Gamezilla

My car has been going nuts on me recently and Im starting to narrow down my search. Here's what it does -

Bad hesitation at 4k rpms. Car always feels like it has a load on it, so I have to give it more gas than Im used to. Wont boost more than 5psi. When I try and boost/rev past 4k rpms it makes a lot of quick pops out the exhaust. Not loud backfire ones; more the kind you get when you run rich as hell. In neutral the car can build up boost. Problem is its a 5spd.

I changed the spark plugs and that seemed to help some. It didnt solve the problem. I have wires in the mail. I doubt thats gonna fix it though. Since the car can build boost at idle and it doesnt want to go over 4krpms unless i floor it, Im thinkin its something related to the timing. I know its spark related. My best guess is its the crank angle sensor. I checked mine and both look to be in good shape and the metal tab that they read seems to be in good shape, but Im not sure if internally they're blown. I cant test and make sure its not my ecu since I have PFC. How would I determine if the problem was from the CAS?

DjRannyKan

does it build full boost at n ???

Gamezilla

Only builds 5psi. But it builds the 5psi at about 4k (the same time I'd see that if I was driving). Boost gauge shows me building boost and BOV hisses. It also pops out the exhaust like when I drive it.

Basically, neutral just act like any other gear when i give it gas, I just dont move anywhere like I would in any other gear.

DjRannyKan

i thought in n it would only buil like 2 psi or something?? 5 seems a bit high to me. Also when was the last time the fuel system has been given a tune up??

Gamezilla

It shouldnt build any. I know for a fact it never did before.

If you've ever heard of two stepping (I think thats what its called) it pretty much changes the timing drasticly and dumps tons of fuel into the engine to allow the car to build boost in neutral by putting an artificial load on it (due to the timing being so crazy). My car suddenly thinks it can do this.

DjRannyKan

u said your running a pfc?? base maps?? tuned?? do any modifications since the tune??

Gamezilla

Its tuned. Car just randomly started doing this one day. Totaly out of nowhere. I had someone suggest I was in limp mode, but I dont see how.

DjRannyKan

u still have the stock ecu?? if so try hooking that up.

Gamezilla

Dont have the stock ecu. There is no point. Car is non-sequential. Stock ECU would just make it go more nuts.

DjRannyKan

well im just throwing ideas out, do u have a ohm meter?? are u getting spark at all plugs?? coils good?? sorry if these seem dumb.

Gamezilla

I have a voltometer, but I dont know what resistance I should be reading from the CAS. Spark is good. Plugs are new. New wires are in the mail, although I know this wont solve it. Bad wires wouldnt cause me to boost in N. Thats timing related. Only thing that controls timing is the CAS and ECU. If I can eliminate the CAS then that leaves me with just the ECU to worry about.

Gamezilla

I checked the resistance on my coil packs. The leading coil pack is reading 8 ohms between the connectors. Spec is 9.6 - 16 ohms. Could a bad coil pack be the cause of these sort of problems (like making boost in neutral)?

Gamezilla

anyone wanna help me on this?

broken93

Since I'm not sure what you mean by "boost in neutral", i.e. static boost vs fluctuating boost needle, I have seen instances where a CAS that is out of phase will cause a spark to be fired when the intake tract is open igniting the charge in the intake and causing it to burn in the manifold, etc, which would certainly cause your boost gauge to jump to positive pressure a bit (you'd usually hear a thump too from the ignition). I had that problem with a piston engine once.

Just an idea.

Gamezilla

If it was the gauge showing I'm boosting I'd probably just think something was wrong with the sender unit. It boosts. BOV hiss and all. I dont think its possible for the spark to fire early enough for it to backfire up the intake. In fact, for the triangle to be in a position where an early spark might occur, its already closed up the intake ports. Its just pushing back against itself. I'm thinkin mine is firing early, but not so early that its causing the engine to stop. Just early enough to give me a rough idle.

FDeez

The Crank Angle Sensors are supposed to measure 0.95-1.25k ohms.