New Engine! - Old problems :(

[LavisLane]

Hey all,

My first post in quite a while – after our first baby arrived I realised how much free time I used to have! Hunter is now 1 ½ yrs old and I’m finally catching my breath…

Recent updates include an engine overhaul with Peter Davis – new short motor, reconditioned heads, new water pump, cleaned radiator and all the usuals that go with an engine rebuild.

So, now after a large amount of ongoing refinement, I’m running out of things to fix and am struggling with a bugger of an issue that I would really like some help with;

I’ve always had a slight miss in idle and nothing seems to cure it. See the list below. Now, after an engine overhaul, there’s a serious power issue that’s difficult to explain;

• Stalling in low revs, hot or cold only about 40% of the time. Seems to happen a lot when leaving the office carpark/coles car park – both have a similar incline to get out.
• Low power in low revs while driving, putting the foot down from 45- 70 kph feels like it’s dropping cylinders, sounding a little rough but not too obvious.
• Slightly missing in idle

Checks include
• No fault codes appearing after check up with Graeme Cooper
• Cats are ok after the old engine was blowing smoke
• MAF sensor cleaned
• Injectors professionally tested and serviced
• Graeme Cooper has tuned in the new engine with my Haltech
• New fuel pump 9mths ago

To me, this feels like a fuel issue, likely connected with a faulty sensor or ECU gremlin?! Does the sloping car park exit have something to with it; when on an angle something disconnects?

I’ve just bought a Kiwi PLX wireless device that integrates with iPhone OBDII software to start tracking the problem a little more, will update as this evolves. DevToaster - Rev - iPhone app development, Great iPhone apps, and more (http://www.devtoaster.com/products/rev/)

Any ideas or similar experiences welcomed!

Thanks guys,

Dave

[PhilipA]

This is only speculation as I have no experience with the Motronic in a 38A only an M3.

Sometimes if the MAF is faulty it will not throw a code, but a new MAF will fix it.
Maybe the TPS is faulty. TPS faults usually show as a miss on "tip in" at low accelerator values , as this is the most used and worn point.
Regards Philip A

[mike 90 RR]

Following on PhilipA's line of thought .... Have a read ...

http://www.aulro.com/afvb/discovery-2/140153-d2-v8-will-not-rev-idle.html

Just borrow a known good 1 ....

Also ... are the spark leads new? ... Regardless .... In the middle of the night and in complete darkness, Pop open the bonnet, Start the motor and look for electrical arching (fireworks)



Old motors have a way of hiding problems wih electrics, and as soon as you install a fresh motor, It brings to light all the dead electrics that the old motor has been hiding

Cheers
Mike

[33chinacars]

I had the same thought as Mike. Possibly leads or even coil pack. Worth checking

Gary