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Good idle, backfire/stumble under load (vid inside)

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Old 10-30-10, 07:25 PM
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Good idle, backfire/stumble under load (vid inside)

I don't know what the hell is going on here


Idles fine..blip the gas and it'll usually stall
Put on load on it in neutral, sometimes it'll rev, other times it'll backfire and stumble

Driving it is impossible

When it does stall, its usually hard to restart

New fuel pump, plugs, injectors, PFC is new, pulls 12-13inHg at idle, no emissions and running on a PFC


video:
http://www.youtube.com/watch?v=Li7d7a_MBvs
Old 10-30-10, 07:56 PM
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looks like u have 0 oil preassure idk if thats it but. temp is a little high but its a s5 so that could mean nothing. i assume u have an after market boost gauge cause its steady in the middle. u swap out the computer?
Old 10-30-10, 08:13 PM
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25-30psi oil pressure at idle, climbs to 75+ under load...

engine temp was 80 degrees (C, not F)....so under 180 degrees F


12-13"Hg at idle
Old 10-30-10, 09:28 PM
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Check the fuel filter. My old S5 did that from time to time. Ended up as a clogged fuel filter.

Also, still have cats? Could be clogged.
Old 10-31-10, 12:06 PM
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filter is fine, no cat



this car is getting parted out soon, I have never been so aggravated in my life...sick of dumping money and time into it just to have the thing **** me over every time I want to drive it...5k on the odometer since 2006, I'm done
Old 10-31-10, 12:34 PM
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pfc is mapped correctly?
Old 10-31-10, 01:38 PM
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yup, written specifically for this car by Chris at Banzai...more money wasted
Old 10-31-10, 02:24 PM
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Honestly, you walked into the money pit. 90% of RX-7's are money pits. If you don't want to spend a lot of time and money, you are basically in the wrong universe.
Old 10-31-10, 03:09 PM
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Originally Posted by hosmer
yup, written specifically for this car by Chris at Banzai...more money wasted
Why would that be money wasted? The base maps we provide are only to get the car started and running. You have to tune the PFC for each vehicle.

Just because we supplied you with a map does not mean that it is going to fix everything else wrong with your car.

I would say you need to start by checking your TPS voltages on the commander and make sure there are not any issues with the sensor.
Old 10-31-10, 04:16 PM
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hey chris


But if it is what chris is saying, we can only add this: It is a base map. You need to get it well tuned on the dyno.

If i see your vid i would guess it has not been tuned yet.

I also bought a pfc and other stuff at banzai lately, chris also made me a base map for stock and 800cc injectors, but he can't guess how the whole map should be from a distance.

I wonder how mine will run and if i can get it to the uk to get remapped


kevin
Old 10-31-10, 05:56 PM
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A bad leading coil gave me similar symptoms to what you're having. One night everything was fine. I started the next morning 8 hours later and the car had trouble starting. Idled steady, but vacuum was poor, and was reluctant to rev and sometimes wanted to die out. So... spend another $25 in the for sale section and see if you can get a "new" leading coil to test.
Old 10-31-10, 07:30 PM
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whats going on?

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um... you need to have it tuned. he gave you a base map. there is now way he can give you a map, and all of a sudden you have a powerhouse with out actually tuning it.

plus, chris said it was a basemap, so... get it tuned.
Old 10-31-10, 08:08 PM
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+1 on the tps. What is the PFC showing the voltage is at idle, and at WOT? Have you set it with a multimeter, or using the test light method (I had better luck with this method)? It should be done, then your idle will probably need to be adjusted via the idle stop screw.

Are you sure you don't have a vacuum leak? My car has 18psi of vacuum at idle.
Old 10-31-10, 09:27 PM
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whats going on?

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Originally Posted by LunchboxCritter
+1 on the tps. What is the PFC showing the voltage is at idle, and at WOT? Have you set it with a multimeter, or using the test light method (I had better luck with this method)? It should be done, then your idle will probably need to be adjusted via the idle stop screw.

Are you sure you don't have a vacuum leak? My car has 18psi of vacuum at idle.

18 psi? mine idles with 8 psi.
Old 10-31-10, 10:20 PM
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Originally Posted by SirCygnus
18 psi? mine idles with 8 psi.
my friends fc that i work on is 17 vacuum
Old 11-01-10, 05:43 AM
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just to set things straight...

