Injector change update-Bosch Gen 1 to Gen 3

[baggy798]

It's around 20% bigger before you have to increase the AMM size as well.

I'm running 0280155830 blue V70R injectors which flow 350cc at 3 bar, car runs great.

[Jimsiss]

Originally Posted by Laird Scooby

Good question! I've always been of the belief that it is +/- 10% around any given parameter, primarily to take into account component tolerances.
Did the Polo GT have a Lambda sensor? Also how much more flow did the injectors you fitted have over stock units? Did you reset the ECU when you fitted them? Did you have any other mods to improve airflow? What was the standard output of the car? What were the original injectors on the Polo?

Those injectors you quote as being stock on your Volvo flow 311cc/min @ 3bar so on a 4 cylinder engine should be more than enough for a 200bhp output, depending on other mods. Bear in mind your FPR keeps the fuel pressure (usually) about 2 bar above manifold pressure so when you're on boost, the fuel pressure will be somewhere around 2.5bar, assuming 0.5bar (7psi~) of boost. That still gives you some room to play a bit.

https://www.polog40.co.uk/article_injector_table.php

Table gives injector flow cc/min @3bar and injector resistance.

I have a feeling they were mk2 1.8 GTI injectors from a golf, I was told they'd be fine but it ran soooooo badly. Reset everything and the air/fuel ratio was stupidly rich (had a wideband lambda on it as I was going to upgrade to an aftermarket ECU and bike throttle bodies but I still haven't finished the manifold...several years later ). I'm pretty sure they were too big for the standard ECU.

I believe standard output was 75bhp (when new) it currently has 80bhp as I hadn't finished all of the engine work. Managed to chip the ECU and run an 8k rev limit (yes it does Rev that hard in stock form but doesn't like it when you hit the limiter in 5th gear as my brother did with it when he borrowed it one time ) 4 branch (4-2-1) with 2" decat single box exhaust, derestricted intake setup.

Still had a ported head and the ECU with bike throttle bodies to go on before I was finished. The aim was 100bhp without a camshaft change as most people struggled to get 90bhp with an aftermarket camshaft but some were trying to run a 280° duration on a nearly standard engine (waste of time and money as they ran like crap) others 268°.

For the Volvo I'm aiming for close to 250bhp eventually but I'm quite happy to play with it over time. I've got a 16T on it with a 3" turbo back stainless exhaust I built on it (two boxes and a "sports" cat still the most quiet 3" exhaust I've ever heard), manual boost controller so I must be around 180-200bhp area with 10-12psi (definitely pulls harder than it used to).

[Laird Scooby]

A rough rule of thumb is divide the flow by 6 to get a figure for how much power each injector will cope with.

You current injectors are 311cc/min so 311/6 is a smidge under 52bhp x 4 cylinders = 208bhp maximum.

However that's for n/asp engines and i'm not sure how the turbo figures compare.

I have heard that people can run 250bhp easily on standard injectors, right or wrong i don't know but i expect one of the turbo people will be along soon and say yes or no.

[Jimsiss]

Originally Posted by baggy798

It's around 20% bigger before you have to increase the AMM size as well.

I'm running 0280155830 blue V70R injectors which flow 350cc at 3 bar, car runs great.

Is that on a standard ECU and AMM, also did you have to ditch the resistor pack?

[Laird Scooby]

Originally Posted by Jimsiss

also did you have to ditch the resistor pack?

Not a wise move!

The purpose of the resistor pack is to allow injectors with lower resistance to be used.

Lower resistance means less turns on the coil that opens the injection valve.

Less turns means a lower Tesla (unit of magnetism) value, lower Tesla value means less electrical hysteresis to hold the injector in the position it's in (open or closed) which means much faster opening and closing times.
It also means much less back emf for the ECU to try and cope with so reducing the amount of heat produced both in the ECU and the injectors making both more reliable.

When running high flow injectors, this becomes very important!

[baggy798]

Yes to all three. They are high impedance.

[Laird Scooby]

My Omega injectors landed today, very quick delivery! Will sort out when i'm going to fit them as i want to do a CO check before i do, two reasons, one because i recently renewed the air filter and suspect that was increasing the CO somewhat for the MoT last year and second, perhaps more importantly, it gives me a base figure for comparison purposes.

A further CO check once fitted will confirm everything is (on the face of it at least) all good.

[Laird Scooby]

Firstly, big thanks to Phil for reminding me of this upgrade and secondly, for giving me the inspiration to do it on mine! Finally got round to doing it today, after the injectors landed the other day :



Just to get a "base" figure, i went out the other day armed with my trusty Gunsons Gasteseter and took a reading at idle - i was expecting (hoping for!) 1%CO at idle as that's what i'd previously set it at last year just before the MoT.



It showed 0.9%CO which could well be down to the nice new, clean, air filter! Then, for no apparent reason, it shot up to 2.6% and started running like a hatful of monkeys a***holes :



In other words, how it's sometimes been running lately and stenching of petrol at the same time - if i've left the car alone for a while, it's been a pig to start (hot or cold) after that, especially if it stinks of fuel when i get in.

When i was doing the air filter i kept getting a whiff of BP Ultimate from the inlet trunking and to be honest, that was the final piece of the jigsaw for me. Told me one or more injectors are leaking when they shouldn't be - the high CO reading simply confirmed that!

Here's a close up of the squirty end of the new injectors - note the 4 spots - those are the pintles that inject the fuel. Only one on the old ones.





Third injector from the left, the pintle is partly withdrawn as if injecting - should be out! Proof positive my theory was correct!

Anyway, back to the actual job of replacing them!

First, i popped off the clips from the injectors, noticing that injectors 2, 3 and 4 were a bit tighter than the other three. More of this later!




