Mixture adjustment on a Rover 3.9 V8 without Lambda Sensors.

[blitzracing]

Kiwibacon said:

Ah yes, I have measured the fuel pressure, first at the pump (solid 37psi) then at the rail (32psi raising to almost 40psi when revved). This fits nicely with ~2.5bar over manifold pressure.

Glad the new map has helped- but recheck this figure- use RoverGauge to turn the fuel pump on with the ignition on, but the engine not running. This means the plenum chamber should be at atmosphere so you should see 37 PSI at the rail- 40 PSI is a bit high. If its genuinely running at 40 PSI, then check you dont have a blocked or kinked fuel return rail. You can check the pressure regulator with an airline and gauge in the input, (having removed it) and notice when it opens. Dont worry about it if it seems to leak air as the pressure drops, its not a fault, I dont think it likes air instead of petrol! Also even 150 mv extra on the AFM output is enough to make the engine over fuel, so double check the AFM readings. Dont forget Rovergauge shows you what the ECU sees, not necessarily whats at the back of the sensor. You can get a high reading if there are any earth issues between the AFM ground wire and the ECU ground. Every sensor has its own ground wire back to the ECU to prevent odd chassis voltages altering the readings the ECU sees. You can digitally rescale the AFM output on the open loop map using a "UAFC" unit made by a company called 14.7, if you want to mess around with fuelling without remapping, but the one I had did not prove to be reliable, and kept corrupting the maps. I think its very sensitive to voltage spikes.

http://www.14point7.com/products/ultra-air-fuel-co...

[Kiwibacon]

blitzracing said:

Glad the new map has helped- but recheck this figure- use RoverGauge to turn the fuel pump on with the ignition on, but the engine not running. This means the plenum chamber should be at atmosphere so you should see 37 PSI at the rail- 40 PSI is a bit high. If its genuinely running at 40 PSI, then check you dont have a blocked or kinked fuel return rail. You can check the pressure regulator with an airline and gauge in the input, (having removed it) and notice when it opens. Dont worry about it if it seems to leak air as the pressure drops, its not a fault, I dont think it likes air instead of petrol! Also even 150 mv extra on the AFM output is enough to make the engine over fuel, so double check the AFM readings. Dont forget Rovergauge shows you what the ECU sees, not necessarily whats at the back of the sensor. You can get a high reading if there are any earth issues between the AFM ground wire and the ECU ground. Every sensor has its own ground wire back to the ECU to prevent odd chassis voltages altering the readings the ECU sees. You can digitally rescale the AFM output on the open loop map using a "UAFC" unit made by a company called 14.7, if you want to mess around with fuelling without remapping, but the one I had did not prove to be reliable, and kept corrupting the maps. I think its very sensitive to voltage spikes.

http://www.14point7.com/products/ultra-air-fuel-co...

Thanks Mark

The fuel pressure didn't hit 40psi, just high 30's, but by that stage I had spilt some fuel on the plastic face and it went all cloudy and hard to read. I wouldn't trust that gauge to be accurate to more than +/-1psi anyway.

With the tunerpro definitions for the 14CUX it's going to be easier and cheaper to write chips than to shag about intercepting MAF signals. But given the time of year it'll take a few weeks to get some chips. I don't have a UV eraser so I'm hoping to find some compatible EEPROM's rather than the UV EPROM.

[blitzracing]

There is a compatable EEROM you can use in place of the Eprom that costs about £6.00. Ill dig out a part number for you.

Edited by blitzracing on Monday 30th December 12:16

[blitzracing]

28c256 EEprom

[Kiwibacon]

blitzracing said:

28c256 EEprom

Brilliant. Thanks Mark and have a good new year.
I've snagged some off ebay for about $US12 incl postage.

Edited by Kiwibacon on Monday 30th December 22:36

[Kiwibacon]

I've pulled the ECU for a look. No socketed chip or lucas cover on my one. Just a 28 pin IC soldered down and a label that's long since faded to unreadable.

So I've ordered a 28 pin ejector socket from Ebay just like Steve has here: http://www.pistonheads.com/gassing/topic.asp?h=0&a...

ECU AMR1424, Date Code 0893 so appears original to the vehicle and unmolested.

[Kiwibacon]

Misfire sorted.

I replaced the Lucas ignition module (electronic points for the old school) with a Bosch BIM024 ignition module. This is as simple as mounting the module, cutting the lucas plugs off and fitting spade lug terminals.

It now revs cleanly to the rev limit both in neutral and loaded. It even sounded different backing it out of the garage. This let me check the A/F ratio under full load, generally around 12.2:1 which isn't too far wrong.

Otherwise I'm still waiting for the chips and socket for the remapping.

[Kiwibacon]

Chips and socket for remapping arrived.

[100SRV]

Kiwibacon said:

Misfire sorted.

