I apologize in advance, because this will be long and detailed.

I have the SOT roots kit, my car fells like it runs strong, I have no reason to believe there is serious mechanical malfunction, and I am not an expert tuner, but my emanage has a tune I think I understand and I think is sound.

Now my car seems to run fine, but it does guzzle a bit and the exhaust tips are black. I only had on chance to dyno the car and it made power until 7500 rpm and then tailed off. No other car with this kit has has a sheet that did not make power all the way to the top. But I am also getting kind of poor milage.

The car is set up with a target AFR map that runs off a PLX wideband sensor. Its hard for me to watch the guage and hit the gas, but it seems to stay in the low 12 range all the way to redline sometimes can dip into the high 11's. The maker of my map, Mark or MugenRio has the target afr set up with a safety feature that it run in the 11 AFR range at above 12 pounds of boost, but the pulley is supposed to be in the 7-8 psi range on an AP1. I am seeing a little higher boost than usually because of cool spring temps here in MN.

When it was at the dyno, I noticed it would blow a lot of black at high rpms near the end of the run. And now a couple random people have pulled up to me and told me the car is making lots of black smoke when I hit the gas. Its hard for me to do some testing and watch the exhaust (I do see some black) or the AFR guage because I am doing this "testing" in first or second gear and I have to watch the road because in those gears I can get a little wheel spin and it goes through the high RPM very fast. I'd love to be able to test in 3rd or 4th but can't seem to find the right stretch of road and don't want to get arrested.

When I drive it for a WOT run to redline and watch the boost, it instantly goes to about 7 psi, as a roots should, then climbs a little until it hits the same 7500 rpm spot that my power coincidently starts dropping off at, then suddenly spikes to 9 psi. My VTEC is set at 4000 rpm.

I am now running stock exhaust, high flow cat and mugen header, but it was the same situation with the stock header. I checked my plugs they seem fine, gap set to about .028-30 range. NGK irridium's one heat range colder. The car has only 30,000 and everything is in good working order as far as I can tell.

I have not been back to the dyno but will go in a few weeks to see if I have every thing sorted out, but I know that it should not be making so much soot, so I must still have an issue.

My theory is that (since I have read on this board) that the PLX boost guage is showing me the boost but the EManage is actually reading off the stock map sensor. That I might see 8-9 psi but the stock MAP sensor is showing something that makes the computer think it has hit the 12psi safety margin in the map and run lots of extra fuel. But what I don't get is the abrupt rise in boost. Is it possible that at 7500 rpm the boost is such that it trips something in my stock map sensor to send some crazy reading that the computer thinks is above 12 psi and dumps fuel? Could an abrupt dumping of fuel cause a jump in pressure in the manifold for some reason and that is why I see a sudden spike on my boost gauge?

Since I have been told by a couple people to get rid of the stock map for a greddy sensor, is there a way to replace it and have it work in the stock harness or do I need to wire it to the EMU and set the map to work off the new sensor?

Anybody else have a different guess as to why the boost suddenly spikes, power tails off, and the car blows unburnt fuel or can a quick burst from the injectors swithcing to a much richer mixture explain that? I feel no bogging or anything like that when I drive.

The car feels like it is running just fine, I would not know this was even occuring if not for the low milage, the black tips and a dyno sheet. Watching the boost guage, it fluctuate around the 7 psi range and then BAM! its 9 at almost exactly 7500 rpm. It is rich from seeing the obvious cloud, but the wideband seems to be working as it should and does not to show a reading that is overly rich that I can tell, unless high 11's for an afr would produce a cloud. The sensor does not require calibration and is installed where it should be in the header.

I am kind of confused. Especially since the car seems to be ridiculously quick and is very smooth.

 

Hate to say it, it's normal to get some black smoke when you're FI'd.

Trust me, in a way, black smoke is good when you're boosted, what you don't want to see is white smoke. You know your fuel pump and injectors are working properly with black smoke.

Your car sounds fine to me, and probably a whole lot of fun to drive.

 

I understand that rich is better than lean, but if it is too rich and that was what was making power drop after 7500, I'd like to get that fixed. I am not looking to hit a number for rear wheel HP but that if it is going down, when everone else with the kit is still going up all the way to redline, then I have something left to sort out.

The only thing I know for sure is that my power starts dropping at 7500 rpm, I suddenly see 2 more pounds of boost on my gauge at that point, and it blows raw fuel.

I don't mind a little soot for safety, or paying for a little extra gas, but i also want the problem sorted out because it is not optimized and safe at the same time.

I also don't think it has anything to do with the fuel system or the map. I think the map is totally solid, but something is causing something goofy and the computer can only do what it is told with the information it gets, but I suspect it might be getting faulty info.

 

stock map sensor is erractic, less resoltuoion.. could be the problem. when you see the 7psi shoot to 9psi, is it on the boost gauge or in the software, oem map sensor?

roots blower should hit near max boost early, and what i have seen is mine still slowly climbs another psi by redline, and higher gears you will see up to 1psi more then i lower gears.

just stuff i have notice.

 

The base map tune was set to have the A/F feed back go rich ~11.5-11.4 if above 8 to 9 psi if I remember correctly I do not have the tune in front of me right now.


This can be pulled back to 11.8 and possible as lean as 12.0 as long as you are not seeing any signs of knock. I am running my at 12.1 to 12.2.

