My va cinq turbo keeps failing its mot test. Previously on first test it was running rough found timing to be out so corrected that, another lambda,cts, new high pressure fuel pump and fpr set correctly, new map and all vac lines checked, exhaust leaks sorted, oil and filter change After this ran and drove a lot better took it back yesterday to fail again but not as badly as the first readings at fast idle were

Co 2.307 max limit.300
Hc 157 max 200 this passes fine
Lambda .953 max 1.030 min.970

Same on second idle at idle

Co 1.983 max .350

So tested suggested a new cat as maybe age, mileage, and poor running buggered it up so put new cat on. sure enough old cat seemed quite blocked up.

took it down today didn't do a full test but failed again :bang:

So any ideas. Car has done about 30 thrashed miles always done test hot not sure what's next with it any help appreciated:worship:

How are you certain that fpr is setup correctly? Your lambda reading is rich, meaning that even the corrections based on sensor readings cannot keep up, or there are no corrections. (Had the lambda show lean I'd suspect leaking exhaust). So one possibility is that the ECU has problems reading the O2 sensor (bad connection or something) and ignores the signal, or you purpously overfuel it with your FPR settings and the ECU's corrections cannot keep up. The high CO is only a result of bad fueling IMO (but I am not always right ).

Ok it's a cheap fpr and setup as good as I can get it but I'll get a new gauge been suggested to me before and then retest

I am not entirely clear on the original VA setup - does the fpr only regulate pressure for boost fueling / second injector, or for all conditions / injectors?

Va originally just use stock pump but these seem to get tired so on blu73 suggestion fitted a high pressure pump to help with hesitancy I had when coming onto boost which this has helped considerably. I fitted it on the in pipe after the tee for the second injector as per diagrams on this forum so would do stock injector only then second inj for boost would get as much as pump can deliver if I'm thinking about it correctly

This?

Ah no mines different I'll see if I can post it

It goes t-in of fpr-out of fpr-stock injector. I stuck another guage on it which read 2.5bar but that was an air guage I'll get a specific guage ordered

they are the same, pic is different but the plumbing is the same.

did you manage to sort the slight vac leak near the fuel controller thingy (the mf2 equivalent it has)?

As we discussed on facebook, it is, or should be at least, just running as a stock cento on the primary injector for the test. Try sticking a inline gauge between the fpr and the TB to see what pressure you got there - you can wind that right back to about 0.8bar in my experience and it will help on emission test a little. Where exactly did you measure 2.5bar???

Being that its just running on the primary injector it should pass easily really, the seiT got zero CO at her last test.

Ok so just changed it so that the pipe goes to the second inj and the fpr tees in then into the stock injector. Just driven it and when you come onto boost it seems a bit less hesitant than before so an improvement I'm loathed to do another lambda swap as so much is in the way unless people think it'll be worth it tempted to do another oil and filter change as my tester said that the sump could have some fuel in it adding to emissions if it's over fuelling that and setting the fpr right is the only thing that I can think of. Also to note that the idle is a little on the high side 1020 or so I've slackened the throttle cable and it didn't make any difference apart from that it's running perfect.

can't figure out how you have changed the fuel lines, to me them pictures are exactly the same

Not yet think that'll be tomorrow's job. Thought they were different might just be me getting used to the slight hesitancy when on boost then. Of boost it drives perfect. Can't be the original injector sticking, weeping something like that? I do have a spare tb that I can swap if needed

Can you not just remove/ cap the second injector to get it through MOT for now? Then play with it later? That's what I'd do to get it passed for now.

blu73 said:

can't figure out how you have changed the fuel lines, to me them pictures are exactly the same

Click to expand...

Literally swapped two outlets on the tee clutching at straws willing to try anything. It's got to be simple for it to be that far out another thought would timing a tooth out cause it worth rechecking thought I'd got it spot on but maybe worth a second look?

GrandeGuy said:

Can you not just remove/ cap the second injector to get it through MOT for now? Then play with it later? That's what I'd do to get it passed for now.

Click to expand...

The mot is done around 2800k second injector comes into play when on boost a bit further into rev range but thanks for the suggestion anyway

What would the reading be like if you unplugged the lambda sensor?
The problems we used to have with turbo cars is undersized return fuel lines, we used to chuck fuel at them but when we started having over fueling problems it was because on idle max fuel pressure couldn't return fast enough. Symptoms were increased idle, hesitant on lower throttle and over fueling on run on, some beautiful bangs but not great fro running

Not sure tbh see this setup past the mot test back in sept 12 and all previous mots before that so something's gone wrong in that time half tempted to get my own gas analyser so I can have a fiddle and see what affects it

i have one Its not been used for fair old while and probably isn't perfectly accurate but it should show things going up and down.

Well my last idea is what's the oil level been like? Because off boost the compressor side of the turbo becomes a vacuum and if the shaft seal is worn oil pressure combined with intake vacuum can draw oil into the engine. . . Other than that breathers or blow by maybe, because rich running doesn't have to mean fueling

Id sort of ruled out oil burning as the hc were low. It's bit hard to judge tbh as it's only
Done few miles and there's a small leak I don't think it's using oil as haven't had to top it up at all.

Today I've got the car hot then put an engine flush in it got hot again dumped oil and filter. Also sorted the vac leak at the mf2 thanks to blu73 suggestion of chemical metal now much better. Also dropped the fpr down as low as it'll go so that should help enormously with emissions. Now got a nail in one of my uniroyals thankfully looks repairable.