5.3 Swap....SOMEONE PLEASE HELP

[Beaureed]

OK, I am new to HP Tuners and somewhat new to LS motors. A little backround, I work for a restoration shop that sees a need for setting up LS motors for customers. Well I got tasked with the job to figure the wiring and tuning out on these motors. I am having some problems with my first motor. The motor is set up as a stand alone unit on an engine run stand. It is a 2004 5.3 DBW motor that we purchased complete with motor, PCM, TAC and Harness. The motor is 100% stock other than the air intake is Air Raid setup. I am getting extremely frustrated at this point. I am using a Corvette regulator and Warlbro Pump feeding from a 1 gallon fuel cell.

So here is what I am dealing with. The only things I have changed in the tune are, deleting VATS, and Rear 02's. I have eliminated some trouble codes I was getting. (mostly EVAP). The motor fires up well and runs pretty good in Open Loop. Once it warms up and goes closed it starts to idle terrible, and is running extremely rich. It idles up pretty good when you hit the pedal, but once it idles down it almost wants to die. To me it definitely seems to be air/fuel related. I am not sure if there is something else I need to eliminate in the tune that could cause this. When I say new to HP tuners, I mean very new. I don't really know what I am looking for while I scan. the code that concerns me is the P0300 misfire code I get. This code comes on everytime. When I leave the shop at night I disconnect the battery on the stand, so this is a code that I see everytime I start the motor. There are a couple others, like fuel level and oil pressure circuit, as well as quite a few transmission codes, which I expected to see on a run stand. The scanner is showing the misfires on every cylinder, not just isolated to 1-2 cylinders. I have searched for Vacuum leaks everywhere, and am on my second set of brand new o2's. (Long Story). There are no exhaust leaks. Everything I read is vacuum leak or o2's. I don't believe it to be o2's, haven't really 100% eliminated vacuum yet I guess. There does not seem to be very many places for a leak. The brake booster port is capped, and nothing else looks available for leaks. I did spray carb cleaner around and did not see any changes in fuel trims, which seem to be somewhat stable from what I can tell.

Tried so far
New Plugs and Wires
Checked all injector plugs with noid light and seem to be working as they should
New o2s
New Maf/IAT and checked wiring to the MAF which looks to be good
I have 50ish pounds of pressure at the rail at idle, but seems to be close to high 60s at idle. Return is unrestricted, I ran the open line back to the tank to make sure.

Coils seem to be firing

There has got to be something dumb here I am missing. I am attaching my tune and a short scan that I did. If there is something I need to scan that would be more beneficial please let me know. I m also going to attach some pictures of my setup to see if anyone notices anything out of the ordinary that pops out at them. Thank you for any help you can provide

[Oleblu]

You should change your Map sensor units to Kpa in your channels list. Wouldn't hurt to add inj pulse width to your channels list also. Can your hear the engine physically missing? all that surging appears to be timing related to me. Do you have a wideband hooked up to this to confirm the rich condition? fuel trims and o2 readings look pretty soild honestly.


By the way love the vise grip clamps for your exhaust flange.

[gofastwclass]

Honestly, without a wideband sensor you simply can not reliably tell if an engine is rich or lean unless it's really far off.

If the exhaust flanges in your image are letting air by them (very likely after they come up to temperature) the O2 sensors are going to see a false lean condition. They will cause the PCM to add fuel to compensate.

[Beaureed]

Thanks everyone for the replies so far. I tend to deffenitly believe this thing is being flooded with fuel. for some reason. after its warm the thing stinks out the shop of unburnt fuel. Im not very familiar with the wideband setup yet, as i thought I really would not need it yet, just to set up a stock motor. However i did order the Pro kit when we purchased this. I didn't think anything in the trims were to shocking but was hoping I was wrong. Any more suggestions would be very appreciated. Thanks for the replies so far. Is there something in the tune that I missed. What are everyones thoughts on the high 60s for fuel pressure at idle.

[IARLLC]

Since this is not a flex fuel motor it should have about 58-62 psi. Hi 60s will affect flow...but in closed loop it should be able to make up for that 12-15% no problem.

With the chambered muffler I wonder if it would help to have a bit of pipe added to decrease the chance of inaccurate O2 readings. Also gofast might be right about false air getting by the flange and messing with O2 settings.

