ALH down on power top end

[jwalman]

Hello again. Yes its another power loss thread - sorry!

The car in question is a 2000 X 1.9 TDI 90bhp ALH engine done 89k with fsh.

I have a decent amount of power at low speed, and in 1st and 2nd gears, there appears to be a decent amount of boost, but the car struggles between 50 - 70 mph with acceleration, especially up hills on the motorway, and the car doesnt go over 90mph, unless your going downhill, when it will maintain the high speed once on level road. I have a VAG COM, and there are no codes displaying. The car does this all the time, and doesnt appear to be in limp mode.

I did have a problem with the plastic vacuum turbo actuator previously as the plastic tube that the hose connects to, broke off in the hose, I have managed to resolve this now. Sucking on the hose makes the vacuum operate fine.

I used a doner car in the form of a GT TDI 110 AHF which runs perfectly which has the same MAF sensor and the same sensors along the bulkhead, and swapped them one by one including the MAF, and tested the doner car each time I changed one. Every time the doner car worked perfectly with loads of power. The original car now has all the sensors from the doner car, and drives exactly the same as it did in the 1st place.

I have now changed the oil and filter, fuel filter and air filter, and still no change. Checked hoses for leaks.

What's next? - Clean out the intake? Turbo Vanes? Im not sure now, thought I would have found a fix with the sensors.

I appreciate anyones help!

[jwalman]

Also, fuel consumption is rubbish, and its displaying about 38mpg when driving at a constant 60mph which should be showing around 60mpg Id reckon.

Also It drives much slower with the MAF disconnected.

[jwalman]

I have now changed the MAP sensor for a new one, still no change. Gave it a cambelt change, and the timing was set up correctly as Im told it was slightly out. I have also got hold of a code reader, that plugs in whilst your driving and monitors the car. Still no codes showing, but I got the following readings.

FC Stored Amount Max 0 Min 0
Calculated Load max 100.00 Min 0.80
Coolant temp Max 81.00 Min 44.00
Intake M.A.P max 200.00 min 99.00
Engine Speed max 3686.00 min 100.00
Vehicle Speed (mph) max 57.79 min 0.00
Ignition Timing max 14.00 min -1.50
Intake Air Temp max 44.00 min 20.00
Mass Air Flow max 100.90 min 7.20
Throttle Pos max 100.00 min 0.00

PLEASE HELP GUYS!!!

[jwalman]

Anyone???

[martin1810]

Have you had the vacuum system tested incase it leaks/fails to hold vacuum. Have you tried changing the N75 valve. If this is faulty it can bleed vacuum when it shouldn't.

[jwalman]

Hi, thanks for your reply. I havent tested the vacuum system, I have changed the N75 for another one from a car that worked perfectly - no joy with that. Ive got the car in with a VW specialist. Will they be able to perform a vacuum test? Im going to ask them to check the intake manifold for clogging too.

[jwalman]

Cleaned out intake manifold, and it was pretty clean in there, no clogging. Im really stuck now. The vacuum system appears to be working. Replaced the hoses with new ones.

[jwalman]

Fuel pump timing was out, and has now been set up correctly, still no change. Now I have changed the turbo - Problem still exists, Costing me a fortune now, what else could it be?

[blackcat]

Hello, I have EXACTLY the same problem as you but no solution. The guys at the garage told me that it might be the turbo but with such a vague answer I don't want to be popping on a new turbo like yourself just for it to carry on doing the same thing...

Did you get anywhere with yours in the end?

Thanks in advance

Keith

[jwalman]

Hi Keith

Yes, I finally got it sorted today. All four injectors were blocked, so I had the nozzles replaced, at a cost of £512 inc vat and labour, by Colchester Fuel injection, a Bosch specialist. Theyre expensive but these boys know what theyre doing.

Have you checked the sensors, MAF etc? Checked for hose leaks etc?