pcmhacking.net

vehicle is a vl with a vs v8 304 mated to a supra gearbox, running the 305 vs v8 manual ecu that i have wired in , car idles and revs fine, however the car surges and has kind of a flat spot when just cruising along or just touching the accelerator, this makes it hard to drive, the problem can be replicated when in neutral at a stand still, by just touching the accelerator a bit, there are no codes but number 12, things i have checked:

the ecu earths on pins d6, a12, d1, d10, d3.
the power at a6 is battery voltage switched with ignition,
the power at b1, and c16 is constantly on with battery voltage.
new sparkplugs and leads
the TPS wire at ecu pin c13 starts at low voltage and sweeps smoothly to around 4,7volts at WOT
MAP wire at ecu pin c10 seems to rise sort of smoothly when revved slowly , fluctuated a little when the surge happened, as expected.

Im now looking a the ignition module wiring, (have swapped module with a mates and his car runs mint with both of them, have kept his for time being)
i have read that its good to take the brown coil driver wire out of the wiring loom, as it interferes with the distributor hall effect signal. anyone done this ?

today it seems to drive fine when dead cold and the symptom starts to develop after about 1min of driving and gets worse as it warms up, if you want i can take a video and put it up on youtube,

any help towards a fix would be appreciated.

youtube clip of it https://www.youtube.com/watch?v=8PJ-jnIAI_Y




as i said if you drive with the throttle a little bit further down, (engine under a little acceleration) it is fine ,also goes very well under hard acceleration,

update:

just separated the coil driver wire from the module wiring, still the same revs up a little then dies the revs up a little the dies, have checked spark with timing light and it looks like spark is staying when its dying, the spark timing advances to maybe 20deg the drops back when it dies, disconnected the tps and it makes the dying worse,

as aside note i pulled the air intake sensor plug of while running and it never triggered a code, however the tps or the map does,
i have also check for vacuum leaks and there are none apparent,

i am more than happy to go and recheck any wiring component or anthing i have done if you wish, have tried another memcal and it still does it,

Has it been tuned at all or any other modification from standard?

Have you checked fuel pressure?

Also, is the vehicle speed sensor working correctly and the correct signal to suit the Holden PCM?

Sounds like a temp sender to me

what your describing sounds like its lean ...

weather its a sensor or something else its hard to say, and the fact that it gets worse as it gets warming ... the only thing thats happening is that as it warms up theres less fuel and it leans off the cold start to running AFR's ... and its particularly worse at cruise because the o2 sensor will be working to keep it at 14.7 (closed loop) rather than a richer mixture in open loop.

could be a sensor, could be a tune issue .... could be anything, but i reckon i can fairly safely say its probably not spark related....

i'd be trying a map sensor or something similar ....

do you have a log of it ?

as crazy as this sounds I have had this problem in my v8 and after chasing my tail it turned out to be the wrong spark plugs... the rite heat range and part number but the wrong gap.. too close of all things and it felt like it was lean on cruse or way too much timing and stumbling it would pull hard as when I booted it but on cruse and just off idle it would stumble like all hell.

to describe the problem its revs up to 2000rpm and then its like a complete cut on all cyls and cuts back in at 1500 rpm, (RPM are a close guess just using example) , this is with your foot just on the the throttle

i will check the spark plugs today, i have seen a v8 ford explorer do that and it was the wrong brand of plugs,

the speed sensor is not hooked up as the toyota gear box and vl commodore are both cable, i was on the understanding that it may have a problem returning to idle when coming to a stop with the clutch in and to just tweak the idle stop screw, however i have no idle problems.

there are no o2 sensors on the car , again i only thought that HSV models ran the knock sensor and o2 sensors, will look into this if even for fuel economy, would have thought it would set a code if the ecu was expecting to see them but didnt, i hope if i fit them they will work

the car is pretty much standard in the engine department, just exhaust and air filter. I did repin the auto loom to suit the manual ecu, i used both wiring diagrams auto and manual , checked every wire with a multimeter to make sure it went where it was supposed to go, then re pinned that 1 wire to the the correct position on the manual ecu connector.

i will check the CTS (coolant temp sensor) today , make sure its not intermittent or not working, BTW i take all my reading and checks from the ecu connector first.

I am wanting to log the data or at least see real time data, that is what im currently working on, do i just need a aldl cable for the 305 ecu?, i wired in the obd port but being obd1 my scanner cannot communicate with it, ( scanner is obdII) , i have been reading but then get to much info so now im looking at nvram and more stuff i don't think i need, i don't need to adjust any settings or tune yet , just want to be able to see what the ecu sees and is doing for now.

Thanks for the quick replies too, its good to know that people are here to help, ( like me, i stop for people who have broken down , and carry a small assortment of tools in my boot for just such occasions, we are a dying breed)

just on a side note, you can probably hook up the speedo as the VL dash has a signal in it that will go to the computer ? ... im pretty sure anyways, I bought a VL dash when I was looking for a speed sensor for trimatic, but I never got to testing it.

I think you're correct, a guy I did a tune for here in NZ had a 304 efi engine in a VL and he used a signal from the dash to run a cruise control function I think. I think he's sold the car now but there was a build thread on JC. Big Red I think it was called.

thanks i will look into that , mine has/had cruise control,

just checked the CTS and its fine, checked the MAT sensor and fine , i checked the tps earths and 5v ref and it its all good,

HERE IS A YOU TUBE OF IT
does get worse

https://www.youtube.com/watch?v=8PJ-jnIAI_Y

I used a 2pulse sender available from Pat Gardner, it screws into the gearbox, and a cable goes into the back of it.

Gives the ecu a speed signal it needs, and the dash gets its cable feed.

Set ppk to 1280 or similar.

Sean