Ignition timing.

[Akane]

If I advance the ignition timing and it accelerates good but dies when I let off the throttle, and if I retard the igntion timing it accelerates like a pile of faeces (sounds like misfiring) but idles okay when I back off the throttle, what can it be?

Took my car for a test drive today and encountered these symptoms.

ECU is tuned for Gen 2 3S-GTE but I have a Gen 3 in there (re: no T-VIS, different cam profiles), I'm running MAP d-jetronic on my Power FC.
I already have full advance on the distributor.

Been playing with the temporary inj/ign settings. 0 seems to be okay, +7 accelerates good, but dies on closing throttle after acceleration (dips down to around 400rpm and then it stalls).

-5 onwards is good when i back off the throttle but it backfires and barely makes it up the road.

One strange thing is that when I step on it a bit, it kind of hold it's rev (around 2000rpm) for about 3 seconds with a sound of misfiring, and then it runs fine (-0 ign correction)

stumped. Any input helps.

Also a puff of black smoke when I back off after I rev it while the car's stationary (-0 ign)

Fuel seems to be okay, when i free rev it at 1.000 inj correction it's fine, anything more or less it doesn't sound good.

[MAGN1T]

You'll find it easier if you can monitor both AFR and knock.
Those NB LED monitor things work well as does the "knocklink". Tuning with guesswork will just end with a blowup.

Steve

[Akane]

Yeah I wanna tune it so I can at least get a WOF..... but in this state I don't think I'd wanna.

knock is pretty wild it goes about 1/3 bar up under acceleration.

AFR... I'm working on that... need some cash for some LC-1 love.

[iOnic]

How well was the static timing set?

[MAGN1T]

LC1 isn't essential. You can get a $20 or so kitset from Jaycar that will do the trick.
One of the problems with MAP based ECUs is that timing affects manifold vac and manifold vac affects AFR so changing the static timing changes AFR as well.

If it was an "oldschool" car you'd set the timing to get best vac at idle warmed up then go from there. That's the best use for a boost/vac gauge.
It's a bit more tricky with EFI.

Steve

[Akane]

How well was the static timing set?

on the old engine the intake cam was retarded a tooth, and then the dizzy was set very advanced to compensate (dizzy runs off intake cam), got it tuned, the guy who tuned it said he didn't have to alter much timing from the base map of the Power FC.

Now the Gen 3 engine i have, all cams are set at factory positions, If I leave the dizzy in the middle, idles ok, revs are pretty bad (misfiring), I've set it to max advance now and revving the engine seems a lot better.

LC1 isn't essential. You can get a $20 or so kitset from Jaycar that will do the trick.

Which kitset are you speaking of Steve?
I understand MAP based ECU's solves some problems while bring new ones into the picture. I want to get this so it at least runs under light throttle conditions so i can get a WOF, then I can bring it to places and get the other stuff fixed.

[AceSniper]

a NB is pointless unless you want pretty lights while cruising and a "rich" light everytime you give it a little.

[MAGN1T]

a NB is pointless unless you want pretty lights while cruising and a "rich" light everytime you give it a little.

Maybe for you.


http://www.jaycar.co.nz/productView.asp ... BCATID=347

That'll work


Better still

http://www.jaycar.co.nz/productView.asp ... BCATID=347


It's more than likely that the oxy sensor has died like they all do so it can't go into closed loop.

No useless light show.
Steve

[Akane]

I have one of those LED things, just that the previous mechanic who touched my car broke the wire that's coming out of the brand new narrowband I have installed 5,000kms ago.

The second one is only a screen, you still need a control module which is around the same price, and then the wideband (Bosch LSU 4.2) which is $125 on trademe.

I might go for the one from 14point7.com........