Timing pull and injector duty cycle

[superkarl]

It would bring injector duty down yes but at the expense of your fuel pump.
There are lots of folks maxing injector duty now that mods have advanced, b5 tip and relentless mani. Adding a 4 bar reg will reduce duty 15%. Mate of mine at stage 2 + a few bells and whistles was running 115% duty on standard injectors. 4 bar reg as a temporary fix, and has now fitted genesis 550s to run them at 3bar with plenty of headroom.
What boost are you seeing? Spike and held? V hard to read your logs

 

[8bit]

Thanks for the post. Isn't the LCR fuel pump rated for 4 bar anyway? Or is it just that operating it at that will place extra stress on it? I guess I'd need to get the map tweaked if I increased fuelling capacity.

Boost peaks at 1.4bar just short of 3krpm and tails off slowly to 1.2 by about 6000. Request is 1.2bar from 3krpm right to 6500.

 

[superkarl]

the car will adapt for any fueling changes, so adding 4bar the car will still fuel as it should and meet lambda request, whilst bringing injector duty down 15%.
these cars are just old so its hard to say whether the fuel pump will deliver.

 

[8bit]

Hmm ok, just I thought a few people had changed to a 4bar FPR and said their cars ran poorly after that.

 

[superkarl]

il send my fellow s3 owner with experience of this in here.....

 

[Westle]

il send my fellow s3 owner with experience of this in here.....

That'll be me then

My injector duty cycle was 130% after I added a relentless exhaust manifold and a large port cylinder head. Car was constantly on EGT protection as a result to try and cool the engine. I fitted a 4 bar FPR which brought the duty cycle under 100% (just) but it made it run healthier and wasn't on EGT protection all the time.

A 4 bar FPR on an old tired in tank fuel pump can finish it off, luckily I fitted a brand new pump a year ago so knew it was going to be fine but this was only ever a temporary solution. I purchased some Bosch 550cc injectors and am having them mapped in this week on a custom map. This will be back on the 3 bar FPR to reduce the strain on the pump.

Looking at your logs the AITs are fine, nothing to worry about there. If you are hitting 100%+ injector duty cycle you need to address that first. Try a 4 bar FPR but be very weary of your fuel pump. Fit and log and see what's happening.

 

[8bit]

Nice one, thanks guys. I looked at Genesis 550cc injectors, think that might be slightly overkill for my requirements and I'd be looking at £275 for a set of those. Would I be as well getting a better in-tank pump and a 4-bar FPR?

Also not sure that'll fix the timing pull, my thinking is that the timing pull seems to be almost as soon as it's under load and/or on boost, not just at the top end once the injectors are working flat out. May be that the downpipe is the restriction there right enough I guess, the intake and intercoolers are now providing more and denser air than the rest of the system can cope with.

 

[swedey21]

I fitted a 4bar pressure reg on my LCR,made it drink a fair bit more fuel...i saw no difference in power..not that your looking for that...i removed it not long after i fitted it...made a massive difference in mpg..

 

[ibizacupra]

as a temp measure you could consider dropping in the 4bar reggy, assumption being the pumps healthy... and unisettings the main fuel terms down so lambda adjust on cruise and idle are somewhere handy (<5%) and see how it goes.. you should see the duty cycle drop with the 15% headroom..

 

[8bit]

I fitted a 4bar pressure reg on my LCR,made it drink a fair bit more fuel...i saw no difference in power..not that your looking for that...i removed it not long after i fitted it...made a massive difference in mpg..

Guess the map does need adjusting then.

as a temp measure you could consider dropping in the 4bar reggy, assumption being the pumps healthy... and unisettings the main fuel terms down so lambda adjust on cruise and idle are somewhere handy (<5%) and see how it goes.. you should see the duty cycle drop with the 15% headroom..

Cheers Bill. Have you seen this on Revo stage 1 maps before at all? Also, what would you suggest the better permanent fix be, 4bar FPR with an uprated pump, or bigger injectors?

 

[ibizacupra]

checking what actual pressure you have under boost is 1st check... and would confirm if your pump is sagging under load.. Other LCRs dont do this, so something else is amiss... Checking will confirm.

 

[Mark One]

RE the EGT channel, you can bet it's an ECU modelled parameter. development work will have been done on the test bed to correlate spark advance, load and RPM to EGT. Then it'll be a reasonably conservative model based on the findings.
Don't worry about overfuelling for component protection, it's a very normal technique, especially with turbocharged port-injected engines. You are forced to phase back combustion to avoid detonation and effectively end up blowing fireballs down the exhaust. Interestingly the car will do this on purpose at low loads when cold to heat the cat faster (at the expense of your MPG!).
I would be carefull going straight in there with a 4 bar reg, although going up in pressure is safer than down. You are likely to soak it with fuel and I'd be surprised if the fuelling trim was permitted to adjust fuelling by that amount. I wouldn't expect the cat to last long swimming in fuel, not to mention your economy will drop off (even though the MPG meter wont show it!).
Personally, I'd be wanting to keep the standard injectors as far as possible for the spray pattern, then have the car mapped with a 4-bar pressure reg. If the fuel pump can't take it, replace it. They are not mega money, particularly if you manage to find an OEM part to do the job.

