Golf 2 Kjet Low Power

[LearningCurve]

I'm new to the forum and I hope there are some people here who might be able to help me as I am currently at a loss.

I am rebuilding a 1984 Mk2 K-jet and I am experiencing low power, Ie. it struggles to pull away on an incline in 1st.

What I've done:

-Rebuilt engine (New lower bearings, piston rings, oil pump, water pump, head redone etc.)
-Timing done & rechecked about 20 times
-Ignition timing at 7° BTDC (Manual says 6° but iirc thats at sea level so I advanced for PTA? could be wrong)
-New injectors
-Injectors "Balanced" as best as I could with my eyes
-Lift pumps flow rate checked was slight above spec (can't recall numbers right now)
-Main pump flow rate checked and in spec (can't recall numbers right now)
-Intake manifold checked & cleaned
-No Fuel leaks
-All air leaks fixed
-Checked air pipes between Fuel dist & intake and all are 100%
-Checked WUR ie. control pressure was ±3.5 bar hot (from what I can see must be 3.4-3.8 bar hot, could not check cold)
-Checked system pressure and added a shim to get to 5.4 bar book says 5.5 max, was at 4.8.
-New TCI (Tp100) and harness
-New dizzy (could be faulty from shelf ?)
-New Spark Plugs BPR6ES NGK recommended alt to BPR6ESZ-N
-New Spark plug leads
-Coil checked and tried a new one(Both perform the same)
-Exhaust manifold had 2 cracks and was repaired, Could still leak ?
-Aux Air valve works according to tests in Haynes Manual
-Cold start injector (5th Injector checked)


The car starts and idle seems fine, the only thing I have yet to set is CO2 (waiting for a probe) what I want to know is does setting CO2 effect everything from idle to max throttle or is it just at idle, cant seem to find a definitive answer.

Other than CO2 is there anything else that can effect power that I may have missed in the above, don't really want to drive it to someone in this state so I'm trying to get it as close as I can before trying to take it to dyno.

[Harmse97]

Hi. Cant give technical advice, but i do have a bunch of K-jet goodies if you need anything, based in PTA

Sent from my CPH2359 using Tapatalk

[VAG Fan]

Welcome to the forum!

A few points from an old K(E)Jet driver.

1) Regarding your second-last question, the CO (not CO2) adjustor changes the mechanical connection between the air flap and the plunger in the fuel distributor. It shifts the plunger up or down, relative to the air flap, but only by a very small amount. At idle, the fuel distributor plunger is hardly off its closed position, so any change on the CO adjustment screw makes a large difference to the amount of fuel metered into the engine at idle. But at medium and full loads, the plunger is sitting at a much higher displacement, so the small adjustments of the CO screw make hardly any difference. In short, the CO adjustor only affects idle and very low loads (e.g. gentle coasting), but not higher loads. If your engine is already starting and idling OK, then the rest of the power band should also be OK. Fiddling on your CO adjustment screw is not the correct fix for the problem.

2) You need to be absolutely sure that there are no air leaks (vacuum leaks) between the air flow meter and the inlet manifold. This includes the large "snorkel" and all hoses / pipes connected to it. I know you already checked them, but if there is ANY vacuum leak, this means that the air flap is not lifted far enough, so the mixture is lean. I would suggest taking a can of brake cleaner or quick-start and spraying short squirts onto each part of the air inlet system, while carefully listening to the idle speed. Wait a few seconds between squirts. If there is any change in idle speed resulting from a squirt, then you've found a vacuum leak. Include areas like the brake booster, manifold gasket, injector seats, etc.

3) Are the new injectors OEM parts (Bosch or VW) and exactly the same part number as the old ones?

4) On K-Jet, the injectors only serve as atomisers. If they work correctly, they don't influence the fuel metering. The metering is done only by the fuel distributor itself. So, by "balancing the injectors", presumably you mean balancing of the 4 differential pressure valves on the fuel distributor. How did you do this balancing? Reason I ask: Depending on whether you "brought the fat ones down" or "brought the lean ones up" you might have changed the overall mixture of the fuel distributor, even though the control pressure and system pressure are still in spec. Also, the fuel distributor, in my experience, should be balanced not only at idle or full throttle, but preferably at a number of different air flap settings.

5) Once the four valves are balanced, then a lambda probe would be great to have... But in its absence, what colour are your spark plugs after a drive (e.g. 20 km on highway)? If they are white, then your mixture is too lean. Powdery brown is good. Black is too rich.

6) Is there a dome-shaped sieve sitting inside the "snorkel" on top of the air flow meter? If so, then the dome must be pointing away from the air flap.

7) 7°BTDC for spark timing should be fine. In my experience, you can actually run quite some advance on the Highveld. 1 degree is not much at all. I assume you have double-checked valve-gear timing after the engine rebuild. (That's what I read from the "20 times".) Compression also good?

8 ) There is no lambda sensor in those models, so even if the exhaust manifold leaks, this should not influence engine performance significantly.

I'm also in Pretoria (East). I'd be open for meeting up at some time. (But I'm not really available before April.) Let me know (e.g. private message) if you're interested.