Hi guys - hope someone can help with this so I can install my new ecu tonight if possible....

Am changing over from a PFC to a Simtek, and I've been given the charge temp sensor with it but it just has two bare wires (green wire and a blue wire) and not any sort of plug on it.

I know it wires into the MAF wires and I believe it specifically goes to the MAF signal and ground (been told they're black and white wires) but does the 'polarity' of the charge sensor wires matter?

I don't know how this sensor works, eg if it's just something that changes resistance across its two wires depending on the temperature it's exposed to then I doubt it matters.
I suspect that's the case, ie a voltage runs through it and returns to the ecu at a lower voltage depending on charge temp, but perhaps there's more to it than that.

If anyone here runs a simtek and could confirm this for me I'd be really grateful as I'm dying to get it plugged in and start fiddling with the maps!

The car is an 89 RS Legacy which has an EJ20G lump. Just mentioning this in case it influences colour codes of the wires going to the MAF sensor plug.

Other question is that while I know it's not recommended to, if I have to briefly run the car without the charge temp sensor (as I can't weld ally myself and need to get a boss on the FMIC piping), which settings in the software do I need to amend to deal with that?

The car is only having very light use anyway so I don't envisage it as being a big problem for the very short time before I can get a boss welded on. As I'm used to FC edit though and not at all used to Act One, I don't know most of the settings yet.

If anyone is interested btw I have an FC datalogit (and possibly apexi boost control kit) available now.

Thanks in advance
Jim

 

Hi Cret

What year is your engine from? im presuming whatever year your engine is the ECU will suit that engine right? and do you have the pinout diagrams for it?

Iv got to do the same, however my car is a 1999 and the air temp sensor fits on pins A1 and A24 (Blue Plug) of my ecu.

arnt sure that will help you what so ever as id imagine its different on another ecu but worth a try..your probably best speaking to your mapper

wrighty

edit: ps is it a legacy saloon, if so get some pics up in the gallery!

 

You are absolutely correct in your explanation of its function, and it requires wiring to the White wire on the MAF and the Black wire 2 up from it. If you can't fit it for a moment the MAF will give you intake temp based compensation till you have time.
This would be a better solution than turning the compensations off.

 

Maf on early car 4 plug ecu doesnt have temp sensor.
Pins 2 and 4 on maf plug on your car.
Doesnt matter which end you count from as it is 5pin so will always be same two.
Doesnt matter which goes where on sensor.

 

Thanks very much for confirming this Martyn/Simon. Much obliged. Interesting to note that the maf can sort of do the job in the absence of the proper charge sensor (on some cars) although obviously that would be of limited use with being pre-turbo/pre-intercooler.

I suppose it should be easy enough to find the bit in the software that I need to adjust re' temp compensation. Do I assume that I'd basically be setting some numbers to zero to achieve that? This won't be for long at all but since I've lots to sort on the car it's only being driven very gently anyway at present.

It's a shame there's no manual for the software as it's quite a bit to take in from a novice point of view but I'm sure I'll get there in time. I'm happy with the principles of mapping and am a programmer by trade so as per my use of the PFC slow and careful (with WB and knocklink) should get me there.

Wrighty - yes it's a 20 year old 1st gen Legacy Saloon, a la McRae era shape.

The engine is apparently a block from an auto (as it has no modine) closed deck, cometic gaskets with STi pistons, v3/v4 reconned heads, apexi RHF5 hybrid, fmic, and a few other bits & bobs. I'm aiming for about 350bhp once I get some progress with maps.
Not sure if the car will even run with the maps it came with but we'll worry about that once it's in. I've got to put my freshly butchered throttle body back on first....

As for pics, there are one or two in the gallery on my forum, but for some reason while these cars look great in person I struggle to get nice photos. Could be because it's stealth



Thanks guys
Jim

 

Bugger! Was about to bolt the sensor into the fmic pipe next to the throttle body using a normal nut on the inside of the pipe with a bit of silicone or loctite etc and found it's not a thread I have in my stocks. M10 x 1.25mm. Going to have to make a bloody nut now so there goes the rest of the evening.

 

same as exhaust stud iirc

 

looks mint, would love one with a big power boxer in!

 

Awesome! Thanks Simon - that's just made life easier!

Well after fighting with pieces of silicone for ages (fmic pipes onto throttle body and turbo - no clearance between them), I've got it back together and got the ecu in.

Unfortunately I hadn't read the bit about the exhaust nuts until after it was all on but just plugged the maf in even though in theory it won't help.

Car fired up no problem with the simtec, although due to extreme decibels and a currently good neighbourly relationship I only ran it for about 30 seconds and decided to call it a night.

Tomorrow I will try to get the sensor in place and wired in, and then I can start messing with act one hopefully and see what happens from there....

Wrighty - cheers mate - I've owned her for about 9 years nearly now and could not part with this car due to the rare factor. The ecu has just come from another example that was making over 500bhp which ended in tears very sadly. All the engine & drivetrain on these cars is almost identical with classic scoobs so parts (except panels) are easy to get.

OMA developments in Ireland have a lovely big power RS as well. Jealous, me?

I'd love a 2.2 or 2.5 with a 6 speed for doing hillclimb events on the island here, but no way I'll ever afford that. I don't get much money these days to spend on the car so everything is done by myself and always has been. I can't blame anyone else for the bodges and cockups mate!

She's been off the road a couple of years while I was doing a rebuild and a certain person persuaded me to swap from a PFC to a Simtek as he says it will be easier for me to map. Has antilag etc too but I doubt I'll bother with that.

 

What charge temp sensor are you using?

which ones are compatable with the simtek?

 

I honestly couldn't tell you sorry mate. I assume it's the sensor that is supplied by Simtek but I've no idea if that's available elsewhere or just from them. No idea if other ones are compatible but I would avoid any hassle by just getting one from Simtek as you know it'll work no problem.

Not worth mucking about with other ones imho. You might find also another type works but is giving different results that aren't accurate etc.

I've got mine hooked up in the FMIC pipe now, and have been out for a couple of drives.
The car has a rock solid cold idle but hunts like mad once it's warm and is a bit sluggish all round.
Can't test stuff properly as my temporary laptop has no working battery so I can't go out and log, but the AFR at warm idle is 7.5!!! No wonder it's bad!

Trying to upload the base map that came with it so I can start mapping from that, as it will be a lot more suitable than what's on the ECU, but the ECU won't let me use the base map!
It appears the base map is from version 1.3.0 ECU (firmware presumably?) and the ECU has been updated to v1.3.2 at some point so it'll load all the other (unsuitable) maps, just not the base map which is the only one I want to use.

So it's drivable now and seems very smooth, until it's warm and then if you have to trundle round a car park it's all over the show.