Exhaust smell, down on power...

[Sirocco20348]

I just bought a little usb borescope, for like $15, hasn't come yet but I'll test it out when it does, if it works any good you could just take the 02 sensor off (carefully, don't want a dead ecu) and put in the there to take a peek at the condition of the CAT

Thank you for your info! I have seen someone use a Borescope to inspect inside their cylinders. I'm not sure how will it would go for a cat, but the option is there! I appreciate it.

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[h100vw]

I found a bad cat in a Polo. The centre of it had broken off and was jammed in the pipe after the cat. probably reducing the surface area by half....

The Polo was really struggling. It was also a metal cat. There was an instant improvement on power. Infact it was over boosting when de-catted. We had to back off the actuator quite a bit.

Would split the exhaust and look inside

[Sirocco20348]

I found a bad cat in a Polo. The centre of it had broken off and was jammed in the pipe after the cat. probably reducing the surface area by half....

The Polo was really struggling. It was also a metal cat. There was an instant improvement on power. Infact it was over boosting when de-catted. We had to back off the actuator quite a bit.

Would split the exhaust and look inside

Thanks for the further info Gav, this is very interesting.

Well I managed to drop my spare fuel pump and brake it last night so I won't be doing that swap anytime soon. I'll focus on the exhaust again.

When you say 'really struggling', can you describe this further? Was it boosting at all? Was the idle strange? Driving up Hills, walking was faster?

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[jmcc]

theoretically, I think what Gavin is suggesting lines up with what you're experiencing with the difference between WOT and a slow spool up.. The more time you're spending at WOT the more back pressure you're building up in the exhaust due to the restriction, less exhaust velocity less spool at high rpm.

Then again, I think there would be so much more exhaust at WOT 5k+ rpm than 1500 that it might not make a difference.

Maybe its your n75 though, bleeding off pressure and releasing the wastegate too soon. when you go straight to WOT it might struggle to deal with the fast change in pressure, whereas the slow build up give it more time to adapt to the pressure. similar situation with the recirc.... maybe.

[Sirocco20348]

TLDR UPDATE:

• I focused on fuelling.
• I changed the Fuel Filter first and it made no difference. Then I installed the Fuel Pump.
• Fuel Pump replaced with a Deatschwerks DW65v.
• Big improvement in my current situation in both Performance and drivability. but not completely resolved.
• Off-boost driving is absolutely back to how it used to be. Very responsive.
• On-boost I am hitting 17 psi and still fading, and the Valve Duty Cycle is still 99.6% across the board so I am not hitting the requested boost which is obvious. 2nd gear is fairly mental and I am apparently not at full boost. 3rd gear and above even thou are at 17psi, it feels lacking due to the Air-Fuel demands not being met.
• Previous pump had degraded in performance and was definitely failing to meet demands.

Fuel Pump:
Previously I had replaced the failing stock Bosch pump with a HFP-A35HV fuel pump. At the time I replaced the pump (2016) it was very prominent on the UK forums and most people were giving back positive feedback that it was a low cost equivalent to the Deatschwerks DW65V. When i researched reviews of the HFP-A35HV recently, there is only bad news stories about reliability issues and poor sales support. Basically overtime the pump would lose efficiency, failing to meet the required fuel pressure of 4 BAR+. The Deatschwerks DW65V now reigns supreme as the go-to intank pump.

I dislike swapping out parts due to 'gut feeling' and forum slander, and I must admit I have started to do that lately which is not good. However, accurately measuring fuel pressure is somewhat problematic. In my mind i thought the test would be simple: Buy a Fuel Pressure Gauge, splice the fuel line, fit it and observe. But the more I read about mechanical gauges, I lost faith fairly quickly in being able to create a quick affordable test.

Most cheaper mechanical gauges had bad reviews due to pressure build up from under bonnet temps and no way to release the pressure. This would result in inaccurate readings. Decent mechanical gauges (Amazon.com: Aeromotive 15633 Fuel Pressure Gauge - 0 to 100 psi: Automotive) had a rubber flap or button to release the pressure for accurate readings but then I was left with another problem of reading the gauge while i'm doing 10/10ths in 3rd gear. A Dyno would be needed for safe readings of a mechanical at all times besides idle. Unless you run the fuel line into your cabin so you can read it [emoji14] Darwin Awards for sure.

