Sprintex / Boostec Supercharger Install

[CobraMarty]

How do you know the O2 sensor sends out a wave. They are all the same and send out a voltage reading. Like Gradon said .45v is 14.7, If the ecu will tolerate/accept mild enrichment to 13.7AFR and a O2 signal voltage of ?.55v, Why not just clamp the O2 signal to that voltage ?.55v when under boost/0 vacuum. Split Second makes a clamp as well as others. Maybe the AEM won't do this but another product will.

So need the AEM to control the timing under boost and the split sec to control/clamp the O2 signal.

 

[O-Gauge Steamer]

Yup. This is why I set aside my E85 project. E85 requires an AFR of 9.6 for stoich... And Talyn had me convinced a goodly time ago. IMO, if he can't get it to work, no one can.

Sort of can't get there from here. Only solutions I see are the either replace the O2 Sensor with a Simulator or, dump the entire PCM and replace it and the gauges with an EMS/wideband O2 and new gauges.

Fact is though, that the F/IC and the PCM will play nice together and you will not get CELs. Only CEL I have seen was my fault for over adjusting the fuel map. Went a bit too rich and got a CEL as a reward... As long as the AFRs stay in the 14s with the exception of under acceleration the PCM will be happy. Under acceleration the PCM goes open loop and dropping down into the 13s is good. The PCM will not get upset.

I have been tinkering with this Sprintex/AEM combination for months now and I do believe, at this point, that I actually might know what I am about. Still learning more as I refine the map but, I'll bet that I understand what is going on better than anyone who niether has or programs a F/IC. To be sure, I did purchase several books on the subject.

I wish CobraMarty good luck. Would like to see where he mounted the knock sensor though (hint, hint...)

Quoted right from the FSM to ensure we are all on the same page.

quoted from page 14-25 of the 1998 FSM:

Modes of Operation
Open and Closed Loop.
During Open Loop modes, the powertrain control module (PCM) receives input signals and responds only according to the preset PCM programming. Input from the oxygen (O2S) sensors is not monitored during Open Loop modes.
During Closed Loop modes, the PCM will monitor the oxygen (O2S) sensors input. This indicates to the PCM whether or not the calculated injector pulse width results in the ideal air-fuel ratio. This ratio is 14.7 parts air-to-1 part fuel. By monitoring the exhaust oxygen content through the O2S sensor, the PCM can fine tune the injector pulse width. This is done to achieve optimum fuel economy combined with low emission engine performance.
The fuel injection syste has the following modes of operation:
. Ignition switch ON
. Engine start-up (crank)
. Engine Warm-up
. Idle
. Cruise
. Acceleration
. Deceleration
. Wide open throttle (WOT)
. Ignition switch OFF

The ignition switch On, engine start-up (crank), engine warm-up, acceleration and wide open throttle modes are Open Loop modes. The idle and cruise modes (with the engine at operating temperature) are Closed Loop modes.

end quote.

So, the only time the O2 sensor is in play, at all is at idle and during cruise. The PCM is OPEN LOOP the rest of the time so the F/IC has the control. And again my opinion is that running out of stoichiometric results in power loss if fat (less than 14.0) and power loss and destructive heat if lean (greater than 14.9) with the exception of under acceleration where dropping into the rich area slightly is OK. What must be kept in mind is that some of these "taken for granted" principles of engine management (i.e. way rich under acceleration) is a hold over from the days of carburetors where getting the AFR corect was always hit or miss. Unless you ran Weber DCOEs that is...

 

[CobraMarty]

Maybe we need 3 devices. AEM to control the timing, Split Second or someone else to clamp the O2 signal, and for me split sec to run the 7th injector.

 

[CobraMarty]

I read somewhere that the ecu stays in closed loop:

1- WOT until 2500rpm and then goes into open loop
2-partial throttle until 4500rpm and then goes into open loop

That makes sense. idle-closed loop, cruise-closed loop, initial acceleration- closed loop until one of the above happens.

Now if the ecu can be adjusted to come OUT of closed loop at WOT after 1000-1500rpm and partial throttle after ?2400rpm. This would solve our problems?

 

[O-Gauge Steamer]

I just quoted the bloody Factory Service Manual folks. As soon as you go WOT, regardless of RPM the PCM goes OPEN LOOP.

If anyone has the actual documentation to prove otherwise, cite the source and post the reference. Not a "I heard it somewhere."

