Thread: 93 Hard Dash, Spark Plugs and Fuses

Well you could start by installing an oxygen sensor to see just how rich it is, then perhaps intercepting/modifying the MAF output to lean it off. An adjustable air bypass pipe for the MAF might work too. Replace the injectors? Enable O2 sensors to the ECU? Cut the exhaust system off? Perhaps it's just carboned up from all the rich running and needs a decoke. The cam could be worn out.

Currently with the dented fuel tank guard

Prop up the LHS side of the tank and take the guard off. Four bolts hold it on, bash it out.

Originally Posted by bee utey

Well you could start by installing an oxygen sensor to see just how rich it is, then perhaps intercepting/modifying the MAF output to lean it off. An adjustable air bypass pipe for the MAF might work too. Replace the injectors? Enable O2 sensors to the ECU? Cut the exhaust system off? Perhaps it's just carboned up from all the rich running and needs a decoke. The cam could be worn out.

Yes I've bought a wide-band A/F ratio gauge with bosch probe that is supposed to even read up to 99:1 for diesel use. I figure it'll pay for itself in two tanks if I can find and fix something good.

I don't want to think about cams. I just don't.

Originally Posted by bee utey

Prop up the LHS side of the tank and take the guard off. Four bolts hold it on, bash it out.

That's the plan. It's on the list and should be done before Christmas.

Wide-band O2 probe attached and first test-drive done.

Idle (cold) around 11.5.
Driving cold 12-12.5
Driving warm 12.5-13
Acceleration drops below 11 then misfiring brings the A/F ratio at the exhaust pipe back up to around 15.

So clearly I'm running too rich, but how rich?
I've heard these run lean cruise, so would they do ~17:1 in light load cruising conditions?
Otherwise should I expect stoich (14.7) at warm idle and enrichment (~12:1) with a foot up it?

Next test-drive will be with MAF disconnected to see if any of this changes.

With MAF unplugged it's about 1 point richer still.

So why even run a MAF if it can only provide so little modification on engine airflow?

If I'm not mistaken, all information points towards a worn cam. At only 160,000km!

Dougal, out of interest, how'd you fix the dash lights? I've been given a Dec '92 (which would be a 1993 MY) which has the same issue. Was it a fuse thing? Your other issues a very similar to some of mine. I get about 17-18l/100kms but have 320000kms which is better than the 20-odd I get in my carb 1981 RRC! I've no idea about the EFI stuff so time for me to start learning!!

Stu, my dash lights (heater controls) were unclipped and fallen out of their place. About half of them are working again, I'm not sure if I bumped them out again on reinstall or bumped a wire off.

On the fuelling issues. I unhooked the battery and gave it a few days to think about what it has done. Just in-case it had somehow hit a limp mode.

And it's slightly better. Not perfect, but better.
Idle is now around 12:1.
Driving when warm I did see 14.5:1 A/F ratio breifly on a few occasions, had it above 14.0:1 for a few km of flat road but mostly high 13's.

Still got misfiring near full throttle, this isn't accompanied by any change in A/F ratio (other than climbing once the mis-fire starts so I'm wondering spark again. I feel it's running about 1 point too rich now.
Interestingly I did have that one trip when it was running close to perfectly. I had plenty of power and no mis-fire. This was immediately after changing the fuel filter.
That one perfect run has me convinced it can do it again. But I won't be water-blasting the engine when I get home next-time.

I've ordered a roverguage cable so I can plug the laptop in and see what signals the ECU thinks it is getting and trouble-shoot from that end too.

Roverguage now working. If anyone else gets stuck, the black connector in the front is EAS. The white one hidden in the back of the seat base is the 14CUX ECU.

Being open loop control (no O2 sensors) the long term and short term fuel trims are on zero. If I can find a way to manually adjust these then I can sort out the rich running.

Rovergauge told me I am running on "map 2".

For those unfamilar, these ECU's contain about 5 different maps plus a limp-home map, for running MAF only, running O2 sensors, running O2 sensors and CAT converters, 4.2 engines etc.

My engine not having any cat converters or O2 sensors should be on map 1. Which is the "Australian" version. This is triggered by a 180 ohm resistor.
But I have a 470 ohm resistor which is indeed map 2. Map 2 is for running oxygen sensors which I don't have.

Time to dig out the box of spare resistors and see if I can conjure up ~180 ohms.