Seriously I am willing to bet that the misfires are false. Without the weight of a converter bolted to the back of the flex plate the behavior of the crankshaft is way different than the computer expects. You could try bolting on a converter and see if those misfires disappear.

[5FDP]

Engines are only balanced with the flex plate and balancer though, having the converter off should make no difference.

I'd curious as to what it ran like if you put the tune into speed density only.

[IARLLC]

This is not a question of the balance of the engine...but the stability of the rotating assembly at low speed when its inertia has been cut in half. The converter does not weigh as much as the crank but much of its weight is at the perimeter. It adds A LOT of stability to the whole rotating assembly. Every event at a MUCH lighter weight has a much larger effect (fore and aft).

Even though it was almost 30 years ago I still clearly remember the first time I set up the idle of a large cammed, high compression small block on an engine stand. I still remember how quick it revved and how jumpy it was until we installed it. Maybe I am wrong about this alone showing false misfires but has the crank learn been done? A combination of less stable rotation and lack of crank position knowledge could lead the computer to make this mistake. I have seen false misfire data on a lot of GMs and some TSBs point to crank learn need, but sometimes there is very little effect from crank learn. Beaureed, do you have the e-brake and brake switch wired up to the PCM? 5FDP, how do people run the crank learn on a swap if they don't hook up the e-brake and brake switch?

I'd be curious what it runs like in SD too and still just as curious if the misfires magically disappear once there is a heavy converter bolted on

[Beaureed]

Thanks everyone again for the continued support. UPDATE.... I replaced the regulator today and dropped my fuel pressure down to 58lbs by doing so. I am not sure if I had a faulty regulator or what seemed to be the problem, but my fuel pressure is where I would like to see it now. HOWEVER.... this did nothing for the idle issues I am having. The misfires I am seeing definitely seem to be there. You can cleary see them in the RPM range and the way the motor sounds at Idle. there is no doubt the motor is running rich (The motor smells horrible of unburnt fuel). However I do not know if this is being caused by to much air somewhere and the PCM is trying to makeup the difference or the motor is getting to much fuel. OR if something totally differnet is my issue.

Where do you think I could be seeing air at the manifolds. I sprayed around the collectors I made and seen no difference in fuel trims.
Crank Relearn is a subject I know little about. What would this do for me. I did a little reading on it and I am not sure how I would perform this in a stand alone set up. I have seen many internet videos of stand alone LS motors running great with no flexplate and converter, so I don't know if that would be an issue. Running in a SD setup might take me a little time to figure out, as I am still trying to navigate around HP Tuners, but maybe I should try to give that a try. I cleaned the injectors tonight but did not have time to fire it up again. Please let me know if you have any more ideas, I am all ears and appreciate all the help I can get. I will scan it again tomorrow, is there anything else that might be of use while I scan that might be helpful info to someone.

[5FDP]

Just be aware that you are not running cat converters, the engines exhaust is always to to smell raw and burn the eyes. There is no way around that even if the engine had no misfire.


Speed density is easy enough to setup and try. Under engine diag, set the MAF fail high to 0hz, then set the 3 MAF dtc's to fail on first error. That's really all it takes to force speed density.

[Oleblu]

Just be aware that you are not running cat converters, the engines exhaust is always to to smell raw and burn the eyes. There is no way around that even if the engine had no misfire.

This is absolutely correct. I believe this is the (flooded with fuel) condition he is thinking he has.

[Beaureed]

Ok Great, I would love to eliminate the to much fuel issue I think I have. I will try to try figure out the SD set up in the morning and see if the condition changes at all. Does anyone have any more info on the crank relearn?

[Beaureed]

So to set this is up as speed density, i would go to ENGINE-Airflow vs. Frequency and set that whole column to 0?

[5FDP]

Just re-read what I said.

Click the Engine Diag tab, in that window under airflow is a MAF FAIL HIGH setting that is something like 13,000 to 14,000hz, set that to 0hz. Then click DTC's and set the MAF dtc's to fail on first error. That would be codes P0101, P0102 and P0103, that's how to get it into speed density.

[IARLLC]

On a production GM you need the e-brake and brake pedal signals to satisfy the computer before it will activate crank position learn process. Then you just smoothly but directly floor it (and let off after the computer cuts you off or some of the engine's internals are now external). On a Tech2 it will let you know if something went wrong and they are pretty touchy. But with HP Tuners it seems to work a lot more often.

