86 RX EFI issues .

discopotato03 · Post by **discopotato03** » Fri Jan 22, 2010 2:22 am

Fingers crossed I'll have an early EA82T computer to replace my ailing one with today .
I had some Skyline tuning time yesterday evening and was offered a Nismo adjustable fuel pressure regulator . These bolt to the Nissan fuel rail and I may be able to get an RB20 rail to murder and fit a second 8mm fuel hose barb to . I really need my fuel rail pressure to be at least std which it isn't atm , its a couple of pounds down so mixtures would be on the lean side .

What is it with L's and EA82T's ? If they're not trying to bleed green blood they're running lean and hot regardless .

Cheers A .

steptoe · Post by **steptoe** » Fri Jan 22, 2010 1:55 pm

Hey! That is a comment for the HATE wall. She is 35 C out there on the road and Cheap Grief is running between 74 and 80 at 80 to 100kph. I am happy, so far.

discopotato03 · Post by **discopotato03** » Fri Jan 22, 2010 7:55 pm

Grrr , Express Post let me down so fingers crossed black box will be here Monday .
Just to rub it in I finally found out where the water is getting in , top drivers side corner of the windscreen . So eventualy both screens have to come out to repair the rust bubbles/holes .

Will have to find ways of making that adjustable pressure reg adaptable because the price is real good .

Cheers A .

discopotato03 · Post by **discopotato03** » Wed Jan 27, 2010 2:50 pm

Crashed and burned again , changed computers and - mad mode still persists .

A .

steptoe · Post by **steptoe** » Wed Jan 27, 2010 8:45 pm

and the wriggle of the wire loom up front still have some temporary effect ?

H-top · Post by **H-top** » Wed Jan 27, 2010 9:13 pm

I had the same problems with my 85 Vortex, cleaned the plugs for the TPS, MAF and fuel pump plug. Fixed it straight up.

Cheers

Gannon · Post by **Gannon** » Wed Jan 27, 2010 9:14 pm

Have you had your injectors cleaned/serviced?

I had a leaning out problem and it ended up being dirty injectors

If you are looking for a FPR with factory pressure, i bought one of these and it worked great, same 36psi, but i dont remember paying that much, but it was alot cheaper than a Subaru one. Fuel Pressure Regulator - Nissan Pulsar N13

nncoolg · Post by **nncoolg** » Wed Jan 27, 2010 10:20 pm

something that worked for me, when I had my flap style EA82T, it would NEVER run properly with the O2 sensor plugged in, it surged terribly from start-up, and didn't get better after warm-up. Tried new sensor, tried moving it to a hotter bit of pipe, in the end I just ran it disconnected, it ran great. I run my Legacy unplugged too, heaps better!

steptoe · Post by **steptoe** » Wed Jan 27, 2010 10:36 pm

Beginning to think that an oil pressure idiot light type , fuel safe sender should be fitted to all efi fuel lines. Red light below 30psi. May only work once but save lot of stuffing around

discopotato03 · Post by **discopotato03** » Thu Jan 28, 2010 9:15 am

Well the TPS plug was changed for a finger release one not that long ago and I had the AFM one off to check it and it looked ok . Will have to have a look at the pumps local connector .

Since its easy I'm going to disconnect the oxygen sensor today .
I was offered a good price on a Turbosmart adjustable FPR so it will go in downstream of the OE one , hey its rebuildable and easily removable so good for diagnostics .

I again drove home , at a reduced pace with the bonnet on the safety catch for temp extra cooling and while it did eventually go into mad mode it reset itself several times after short periods of closed throttle .
This is what makes me think the problem is not fuel pressure based , how could the computer know if fuel pressure suddenly dropped and start flashing the red light immediately ? Only thing I can think of is if the oxygen sensor overheated and sent danger Will Robinson messages - but these are a dumb single wire probe ...

I was also looking at what wiring lives close to the turbo/dump pipe to see if anything could heat up and start playing up . There is the elec fan and A/C relay back there but these shouldn't do anything nor should the gearboxes wiring loom .

My gut feeling is that the grungy injector wiring in the engine loom is shot and needs replacing but my mechanic friend said if that was the case it'd do it all the time .
The oil pressure switch is a good idea though I did read when looking into electric fuel pressure gauges that oil type senders are not long term reliable with petrol . Most oil switches wouldn't be 30 pound rated but I know some specialist ones are - the rally people use them because at 5 psi its too late to save an engine with an oil pressure problem . Rally idiot light switch .

A .

steptoe · Post by **steptoe** » Thu Jan 28, 2010 10:39 am

Hey Adrian, could you please put your best description of mad mode in your signature for quick reference until this is over. What if, if it is in the wiring, and wiring goes a little limp as heat softens the insulation - what if you place some tension of better securing to the questionable looms so there is no movement or slack as you drive along, singin' a song...

discopotato03 · Post by **discopotato03** » Thu Jan 28, 2010 3:48 pm

nncoolg wrote:something that worked for me, when I had my flap style EA82T, it would NEVER run properly with the O2 sensor plugged in, it surged terribly from start-up, and didn't get better after warm-up. Tried new sensor, tried moving it to a hotter bit of pipe, in the end I just ran it disconnected, it ran great. I run my Legacy unplugged too, heaps better!

What can I say , unplug the oxygen thief and so far lose the grief .
I drove as far today as I did yesterday and while I'm not 100% sure the problems solved it hasn't played up since .

If it continues to behave itself I'll be interested to see if theres any difference in fuel consumption , it wasn't brilliant when it was acting up .
Also I reckon its running cooler which has to be a bonus for an L Series .

