Very curious.

I'm having nearly identical problems with my car, and I replaced an OMP line. HAHA. go figure.

Same thing, the thing falls on it's face at anything over 10-20% throttle. I can get it to rev up to say 3-4-5 k RPM and it'll run, but NO acceleration. I have a PFC, and have tried putting a stock ECU back in and expereince the same problems. I"m suspect of the wiring harness, though I did have the coils out since it was a bit easier for me to get to things.

My car will actually run better with the map sensor disconnected..... I can rev a bit more quickly without it... though obivously the car isn't as smooth.

 

thats yours does it WITH the pfc, really points to the wiring...

 

Yeah, I tend to agree. I tried putting a stock ECU back in the car.... it ran a *little* better, but still had problems. I have tried swapping TPS, airtemp, and map sensors as well with known good units just to check.

I'm going back under the manifold when I get a change to check it out.

 

lol. one time a buddy was helping me with some things andi told him to connect the map sensor to the uim real quick for me and he picked up a check valve instead of the normal little filter thingy and omg that sucked...he atleast had it facing into the manifold so it would idle but as soon as it wanted to boost the checkvalve would close and nothing..lol.

 

I am now thinking my problem might have something to do with the MAP sensor

 

lol. it would make sense..as if everything else is fine then that's the only thing i can think of with those symptoms. and it's common. and well fuel supply getting cut off right at 0psi when theres no limp mode will probably mean the map sensor isnt seeing the boost...so either your sensor is busted, or the vac line its connected with is clogged(which would make it run crappy even at idle) it's not plugged in(but you said it was) or theres not a vac line attached.(same problem as a clogged/blocked line) tho i dont want to accuse of something so simple in danger of insulting your intelligence...it can always happen

 

Might not be a bad idea to borrow one from someone local and try it.

 

I"m curious to know if you have tried just disconnecting the MAP, since our symptoms appear very simliar with it connected.

When I did try driving my car on the stock ECU, as I said it did run better, but not great. I do have 1300 secodaries though, so obviously, when the secondaries are comming on line the car would be flooding itself. I am partially suspicious that my PFC map managed to get corrupted some how as well.

It'll probalby be the weekend before I bother to look at it again though.

 

yes i am going to test the map sensor and possibly swap it ot with a known good one... i'm thinking maybe my MAP sensor isnt reading correctly in boost (or not reading at all in boost) so we'll see what happens.

 

i hope that goes well i hope you come to a conclusion soon..it's so frustrating to do something and then have there be some stupid problem that's keeping you from driving the car. I think mine was that after i did my non-seq mod, the grommet that seats in the injector rail for the front secondary injector that the injector sits on and seals the injector once it tightens down was gone...i was leaking vac and boost pas the injector...so i took a piece of 3/5 inch coolant hose..cut a piece out of it so i could lessen the circumference of it (diagonal slit to make sure it sealed) put it in there and voila, no more leaks

btw if anyone has one of these injector grommets let me know i might like to swap in a real one when the new motor is in lol

 

bumping this up incase anyone has any other ideas. i'll report back friday night after i swap the MAP's

 

well, i'm driving the car, as it runs perfectly fine in vacuum. it only hesitates when i stab the throttle or try to get into boost (totally bogs in boost)


driving it in vacuum is really like driving a haltech car with the throttle pumps disabled...

 

Did you replace the plugs/wires?

Dave

 

i replaced the plugs and the wires looked fine on both ends. i didnt measure the resistance or anything though

 

IIRC, my bad wire did not look bad, but was discontinuous (high resistance) internally.

Dave

 

would this really come into affect right at 0psi? i mean an ignition problem is more rpm based...if you're ignition is screwed its gonna be noticable anytime, and maybe slightly more under boost, but it wont just come on like a brick wall. I'm still definately thinking map sensor for now. it's no coincidence that at the exact moment that the ecu goes from reading it's last bit of vac to the point it should be reading boost (with a WOT or close to it, the motor wants to suck in everything it can and it tries to, only for the injectors dont get their signal from the map sensor to dump the extra fuel and then smack on it's face it lands..makes sense to me atlast.

 

either that or you have a ****** grapefruit stuck in your exhaust lol.

 

My plug-wire problem was throttle-pedal position related. It revved just fine at 1/4 throttle (I did not have a boost gauge at that time). More throttle than that and it went flat. This is related to taking more voltage to jump the plug gap with a denser mixture in the combustion chamber (wider throttle/more boost).

Dave

 

yea...but i think he's saying he can even floor it at idle at it'll rev up fine till it tries to hit 0psi..as far as i've gathered..the chances that it's purely coincidence that something of that nature is occuring directly at the 0psi mark is pretty small...although possible

 

by the way dude if you want to check if your map sensor is working or not you can always take a mity vac or anything that can pressurize and hook it up to you map sensor and at idle give it a few pumps for pressure and it should stumble and die if not backfire first for running rich...or do something atleast...atleast it'll tell you if it's recognizing boost

 

I'm local to him and have a stock map sensor sitting around somewhere. I believe he is planning to try it this weekend in his car.

 

replaced map sensor, problem persisted.

replaced ECU, problem persisted.

replaced spark plugs AND spark plug wires, problem persisted.

 

well ****.

I'm out doing some of that same stuff

My buddy suggested that perhaps the air temp and fuel temp wires were crossed. I guess depending on the condition of the harness this is possible since the connectors are the same (green). Anyway, mine are correct, you might try that.


Hmmm, same problem with a different ECU.......

i'm looking at my wiring... but itdoesn't seem *that* bad.... ok well... I've seen worse on a running car.....

 

ok, I swapped the coils, and wires not much luck with the PFC.

Tried a factory ECU which started the car, but it still stumbled. I took it out and drove it around for 10 minutes anyway, really cautiously and it got better over time. Actually, got to the point that I could rev freely.... and I was able to get just over positive pressure and it still drove.

I have 1300's in the secondaries so I didn't push it at all. came back, plugged in the PFC, and it won't start.

I guess I"m going to search now... do the PFC maps get corrupted?

 

i was just out relocating my boost and water temp gauges (DIN above the stereo), washed the car and went for a drive.

anyways, i determined that if i am in 3rd or fourth gear at low throttle position and roll into boost it will boost fine and then start studdering, which leads me to believe that it is running out of fuel. What i am thinking is that the fuel pump is either A) getting very weak, or B) the ECU isnt kicking the fuel pump voltage up when it is supposed to.

does anyone have any information about the fuel pump voltage and how it is supposed to kick from 10v to 12v or whatever it is? i can't seem to locate it in the FSM