86 RX EFI issues .

[discopotato03]

After reading something about water getting into the computer I removed mine and found signs of water around the main power etc plug and socket .
I cleaned up both as best I could but couldn't be certain if there was any damage . I sprayed some elec grade silicon into the plug etc but mad mode still prevails .

A .

[steptoe]

Mine had the green verdigris build up in the drainage corner? of ecu board and plugs. "nother Brumby owner had his MTX 8 ECU under his glovebox and a shower cap fitted above that to keep things dry

[discopotato03]

So did the water damage the computer or just mess things up a little ?

I did try running slowly part way home this evening with the bonnet on the safety catch to see if the engine/bay ran any cooler . Funny thing was that mad mode wasn't as bad as it can be and may have been resetting itself .
I noticed the crossover pipe from the turbo to the TB was cooler as was the spider top section .

I would not recommend anyone do the second bonnet latch business because I have seen them give on other cars and slam the bonnett back into the windscreen . Even if you don't cop it or the shattered glass you can't then see where you're going .

An old dogs trick years ago was to shim the bonnet up on its brackets to let some of the hot engine bay air out . I may try that and also shim up the support rubbers that sit either side of the bay as well .
My turbo really needs the std heat shield modified and refitted .

A .

[steptoe]

No damage as such to report other than the control over the EGR is not restricted as it should be.

Have you got the turbo under bonnet sound heat blanket?

Another old dog racer look was the removal of one head light and duct air through from there.

I have been tempted to make two 90mm holes directly over each strut for a bit of mesh as an outlet or a transverse electric fan across engine. Gees these turbos get things hot under there

[discopotato03]

No the heat shield is not in place yet , sadly I didn't have it with the car when the header/turbo conversion was done . It had been modified once I think when the spider went on but needs to have its tubes re jigged to fit over the Garrett turbo and dump pipe . It used to hang off that tongue that the spare wheel bolted to and the strut tower mount .
Which reminds me , I must remember to get my rally fab people to modify a wheel tie down bolt to screw into the threaded hole in the boot floor .

Also my dump pipe needs to be thermotech wrapped because you can feel heat from it radiated into the trans tunnel and floor . Hot in summer .
That and slightly raising the bonnet at its hinges and front latch may help .

From the air/air intercooler people what is being used for the scoop ? Don't really want a Rex one and the less obvious the better .

Cheers A .

[steptoe]

I meant the blanket that sticks to the underside of the bonnet. From the dude with STi Brumby who wrapped his dump pipe in 'that heat wrap' rusted out in a year.Got his pipe aluminium? coated inside and out the next time.

I get a lot of heat through my wire hole in firewall that plug fell out. Maybe just more of that Falcon underbody heat panel for me

[discopotato03]

Back into Sydney today and found a few interesting things with the RX .
Tuesday is usually cheap fuel day in Sinn City so was about to gas up with the usual 95 E10 and wondered if it would go any better with half a gut full of 98 PULP . The 98 went in close to work and was too busy to think much about it . The car ran pretty well in the running around this afternoon and I thought hmm wonder if it had been detonation and its knock box retarding the timing and making things hot and nasty .
Close to home mad mode finally reared its ugly head so scratch the knocking theory .
Out of curiosity I flexed the loom around the engine to body plugs and AFM section and it cuts out . Then it cranked without even trying to fire and the fuel pump ran constantly whilever the ignition was on . With a bit of mucking around I narrowed the problem down to the black set of plugs with the fewest wires and could kill it by flexing its wires in a certain direction .
Herm , time to look at the WSM EFI section to see which wires run through that set of plugs .
The gang I most suspected - but at other places .

BG ECU coolant thermo sensor
GR Throttle switch - full
LW Throttle switch - idle
BY Turbo/NA descrimination
BR Ground for control (ECU)
B Auxilary Air Valve ground - for body .
BrR EGR Solenoid

I can see all sorts of silly things happening if some of these wires have chaffed through their insulation or have some sort of issue within the plug itself . The ECU only has one eventual control ground the switch its mini relays to and that runs through this plug to the single eye on the back of the spider .
Self explanatory what would happen if the TPS switches didn't ground to the ECU at the right times .
BrR is the EGR solenoids earth return to the ECU , backfeeding stray currents could show up as a fault .

So , will have to "unearth" the issue here and hope it cures mad mode .
It may pay people to take a look at MPFI L's around these plugs if you get strange things going on .

Later , cheers A .

[T'subaru]

I'm not sure if this will help or not, but in my dealings with mechanics servicing dc powered equipment they used to use a "cool" spray..cant remember just what it was, on circuit boards to determine if a circuit path was cracked and was expanding under "circuit heat"...may be able to run with out ecu cover and try the spray when it acts up?

[steptoe]

that is good thinking....I wonder if you pull those plugs from each other, then prise the rubber backing plug to check the integrity of connections in the back. These being plugs have a way to release each wire one at a time, involves a fine straight blade jewellers screwdriver slid down back or front of each pin, one at a time

E fuel? What of the warning someone posted in his sig that ethanol rusts metal tanks?

