programable memcal ?

[wanglemoose]

does anyone know if there is a programable chip for the p38 ecu. i know i could piggy back an aftermarket one but there is only a few of the std settings i need to change like the base idle and cold start enrichment and a small tinker with the fuel/ignition map. the std settings just dont do the trick on the new 5 litre.

cheers
mick

[Rupert Prior]

the old GEMS (upto 1999) ecu can have the CO% base setting changed and then disconnect the O2 sensors so it cannot relearn a new setting (same as 1995 spec). the ign timing can be changed by fiddling with the wiring.
i do not think there are any tricks on the Thor (1999 on) ecu, although it never reads the throttle position at 100%.
the restriction with both is the inlet manifold.
normally the 5.0 go ok with the standard set up. are the cats and air flow meter all good?

[ytt105]

What wiring changes will adjust the timing? May be beneficial for LPG installations?

[Rupert Prior]

cam angle (not crank) sensor failure default timing setting is different (i think it is 15deg) and i have been told that swapping the wire positions can give more advance, but i have never tried either so be careful.

[wanglemoose]

cam angle (not crank) sensor failure default timing setting is different (i think it is 15deg) and i have been told that swapping the wire positions can give more advance, but i have never tried either so be careful.
i defiantly dont need any more advance as it runs between 30-45 degrees according to the hawkeye. cheers anyway

[wanglemoose]

the old GEMS (upto 1999) ecu can have the CO% base setting changed and then disconnect the O2 sensors so it cannot relearn a new setting (same as 1995 spec). the ign timing can be changed by fiddling with the wiring.
i do not think there are any tricks on the Thor (1999 on) ecu, although it never reads the throttle position at 100%.
the restriction with both is the inlet manifold.
normally the 5.0 go ok with the standard set up. are the cats and air flow meter all good?
afm is fine and to spec and there is no cats. my problem lies in the cold start enrichment and base idle as it idles at 1800rpm until it warms up and then hunts like a **** warm, warm idle jumps between 450-900rpm, also im running 40 psi constant fuel pressure with 20% larger injectors and still have the ecu adding up to 15% fuel ontop of the std map. i can see what the settings are withe the hawkeye hooked up but unfortunately cant change anything:mad:. i think im just going to have to piggyback and autronic into it. and no there isnt any air leaks either.

[PhilipA]

Is it a GEMS or Thor?

Why did you increase both fuel pressure and injectors size?

Regards Philip A

[PhilipA]

OK, I was thinking about it, and have decided you have a GEMS , as The GEMS works on 2.5ATM and the Thor is already 3ATM and you cannot get easily to the fuel pressure regulator.

If you started with a GEMS, did you try to run it with standard injectors and pressure as there is usually a 15% ceiling that the ECU can handle.

Have you contacted Mark Adams who is considered THE authority on 14CUX and also GEMS? He usually can program a chip to accommodate larger capacity with near stock driveability AFAIK.

Do you have a standard cam in the new engine or have you installed an aftermaket cam? the symptoms you have described are often the result insufficient vacuum caused by a cam with incorrect phasing of inlet and exhaust timing, although who knows with the higher pressure and volume of the injectors.

Regards Philip A

[wanglemoose]

OK, I was thinking about it, and have decided you have a GEMS , as The GEMS works on 2.5ATM and the Thor is already 3ATM and you cannot get easily to the fuel pressure regulator.

If you started with a GEMS, did you try to run it with standard injectors and pressure as there is usually a 15% ceiling that the ECU can handle.

Have you contacted Mark Adams who is considered THE authority on 14CUX and also GEMS? He usually can program a chip to accommodate larger capacity with near stock driveability AFAIK.

Do you have a standard cam in the new engine or have you installed an aftermaket cam? the symptoms you have described are often the result insufficient vacuum caused by a cam with incorrect phasing of inlet and exhaust timing, although who knows with the higher pressure and volume of the injectors.