It could be interesting to check the 02 probes wire and shield to see if its chaffed through somewhere .

Fingers crossed this is the fix , thanks for the heads up Nncoolg .

Cheers Adrian .

twilightprotege · Post by **twilightprotege** » Thu Jan 28, 2010 4:19 pm

i'm going to give that a go on mine as well. i'll report back

and also, why are you putting an additional fpr after the stock one? just remove the stocko one all together

maybe as another option, try keeping the o2 sensor in, but up the fuel pressure? 36psi is low for an efi car. most i've worked with are 3bar - 43psi. dont forget too, the higher the pressure, the finer the spray (usually), and most importantly, the cooler the spray

discopotato03 · Post by **discopotato03** » Thu Jan 28, 2010 6:09 pm

Initially the aftermarket one will be used for test purposes , it will be placed downstream of the std one because a second reg can raise pressure regardless of what the primary one does .

Just to spell things out my EA82T has the spider inlet manifold on it and the std FPR is a cow to get at . The other one will most likely be placed between the end of the steel return rail and the steel return tube under the fuel filter . I'm thinking along the lines of a bracket on the inner near side shock tower so its not too obvious and in the general flight path of the std supply and return rubber hoses .

The 87 Factory WSM shows fuel pressure as being 36.3 psi above manifold pressure . Easy way to test is to plug your two green test connectors together (in an L series) and switch on the ignition . Pump will cycle on and off without starting the engine . With atmospheric pressure in the inlet manifold the pressure should be zero plus the regs pressure head or 36.3 in a healthy std system .

I forgot to add I've opted for the pressure gauge that can be screwed into the side of these Turbosmart 800 series regs . Handy .

Cheers A .

nncoolg · Post by **nncoolg** » Thu Jan 28, 2010 6:43 pm

When I had mine, It got 36mpg on a trip, never ran an O2 sensor, I have a switch on the Legacy, so I can run it with the sensor wire connected or disconnected, as due to the 3 wire heated sensor, they can't be just unplugged. It also, runs heaps better without it.

discopotato03 · Post by **discopotato03** » Thu Jan 28, 2010 9:44 pm

Not long back from a short run on the Princes Hwy , can do 100 legally long enough to provoke mad mode but not this time . Also the longish hill from a certain creek where you can hold flat at 80 in 5th to load things up for a while . No shudders no flashing red light so elec nose or its wiring must have been the problem - I think .

So if your early RX L Series starts doing silly things try disconnecting the oxygen sensor .

Cheers A .

PS will be trying the new reg at 37-38 pounds to see if it makes any difference .

Gannon · Post by **Gannon** » Fri Jan 29, 2010 5:35 am

Why should the o2 sensor be affecting it? I thought all o2 sensors were ignored for open loop fuelling whenever you are on boost

nncoolg · Post by **nncoolg** » Fri Jan 29, 2010 6:31 am

Yeah, people speculate A LOT about how o2 sensors work in a EFI system, who knows really, except maybe a JECS programmer. I can tell you this though, that my EA82T RIGHT FROM START UP was horribly affected by the o2 sensor when it was plugged in. I speculate that it is because after we play around with exhausts and what not that the o2 sensor doesn't stay hot enough to read the right voltage. Having said that, I never played with the Fuel Pressure, so that could have something to do with it, I mean all the 3 plug distributors have the diaphragm rotted out, so I guess all the FPR's could too!

steptoe · Post by **steptoe** » Fri Jan 29, 2010 7:59 am

Neville right about those diaphragms. I had three, two were very religious, and the third could hold five pounds of boost then leaked off - boosted LPG vapour inside my dizzy cap to get ignited by a spark

Took five months to solve. If only more vapou got in there to blow the crap out of the cap I'da found it sooner.

Disco, i reckon you were waiting for your ECU upgrade before you got a new O2 sensor. They are a replaceable item, at a small outlay, as you know. You have upgraded/ modernised lots ut the ECU and O2 sensor. When I ran the new $1800 Vane on road analyser on mine on petrol on old O2 sensor all was good. The readings reflected the O2 sensor was not controling things Lamda under boost!

When I fitted cheapy mixture LED gauge it indicated things were rich, so a new single wire O2 sensor went in, no change. Concerned i used the Vane again to indicate things had richened up a tad in idle . I leaned idle off with a leaning ring, wound power valve down half a notch for more acceptable boost levels and gained 600ml per 100km economy AND mixture meter dances around as I expect, but stil reads on the rich side when VANE says perfect. The technology of the mid eighties and ECU may have been a rough (but acceptable) BUT the Disco mods may be pushing luck at some pont. MAP for fuel, and Gannon may have improved things when he fitted his up as a heated O2 sensor - was it wideband? is wideband still same voltage output? Disconnection is good diagnostic process in this case by the looks

T'subaru · Post by **T'subaru** » Fri Jan 29, 2010 8:51 am

[quote="steptoe"]Neville right about those diaphragms. I had three, two were very religious, and the third could hold five pounds of boost then leaked off - boosted LPG vapour inside my dizzy cap to get ignited by a spark

Took five months to solve. If only more vapou got in there to blow the crap out of the cap I'da found it sooner.

LOL, thats good stuff steptoe. Hey, just for kicks I unplugged my o2 sensor this am before heading to work after catching up on this thread, ran abit better than what is currently normal. I havnt been experiencing any mad mode stuff, and no cel either...so whats up?
If only all our problem parts would explode,trouble shooting would be much easier:)