FD, Misfire and loss of power on anything more than part throttle

[IanFiTheDwarf1]

file:///C:%5CDOCUME%7E1%5CADMINI%7E1.002%5CLOCALS%7E1%5CTemp%5Cmsohtml1%5C01%5Cclip_filelist.xml">  Hi gents,
 
  Wondering if anyone can help me here with my rex?
 
  It’s a 92 FD standard apart from HKS Mushroom filters and a SS exhaust and had been sitting in a garage for about three years unregistered so its now mine but has a bit of a problem. It starts without any problem ticks over fine and will accelerate right up threw the revs fine on part throttle but if I open the throttle it misfires badly and losses all power.
 
  I have stuck a boost gauge on and can get full boost if the throttle is feathered right threw the rev range, I have also checked that the double throttle operates, that the throttle position sensor is ok and there are no leaks to the boost sensor although I couldn’t get a connection to it to check for the correct voltage.
 
  There are no fault codes present
 
  Any help much appreciated,
 
  Cheers
  Ian.

[Jovic82]

coil pack maybe or maybe fueling problem (fuel Filter, Fuel Pump) if it has been sitting for a long time the filter might be shagged!

[DC-TYPER]

yeh man, full of poo

[IanFiTheDwarf1]

file:///C:%5CDOCUME%7E1%5CADMINI%7E1.002%5CLOCALS%7E1%5CTemp%5Cmsohtml1%5C01%5Cclip_filelist.xml">  Cheers guys, sorry for not getting back but I’ve just became a dad yesterday so the cars not been pushed way down my to do list at the moment.
 
  it dose seem very regular to be a partial blockage but I might as well change the filter and flush out the pipes anyway, that is when I get a chance.
 
  You got me thinking along the fuel starvation lines and I’m thinking fuel pump relay? I might get five minuets to check some time.

[od404]

I\'d check your plugs too.  Worn, damaged or plain wrong plugs will give similar symptoms.  I had the same issue on mine, new set of quality plugs and it was like it was another car!

[IanFiTheDwarf1]

file:///C:%5CDOCUME%7E1%5CADMINI%7E1.002%5CLOCALS%7E1%5CTemp%5Cmsohtml1%5C01%5Cclip_filelist.xml">  Changed the fuel filter (well bypassed it and fitted a cheap one under the bonnet) and fitted new plugs but the problem is still there.
  [FONT="]It dose seem to be ok or at least a lot better when the car is cold but once hot any more than about 1/4 throttle or half boost and there is a sudden and very severe misfire. Could there be something causing the ECU to cut fuel?[/FONT]

[ianelvar]

Check the throttle position sensor is working right. http://www.fd3s.net/tps_adjustment.html
The ECU does strange stuff if it thinks the throttle is shut when it\'s actually not.

[IanFiTheDwarf1]

file:///C:%5CDOCUME%7E1%5CADMINI%7E1.002%5CLOCALS%7E1%5CTemp%5Cmsohtml1%5C01%5Cclip_filelist.xml">  Had another check of the TPS and all well there, even swapped it for a spare just in case and no change, traced the wiring back threw the loom to the ECU looking for a bad connection only to find the ECU wasn’t screwed to the bracket so could be a bad earth and there is about three or four scotch lock type things and a couple of crossed links in the wiring which makes me think there has been another ECU in there at some time.
 
  I didn’t get time to try screwing the ECU back in place yet but the ecu part number also seems a bit strange N3Z7 18 881. I have a spare which is N3A7 18 881C which I believe is quite common but have never seen a N3Z7 before. Can anyone tell me anything about this ECU and if I can exchange it for my N3A7?

[Initial-D]

Check your plugs connecting to the eccenric main shaft, mine had a repair and picked up noise at higher RPM which made mine cutout.

[mx1311]

map sensor!

[IanFiTheDwarf1]

file:///C:%5CDOCUME%7E1%5CADMINI%7E1.002%5CLOCALS%7E1%5CTemp%5Cmsohtml1%5C01%5Cclip_filelist.xml">  Changed the MAP sensor for a known good one and no change, bolted the ECU to the bracket and for a little while it seemed ok then went back to misfiring!
 
  Had a look at the wiring to the ECU and there seems to have been a few mods done, there is a green wire disconnected from the top connector and taped up, a link between two pins on the top connector, a link between the top and bottom connectors and a red wire connected to the green wire on the bottom connector.
 
  The top bracket also has the corner cut off as if another ECU has been fitted at some time and removed
 
  I think I need to return the wiring back to standard but mot sure where to start.
 

[ashc]

is it overboosting, maybe there was a pfc in it and the previous owner sold it, & swapped back the stock ecu, and left the exhaust/air filter mods = possible overboost = fuel starvation = det = bad ?!!

[IanFiTheDwarf1]

file:///C:%5CDOCUME%7E1%5CADMINI%7E1.002%5CLOCALS%7E1%5CTemp%5Cmsohtml1%5C01%5Cclip_filelist.xml">  The boost gauge I have been using to test it is a gussons diagnostic gauge. It appears to be boosting correctly but I am unsure of the accuracy of the gauge.
 
  If there has been a PFC or similar ECU fitted could something have been modified during fitting to cause over boost?
 
  What else could cause over boost?

[gear1275]

i had this on mine, changed plugs and coil packs and map sensor and it was still the same, i cured it in the end by, replacing the 4mm vacuum hose from the plenum to the map sensor, cleaning all earth straps and re-setting the stock ecu that i was running at the time, that sorted it and i had no issues after that! unfortunately for you, i did all three things at the same time so im not sure exactly cured it! but it was flawless after that
james

[yappa]

ive got exacly the same problem an im really scratching my head . did u clean all the earthpoints on the engine up and how do u resest the standard ecu and do you need to get it re programmed or anythink?