Regards Philip A


sorry its a gems, and originally 4.0L. the injectors were fitted when i first bought it they are bosch late model, they increased my torque and fuel economy on the std engine. the fuel pressure reg is no longer connected to a vacuum source as when it was hooked up it leaned out too much, ecu showed constant +25% in fuel trim. as for the cam its 204 @.050 both intake and exhaust with 450 thou lift.

[PhilipA]

as for the cam its 204 @.050 both intake and exhaust with 450 thou lift.

What is the LSA, as you need a narrow LSA to give vacuum for a MAF to read correctly.Standard 4.0 litre LSA is 109degrees.

Rover,ERR3720, IO28,IC77,EO66,EC39,DUR285/285,LSA109,OL67, lift0.390, 5.5,,Production ,4.0-litre, 109degrees LSA is theoretically correct for a RV8.

How many Lbs per hour are the injectors? Standard 4.0 are 23.5 and Bosch yellow Gen11 or 111 are 19Lb. So how big did you fit?? as 19Lb per hour is plenty for a 4.6 and should be OK with 5 litre if the duty % in the chip is increased. Holden 5 litre uses 19lb.
I guess my assessment without knowing much of the story is that your injectors are too big and the cam has too large an LSA.
Regards Philip A

[wanglemoose]

What is the LSA, as you need a narrow LSA to give vacuum for a MAF to read correctly.Standard 4.0 litre LSA is 109degrees.

Rover,ERR3720, IO28,IC77,EO66,EC39,DUR285/285,LSA109,OL67, lift0.390, 5.5,,Production ,4.0-litre, 109degrees LSA is theoretically correct for a RV8.

How many Lbs per hour are the injectors? Standard 4.0 are 23.5 and Bosch yellow Gen11 or 111 are 19Lb. So how big did you fit?? as 19Lb per hour is plenty for a 4.6 and should be OK with 5 litre if the duty % in the chip is increased. Holden 5 litre uses 19lb.
I guess my assessment without knowing much of the story is that your injectors are too big and the cam has too large an LSA.
Regards Philip A

LSA is 112 and dont remember the Lb/hr for the injectors but when we run them on the injector bench when we first put them in they came up roughly 20% in cc larger to the original BUT they ran in the std 4.0 and returned better economy and power, the computer used to run at -7% fuel trim on the old 4.0. apparently the set up in the 5.0 we used has been used before replacing the 4.6 with no problems, im wondering if there is much difference in the 4.0-4.6 maps. it drives like a dream when its over idle, it even chirped the tyres (32" maxxis 764's) on take off a few days ago.

[PhilipA]

im wondering if there is much difference in the 4.0-4.6 maps.

Yes I was wondering that also.
The problem is that you cannot swap ECUs easily, although I understand it is possible using the dealer computer to change the security settings.

REgards Philip A

[wanglemoose]

been playing with some interesting results. first off unplug the stepper motor cold and it idles at 1250 instead of 1850, plug it back in and idle is back up to 1850. fuel trim with stepper motor unplugged -1-2% and plugged in -4-5% also no vacuum to fuel pressure reg. with vacuum to fuel pressure reg, fuel trim with stepper motor unplugged +3-4% and plugged in +12-15%. now when warm with the stepper motor unplugged and vacuum to fuel pressure reg, idle 1800 fuel trim +9-12% withe no vacuum to fpr and stepper plugged in warm idle hunts between 550 and 750 and fuel trim is at + 2-5%.

[PhilipA]

first off unplug the stepper motor cold and it idles at 1250 instead of 1850

That is part of what the stepper does, at high resistance values on the ECU temp sensor it will add steps.



fuel trim with stepper motor unplugged -1-2% and plugged in -4-5% also no vacuum to fuel pressure reg

It seems to me that the ECU is not adding fuel as the revs rise with stepper.

I don't think the stepper has much to do with your problem, I think it is more probably inconsistent air volume through the MAF. See what it does with MAF disconnected, as it will be in "limp home" which is usually rich.

I take it this is a non cat car.

Regards Philip A