Badly Running Arx

[luvsno.stagea]

Hi, got 2001arx 2.5det about 2 weeks ago. pretty much off side of road. went great on short test drive. Purchased then drove 40kms before flooring it on country road. started missing badly at 100kph, v.rough idling, poor economy (6km/ltr), rang seller who denied everything. changed plugs (rooted), noticed one coil had been shorting but this may have been due plug.Now goes better but still misses at 2000rpm & rough idle. occasional surging (fuel filter?) My 1997 stag did same at 2000rpm till i changed plkug gap to 0.8mm. I'm pretty sure coils are problem but unsure as to bad idle. any advice? Car has done 145000km, No fault codes showing. Thanks. Brent

[scotty nm35]

Very unlikely to be a coil, they are fairly hardy on the VQ's. Sounds like a boost leak or dirty AFM.

[luvsno.stagea]

Hi, Thanks for info. Just found equilizer tube between upper cylinder heads broken (thought we could somtimes smell oil burning on manifold!). is this possible cause? I'm thinking you are probaly right in checking afm and/or boost leak. Thanks Brent

[scotty nm35]

It will be the passenger side rocker gasket leaking onto the turbo. Very common due to the turbo heat.

You can make a 3 inch bung with an air fitting on it, to clamp into the afm rubber pipe, pump the whole intake to 20psi using a compressor, its the easiest way to check for leaks.

[luvsno.stagea]

Hi, pretty sure oil burning is due to broken equilizer pipe. have now fixed this. Have started taking plugs out for a look. done three on passenger side (while looking at afm) they all look the same showing a light carbon coating. only been in for 1000km so somthing going on. checked resistance on coils, look ok. Will check other side tomorrow. It sounds like one or somtimes two cylinders going down to me. Brent.

[scotty nm35]

You can't check the resistance of the secondary coil to prove it's working, coils break down from leaking plasma through cracks in the epoxy. I have some spares here if you want to try swapping them around...

[luvsno.stagea]

Hi, found coil still leaking through 'shaft' even with new plugs. Suspect radio suppressor componant faulty.( it's the small white resistor looking thing in shaft to plug-(i think)). I can see it's been shorting on coil side of this componant. I've also gapped the plugs at 0.8mm (copper yittium plugs). Cars going pretty good now. Idles not perfect (650rpm) & wee bit surging which i think is boost leak/fuel filter or maybe afm. So two questions. Has anyone heard of the suppressors failing and will the shorter gap cause any problems done the line. What about fuel economy? Thanks Brent

[Daleo]

650rpm idle is actually spot on.

Fuel economy depends on your right foot, but average can be between 550-650km per tank depending on how much stop start/highway you do.