When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Interested to find out about the population of alternates for the DME and KLR installed in Turbo cars.
The challenge with our existing systems is lack of troubleshooting info. So part of my interest is to see what systems have been installed and what the experience has been. Seems like the choices fall to : MAF, Speed Density, and Alpha-N.
I like the direct measure from the MAF systems, but there is little room in our engine compartment, and I am not a fan of the cone filter. Now if we could move the MAF to the IC piping, that would help.
Speed Density does require the mapping of the RPM and Volumetric Efficiency of the engine. Once defined, SD, may produce good results.
Plug and Play also an important consideration.
This can be an emotional subject for some. Please stick to factual info.
Running Megasquirt 2 in speed density with ls1 wasted spark CNP ignition (distributorless). 36-1 reluctor wheel on the front of the crank replaces factory speed/reference sensors. 80 lb injectors firing in semi sequential mode. The car made ~375 rwhp on a smallish turbo before violently ejecting a rod through the block due to a failed rod nut. Read the thread in my sig for more info, I sorta wrote the book on megasquirting these cars since there was hardly any documentation available at all. Also check out user Odonnell's threads about it, he's done a very nice megasquirt install on an NA using a slightly different setup than my 951.
I'm still actively working on optimizing the tune (dyno soon) and adding features like knock sensing. You can see the major points in my sig. Doug and I are using similar setups, same trigger wheel and ignition strategy, and same MSExtra firmware on our controllers. If you want to go down the megasquirt road, forget about plug and play. You should look at VEMS if you don't want to bother with a lot of stuff Doug and I mention/document in our threads.
Here are the facts about speed density vs. MAF.
With a MAF you don't have to do as much tuning/constant tweaking because of the nature of the data it reports. However, you DO need to make sure the MAF is calibrated correctly, which requires a transfer function. This is reliant on physical dimensions as well as on the actual IC of the sensor and how it correlates mass flow to reference voltage. There's a thread on the main 944 forum here about figuring this out.
Speed density is generally used for standalones for 2 reasons: 1) you just need a simple manifold pressure signal instead of an intake meter and 2) for turbo cars, you can manipulate timing and fuel duty with respect to that sensor's reading. That's important when you're in boost for obvious reasons. Speed density uses a VE table which has to be set up for whatever engine is installed. If you're lucky you can find someone with the same engine/same mods and use that as a basis. Doug and I pretty much had to make our own and have posted our tables publicly. The average DIY guy can tune speed density with a little practice, it really isn't that hard, it just seems overwhelming at first.
You can also do blended MAF/MAP which can be useful in a case where one algorithm loses resolution in one part of the RPM/load range. As for alpha-N, you can also blend it, but it's mostly for people with ITBs where a smooth manifold pressure signal is hard to get.
I run VEMS on my 2.5 16v Turbo, with S2 flywheel (60-2 trigger pattern), stock crank sensor, stock coolant sensor, Audi TPS with BMW throttle body and custom intake manifold. ECU has Bluetooth connectivity. I am running speed density. I have ran my engine at various boost levels (lately at 1.4 bars), done tuning in spring, never had to touch it afterwards. I don't even have any gauge in the cabin, even boost gauge. If I need to check something, just start the Android app in the phone and that's it.
Raceboy - can you tune it just with the android phone?
I believe the VEMS app is for displaying parameters/gauges only. I know a few people doing actual tuning on cheap Windows tablets with the full VEMS software though.
If you want Plug and Play Chris White's tech GT is a great setup. I installed it in my 944 turbo racer. Very easy setup, he provides an out of the box tune that is very good. I tweaked a little on 2 parameters before my first track event using it. Tell him what you want it to do, he sells you a system that works and support to figure out any problems you have with it.
I did megasquirt with EDIS spark on my 944 turbo street car. Figuring out how to make my own wire harness and all the maps has been great fun. Lots of research time, soldering, tweaking. If you get a kick out of DIY, this is a great way to go.
No MAF in either system. Both have a single pickup wheel on the crank in front and run wasted spark.
Vacuum leaks don't cause the mixture to go off in the weeds.
I love being rid of the speed & reference sensors on the back of the motor.
I love having a wire harness that isn't crispy. The spring clips on the new harness are SO much nicer than on the factory one.
I have been happy with the results of both systems. I've been able to make them do exactly what I want. Both are tuned with windows software and connect with a serial cable.
I did not know how many ECU systems there are, to support our cars. Thank you for great input. The systems with the Plug and Play option make the transition easier. A complete rewire is also a good idea, based on the age of the wiring systems. And those pesky spring clips for the injectors, I do like the press clip option.
The android or tablet display options are very nice for system evaluation and troubleshooting.
The most interesting outcome is the MAF vs Speed Density (SD) approaches. Early year OEMs preferred MAF, due to the lesser need for numerical computation for the ECU. Current retrofit systems seem to prefer SD as the O2 sensor is much more accurate than a MAF, inserted in an intake with variations of locations. So the choice became add fuel to the amount of air you measure, or control fuel based on MAP, AIT and O2, as MAP, AIT and RPM define the airflow (Mass of air) in the engine. Comes down to the sensor you trust the most, and how much numerical processing power you have.
Last edited by Alan 91 C2; 12-03-2015 at 09:54 AM.
Do you have a map for your Link? Mine has been in the car just sitting in the driveway for about 5 yrs; maybe time to finally get it running. Sigh. Hoping someone will have a map I can install.
I did not know how many ECU systems there are, to support our cars. Thank you for great input. The systems with the Plug and Play option make the transition easier. A complete rewire is also a good idea, based on the age of the wiring systems. And those pesky spring clips for the injectors, I do like the press clip option.
The android or tablet display options are very nice for system evaluation and troubleshooting.
The most interesting outcome is the MAF vs Speed Density (SD) approaches. Early year OEMs preferred MAF, due to the lesser need for numerical computation for the ECU. Current retrofit systems seem to prefer SD as the O2 sensor is much more accurate than a MAF, inserted in an intake with variations of locations. So the choice became add fuel to the amount of air you measure, or control fuel based on MAP, AIT and O2, as MAP, AIT and RPM define the airflow (Mass of air) in the engine. Comes down to the sensor you trust the most, and how much numerical processing power you have.
What I can't wrap my head around currently is how a SD system can figure VE or ideal VE for a given RPM range...how does it know if an engine could be pulling in more air?
12-02-2015, 12:17 PM
Who is running alternate Engine Controls DME KLR
