HELP!!!!!! car not running well

[dadamsv8]

Car has developed flat spot in low gears once I get the revs going seems to pull ok just does not feel as responsive

Have also lost pops and bangs from exhaust ( exhaust mod)

Did have a split in pipe on vacuum advance all changed and re-set ECU but problem still there

any guidance greatly appreciated

[Good soil (pete)]

I'm guessing you tried the obvious stuff like making sure one of the HT leads has not come loose??....this happened to me recently.

[poorpeet]

Is it better or worse, or the same, before its warmed up properly?

[dadamsv8]

I would say its the same when warmed up also fine when at higer speeds and revs just a flat spot when low down on speed and revs

[poorpeet]

OK so it's not likely to be a faulty temp sensor signal to the injection. How about the advance retard mechanism? With the engine warmed up disconnect the vac pipe that runs from the dizzy to the plenum. Blank off the hole & with the engine ticking over suck on the tube. This will alter the timing & should change the tick over speed enough to be obivous if all is well.
A timing light will be a better check if you have one. Connect it up & do the same test but look at the timing marks & observe the change. If it seems ok leave it diconnected & watching the timing marks again, rev the engine. The timing should change as the mechanical weights move.
If this all checks out. You need to look for air leaks etc, have you filled up recently? Could it be duff fuel?

[dadamsv8]

appreciate you help will try your suggestion at the weekend...if the engine speed does not change whn I suck the pipe what would that suggest is the problem?

always use optimax so assume not a fuel issue

[poorpeet]

Sucking on the pipe will act on a diagphram which is linked to the distributor & changes the timing. The weights do the same but react to engine revs rather than manifold pressure.
If nothing changes when you suck, or rev, then yes it suggest a problem. The main thing is its easy & free to check & rule out

[GreenV8S]

Since you've had an air leak you may have run out of lambda control range and raised a fault code. If you're lucky, all you need to do is reset the ECU. Also have a carefull look around the engine bay for anything that you may have disturbed while you were fixing the leak, for example if the throttle pot is duff/disconnected you will get terrible throttle response. It's also possible you still have some fault which is preventing closed loop operation, so it would be worth doing a general check of all the sensors especially the coolant temp and lambda sensors. You don't need any special tools to do this, but unless you're reasonably comfortable with electrics and simple electronics you may be better off getting an expert to look at it. It's unlikely to be difficult or expensive to fix, and could be trivial, but you could end up chasing your tail if you don't know what you're doing, you could waste time and money replacing things that don't need it, you could even end up damaging something.

[dadamsv8]

sound advise maybe I will just take it to my friendly mechanic