Ok for the last month I've been trying to figure this out. every now and then when I step on the gas and get into boost the car will stop accelerating and jerk a few times then take off, I've replaced TPS, rewired the fuel pump, checked for vaccum leaks. this can happen at 3psi, or full boost, boost gaugue doesn't budge. it will stop climbing, but doesn't drop off, feels like it may not be sparking or may be getting too much fuel. I don't think its leaning out. it seems to happen more when its raining. but I've had it happen when the weather was nice. sometimes it happens once a day somtimes multiple times in a row. happens in any gear. also makes a horable sound, not a knock or a ping, more like a wrong answer buzzer, errrrrrrrnt maybe its retarding too far? or not sparking at all and ingniting in the manifold. what should I look at?

 

Coil perhaps gone bad? The leading one would produce the worst effect as it controls both rotors and the majority of the ignition process.

 

Give a good look at your coils and plug wires. The fact that you mention it happens more in the rain leads me to believe that you have a ground short. The rain and moister makes it easier for the ground arc to occur.

Look for any cracks or "burnt" looking spots. D/C power can make some pretty big jumps to arc to ground.

 

Had the exact same thing happen to my Turbo Fb with a S-5 swap, ending up being a bad afm, put in a spare I had, and back to business.

 

Coil possably, AFM may be a good bet, it came out of nowhere, it is always as it starts too boost, then goes away. somtimes stays longer than longer than others. Plugs and wires are fairly new, May replace plugs anyway, I want to run trailing plugs all around for the summer anyway.

Anyone know if s4 NA vs T2 MAF's are interchangable? Or what needs to change to run a S5 if possable?

 

You cannot swap a N/A AFM for a T2 AFM . You can't swap a s5 AFM into a s4 system.

 

You can swap na and t2 afm, you have to have at a mininum a fuel computer to compensate for the swing into boost. BE CAREFUL

 

I was under the impression that the output values were totally different between the two AFM's. However I haven't actually tested the two side by side. I suppose a fuel computer might be able to compensate for the difference, but that seems like a pretty dirty solution.

 

I think I found a s4 T2 one. No fuel computer, but getting rtek soon. just got sent out. car had been running fine, then one day it caught fire by a cigarette cherry (passenger) burnt right behind the seat at the seatbelt on the passenger side. I don't think any important wires or any thing is there. this started the same night. started about an hour or so later.

more info is the resistances on my FCD, was out of spec by quite a bit, thats why I'm getting rtek and to run 720cc's

 

I hear ya, but I have actually done it with a AFC running about 10 psi, just fattened everything up and it was fine, until I went big time and rocked the pfc. It took for ever to find out it was a bad afm, but it was bad...real bad.

 

Had no idea it was correctable with a AFC. Badass.

 

mine does the same thing ,,,,, spits and stumbles ............... then ripps your head off . smooth and clean .............. booost ya .. 10 mm

 

mines getting really bad! happens all the time, I'm scared to boost.

 

mines not that bad .....timing mabey