Bar I should be able to set a decent idle using the Wideband.

This is just my weekend car as I only use it a few time out of the month for a quick ride around the city to the local car meets and it will see track duties as well.


I am still having the same issues with Bank 1 02 Sensor. I've gone over the manifold again and did not find it to be leaking or cracking. I swapped in a new O2 Sensor and the problem still continues although it only happens every so often. I also checked the voltage on both Bank 1 and Bank 2 O2 sensor harness pins and found the following results with the Key On Engine Off

Bank 1 A-(7.85V) B-(8.90V) C-(13.25V) D-(ground)
Bank 2 A-(2.35V) B-(4.85V) C-(13.70V) D-(ground)

I'm not sure what the voltage should be but Bank 1 the problem side is a bit high on both the Low Signal and High Signal as opposed to Bank 2 but I am not sure what the true value should be.


I've attached the logs of my initial start-up from yesterday and now that I switched over to E-85 I am having the following problems.

The car will not start on its own as it used it. I now have to hold the pedal a bit so that it can stay on while it warms up. After it warms up it will hold idle.


Once it warms up I will stab the throttle in Park while idleing and it hangs the RPMS for a few seconds then when it finally decides to come down the car just dies and I have to turn it on again by holding the throttle a bit.

Not sure why this is happening now. Perhaps I still need to fine tune the VE table some more but it is between .90 and 1.02 lambda on a commanded idle at 850

I also noticed that the idle timing jumps around alot from 15-30 degrees but if i hold the pedal a bit the timing will stay linear at the commanded timing like at 24 degrees.

Also from looking at the scanner, I see that the car dips down into .78 lamda (very rich) after I release the throttle.

Any input on this is greatly appreciated.

a few things

PE
lower your TPS to say 50% from 90 at which you have
add 5 MAP hyst
enable torque
50
hyst 5

setting above is safer

I'm not sure i follow in the TPS!?

I already have the PE throttle/pedal set at
20 Hot
30 Cold
Unless I'm supposed to be looking somewhere else?

On the Enable Torque . Does it matter that I am running a TH350?

Thanks for your help

Made the changes recommended by SultanHassan and I still need to feather the throttle in order for it to start. And if I stab the throttle the rpms will still hang and then the car dies when they try to settle down.

Perhaps I need add some fuel to the cold cranking tables?

Ran the RussK config IAC is at 96 at operating temp. (attached the log)


Also did a bit of idle tuning with the VE table. I added a bit of fuel to cranking tables. Now its starts a bit easier, after the third or fourth rotation. However it still hangs the rpms after i blip the throttle, but not as bad as it used to be.

I thinking I may have to mess with the Throttle follower decay a bit.

I rechecked the lines and intake and could not find any leaks.