I replaced the Lucas ignition module (electronic points for the old school) with a Bosch BIM024 ignition module. This is as simple as mounting the module, cutting the lucas plugs off and fitting spade lug terminals.

It now revs cleanly to the rev limit both in neutral and loaded. It even sounded different backing it out of the garage. This let me check the A/F ratio under full load, generally around 12.2:1 which isn't too far wrong.

Otherwise I'm still waiting for the chips and socket for the remapping.

Would that be the ignition amplifier which is either on the side of the distributor (early IIRC) or remotely mounted (e.g. NAS 90 / 110)?
O/T
We had a bit of trouble with the distributor mounted one on the Bowler racer, only once but it meant we couldn't start a rally because the car couldn't get out of parc ferme under it's own power :-( auto too so no chance of "driving" it out on the starter motor having pushed it to the exit.

[paintman]

Early ones on the RRC EFi are remotely mounted on top of the inner wing under the coil.
The later ones were dizzy mounted, but there was a kit to remotely mount those as well which suggests that there was a problem.
http://www.rangerovers.net/repairdetails/classic/e...
STC1856 http://www.roverparts.com/Instructions/STC1856.cfm

[blitzracing]

It was simply a matter of heat and switching electronics not mixing well when its mounted on the dizzy- hence the move.

[100SRV]

blitzracing said:

It was simply a matter of heat and switching electronics not mixing well when its mounted on the dizzy- hence the move.

That was the conclusion I came to but for some reason on the racer we stayed with dizzy-mounted amplifier. I think it was damp which prevented it starting on the rally, it was October and rained all the way from the Midlands to Arras. With the racer being on a trailer behind a Range Rover it was in a perpetual jetwash! The racer was only run for long enough to get it off the trailer so never got warm enough to dry any under-bonnet damp out.

I fitted lumention to my own Bowler and put a spare mounting plate, points and condenser in the spares kit just in case ;-)

Sorry for thread hijack...

[Kiwibacon]

It appears mine was originally mounted on the distributor and had the genuine upgrade remote mount kit later. The original plug is there hanging freely by the distributor. The extension lead and plug to move the module to the aluminium heat-sink plate bolted under the coil all look like factory lucas with the correct plugs etc.

So while I'm sure this was an improvement over factory it clearly still had some issues. I wasn't going to gamble with more lucas parts for the 60 quid eqivalent the bosch cost me.

[Kiwibacon]

I had a crack at unsoldering the chip from the ECU board today. No good.
As well as being soldered down, it's glued down with the resin that coats everything.

I have a backup plan that involves bribing an electronics tech I know. He's got a nice targeted heat-gun that can melt and release without going all "scorched earth".

[anonymous-user]

Generally, if you haven't got access to the "right" tools it's best to sacrifice the chip and not the entire ecu. By that i mean, use mechanical methods(sharp, small, side cutters) to cut the legs of the PROM, then remove it using careful leverage, preferably with a plastic object to avoid damaging any tracks on the pcb. After that, you can individually un-solder and remove the remains of each "leg" from the individual through holes of the pcb, which is easily done with a normal soldering iron and some tweasers.

[anonymous-user]

OH, and if you want to read the contents of the removed PROM afterwards, glue it upside down on to some prototyping strip board and use some fine wire to make up little wire jumpers to each pin from a row of male header pins soldered to the same strip board under the "Upsidedown" device (sometimes, depending on how mangled the PROM is after removal, you can keep it the right way up, which makes the pinout unaltered)

[Kiwibacon]

Max_Torque said:

Generally, if you haven't got access to the "right" tools it's best to sacrifice the chip and not the entire ecu. By that i mean, use mechanical methods(sharp, small, side cutters) to cut the legs of the PROM, then remove it using careful leverage, preferably with a plastic object to avoid damaging any tracks on the pcb. After that, you can individually un-solder and remove the remains of each "leg" from the individual through holes of the pcb, which is easily done with a normal soldering iron and some tweasers.

That exact thought had passed my mind. I've saved a ROM dump from rovergauge, but I don't know if that is exactly the same image I'd get from removing the chip and reading it.

If I can extract the chip whole, then I can test my socket soldering with the stock chip and one or two less variables.

[blitzracing]

As Maxtorque says- you have to cut all the legs off to start with, then soak the chip area in white spirit, it will dissolve the sealant. It gets messy, but use a paint brush just where you need it, then let it all dry out again, and the sealant will re set . Not much to be gained by trying to read it afterward as RoverGauge has pulled the .bin file that can be blown back into another chip if you wanted to.

[Kiwibacon]

I've had good luck (with the help of that electronics tech) removing stuck down chips before. He has a targetted heat gun which melts all the resin and uses tin-foil to shield the surrounding parts from the heat.
So we'll try that again, if it doesn't work then it's butchery time.

[blitzracing]

Not tried heat- Ive got a damaged PCB in the shed, Ill try heating it and see what happens to the goo.