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okay, i posted this a few weeks ago, and JR sent me a new FMU, but the problem is still there, and i think its linked to my TPS mod, which was done around 6 months ago or so..
This problem has been going on for about 2months now.
Okay, at idle, at a light or stop sign when i start to pull off.. right at 0 vac, before the transition or at the transition to boost, the car surges, a/f bounces all over the places, sometime going lean, sounds like the engine needs fuel to me,, but then at full boost its fine. at high gear low rpm pulls at 0 vac, it does this too, anyone know what it could be? thinking about taking out the TPS mod, and see what it does then, i really am unsure of the problems..
My mods are
jrsc
intake
apexi vafc
jr btc
tps mod
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I've heard of some folks with Si's having problems with the TPS mod. I think it's posible that some ECUs don't like the fact that the circuit is not debounced. I've got a scope now, so I'll be working on this the next weekend or so. Stay tuned, I'll update the original TPS mod post when I have an update.
Let me know if removing the TPS mod eliminates the problem you're experiencing.
Thanks.
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I will let you know, i'm taking it off today.
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ok i took off the TPS mod, but the problem still exists,
can anyone help me figure out what could be causing this.
The FMU is brand new. The TPS is gone,
Ok, let me clarify.
On a warmed up engine, after being driven awhile, the car jerks and stutters, and the a/f gauge bounce all over the place at 0 vac, at low rpm high gears, and at stop lights as i pull off and get into the 0 vac.
if i'm driving and go into it it don't do it except at the times stated above. I'm sure someone with a charger has had this problem. Basically if feels like the car is going to stall if i don't let off the gas and let the rpms rise a little bit, because at a green light or stop sign the rpms are low and i have to real careful not to let the boost gauge hit 0vac until my rpms rise alitte.
Anyone have any ideas?
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I've experienced the exact thing you speak of. Although, I haven't experienced it during high gear low rpm pulls...I try to avoid that. Your problem could be a sticking FMU. Are you using a cartech or the JR one? I have the TPS mod and am using a cartech. My observations: At 0" my a/f gauge bounces around in the stoich range and my fuel pressure starts rising somewhere between 5"-10". When I get this surging, my fuel pressure will only go down to 55 psi when I let off the gas instead of 50 psi like it should. Usually, my a/f gauge will show rich right at the surge. I think my FMU is sticking in a position causing a rich situation. Your FMU may be sticking in a position causing a lean situation. Also, one other thing you might want to check is the bypass valve on the SC. Some people have reported surging/hesitation at 0" due to a sticking bypass valve. With the car off, move that spring loaded black thing by hand and see if it travels freely with no sticky spots. Good luck.
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Fred G.
'97 Civic EX supercharged http://www.geocities.com/motorcity/track/4059
Beech 1900D driver...2,558 shp, 10,000+ ft./lbs. tq., top speed 331 mph http://www.hostboard.com/ubb/smile.gif
[This message has been edited by waveoff (edited June 27, 2001).]
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IMO: You should shot that JR FMU to the moon and get a Cartech.
I have had your problem in my JR FMU days, but only a little bit in 5th gear above 5000rpm. It thought, that something is not 100% exact tuned with the fuel press or fuel quantity. This problem completly gone after I installed me an Cartech FMU.
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Supercharged ITR?98 @ 5.5psi
BTC unit, Apexi VAFC, K&N short ram intake, skunk2 cam gears, Kamikaze 2.5", ceramic header, Thermal 3" exhaust, RC 310 injectors, Cartech FMU, AEM FPR
http://www.geocities.com/superchargedtyper
http://albums.photopoint.com/j/Album...622&a=12515817
http://www.geocities.com/autitr/myin...l?991952862150
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yeah i understand that, but this JR unit is only 2 or 3 days old, so it can't be that, unless i have two bad ones, which i could see be a problem but i doubt it..
TOO, said my fuel pressure is probably too low,, 58PSI static?
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It could be my pump, but when i'm punch the throttle its fine, its only during starts i.e red to green light, once the cars is warm, and low rpm 0-boost transition. But you have a possible solution...
But what I'll guess i'll have to do is buy a new fuel pump,, getting a cartech fmu, and the jr map converter is on its way.. So if that doesn't fix it, then i'm cluess... This weekend i'll be changing out fuel filter, and plugs see if that helps, because i think my last filter change was at 15K, and i have 23 now, but that should be still good, but i'll go ahead and change plugs and filter, and get me a new fuel pump,, Any recommendations. I have the base model JR one, i think its the GSS317
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Bet you $10 it's your fuel pump and it gets worse very soon
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AAAAWWWWWWW YYYYYEEEAAAHHH!!!
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Get a higher output..GSS 342..You do not have enough fuel delivery with that 317.
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loos the TPS mod and get a JR MAO controller...you won't be sorry. It fixes the tip in and the driveability issues associated wit it. It also gets rid of the presure switch and relay supplied with the kit.
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Sounds to me like a dirty or bad map sensor. does your car jerk your head forward when you shifting at full boost, and a/f jumps around then back to normal when car starts to pull?
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A vacuum or manifold leak can cause erratic running. I have a cracked intake manifold and am having similar effects. At idle, its OK. Under mild load (no boost) it runs a little rough. Under boost, it runs fine.
The crack is sealed as best I can do until I repair it. I beleive there's only a small amount of air leaking in, but that it's enough to drive my ECU crazy in "closed loop".
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I agree with NDM as this was occuring on a friend's car and yes it was the fuel pump.. it jerks you all around inside the car.. I know this is your problem.. his did the saaame thing.
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Take a few minutes and check your TPS. My car has the same symptoms as your, and I think I've narrowed it down to a bad TPS, or perhaps a faulty ground wire for the TPS. Check for 5v at the plug and check for continuity of all 3 wires, especially the ground wire.
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well if a light turns green and i go at normal throttle, it stutters and jerks and acts like it wants to die, the a/f gauge goes nutz, but if i baby it and keep it out of 0 vac its fine, if i punch the throttle, and the rpms are high enough, its fine. Basically it only does it at 0 vac, when the car is warm when i'm at a high gear low rpm pull or at a dead stop and begin to start driving... If i speed shift from lets say 2nd to 3rd and so on, its fine.. Hope this clarifies it, its hard to explain in writing.. But it very annoying, and definetly not good for the car.
JR map convt on its way, i'll check the tps this weekend, i've already diconnected the Tps mod, so that may be it, but i had soldered all the wires before and after taking the TPS mod out..
[This message has been edited by 00ITR006 (edited July 18, 2001).]
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The problem is likely to be that the car is running in closed loop while under 25% throttle. When you boost at less than 25% throttle, the computer tries to lean the fuel by up to 30 %. This cycles at around 1-3 times per second. At more than 25% throttle the computer switches to open loop. We have reprogrammed the Honda ecus to switch to open loop under boost.
For more information see:
http://Hondata.com/boostjrsc.html
http://Hondata.com/tech.html