The basemap was set to richen up at the higher pressure levels to ensure that the tune is safe until you make it to the dyno.
Being that I have never seen pressures higher then 6.5 the base map fuel curves (which were built on my car up to 6.5/7 psi) and A/F feedback above 7 psi were scaled to get progressively richer.
It was really put in there in case an owner decides to go out and romp on the kit on the base map prior to going to the dyno and having the tune verified locally.

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You mentioned the stock MAP sensor.

The stock map sensor can be very erratic and can read hi with any sort of boost.
I have seen my own data logs where the stock map sensor was fluxing between 4 and 10 psi while my defi pressure gauge was staying at a constant 6.4 psi and the Greddy pressure sensor was fluxing between 6.2 and 6.8.

Since you are currently set up to use the stock map sensor It sounds like the ULT jumping up into a control point value in the +10 psi in msec intervals.

First thing to do is change the A/F feedback map to be 11.8 in areas where the stock map is putting out the higher then expected psi.

Using the tracing feature this should be an easy thing to see which A/F cells need to be changed.

Apply the secondary fuel values to MAP1 (Copy and then Add past)
Verify that none of the values in map 1 when above 100% before hitting enter.
If they did then add then difference back into MAP2
Turn tracing on in the secondary I/J map with the initial secondary values set to 0
do a 4 gear long pull. You will see the cells that were passed through during the pull

This will tell you exactly where the ULT is going in the fuel map during the pull

Better yet Vader hook up your lap top and go out for a drive and data log for me send me the exact flash file you have with the data log.

I make the map adjustments for you remotely.




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And yes black smoke during a pull is a good thing but should not be excessive.
I was seeing the same thing every once and a while and decided to vent the front, PCV valve (drilled out) and a breather port on the Oil cap to ambient.

All thought I still have black smoke ( as expected) the amount of smoke has been reduced significantly.
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The psi rise and the power roll over at the same time is the correct performance of the system if it happens at the same rate. one going up and one going down with the same integral result.
The following statements apply to positive displacement setup only

PSI rise as you approach redline is function of the flow capacity of the head and exhaust system starting to reach it maximum loss free ( AKA restriction) point.

As you reach the capacity of the head /exhaust psi should go up and as a result there is increased effort required of the blower to keep putting out its specked CFM as it is now trying to overcome the restriction of the head and exhaust likewise you are not getting an increase in mass flow through the motor so power (tq) will either flat line or roll over.


If you are experiencing a sudden psi spike then that one is a bit harder to explain.
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[QUOTE] is it possible to use my PLX pressure sensor instead of the Stock MAP sensor.[QUOTE]
If you are willing to tap into then signal wire from the PLX and then wire it in to the ULT. Yes it is but you will need to perform a conversion calculation to figure out how to integrate the current fuel map to a new one for the PLX.

 

I see it on the PLX boost guage which is in no way linked to the ECU. It shoots up about 1.5 psi in an instant after holding around 7 psi the rest of the way.

The computer is only reading pressure off of the stock MAP.

I am rarely ever doing much more than part throttle in the higher gears. The only gears that may see redline are 1&2, and if I am trying to put space between me and a total butthole maybe 3.

The greddy MAP is only $120 or so, I have no problem spending the money to install it and find out if it corrects the problem or not, just not sure how to make it work with what I am using now. Or if there is a way to make the EMU use a reading off my PLX boost guage instead of the MAP beacuas that is a sunk cost and the boost guage control unit sits right next to the emu anyway.

 

Thanks for the feedback Mark.

If it is going to be complicated to use my PLX boost guage for a pressure sensor, then I think I will just order up a greddy. If I buy the harness and use input 2 on the EMU (slot 1 is the wideband) I mount the sensor, wire it to the harness and then do you know what I would activate in the software to get the map you sent to read off the new MAP sensor?

Since the only area of the map that really runs rich on what you sent me is the one with the rich values at 12psi, I just have a hunch that it is the stock map is sending the wrong signal. I don't blow smoke anywhere but when the boost goes up and since the am willing to bet $150 bucks in greddy parts that that is the problem and seems like it is worth a try.

I understand what that AFR adjustment map is doing and think it would be foolproof unless the computer gets a bad reading, and that makes me have doubts about the stock sensor.

john

 

This is a plot of the stock map sensor you cans see it gets erratic above 0 psi



When I was figuring out the stock map’s pressure formula and how NA pressure relates to throttle position and rpm.
The final plot is actually a 3D histogram but I never uploaded it to s2ki and it was on my old comp that had the HD crash

 

Well I am going to order a greddy today and another EMU harness. If I go into the emanage software and enable slot 2 as a map sensor is that all it will take to get it to work with the current fuel map?

 

You should not need another EMU harness

Just the Greddy P. Sensor and the P. Sensor harness wire.



and no there is more to it then just plugging it in and turning the port on.

The Fuel, ignition and A/F feedback maps need to be changed to look to the Greddy pressure sensor voltage.

If you send me the exact map you are running right now I can map the current fuel trims (control point MAP pressure) over to the new setup which will use Greddy voltage input as the control point.

Don’t turn on the port and/or modify the tune

Please let me modify it for you.

If you do not do this correctly you could put your self in a situation where then ULT does not see the boost control points and you will not add fuel when in boost.