andrethx Posted May 9, 2013 Report Share Posted May 9, 2013 a future project i have planned for my car is rebuilding the CIS harness -- it's very commonly done by owners of other CIS equipped cars. in doing research on that, i stumbled on some internet write-ups on a method of tuning k-jet engines. the idea is, one swaps out the O2 (lambda) sensor for a new unit that is connected to a controller...in the above linked article, the OP suggests a setup that utilizes an air/fuel gauge that has a controller built right into the gauge. these controllers are nominally used to make sure that the O2 sensor knows what type of system it is monitoring (gas, diesel, etc.) but it can also be used to adjust the air/fuel ration in the car; the controller connects to a PC and one makes the adjustments using connection software. as best i can determine (since it is not explicitly explained anywhere that i saw), this works by "tricking" the ecu into adjusting the fuel/air ratio up or down by the controller tweaking the signal output from the O2 sensor to the ecu...as the original thread mentions, this only works on original CIS systems (not CIS-E systems, which handle the fuel/air mixture a bit differently)...maybe some of the more experienced forum members can comment on this (rabin? nick? joe?)... it's also possible to connect the controller to a gateway device that outputs data to a smartphone via bluetooth... now, this is not something i'm looking at doing any time soon; as the original article i linked to points out, this is probably worth doing only if one has done all of the other obvious performance tweaks. i'm looking to get my car to stage 0, this is probably stage 5 or so... using the O2 sensor broadband controller setup requires changes to the CIS wiring harness, is how i stumbled onto this. it's an interesting approach! andré Quote Link to comment Share on other sites More sharing options...
JunktionFET Posted May 10, 2013 Report Share Posted May 10, 2013 I like it... It's the closest you can get to doing a "custom tune" on our CIS-Lambda systems. The XN6 is tuned reasonable well from the factory. It's 2.0 liters, 8 valves, has a paltry 8.35:1 compression, is bestowed with just a basic 60mm CIS-lambda system, and a simple centrifugal/vacuum advance distrbutor... its nearly 100bhp output doesn't like much but it's not bad consider what's there. This wideband custom tune would probably give you a smoother powerband but I don't think it would make massive gains in power or torque... a few here and there, that's it. What would be awesomesauce is to get a reground cam, some early XN1 valve springs (less likely to float), an 80mm thick rimmed air flow sensor from a Volvo 240 Turbo, 8.8:1 pistons and/or shave the cylinder head as much as possible. Then you could really play with the air/fuel ratio and probably get a healthy and very drivable 125-130bhp. Quote Link to comment Share on other sites More sharing options...
andrethx Posted May 10, 2013 Author Report Share Posted May 10, 2013 This wideband custom tune would probably give you a smoother powerband but I don't think it would make massive gains in power or torque... a few here and there, that's it. this is consistent with what i've read -- this sort of tuning won't give you big power increases, but can go a long way towards smoothing out power delivery, which is what i want. What would be awesomesauce is to get a reground cam, some early XN1 valve springs (less likely to float), an 80mm thick rimmed air flow sensor from a Volvo 240 Turbo, 8.8:1 pistons and/or shave the cylinder head as much as possible. Then you could really play with the air/fuel ratio and probably get a healthy and very drivable 125-130bhp. wow, all that for just 25-30 hp? i realize that is a 25-30% increase, but it still isn't a lot. my long term plan (3-5 years out) is to rebuild my engine, i already have an xn1 "engine in a box" (new liners & pistons) which should bump up my CR a bit...i'm also considering at a reworked head and cam as well... andré Quote Link to comment Share on other sites More sharing options...
Stewart Posted May 11, 2013 Report Share Posted May 11, 2013 I use the LM-2 Innovate and data log from it to the Link G3 I run. It is the first piece of equipment I would buy before changing anything. It is just so easy , fast and accurate! Love it. The fine tuning is awesome and smooth power one can get. The LM-2 will log for you as well. Go for a drive, press record then stop it after the run and watch the mixture on the Log Works software. Just incredible. Of course the gauge unit is even better as then, it can send data to the ECU you run. Your car can run in closed loop fuel control all the time, if you want. I must put one on the shopping list for the 505! It just makes tuning so much safer, easier and faster. Quote Link to comment Share on other sites More sharing options...
Stewart Posted May 11, 2013 Report Share Posted May 11, 2013 By the way, if you want some decent valve springs for the XN engines I do them here in kit form, in Australia. Retainers, twin springs and shims to fit the Peugeot head pocket. They are 105 lbs on the seat and take 0.450" lift. Tuned to the weight of the valve train too. The old Peugeot springs are like sponges now. Too old. Some have tested at 50 lbs seat pressure. You can actually push the valve open with your thumb! Quote Link to comment Share on other sites More sharing options...
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