With the SMT8-L, Sprintex attempted to convince the PCM that the throttle had gone WOT at an earlier point the the physical travel by altering the TPS signal. This not only did not work but it threw CELs for TPS over voltage. Sprintex did not want to accept that the US PCMs have a 4.88VDc limit on the TPS signal. They kept attempting to send a 5VDc signal.

I will be hitting the 1 year mark with the Sprintex very shortly and whether or not anyone cares to accept what I say here, some things just are what they are. Sprintex did not want to believe that the PCMs in the US are different from what they had spent tons of development time and money on but it did not change the fact that they were wrong. Just plain and simple wrong. And, after I installed the AEM and demonstrated how all of the issues associated with the SMT8-L had gone away with the electronics, Sprintex committed to going back to Perfect Power to get a Controller for the US market. If they did this, I do not know. What I suspect is that they will drop anything 2004 and older from thier consideration as the PCM s on the '05 and up Heeps can be easily reprogrammed.

And, as an FYI, I have installed and programmed the Sprintex/AEM combination on a '93 YJ that is OBDI as the AEM really does not care what PCM it is attached to. It just works...

 

[CobraMarty]

So you didn't intercept and alter the O2 sensor or the MAP? Just the injectors, CrankPS, CamPS, TPS, power and ground.

 

[CobraMarty]

It was mmag1982 on AEM forum:
http://forum.aempower.com/forum/index.php/topic,28598.0.html
here is his post-

Hello,
I am planning an install of the 1913 on a 2001 jeep cherokee 4.0.
appreciate if someone here can go through these questions one by one with your comments, apologize for the legnth, but i want to get this right.
-I am using the FIC currently with the engine in naturally aspirated form. my objective is to achieve 12.5:1 afr at all heavy loads and a 13:1 at all part throttle loads. for this purpose i would only need the MAF voltage based fuel map ( OEM jeep MAP sensor in this case as the load input reading in the MAF channel) and the 02 narrow band map in offset mode with load set to MAF ( the jeep's MAP sensor ). correct?
- If I have a supercharged setup where the throttle is before the supercharger, i.e the OEM MAP sensor sees no boost, I would need no MAF clamp in that case correct? what would be a general rule of thumb for fuel delivery in the fuel map corresponding to each psi of boost ? I am trying to narrow down a range to make it easier.
- why does your video recommend using an OBDII scanner for monitoring fuel trims, i can see there is a fuel trim display in the FIC gauge screen, can't I use that to monitor fuel trims?
- I still don't understand why would i go lean over time if I just set the o2 map to my target closed loop afr and do nothing to the fuel map. ? I know its explained in the video, just hoping for more details
- do you have sort of a rule of thumb for the relationship between offset o2 voltage and the corresponding fuel trim. if i lets say use -.035v and it gives me 13:1 afr, what would be the corresponding number to input in the fuel map, 5, 10, 15? I am trying to narrow it down to a range to make it easier .
-The jeeps ECU is in closed loop up to around 2500rpm for full throttle mode and stays in closed loop at all partial throttle modes except after 4500 rpm. what tuning approach do you recommend given this ecu logic, can a closed loop afr of 13:1 or 12.5 :1 be obtained through the o2 and fuel map?
- the jeep has 2 narrow band o2 sensors, pre and post cat, do i need to connect both or only the pre cat? i noticed there is only 1 02 map
- when I edit a map with the FIC connected and installed in the car, do my changes become automatically applied to the car and saved on the FIC or do i need to save my edited map somewhere 1st.?
- why do I need the resistors in the o2 connection before the FIC, to stabilize the voltage or reduce it?

Appreciate your response
Mostafa AG

 

[CobraMarty]

With the SMT8-L, Sprintex attempted to convince the PCM that the throttle had gone WOT at an earlier point the the physical travel by altering the TPS signal. This not only did not work but it threw CELs for TPS over voltage. Sprintex did not want to accept that the US PCMs have a 4.88VDc limit on the TPS signal. They kept attempting to send a 5VDc signal.

So why not just intercept the TPS and alter it so that when there is 0vac/boost the TPS signal goes to 4.85v and the ecu thinks it is WOT and goes into open loop.

 

[gradon]

Maybe on Monday or Wednesday I'll get a video of me playing with the o2 offset, so you can see that I can get in the 12's while idling in closed loop. Best power for NA engines is in the 12.5-.8:1 range(I think Hesco likes 12.7). Boosted engines want WOT to be richer to get best power, so low 12's and under. I think I used 1.2K ohm resistors on the o2 sensors' outputs(instructions called for 1k and if you read on the AEM forum, some had to use higher values before the offset would work). You don't need to connect the post cat o2 sensor. Use the second o2 sensor connection if you have two primary banks(ala the 00-01 XJs with the o2's in the manifolds).

