Big Injectors = Lumpy Idling?

Could be the MAP sensor ? Check all your sensor connections and the manifold feed to the MAP .I have a couple of std 2 bar MAP sensors yours for the price of a Christmas pud
Nah ! Only joshing ........you can borrow one if it helps .

Intermittent usually means something is loose .....................

How does the twiddly pot work on the GTA? is it an offset or a mutiplier?

It's been a while but ....

Fuelling is basically a graph of fuel against air, right? This relationship is essentailly linear and can be described by the standard y = Mx + C where M is the gradient and C is where the graph crosses the Y axis.

The K-jetronic system has the facility to adjust both M and C. C is an offset screw on the intake flap (mechanical air mass meter) which adds or subtracts fuel at idle, but makes almost no difference in % terms higher up the revs. M is adjusted by playing with the primary fuel pressure.

Basically an offset shifts the entire graph slightly, a multiplier will multiply (or divide) the entire graph by the same amount.

What I'm getting at is whether different injectors can be run off the stock ECU simply by twiddling the adjustment pot. If it's a multiplier, then they can, if it's an offset, then it can only be tuned at idle.

I'm pretty sure it only works at idle .

Likewise....

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The MAP sensor doeshave a restrictor in it i think (small plastic thing that looks like a hose joint?). I'll get the IAV wiring sorted then start fiddling with the throttle etc It really does seem to run sweetly when the IAV is ok it's just tracing this fault i think (hope!)

Just been out for the day with work in the Alp and she's running brilliantly, fiddled with the boost a bit more and have found a great setting. Lot of poooowwwweeeerrrrr

Idling is still intermittent though, if i re-wire the IAV on Sunday could anyone tell me where the source of the wire is?

It all runs back to the ECU .You would need to strip the loom right back to the multiplug to replace the full wire run .I'd just have a look at the plug end and do a continuity check at the ECU plug .I'll dig out which pins they are on the ECU plug .

Thanks lee! Does your book tell you what colour they are out of the ECU as well? Is bridging a possibility? Ie could i leave the original wires in the ECU plug in place, attach new wires to them and then wire to the new plug?

Cheers

Jon

Ok so have replaced the plug, now it just idles at 2800 rpm, so beautifully i got pulled by the fuzz on the way home from the lock up! Oh and yes that is the right way round, i tried switching the wires and it just dies.

Any suggestions?

Hi Jon, how are you getting on, are you all sorted out now?

Don't know yet, been madly busy with work so car been left, will fit new IAV from Lee tomorrow and see what happens.....

..just a quick thought Jon before you condemn the IAV- the IAV probably won't move if your mech valve is holding good idle speed. You would need to swing the opening of you mech valve to force the idle up and down, and then see what the IAV position does under command of the ecu.

By the way, your shorted wiring loom could have still killed the IAV driver in the 2nd ecu without the complete melt down barbeque of your first, but hopefully that hasn't happened. I haven't checked, but I wouldn't be surprised if the phase 1 ecu doesn't have any current fold-back protection to prevent thermal overload in the event of shorts in the wiring. If it's now U/S let me know and can sort it out, otherwise a GTA with a nice plumbing stopcock with a red handle sounds great... may even be able to convince Stunned it's connected to your flux capacitor