 

[8bit]

checking what actual pressure you have under boost is 1st check... and would confirm if your pump is sagging under load.. Other LCRs dont do this, so something else is amiss... Checking will confirm.

Cheers, I take it you mean checking fuel pressure? Is that something that can be done with VAGCOM?

Also, have you ever seen FPRs fail or deteriorate at all?

 

[8bit]

RE the EGT channel, you can bet it's an ECU modelled parameter. development work will have been done on the test bed to correlate spark advance, load and RPM to EGT. Then it'll be a reasonably conservative model based on the findings.
Don't worry about overfuelling for component protection, it's a very normal technique, especially with turbocharged port-injected engines. You are forced to phase back combustion to avoid detonation and effectively end up blowing fireballs down the exhaust. Interestingly the car will do this on purpose at low loads when cold to heat the cat faster (at the expense of your MPG!).
I would be carefull going straight in there with a 4 bar reg, although going up in pressure is safer than down. You are likely to soak it with fuel and I'd be surprised if the fuelling trim was permitted to adjust fuelling by that amount. I wouldn't expect the cat to last long swimming in fuel, not to mention your economy will drop off (even though the MPG meter wont show it!).
Personally, I'd be wanting to keep the standard injectors as far as possible for the spray pattern, then have the car mapped with a 4-bar pressure reg. If the fuel pump can't take it, replace it. They are not mega money, particularly if you manage to find an OEM part to do the job.

Thanks for the input. How come the car will model/estimate EGT then, when it has a sensor for that job?

 

[Mark One]

Also, have you ever seen FPRs fail or deteriorate at all?

I've tested about 20 4bar FPRs from scrap yards before selling. Never had one more than 0.05 bar out. It's more likely to fail dramatically than be down by 0.5bar or something.

 

[Mark One]

Thanks for the input. How come the car will model/estimate EGT then, when it has a sensor for that job?

News to me. I wasn't aware that LCRs were equipped with G235 sensors. Thought that was more B5 S4/RS4

 

[8bit]

News to me. I wasn't aware that LCRs were equipped with G235 sensors. Thought that was more B5 S4/RS4

They do, all but the very early AMK models have them apparently, mine certainly does. The sensor is mounted in a boss in the hotside housing and feeds round to the electronics mounted round the front of the block.

I've tested about 20 4bar FPRs from scrap yards before selling. Never had one more than 0.05 bar out. It's more likely to fail dramatically than be down by 0.5bar or something.

Noted, thanks for that.

 

[Mark One]

They do, all but the very early AMK models have them apparently, mine certainly does. The sensor is mounted in a boss in the hotside housing and feeds round to the electronics mounted round the front of the block.



Noted, thanks for that.

Awesome, I'll have to check mine. It's a 54 BAM so hopefully it's got one.

 

[ibizacupra]

Cheers, I take it you mean checking fuel pressure? Is that something that can be done with VAGCOM?

Also, have you ever seen FPRs fail or deteriorate at all?

yes I mean check fuel pressure under load..
it should follow boost... so 3bar with no vac, usually 2.7bar on idle vac, and when driving 1.5bar boost should equate to 4.5bar fuel pressure.. if not, and its significantly less you will see block 001 trying to adapt up to compensate.

Worth logging 001 and 031 and 118 sometime to see how the fuel adj is coping..

if its going additive by more than say 5% its working to add more fuel than expected... 25% is its limit before it throws the towel in

 

[ibizacupra]

RE the EGT channel, you can bet it's an ECU modelled parameter. development work will have been done on the test bed to correlate spark advance, load and RPM to EGT. Then it'll be a reasonably conservative model based on the findings.
Don't worry about overfuelling for component protection, it's a very normal technique, especially with turbocharged port-injected engines. You are forced to phase back combustion to avoid detonation and effectively end up blowing fireballs down the exhaust. Interestingly the car will do this on purpose at low loads when cold to heat the cat faster (at the expense of your MPG!).
I would be carefull going straight in there with a 4 bar reg, although going up in pressure is safer than down. You are likely to soak it with fuel and I'd be surprised if the fuelling trim was permitted to adjust fuelling by that amount. I wouldn't expect the cat to last long swimming in fuel, not to mention your economy will drop off (even though the MPG meter wont show it!).
Personally, I'd be wanting to keep the standard injectors as far as possible for the spray pattern, then have the car mapped with a 4-bar pressure reg. If the fuel pump can't take it, replace it. They are not mega money, particularly if you manage to find an OEM part to do the job.

the 210/225 LCR's model is to maintain lambda =1 apart from the max load column where it sits at 0.953

This wont be the value used in revo, although a lot of shyte maps dont change stock fueling !!!!

920'c is the threshold for the fuel dump, but there is another lambda table which ironically in std map on LCR is set to 1's which would kick in enrichment from 820c.. but being its set to 1's it does nowt... and egt protection is the only enrichment it will typically do.

non egt equipped cars have this other egt temp related table with active numbers (talking wideband cars)

from logs I have done on assorted cars, learning me7, the lambda temp seems to correlate to the temp thresholds used for switching in these other map adjustments.