Fiat 16vt - lack of power/boost

I was pointed over this way by Jack155Q4, I know it's not in the Fiat section but this seemed more appropriate.

History - I saw this engine (a coupe 16vt) running in a scrapper, I completely rebuilt it (one cylinder had gone oval so had to get oversized pistons/rings), put it in an Alfa 145.
The other work done was lightened & balanced flywheel & internals, 3 angle valves & seats cut.

It fired up first time (woohoo) but has never wanted to idle properly and seems sluggish when the engine is accelerated.

I've gone over every air pipe to make sure there are no leaks, proved it by spraying everything with a bit of carb cleaner to see if the revs go up but they don't. The map pipe is good and the original length.

I've cleaned the ICV valve, cleaned the brass screw. It does't make any difference. I noticed by turning the nut on the ICV in a few more turns the idle has picked up slightly. There is a very slight change when the idle screw is turned, but very slight not enough to adjust it to a decent rpm.

I tried setting the idle speed using a FAQ on the Fiat forum but that didn't change it.

It is running a standard map, standard injectors, cams etc. It has standard plugs (6 series, I think bp6re or somewhere similar).

Here is the interesting thing - if I disconnect the MAP sensor connector, it makes no difference to the running.
If I disconnect the Pierburg connector it also makes no difference.

The wires for both connectors are not broken, they ohm out to the relevant pins on the ecu and the positives switch high.

What happens is when I stamp the throttle the revs increase but not exactly quickly - it doesn't miss fire and the revs do climb, just slowly. It's like it isn't boosting

Can anyone please shed any light on where to start looking at?!!

Silly questions, wich ECU and harness are you using?

Coupe ecu iaw 4wf p8. It was a 194.05 but I'm using a 194.04 standard chip in it (no CODE code).

Harness is the original for the engine from the coupe. I get no error codes logged, it thinks all is good. I can make an error code by disconnecting each sensor in turn proving it is happy with each one.

I'm thinking it's a boost issue, will investigate further tomorrow night.

I'd be lookin at all the stooooopid vacum hoses, over and over.

Also, just out of interest, what fuel pump you usin? and what fuel lines? and what fuel filter?

whats the lambda reading? could be low fuel pressure once you try to boost it, but fine on idle.

AJ, a fella called Turbo_145 has done this conversion - he harldy ever logs on but might be worth a PM... http://forum.berlinasportivo.org/member.php?u=192

'oversized pistons/rings, lightened & balanced flywheel & internals, 3 angle valves & seats cut' ...

you can not expect to have an engine like that {oversized and 3 angle cut} and work properly with the OEM chip! You need a proper - modified chip just for a start. Even the Evocars 'fastroad' chip won't work properly in such an engine. I believe there was another chip from Evocars {at least for the Integrale} that was programmed for such mods. Late B. Waterhouse used to call this chip as "three angle cut" and it was a different one.

Nick

Well tonight, it was solved - it boosted. I took off every pipe from the inlet manifold, checked and replaced. All were OK. The MAP pipe was hard to get to but easier with the rocker cover off. Checked all pipes to the Pierburg valve, reseated, checked the connector to the valve, all ok.
Fired it up and woah it idled, from cold. I let it warm up and it revved up properly this time, we went for a gentle drive - now it's boosting properly. The annoying thing is not knowing what has fixed it.

@Aforalfa {hello} - The Alfa phase 2 TS pump (4.x bar?) , 16vt standard regulator (3.4 bar?) original fuel feed line, 5/16" fuel hose for the return (yeah I know, bigger than the feed..)
The pump should produce more pressure than the reg needs, the reg then regulates the pressure between the pump & injectors, was my understanding of it.

@Jack - thanks, he went walkies from the 145 forum when I started getting technical, his english wasn't too goo unfortunately. Better than my Croatian though..

@arjunior - I will be looking at the maps shortly when I get the wide band o2 sensor. Not sure what will be needed to be adjusted yet but the stock chip should have been a good starting point I would think.

Nice one AJ - amazing what a small air leak can cause on these engines!