Depending on what kind of transmission you plan to run you might want the brake switch connected to your PCM anyway (for converter clutch). I think HP Tuners does not require the e-brake signal so for now you could just find the brake signal wire (Blue ECM connector C, pin #33, purple wire). It needs +12 when you are NOT hitting the brakes and no signal when you hit the brakes. For the sake of doing the crank learn you could just temporarily connect it to +12, then open VCM Scanner>Connect to vehicle>Vehicle Controls & Special Functions (five buttons further to the right)>Crank Learn then follow the instructions. One thing people often fail at is holding the brake until the end so in your case, when instructed to apply the brakes you can just disconnect the purple wire from +12 and proceed to the end. Sometimes it makes a difference/sometimes not but it will at least keep you from getting the "need to perform crank learn" code and the computer's commands can take place more accurately with relation to position.

[Beaureed]

UPDATE...I started up today with the same result. The first scan was with the MAF tune and the second time I ran it was in speed density setup. The idle acted differently but not better, it seemed to idle at a lower RPM, but still sounded rough. I received the p0300 code when it was tuned for MAf but not Speed density. I also did a scan with the 02s unplugged and then plugged them in halfway through the scan. Definitely ran better with the 02s. I will still have to try the crank relearn, I did not get a chance to try this yet. on this run the LTFT seemed to be climbing and went higher that I am use to seeing. Here are a couple pictures of the DTCS I got while in MAF and SD. There are a couple things I would like to eliminate as possible issues that I am not quite sure of. The only thing I did for the evap was eliminate the DTC, the purge solenoid on the manifold is still there but just has the hose to nothing. I plugged it and it made no difference. With out that solenoid could it possibly not be eliminating vapor like it needs too? Also I have one blue wire coming off of the 3 wire alt plug that is not hooked up to anything. When I did he harness it was pulled from the PCM. Anyone know why this wouldn't need to be hooked up. I also have the TCC wire which is obviously not hooked up to anything right now, does anyone know I this could be an issue. Ok, so here are todays scans.

[IARLLC]

Dark blue wire from position A of the alternator plug is not needed. It runs to the brake warning system...

Are you refering to the tan/black TCC wire (pin#42 on the green connector)? Not important for now but will be if you plan to use a transmission with TCC
or
The purple brake signal wire (pin#33 on the blue connector)? Not important for now except for crank learn and later for TCC control if you plan for such a trans.

I would definitely keep the evap tube plugged or you will get a vacuum leak when the computer commands purge.

For the codes none of them seem related to the issues you refer to. Except for P0300, all of them down to P0654 can be switched to "no error reported" under engine diag>DTCs. The last 5 will depend on your choice of transmissions.

[Beaureed]

OK, Thanks again for all the help. The evap purge solenoid has been eliminated from the harness so it is not hooked to the solenoid. Since this sensor is not hooked up I would assume that the solenoid will always remain closed since the PCM can not control the solenoid open and closed? I am not sure what happens with the extra fumes since the evap is not functioning.

[IARLLC]

It is just for fumes from the gas tank. So if it is an old enough car all it ever had was a vented gas cap....nothing new needed. The canister was just added to absorb fumes temporarily until the engine gradually sucked them out and burned them. By the 70s GMs had very simple canisters that just required vented vacuum...just depends what kind of car you are installing into.

[Beaureed]

Has anyone been able to check out my tune file and see if there is anything that I disabled wrong, or something that I missed?

[IARLLC]

All of the rear O2 sensor codes are still reporting, just no lamp. They should be set to "no error reported". On that subject I have read over and over lately about people removing the rear O2 sensors and getting a recurrent "cat test" where the computer commands extra fuel to see what reaction it gets behind the cats. Because of this a lot of guys are now leaving their rear O2s connected but "no error reported". If such a thing happens without cats I am not too surprised if it adds to the fuel smell. Your trims are not that far enough off to cause any misfires.

Also I would change P0420 and P0430 to no error reported if it won't end up with cats. And if I remember correctly P0446 could be shut down too.

Also pretty crazy how the timing bounces around at idle. I am still guessing this "edgy" idle will smooth out with the weight of a flywheel or torque converter.