 

[Talyn]

But its not a steady .45v @ 14.7, it cycles from 1 to 0, in a wave like fashion. Simply shifting the voltage will just shift the wave.

 

[CobraMarty]

Installed the gauges- wide band is not permanently installed, just sitting there.

 

[CobraMarty]

So why not just let the O2 sensor see rich while under boost and throw a code and CEL. Leave it be and just reset the code before inspection. There is no limp home mode.

If I plan to boost retard the timing with the AEM, 1 degree/ 1pound boost, etc to 6*/6pounds. But my problem is there is all ready a built in 'boost retard' stock. There is so little total advance stock that you can do the CPS mod and increase timing 6* and still not detonate. It is already timing retard(less total timing) that I don't need to pull any timing out of it.

Does anyone know what is the stock total timing?

 

[gradon]

You get a steady 14.7 in closed loop even though the wave cycles .1-.8v. When I offset the voltage, I get whatever afr I choose to set it at. Sorry you haven't gotten it to work on your Jeep(yet).

 

[CobraMarty]

Belt Info: Gates # K061015 effective length=101.5" outside circumference=102 1/8".

 

[sidewaysstarion]

So why not just let the O2 sensor see rich while under boost and throw a code and CEL. Leave it be and just reset the code before inspection. There is no limp home mode.

It will see rich and pull fuel out of the main injectors till it sees 14.7.:wave:

 

[Alexia]

Responding so I can bookmark this in my history. Planning fitting one of these with the AEM setup to my stroker engine. I love seeing that this can be done much easier than some other supercharger setups out there.

 

[Boostwerks.com]

You get a steady 14.7 in closed loop even though the wave cycles .1-.8v. When I offset the voltage, I get whatever afr I choose to set it at. Sorry you haven't gotten it to work on your Jeep(yet).

X2. The O2 offset table has worked great for me. In closed loop and in low boost I have a stable 13:1 AFR. It allows for a smooth closed to open loop transition. Open loop I am tuned for 12.5:1. Are you guy's making sure to offset the fuel table as well? This is the only thing I can think of that would cause the ECU to tune out the offset. It takes some tinkering with, but it does work.

Another way to think about it is: by offsetting the O2 voltage you create a scenerio in which you can add more fuel VIA the FIC's fuel map without the ECU making long term fuel trim adjustments. Having understood this it is imperitive that you check your STFT and LTFT's via a OBD2 scanner. If you have done the correct fuel table adjustments you will end up with your desired closed loop AFR along with low fuel trim %'s. Just keep in mind that your injectors fuel trims are referencing the FIC's fuel table at all times. It's very easy to think that during closed loop your engine is running off the factory ECU and 02 sensor data only. This used to be the case of most piggyback controllers, but this is not how the AEM FIC operates.

 

[180ls1]

That supercharger looks like its going to get real hot with the exhaust right there and in that configuration.

 

[CobraMarty]

You're absolutely right except we took some steps to decrease this problem. We used Gibson headers which are ceramic coated and also thermal wrapped them. We also lined the bottom of the intake manifold with DEI gold reflective barrier. We also have a hood lift to help vent the hot underhood temps at low speed and today installed a hood vent to help vent the hot underhood air at speed.

With our dual temp sensor gauge we show only a 20 degree difference/increase in the engine manifold temp when compared to the temp at the throttle body. That is without boost but every day driving around. A more difficult and concerning problem with the cherokees is the lack of cold air for the intake. Today we did some weird and extreme testing. Getting cooler air to the intake is difficult.

 

[urban yan]

That supercharger looks like its going to get real hot with the exhaust right there and in that configuration.

It's a pretty small supercharger. It's the same unit Rick uses in his 1.6L MINI cooper kits (equivalent to an M62).... which makes a whole heap of sense on a 4.0L. I'm not sure how that will relate to it's overall longevity or heat build-up though.

....and I just double-checked the site. The kit's actually 4K, and the listing specifically says that it "comes complete with a plug-and-play piggyback computer". There should be no splicing involved at that price-point/ with that description.

and today installed a hood vent to help vent the hot underhood air at speed.

Yeah, I saw that hood vent on CF. I thought you guys were vehemently opposed to hacking your jeep?
You didn't want to cut small holes in your headlight buckets for proper bi-xenons but you were willing to cut ALL of your hood supports