After the PFC was installed 6 months ago, it had a whacked out map in it. The car was at my tuners (DSG in Mass, VERY well known). They called Chris, sent him the map, he said WTF is this, told them he could write me a new one for a few $$ (which I had NO PROBLEM with) but I had to call him. So I did, gave him a few specs on the car, paypal'd a couple bucks, new map was written, installed, and slightly tinkered with at DSG. It did not get tuned that day due to another issue which I straightened out but the car ran 110% for months after the map was loaded. It was running in the high 80's (Celsius), due to the OEM radiator so I bought a Koyo N-Flo, installed it, and have never been able to drive the car since.

I said it was wasted money because I should have left the car alone a long time ago. I knew in the back of my head it was going to be a trouble ridden car but ignored my gut.

TPS ohms out 100% in spec both narrow and wide ranges with a nice steady sweep
Leading coil ohm'd out in spec but I changed it anyway, no difference
Plugs have been changed, no difference

Last edited by hosmer; 11-01-10 at 05:46 AM.
Old 11-01-10, 06:31 AM
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OK, so then spending money on a map was not wasted. You are saying the car ran perfect with our base map until now.

Once the PFC is installed the TPS is no longer about ohms, it is all voltage. You check the TPS on the sensor screen of the commander. The TPS is VTA1 & VTA2. The same screen will help you to identify what else could be wrong with your car as it contains all the data for all the sensors and solenoids.

Verify that your fuel pump has not develpoed an issue, check your fuel pressure. Do you have the pump wired to 12V constant?
Old 11-01-10, 09:16 AM
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Yes, the car ran 100% with the map

I checked fuel pressure and even swapped the pump out for a spare (new) walbro I had...and yes it's rewired for a constant 12v

I'll double check the sensor screen after work, I know the VMOP(?) reads 0.00 but when I looked it up it was for something I no longer have, cant remember off the top of my head and I'm typing this from my phone.

The "FUEL" sensor reads 4.98, I remember this because it's always highlighted (like the VMOP), but I swear it's always read that...maybe I've gone mad with rage but I'm pretty sure that's been the voltage since it's been installed
Old 11-01-10, 09:44 AM
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Your blue led digital meter (in the video showing 14.8) is that Battery Voltage or A/F?

What else did you change when you changed radiators? Did you install an electric cooling fan also, were you already using one, or were/are you using the oem fan and shroud?

I'm just thinking that maybe if you installed an electric fan at the same time. Is it possible that where you wired it to the thermosensor (however you're triggering it high speed) it's changed the input to the PFC and in turn is effecting how it's running.

It just seems strange that your problems started after upgrading the radiator. I would question every step that was performed during the mod like they are the prime suspects in the disorder.
Old 11-01-10, 10:28 AM
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VMOP is the Oil metering pump, if you have it blocked off it will be highlighted, FUEL is the fuel temp sensor, which your car does not have. Neither of these will cause the car to run poorly.

You are premixing 2 cycle in your fuel tank?

Last edited by Banzai-Racing; 11-01-10 at 10:32 AM.
Old 11-01-10, 11:22 AM
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I'm running premix (always have a case from Petit in the trunk, never trusted the OMP's)..also, have an s4 block with s5 manifolds/sensors so I can't plug it in anyway




Well I can, but I don't like the idea of it zip-tied to the unibody banging around up there...

It's a wideband gauge, electric fan has been on the car for years
Old 11-01-10, 12:21 PM
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14.8 idle ratio? Is that thing calibrated right?
Old 11-01-10, 01:29 PM
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no one hase even suggested looking at your coolant temps eh? check that. maybe the coolant temp sensor is fouled?
Old 11-01-10, 05:36 PM
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Coolant temp is fine...high 70's on the PFC (Celsius)

TPS 0%
VTA1 - 0.78
VTA2 - 1.00

100%
VTA1 - 3.83
VTA2 - 4.67

The following sensors are highlighted while the car is idling:
NTR
ELD
HWL
FPD
APR
CCN


trying to find out what they all are, but I can't seem to find a "list" so-to-speak

also I noticed my o2 sensor is reading 0.7 at idle which seems high?

Last edited by hosmer; 11-01-10 at 06:03 PM.
Old 11-01-10, 05:57 PM
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neutral switch ,
electric load switch,
exhaust temp warning ,
fuel pump operation,
air pump relay,
charge control.

check for boost leaks/ vaccum lines.. or boost controller leak


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