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Hey all,
I know its a tricky one but could anyone shed some light on this issue I've been having? Car is of course my little red coupe, it has a 1993 JDM GT EJ20G motor.
At idle it sounds real normal. I replaced the IAC valve again today (had the code again) and tested it, its running good. Freely revving it up it sounds ready to go.
The problem occurs when I load it up. As I take off it still sounds ok, but the instant I give it any sort of throttle it stutters and misses.
I am running the HEC716 coils and I have not yet installed the big injectors. This is the exact problem I had with the car before my recent re-conversion and I thought all the little problems I fixed would make it go away.

My biggest suspects are the coils, the injectors or the fuel pressure reg. At the moment there is no fault codes.

Any ideas at all?

Does it have a MAF?

Otherwise TPS maybe? Or any of the things you mentioned.

Does have a MAF. Is there any way to test it? I'm not getting that fault code...

My first thought is coil packs but if these are fine my secound thought is plug gap, these engines really hate not having the correct gap and will miss like a bit@h if they are out.

Tim you would be very Very lucky to actually get a MAF code when its not working correctly....they never seem to issue it when that is the issue(altho I have been lucky enough to have one car with a itermittant maf issue actually issue a MAF code so I could sus the problem).

One way, maybe the only way to check maf is to monitor the voltage(with a PFC this is easy)....go the sensor check screen and look what the MAF voltage is when the problem happens.....trouble is this may be VERY hard to see as it may happen real quick..... or not make much sense.

I have a 90mm STI/GTB MAF and adapter&filter etc on my car(don`t have another std one......sold my last one... need another actually), if you set the PFC to VG40 you can use this unit to test with....... would be a step in the right direction to eliminate/test the MAF as the sytoms you describe are what a dead maf does, you could borrow an ignitor etc too if you wanna swap that out and test.

*edit* ....hmnmm you couldn`t use the 90mm MAF without installing the plug for it.... you could try the std leggy one on my NZ car,, should be getting licensed today I hope.....dang what a FN that car has been, had to fit side intrustion bars and all sort of shite... I`m an expert on stripping&reassembling Lib/Leg doors & pwr windows and crap now....damn thing now has 10-20+Kg of extra steel in the doors !...did 8 doors in a day and a half....engineer was impressed with my method/design and will sign off on them, better than paying them $200 a door to have it done !

OS

Thanks for the input guys.

I checked the plug gap before putting the plugs in, to get to the rear two plugs in my engine bay requires the engine to be lifted .

OS I will take a good look throught the PFC manual. Still learning about this damn thing. Glad to hear the Leggy is finally getting registered too.

I'll have another stuff around today and see what I can do.

OK, somehow I've managed to put it in limp mode, it refuses to rev over 2000rpm and it won't idle steadily.

My PFC manual is in Japanese, that's what you get for buying stuff off eBay. I have located the English manual in PDF format, will have a good read later on.

My MAF is buggered too BTW.

I`m pretty sure the PFC doesn`t really have a limp mode.......altho it will light the CEL permenatly and run like crap because of a fatal sensor failure...... You may want to do what I do in this situation, stick a factory ecu back in and make it run right before using the PFC if the problem is real serious, you get codes then and you won`t have to nut the PFC.

...all the manuals are in Jap no matter where you buy(except US I spose), and even when you get the english one its not that detailed...and probally specific for a honda or something(yanks seem to love the Hondas !!)

Get another MAF dude, may as well get a 90mm one for when you want to boost da shiz out of it...std one will flat line not much over 18psi at peak torque........ I can weld you up some SS pipe for an adapter/new intake section to suit. I`ll ask if Terry wants to sell his V3 STI one I have !...basstards got a Motec after all !....and some JUN cams just come if from Jap land !!

OS

LOL. 12 seconds not quick enough for Terry?

I've already fitted the factory computer, and it's doing the same thing. I figured I'd keep the factory one in there until this problem is sorted, that way if I put an ECU at risk it's not my expensive one.

You are right, the only manual I can find for the PFC is for a US market Civic, and its detail is sparse to say the least. Written for the kind of people who drive Civics.

The CEL wasn't on at all, although this could be my dodgy wiring. The CEL is on with the factory ECU though....

I might give your stock MAF a try for now, I've also got my EJ16 one back at my parents house, not sure if its different. I'll go for a big MAF once I've got it all working properly and I decide to go for more power.

Thanks heaps for your help Justin.