Apexi Power FC puzzle! SOLVED!

loadswine · April 30, 2016, 17:27

I wonder if anyone has any bright ideas to help me solve an interesting issue, I have?
I got an Apexi PFC standalone ECU, with my car when I bought it. IT wouldn't fire up the newly rebuilt engine for Nic ( wabbitkilla), previous owner, after he rebuilt the engine and indeed the engine has never started, when I have tried it on the car. The engine starts on the button, with the stock ECU though. It also runs okay, with no codes.
Now, I thought that there was a fault in the Apexi PFC, but today, I plugged it into my mate James' car and WTF, it started first time, on the turn of the key!!! s:shock: :shock: s:shock: You could have knocked me down with a feather! lol James' engine ran fine with it.
Now..... the big question, if James' engine runs okay on the PFC and mine will not start with it, but has no problem starting on stock ecu, what is possibly the issue with my car?
I would love to find a fix for this, so sensible ideas much appreciated folks.
The silver lining in this for me, is that, even if my car will not run with the PFC, the ECU itself does work and I can at least sell it if need be! s;)

s;)

s12vea · April 30, 2016, 19:34

Could it be a wiring fault on your car / loom ?

loadswine · April 30, 2016, 19:38

That is a possibility Steve, but where to look for something that allows it to run on stock ecu, but not the PFC?
I wonder what direction to go, to hunt that down?

s12vea · April 30, 2016, 19:44

a job for an auto electrician

loadswine · April 30, 2016, 19:49

A magician probably!!
I think, if I can't track this down myself and it still runs okay, I will get things as near stock as possible, and sell the PFC and the other mods. I have a stock throttle body to replace the maxbore item, so watch this space to see if there will be some unusual goodies on sale resulting from this. s;)

s;)

headcase · April 30, 2016, 19:52

possible earths

loadswine · April 30, 2016, 19:57

That is going to be my first job for tomorrow Patrick, to see if I can identify and double check all the earth connections.
Not completely sure, off the top of my head, where every single one is, but will have a go.
I know the earth bolt on the nearside suspension tower was a bit rusty, so will take a close look at that.

1979scotte · April 30, 2016, 21:55

I really hope you sort this out but if not DIBS!

beavisrules · April 30, 2016, 22:01

Quicker to swap in a new loom rather than try find weak joints/bad earths?.

Wabbitkilla · April 30, 2016, 22:55

It is a quandary Nigel and yes you could have knocked me over with a feather too!

I did explore ecu earth as i found the car would run with neither ecu unless the ecu body was earthed even on the oem ecu.
Maybe there is an engine earth problem but i am certain everything was reconnected as it was removed from the engine during and after rebuild.
One earth that was a problem was the small earth to the nsr suspension tower which needed re-drilling and tapping.

It would be a shame to remove the mods from the car, but as i've always said ... when i sold it it was yours to do with as you wish.
All the small mods go together to make a whole package so the engine and the ecu are supposed to go together but I find it rather gratifying, and amusing, the standard ecu copes so well with the modifications even if it's not making the outright power originally tuned for.

I did try another PFC and it behaved in exactly the same way.
I tried the original E-Manage Ultimate and while it ran fine it had a "false" rev limit suggesting, again, what i think may be an electrical issue.
Could it be the knock sensor, could it be the crank or cam position sensor? ..... all worthy questions.
Certainly an engine loom should be easy to get hold of these days and may be worth a try but i would tend to test wiring and check sensors.

loadswine · April 30, 2016, 23:16

Yes, earths will be the first check. I will see if the tower earth can be improved a bit as well. The selection of mods have changed a bit, and still the stock ECU copes pretty much. If the odd sensor was off, I think the stock ECU might not fire it up, but will have a bit of a play tomorrow. I am thinking, if it worked pre rebuild, it shouldn't be too much. Well that's my theory anyway. s;)

s;)

Wabbitkilla · April 30, 2016, 23:40

The only issue pre-build to post build mechanically was (as far as i know) .... the vvti controller on the inlet cam.
Before build it may have been locked out, after build it was working properly.
But that wouldn't explain why the PFC works ok on the other car.

loadswine · April 30, 2016, 23:45

I have read that the PFC is quite voltage sensitive, so a poor earth might well explain things, when the stock ecu might be less sensitive.