One bank of injectors disconnected ^^^^^ and the other bank :



Right hand bank fuel rail unbolted from the inlet manifold :



Left bank and FPR unbolted :



New injectors ready to go in after giving the "O" rings a vital bit of lube to help them "slip in nicely" - oooooo-errrrrr missus!



Right bank of new injectors in place :



Left bank looked the same from the other side!

All bolts etc replaced (except one i dropped, it might surface one day unexpectedly but not a problem for now) and i decided that seeing as the new injectors had the grooves for the clips, i would fit them anyway - "belt & braces" so to speak.

Fired up and it coughed and spluttered a bit until the fuel rail had fully pressurised then it ran perfectly on all..................... errrrr............ five!

The problem was #3 injector - i hadn't quite pushed the injector connector plug fully home! Pushed it fully on, the click i heard previously thinking the wire clip was going over the lugs was in fact the wire clip popping off the lugs! D'oh!

Anyway, fired it up again and it ran nice and smooth on all 6, still slightly hesitant at first which i'm fairly sure was down to the injectors probably being a bit dry, then it smoothed out to smoother than it had been on the old injectors.

The "proper" test drive came at walkies time. At first, it didn't seem that different then i pulled out of the cul-de-sac i live in and tickled the loud pedal how i normally would to get to the next junction. I don't usually have to brake for that junction, just ease up on the loud pedal - 'nuff said!

Being a bit more gentle, at least until i had room to be a bit more adventurous without speed humps, potholes and pedestrians getting in the way, i noticed it was much smoother and i now had throttle response - instantly!
Before it always responded but was a case of sending the engine a polite request by carrier pigeon and hoping! Now it's much more "now if not sooner".

Generally speaking it's much smoother and i can make better progress at lighter throttle openings. The most impressive bit is what i've decided to call the "wall of torque".
Being a 90 degree V6, it always was a torquey unit but now it feels like all the torque is available at much lower engine speeds. It feels like no matter what or when, firstly it responds instantly and secondly, it's much livelier because of the better torque delivery.

This should (eventually) translate into better fuel economy, for now that "wall of torque" is incredibly addictive!

For those that are wondering, mine hasn't taken time to re-learn fuel trims etc because it has no Lambda sensor, no cat and no feedback system - all the improvement is simply down to the injectors!

I will check and if necessary adjust the CO in a few days time once the injectors have bedded in a bit. Next job on the agenda is the valve clearances, it's sounding a wee bit tappety!

Then the LPG conversion and get the A/C going again but those are for other threads!

[Laird Scooby]

A further update - note that those with a Lambda and cat won't have the mixture screw on the MAF and the Lambda and ECU will do the mixture adjustment.

As i hadn't checked the CO after fitting the new injectors, today gave me a good time to check it. Took the car for a spin with the Gastester in the back, warming up on my jump-pack.

Calibrated it before starting :



Then shoved the probe up one of the tailpipes :





Then the electric cooling fan kicked in :





Next, i tried something else :





That's a tad high at 6.7%! Only to be expected as i'd pulled the vac hose off the FPR and plugged it - first so i could check the FPR would richen the mixture when vacuum was removed, second so i could check for any fuel leaking from the FPR and third to eliminate the FPR from the process of working out why the CO level was now much higher.

Refitting the vacuum hose, i turned my attention to the thermostatically controlled flap valve on the air cleaner. Given it was a warm day today, i would have expected the flap valve to mainly pull air from the colder side, not from the hot side where air is passed over the exhaust manifold first.

Wasn't happening that way, i removed the hot air trunking from the air filter end and noted the CO dropped by at least 1% - difficult to say exactly how much over that as the cooling fan kicked in again.

Then i looked at the mixture screw on the MAF. In the past, someone had drilled two holes in the plug on it and when i checked the CO for the MoT last year, it didn't need adjustment. Normally they won't need adjustment unless something is out of kilter somewhere so this got me thinking.

As the CO level drops and the engine runs extremely lean, this can push the HC content up a lot. My guess is that over successive years with the old injectors getting a bit worse each year that the HC level went up due to some cylinders (those with the duff injectors) weren't firing properly so each year, the mixture was tweaked richer until the duff cylinders were running right.

Now all the injectors are squirting better, this is no longer a problem and the CO ends up higher than it should be.

After turning the screw on the MAF 7 1/2 turns anti-clockwise, i finally got there :



As a final check that the calibration hadn't wandered or been knocked by me :



Yes, i know - it's only at 1.8% in that pic and should be 2% for the air calibration point but first it had swung there pretty quickly and experience with this Gastester tells me it does that then the last little bit can take a few minutes and secondly, by the time i'd shut the bonnet etc and come back, it was up to bang on 2% so i know i finally reached 1% approximately.

Driving home, the car felt even smoother and livelier but in a more progressive way. I'd done a 0-60 run on the way there, using a stopwatch app on my phone which i can reach without taking my hands off the wheel. On the way there, i got about 11 secs - not good!

On the way back, i did another but had forgotten to reset the stopwatch! It came up somewhere around the 8 second mark although i can't be too sure. As such i did another after resetting the stopwatch. Even after fluffing the start, i still got 0-66 in 9.47 so 0-60 would have been mid to low 8 seconds.

This concurs with how it felt during the 0-60 on the way to where i checked the CO - it felt good up to a certain point then felt like it was overfueling.

Anyway, aside from a precautionary check before the MoT, unless any other anomalies show up i think that's it on the fuel front for now!

[LPTJoe]

Hmmm, this thread has my beard twitching.

I appreciate that people often upgrade the injectors on turbo cars to allow for mods etc, but I can't help but wonder if there's a decent/modern and easy to fit replacement for the standard green 0280150804 injectors to suit standard cars that don't require resistor mods etc...