exhaust banging under car

Hi have a car with a heavily modified abf engine. It's been polished and ported, re mapped with high lift cams and a k&n air system.

If while driving I'm just feathering the throttle the exhaust bangs the underside of the car and I can feel it at my feet while the car kangaroos.  If I give it a little push on the throttle it goes away. It's always been like this since iv had it so just put it down to the cams and other engine mods but recently seems to be doing it more and starting it is taking a little longer to get it going and hold revs. What's your thoughts guys rubjonny ?

Adjust it so it doesn't bang! Its probably been poorly fitted at some point, if left to hang on its own will droop then bang on something, needs to be lifted up then clamps tightened.

So it could be just that it all needs nipping up? What about the stalling when starring? 

How was it remapped?

Its most likely the downpipe on the arb

paul_c said

How was it remapped?

To be honest I don't fully know as was done before I got it but all aimed at the top end.

what exhaust setup is it, most are designed for a KR lump so they dont fit well on an abf at all. as said get under and see whats occurring

as for running issues what engine managment are you using? the abf ecu isnt a fan of lumpy cams it messes up the vacuum signal to the MAP

Righto will get it on a ramp and have a good look!!!!

Don't know if this helps but have a look and see what you think. This a list from last owner.

ABF Engine 190bhp.
Fully rebuilt top end and bottom end. Lightened and balanced crank. rods. pistons. flywheel etc. upgraded valve springs. black diamond uprated clutch and bearing. . Newman high lift camshafts & adjustable vernier pulley. remapped. all set up on the dyno by TSR Performance in Somerset. K&N 57i kit. . full straight through Milltek stainless exhaust system. gas flowed cylinder head. ported and polished inlet manifold and throttle body.

Sounds like it needs the remap looking at again for cold start/warm start/warm up phase.

The other thing it could be is a loss of compression, that will make starting more troublesome.

Thanks paul

what engine management has it got? as i say lumpy cams can throw off the abf map sensor

rubjonny said

what engine management has it got? as i say lumpy cams can throw off the abf map sensor

I really don't know. If I take a picture would that help?

After getting it on the ramp found the centre rubber was broken so that's now sorted. As for the stalling cos it sometimes does it while driving if I take it out of gear, could it just need a new fuel filter?????

yeah if you can find ecu and piccy it that may help?

not sure if a filter would help, but it certainly wouldnty hurt

thats abf i see there are some bare wires there, looks to be the ignition live for ecu? if so and its shorted it may have popped a fuse. the isv is usually on the same fuse so this could explain the stalling

Thanks for that. Will tidy up the wires and check my fuses. By any chance you dont know what number fuse it is do you? Thanks pal

it depends on how the loom was made, but 17 and 18 a good start

No blown fuses