Wabbitkilla · May 1, 2016, 09:08

Car had a new battery on it when i sold it (that did annoy the neighbours while the car sat and the old battery died several times s:lol: :lol: s:lol: )

The PFC would talk to a laptop on the car, but i can't remember my observations during starting attempts ... they could provide a clue.
Then there's the non-oem immobiliser

loadswine · May 1, 2016, 09:14

Battery is well charged currently. Going out to play with bits shortly.
Interestingly, I didn't have the commander unit plugged in when I tested it on James' car yesterday. Always had it plugged in before. I will try it without, just to see.

loadswine · May 1, 2016, 13:46

Mmmm, this is not looking good. s:(

s:( I have refreshed every earth point I could find, including the drivers side suspension tower which I had to redo completely due to a snapped bolt and still no joy from the PFC. Think I will sell the PFC and commander unit and go back nearer to stock. Changing the throttle body back to stock later today or tomorrow, to try and get rid of the 'flat spot' it seems to have under 2k rpm, so maxbore throttle body will be for sale soon also.

cabbydave · May 1, 2016, 22:57

Many years ago I reshelled a Rover 216 Vitesse that wouldn't start but the ecu would work on another car. I checked all the earths and they were all fine but my clever Dic k foreman retested the earths while I cranked the car and found a bad earth but it only came to light when you cranked the car. I ended up tapping the earth nut out in my case it was too much paint causing the issue but it could be a little bit of rust causing the problem, Either way it might be worth just checking the earths are still there when you crank the car. Just a thought

stupink · May 1, 2016, 23:16

you shouldn't have to earth the ecu chassis to get the car to work, the loom should provide an earth, have you checked that with a multimeter?
the pfc probably just hasn't got the chassis earthed and the stock ecu does.. find the earth pins on the PFC/loom, and run them to a temporary good-earth (just run it off the neg terminal or something like that... I'd probably also try a temporary permanent from the + terminal also if that didn't work. I'm fairly sure there are a few earth points in the loom, one for the power, one for the injectors,

not sure if any of that made sense.. its too late for braining.

cabbydave · May 1, 2016, 23:56

Quote from: "stupink"you shouldn't have to earth the ecu chassis to get the car to work, the loom should provide an earth, have you checked that with a multimeter?
the pfc probably just hasn't got the chassis earthed and the stock ecu does.. find the earth pins on the PFC/loom, and run them to a temporary good-earth (just run it off the neg terminal or something like that... I'd probably also try a temporary permanent from the + terminal also if that didn't work. I'm fairly sure there are a few earth points in the loom, one for the power, one for the injectors,

not sure if any of that made sense.. its too late for braining.

But the ecu works on another roadster so it's not the ecu

cabbydave · May 1, 2016, 23:58

Or get a jump lead from the negative of the battery to the engine block and try

stupink · May 2, 2016, 08:41

Exactly dave, and if the other car has a working earth being supplied on the loom, then the fact the pfc chassis isn't earthed won't effect it, but on a car that's not providing earth through the loom, the fact the stock ecu's chassis is connected to earth makes it work.

stupink · May 2, 2016, 08:52

Just to clarify..

Car A starts with both ecu's = ecu's are good.
Car B starts with neither ECU if held in your hand = loom bad

Car B starts with stock ecu chassis touching car ground = ECU loom bad.
Car B wont start in same situation with PFC doing same = PFC simply don't ground the ECU via the case.

I'd remove the ecu, and test the pins of the loom with multimeter (resistance) and check it against the shell of the car, and then against the engine, and then against the battery neg terminal.. see what all three show.

you have two grounds in the loom.. Main, and sensor.. sensor earth is the big plug, middle row towards the edge of the Ecu (on its own), main ground is the next plug along, the bottom row (away from the clip) and the pin closest to the center of the ecu.

loadswine · May 2, 2016, 09:27

Thanks chaps, I will conduct some more tests and investigations.

loadswine · May 2, 2016, 13:10

Sorted! s:bounce: :bounce: s:bounce:
Today, I had a look at the crank position sensor. The earth looked horrible to be honest, so I spent a good while cleaning the tab and bolt and tapping out the thread for the bolt. Reassembled, so I thought, give it a try on the PFC, fired up first time and the car feels so much better. Won't idle properly, but I think that's down to the fact I changed over the throttle bodies yesterday and am running a stock one now. Plus, I couldn't remember the procedure for learning idle on the pfc. Not sure if its running on the map for the previous set of mods or the base map. I'm not clever enough to tell that. s;)

s;)
But at least I have answered the question that was driving me nuts! s:D

s:D

cabbydave · May 2, 2016, 13:28

So it was a earth that was dissapearing when you crank the car then?