Otherwise purchase an electronic fuel pressure gauge that has a sensor and allows the gauge to be fitted in the cabin. These started to get expensive. $250+ for a decent brand and quite frankly when the pump costs $250 I think Ill just chance it based on what I was experiencing.

So I went with good ole gut feeling, and it was somewhat positive. I just need to find out where the remaining boost pressure is.

NEXT UP:

• Gav's Exhaust theory.
• I am also researching more about my injectors and how to clean them. I rang two companies and they said that you don't clean the ones I have you just replace them? Is this a load of horsecrap?

[Umai Naa!!]

Re: injector cleaning, yes some can't be cleaned. Whether this applies to yours I'm not sure.

Have you looked at the fuel pressure regulator as well?

[Sirocco20348]

Re: injector cleaning, yes some can't be cleaned. Whether this applies to yours I'm not sure.

Have you looked at the fuel pressure regulator as well?

How do you know of it's working correctly?

I have a 4 bar, but it's not Bosch. I think it was left over from Lito's Frankenturbo kit years ago. He gifted it to me.

Maybe I just get rid of anything of questionable quality. Get a Bosch FPR.

The injectors are at 220,000km. Standard driving they might suffice, but these tiny injectors are already being overdriven due to the 4BAR reg. Maybe new ones are in order?

[Sirocco20348]

Monitored the boost gauge today while driving, performing some wot throttle when I could. Really inconsistent results. Mainly getting 17, twice I maintained 20psi, and I had one real dud 3rd gear run where it maxed at 12psi and faded..... Bizarre.

I'm still going ahead with the fuelling side of things as I'm thinking it's leaning out and reducing boost. I ordered a genuine Bosch 4BAR FPR today, I'll install when I receive it next week. I'll probably end up doing the injectors as well.

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[Sirocco20348]

The AGU block uses BOSCH 0280150464 Fuel Injectors.

Any reason why these cannot be cleaned? When I have rung 2 fuel injector cleaning places they say that these are replaceable parts and cannot be cleaned? But don't specify why, even when asked for specifics.

Sounds crazy, anyone had their AGU injectors cleaned? Any advice would be great.

[h100vw]

Cant see why the injectors couldnt be cleaned. You power them up and blow cleaning fluid through them AFAIK. Ultrasonic baths etc.

Could pull the rail and crank it over and squirt them into some jars. I did this with a polo recently. Hardly any fuel comes through so not a deadly test.

I know the tune is written for 4 BAR but refit a 3 BAR if you have one. Would work better than a bad 4 BAR I reckon.

[Sirocco20348]

Ok one last boost leak test this morning..

This time with the soapy water spray. I identifed that my injector seals are leaking quite badly. I always thought it was the hiss from the oil fill hole. But soapy water spray does not lie....

Tomorrow morning 9am, injectors are being cleaned and o-rings replaced.

Hopefully t's just the seals and not the injector seats themselves..

[Sirocco20348]

Injectors were in excellent condition, the flow rate was slightly different between all 4

I reinstalled everything and conducted a boost leak test again, and as expected, the injector seals are no longer the problem, the injector seats are leaking air.

Drivability is getting better. I have ordered some billet injector cups from Phenix Engineering and some slightly bigger o-rings they offer. This should nail the leaking injector seat situation.

[Sirocco20348]

I got around to installing the cups. Removal of the old ones was a pain in the ass. The first two cracked when I tried to remove them. I then used a flame to heat up the outside of the manifold, this helped a bit.... They still ended up cracking..

The aluminium threads were messed up a bit as well. Here's hoping the thread sealant does its job.

I will put it back on the car today.

[Sirocco20348]

All installed back in and the car starts which is a bonus. I haven't driven it yet, I'll give it a few more days for the sealant to cure...

[jmcc]

looks alot better, good luck! Aluminium threads are a pain all around this engine it seems, my sump looked like someone had been spinning the bolt with an impact driver or something when I got it out the first time.