Just got a DOHC done on the 4G15.

Having some issues at the moment - namely that I can't maintain 2500 to 3000 RPM, and hold it there constantly.

The car rev's drop, and I jolt back and forth - so crusing is impossible. The engine alert lamp also comes on the dash - which is of concern.

Was reading on another thread something similar, but want to make certain that this was what they were experiencing as well?

 

hmmm thats a bit weird... would also like to know what the hell would cause that....

 

problem fixed - it was the TPS (Throttle Postion Sensor) playing up.

There is a difference between the Jap spec and the Aus one, therefore when it was plugged in the computer could not sense it...

I have put the TPS from my old 4G15 SOHC onto the new 4G15 DOHC carbie... (which is 50mm).

 

all,

i' getting another issue with the DOHC.

when I hit the pedel, the car seems to not want to accelerate, like something is holding it back - but when it hits about 4000RPM, the car recovers.

It's not the TPS, but could be something else.

Could it be a timing issue, or something not sparking?

 

What ECU are you using? I assume factory? I would thing you will need a piggyback ECU to tune that setup properly.

From 4000 Rpm on how does it perform? Does it go hard at the top end? The up to 4000 thing won't be a spark engergy thing rather timing of cam/s or ignition timing itself. I would also suppose you are using different injectors.

Did someone supply you a kit or did you get an engine from a Jap Engine place and DIY?

 

To be honest we have used the stock jap spec TPS on the conversion we have done and not had a problem. Sounds like you just had a bad TPS switch on the unit which happens. No reason why the australian spec one woudln't work just as well though.

You also don't need any ecu mods - we have done these on stock ecu before with no issues.

The spluttering / missing at 4000rpm sound weird - the 1.5 DOHC uses same injectors as teh 1.5 SOHC.

Sounds like it could be running lean - or teh ignition timing is retarded or camshaft timing may be out.

Does it idle dead smooth?

 

the idle is smooth - but I have a A/F guage installed, and it pulsates up and down (lean to rich)..

I'm gonna check the timing soon just to make sure...thanks for the tips.

I also found a large puddle in spark plug #1...clean that out and it aint too bad now...

Past 4000 it keeps pulling all the way up to about 7000...haven't hit 8500 (The engine feels like it can rev much higher).....

 

MirageHatchVRX

Would like to see it go on the rollers for a power reading.

 

The pulsing in the O2 sensor is how the factory ECU works by pulising between rich and lean - if you want a consistent signal you need to wire in a 2nd o2 sensor with a constant earth and power feed.

 

me too Raptor - although I wouldn't be anything near your power level...and trying to find people in Melbourne even interested in the Mitsu is near impossible...but if I do, you guys will be the first to hear about it.

I have another stock O2 sensor off the old header - wondering if I can plug this in too (although I'd imagine a considerable modification to the current stock header and also to the new header??)...and then the question on how to hook this up (to the stock ECU or through to a piggy back??).