My 2.0 ABF Dyno run. Power seems down and AFR is high.

Took the Golf with new engine for a dyno setup today.


Power is 154HP and 129lb/ft.

The engine is pretty much standard, just has a set of KR exhaust cams in it. WUR Mod has been done and was checked through the entire dyno setup, the fuel pressure never moved, supplied full pressure at all rev ranges with no falloff at the top end, suggesting the pump / filters are all fine. Timing was set at 6degrees, mixture tweaked but made no real difference at either 1% co or 3% co

Compression readings on all cylinders are between 12.5 and 13 Bar.

Car has 4-branch manifold and decent exhaust.

The AFR (wavy line on the graph) was very poor, we couldn`t get it any lower, 14 > 15 90% of the time and rising from 6,000 > 7000 from 14.5 > 16.5 !




The Dyno let us set the rpm at 3,000, 4th gear full throttle and we could then adjust the engine to try and gain power / AFR, but nothing really made much difference to the curve or final output.


We did have a particularly bad run that peaked at a whopping 138HP


Basically, it seems down on power and torque and the AFR above 6k is a concern.

Suggestions ?

 

did you set the co to 2% at idle with the red lead disconnected and isv breather blocked?

id be suspicious of something else as well, as when i had mine rr'ed (standard abf kjet) it was running lean up top and made 154bhp as well, but it still had 150ftlb torque

 

Maybe put different cams in it, or just some original ABF cams ?

KR cams make less torque than ABF cams, and the KR inlet cam has less lift (9.6 to 10.8) and less duration (212 to 219) than the ABF inlet cam.

EDIT: Sorry, just read you have a pair of KR exhaust cams..... Will 2 KR exhaust cams have a lot more overlap?...

 

Nige is swapping the cams back to the KR cams he's used on his last ABF motor.

The twin exhaust cams can work well as I had the very same ones he's got in my car, which with a 'shed' head gave 183bhp @ Stealth on a 9A block.

Nige,If all the cam and inter cam timings are all correct, compressions are within spec, fuel pressure and mixtures are all ok, not a lot else you can do in the time you have before Friday.

As I said on the phone, I have no AFR data to compare to your readings from when I was running a 16v, be interested to see if anyone else has.

 

rubjonny, it's been around the houses (in about 3 or 4 peoples engines) but originally normancoal had the cam done at Stealth, in about 2002 - it's been in my car, loadsavalves grey mk2 which has had another 2 owners since and now Nige has it.

We compared pics and vital markings on it prove it's THE cam, not just one like it.

 

In the last car they were in, it was a 9a, ported head and these cams and gave 185HP.

 

Was the 185 bhp on the same dyno?

That AFR is way too lean - should be about 13:1, or even as low as 12.5, surely. If you got it to that, it should be possible to run a bit more advance as well. Should make a lot more power too.

If you rag it round a track with that AFR you'll be buying another engine I reckon, and it could well be what killed the last one.

If you've got plenty of fuel pressure at the top end, then I'd start to suspect a sticky metering head, or what are the injectors like, as RJ suggests?

 

Mate, all questions are good ones

Car drives fine, not lumpy or hesitant just generally slower than before.

Injectors are unknown, I may do a test on them later.

Within a mile of driving it this afternoon with this engine, I said to my passenger "this seems slow".

Didn`t know about the metering head test

Also the cam chain tension was fine, no slack

 

Mike, we can`t get the AFR lower. No adjustment we made had any real difference. Mixture to 4% cos, 6degrees timing (tried at 2 degrees once!), wur pressure raised or lowered all made no huge impact on the graph.

DYNO VIDEO

 

Have to agree with this, that AFR is dangerous, you don't want to be driving it over 5000rpm at 14 / 15 etc :1

I'd be inclined to think the same, shoot me down if I have the wrong end of the stick but have you just popped a "new" ABF in with the same fuel system that sh4gged your old engine?

Also (and again, I apologise if I'm not clear on your methods), you say the pressure was "tested" and "OK" how exactly was the pressure tested i.e. under full load (5500rpm +)?

If so then I'm with Mike and RJ, metering head & injectors

Cheers

Simon

 

There goes RJ - straight in with the detail! "Here's one I fixed earlier"

Nige - was the 4% CO reading at tickover? Assume you can't get that rich at full throttle, if your AFR is on the lean side.

Assuming that's the case for now, if you've got plenty of fuel delivery, but it's not getting to the cylinders fast enough, then I'm guessing it's either a restriction at the metering head (see above), or the injectors aren't flowing enough.

Given that all of your previous pistons had about the same amount of damage, the metering head would seem more likely, as individual injectors wouldn't all fail at the same time, by the same amount.

Did your dyno operator try any sort of injector cleaner?

 

We had a vehicle that was giving correct fuel pressure at idle but the AFR's way down at higher rpm. After much checking it was discovered the fuel filter was full of gunge, the pump was able to provide enough pressure i.e. it passed a pressure check at low rpm. It was not correctly diagnosed until pressure tested under full load.

Hence my question about the fuel pressure testing above.

If it has had a bad tank of fuel with particles of some kind it's possible that all 4 injectors are partially blocked, I guess he did not try my "quick & dirty" (and very risky) test method from the other post lol...

Cheers

Simon

 

I`m going to check the injectors now, but I`m not sure what to take apart to clean / check the metering head .I`m not sure what I need to remove to expose the spindle you showed in the photo of

The fuel pressure gauge was fitted as you would when setting up a WUR and the pressure was 3.3Bar and left connected for the Dyno runs so we could see if it fluctuated or blipped at all.

The fuel system is the same as before and the one I`ve had in since I`ve owned the car, fuel filter was changed 3 months ago.

 

Fuel filter genuine?

 

When you say the fuel pressure was checked, you do mean control fuel pressure on the meetering flap?

If this is to high it will run lean

 

OK, well that answers that question so you've narrowed it down to the metering head or the injectors

You might want to just check the plate and the bits you can get to for free movement first?

If it seems OK then remove the fuel distributor from the airflow sensor and check it again (like in the pic)

Cheers

Simon

 

I`m still not sure what I need to check, so I did the test on the metering flap as on this video. It seems pretty free to me, I can move it by blowing and it slowly returns into place, that seems right ?

Clip of metering flap checking