Hi there, I've got an AAZ conversion with the 0460494368 pump. This has got an LDA on the top linked to the inlet manifold with a rubber hose. When boost is on the extra air pressure coming through the hose depresses a diaphragm in the top of the pump, pressing down on a spring-loaded needle to increase the fuelling. That's the theory.
Van has been running very flat recently and I suspect the LDA. I have tested for boost at the pump end of the hose and there is some (without the correct meter I am unable to measure it). I need to buy one but for now assume the turbo is doing its job.
Question is: how to I test the LDA is responding as it should? I tried blowing into the LDA via a tube while the engine was at the idle, but this appeared to have no effect on anything. Does it need more pressure (bicycle pump etc), or is the effect too subtle to detect and an invasive test therefore required?
Many thanks.
How to test LDA?
Moderators: User administrators, Moderators
How to test LDA?
1987 Westy Joker
Re: How to test LDA?
The standard aaz boost pin is straight cut so I doesn't add any fuel on boost the turbo is just there for a cleaner burn.
If your performance has suffered after someone has done some work involving the timing belt then it's probably not been timed correctly, you said on your other thread that you had some work done to the pump, it's possible that the governor shaft has not been fitted in the correct place although if the work was done by a specialist then it should have been run up on a test bench.
If the drop in performance has come about gradually then in the k14 turbo the the wastegate opperates a valve which has a habit of siezing and also rusting the seat which will make the boost build up slower than it should or not reach max boost.
Sent from my SM-G920F using Tapatalk
If your performance has suffered after someone has done some work involving the timing belt then it's probably not been timed correctly, you said on your other thread that you had some work done to the pump, it's possible that the governor shaft has not been fitted in the correct place although if the work was done by a specialist then it should have been run up on a test bench.
If the drop in performance has come about gradually then in the k14 turbo the the wastegate opperates a valve which has a habit of siezing and also rusting the seat which will make the boost build up slower than it should or not reach max boost.
Sent from my SM-G920F using Tapatalk
'89 1.9td AAZ engine
http://www.dubsonthefritz.co.uk" onclick="window.open(this.href);return false;
http://www.dubsonthefritz.co.uk" onclick="window.open(this.href);return false;
-
syncroandy
- Trader
- Posts: 1905
- Joined: 18 Oct 2005, 18:15
- 80-90 Mem No: 851
- Location: North Lancs. UK
- Contact:
Re: How to test LDA?
I find a Mityvac pump useful for checking vacuum and pressure components. Fitting a boost gauge might be informative.
Syncrosport (taking a break as of summer 2024)
Volkswagen Transporter, reloaded.
252 GC5 EJ25 AAN L90D
Volkswagen Transporter, reloaded.
252 GC5 EJ25 AAN L90D
Re: How to test LDA?
Great, thanks. It looks as though the LDA doesn't actually do anything on the AAZ, unless the boost pin is changed! No point in testing it then! I'm looking for a GTD pin but want to get it back to its old state first. Seems a bit crazy that they would go to the trouble of building and plumbing in a device designed to have no effect.
It has always worked fine (even with no boost enrichment) until someone worked on it. They did the work in situ so I don't think the timing was changed, but it is worth a check. It's possible they wound out the power screw as the idle seems low and it also runs very cool.
Turbo is delivering some boost, according to my home-made boost meter (a doggy-doo bag) but I need to buy a proper meter to find out exactly how much. It would be a coincidence if the turbo had deteriorated while it was in the workshop as all seemed fine on the way in there.
It has always worked fine (even with no boost enrichment) until someone worked on it. They did the work in situ so I don't think the timing was changed, but it is worth a check. It's possible they wound out the power screw as the idle seems low and it also runs very cool.
Turbo is delivering some boost, according to my home-made boost meter (a doggy-doo bag) but I need to buy a proper meter to find out exactly how much. It would be a coincidence if the turbo had deteriorated while it was in the workshop as all seemed fine on the way in there.
1987 Westy Joker
Re: How to test LDA?
Ok simple things first, have you checked that you are still getting full throttle on the cable.
Next check, if you look at the throttle levers where the fit on the shaft that goes into the pump look closely for any marks that should have been made before the levers were taken off, if they were taken off and put back on a spline out you will get what you think is full throttle on the cable and the levers will hit the stops however inside the pump you will not, this would also explain the low tick over.
If the max fuel screw has been moved it would also account for the low tick over but it should have a security collar on it so that should be easy to check.
Sent from my SM-G920F using Tapatalk
Next check, if you look at the throttle levers where the fit on the shaft that goes into the pump look closely for any marks that should have been made before the levers were taken off, if they were taken off and put back on a spline out you will get what you think is full throttle on the cable and the levers will hit the stops however inside the pump you will not, this would also explain the low tick over.
If the max fuel screw has been moved it would also account for the low tick over but it should have a security collar on it so that should be easy to check.
Sent from my SM-G920F using Tapatalk
'89 1.9td AAZ engine
http://www.dubsonthefritz.co.uk" onclick="window.open(this.href);return false;
http://www.dubsonthefritz.co.uk" onclick="window.open(this.href);return false;
Re: How to test LDA?
I'll look into it. It will rev out in fine form when not under load but the pick-up seems a little slow. But it needs to be driven in 'dodgem' mode. Even then, the poor performance is embarrassing if not dangerous. It's even more gutless than my old CS.
The problem I had with the pump to necessitate the work was that it was dripping diesel off the arm. They fixed that problem but I don't know exactly what they did to it or what level of recalibration it underwent. They shouldn't have been changing any of that at all but if they took the arm off and didn't put it back on in the right position, that might explain it.
Another symptom is that it now dips badly in the overrun - when coming off the gas suddenly at high revs it almost dies briefly before recovering to the idle.
The problem I had with the pump to necessitate the work was that it was dripping diesel off the arm. They fixed that problem but I don't know exactly what they did to it or what level of recalibration it underwent. They shouldn't have been changing any of that at all but if they took the arm off and didn't put it back on in the right position, that might explain it.
Another symptom is that it now dips badly in the overrun - when coming off the gas suddenly at high revs it almost dies briefly before recovering to the idle.
1987 Westy Joker
Re: How to test LDA?
Follow-up: it went back to the company that 'repaired' the pump. It was not quite the case of the arm being in the wrong position as apparently it will only fit one way with this model, but there was an equivalent internal adjustment that was out. It seems to be going a lot better but now the wretched accelerator cable is sticking!
1987 Westy Joker