I'd be undong wire wrap back further to expose each wire first then jiggle one wire at a time while running at either side of the plug before anything else

Feels good when you get this close eh?

[discopotato03]

Actually these looms have just the wires for several inches either side of the connectors themselves .
I'd rather my mate attack it because he has a better idea of how to fix wayward electricals .

Thanks for the tip on stripping the terminals from the plug bodies , I think between us we have the proper tools for removing socket terminal pins .
I don't want to break any connections here because the daily is the only one drivable ATM , if he breaks anything he has to fix it at his joint to get rid of us . Be at his place when he gets home this evening . Please don't rain .

Cheers A .

[discopotato03]

It looks like we finally had some luck in the mad mode saga .

I showed my mate the flex the loom and it cuts out thing and he found something I certainly wasn't looking for .
In the body loom side of the offending plug was another female terminal so from the factory it had two female terminals butted together instead of the pin and socket pairs like the other six wires had . Five actually as there is six wires on one side of the plug and seven on the other , odd one out is the turbo/no turbo discrimination one .
Anyhow the one with two female terminals was the control ground for the computer which can explain a lot of engine antics .
My mate tried to replace the odd terminal but the connectors seals would not stay in place so it went over the shoulder for a nice new set of flat six wire weather pack connectors .

It has not done the mad lean thing yet though after a burn down the Princes Hwy for a few miles the red ECU light flashed a few times . Thats probably because it doesn't have a EGR solenoid valve plugged into the engine loom ATM , will fit one (plug one in) tomorrow and see if it stops it .

Fingers crossed , cheers A .

[discopotato03]

Ended up changing the fuel filter yesterday to eliminate any pressure drop there . It does feel better when not in mad mode though that is still there .
Will be trying an external fuel pressure gauge hopefully later this afternoon taped to the outside oif the windscreen to tell once and for all if this is a fuel supply issue . If it is we need to check the pump and inside the tank for restrictions . Does anyone know what style of strainer lives inside the fuel tank on a fuel injected L ?

Cheers A .

[T'subaru]

Cant tell by fsm's, I would guess brass. After bringing home the gl I was cleaning out leaves and such from the trunk and found the fuel gauge sending unit removed from the tank. Looks like some found their way in. Good luck chasing Disco
Mark

[discopotato03]

Only got to static test fuel pressure and at atmospheric pressure the reg was holding at 34 PSIG . Free reving it would go to the high 30's and idle at about 28-9 . Not flash but livable short term . WSM reckons 36.3 .

Also changed the coil to a Bosch cylindrical transformer type and got the starters cable further away from the coil .

Mad mode still present , still flashing code 35 with the green check connectors together . Plugged in another EGR solenoid , same , disconnected EGR wire at body loom connector - same .

Hope to try another computer soon , cheers A .

[steptoe]

I do not believe there is any tank filter in 86 L sedan turbo mpfi. I had my tank out, washed out with hydrochloric acid, neutralised with carb soda, washed and pressure washed the innards out of it and let it dry. Do not recall being able to see into it beyond the baffled interior. Just the half inch supply to the external pump and off to the front filter. I found static testing did not reveal pressure drop I got when driving - only needed a few house blocks and 10% gradient up to create the load to do it--- blaaaaa down to low figure and no go.

Before you try another ECU run a new wire from ECU to the solenoid (or where it needs to go) been a good way to fix some errors in the past with ECU's

[T'subaru]

Maybe not, '89 fsm shows filter in tank for spfi and mpfi.Running an aux test wire is a good idea, takes alot out of the loop. Considering an ecu swap just to see if any dfference in run condition, not getting check engine light and found that check engine bulb was missing a bit back, and at that time I was getting codes in d check, but only after green plugs disconnceted..
Cheers,Mark

[Gannon]

I found a cheap alternative for a FPR

One from a early nissan pulsar, 36psi static pressure and cost around $30

[discopotato03]

Steptoe I wanted to cut that BrR wire close to the ECU plug and crimp a couple of connectors to it so it could be reconnected if necessary .

All I can put the EGR issue down to is the body loom from the engine loom connector to the ECU connector or the ECU itself . Either way a ground short in the loom or on the computers board is the possible gremlin .

My mate reckons that ECUs have transister type switches and its possible that one has suffered water damage and acts up when it gets warm .
It is significant that isolating the engine looms connector made no difference so has to be upstream of the engine loom . I've probed the FPRs blue power supply at the EGR solenoid valves engine loom connector and it doesnt seem to have any issues . I possibly should check the cold start air bypass (AAV) , same FP relay power supply , but if there were probs on the power side it'd be blowing fuses you'd think .

Think I'll disconnect near the ECU before changing it , can easily be made to connect again , or to run another wire to the engine loom connector .

Cheers A .

[steptoe]

Then there is the Checkers old ECU.....

[discopotato03]

Wire cut and no difference , doesn't look like an EGR loom problem .

A .