AFN quirk , no power until reved , ECU / cruise control ?

[ewenmaclean]

Hello,

just to add my speculative 2-pennyworth - on that ECU the brake and clutch switches should both be earthed when the pedals are not pressed - so to be absolutely sure I'd make sure the brake switch wire and the clutch switch wire (white/yellow and white/red from memory) are actually earthed. Some later ECUs had them switched to 12V, but I think for your one (oddly says AHU not AFN there), it needs to be earthed - syncroandy will know.

I only post this because mine did exactly the same before I earthed them.

Ewen

[16vmini]

guess you didn't do this in your weekend engine swap?

well i remember swapping the stat housing over .. cant remember if i swapped the stat it self

[max and caddy]

Lack of rev building ability at start up is often caused by bad timing or a dead Maf...what timing figure are you showing?

[mazz]

On some TDi Ecu' s there was a system in place to stop you thrashing engine when cold and on start up, obviously this is also controlled by temp sensor,, it was very random and can not be removed in coding. We mainly saw its introduction on 1997 to 98 VWs, mostly commercial
So long as your measuring blocks are good for your brake switch (all 111) then this is probably your problem

[16vmini]

On some TDi Ecu' s there was a system in place to stop you thrashing engine when cold and on start up, obviously this is also controlled by temp sensor,, it was very random and can not be removed in coding. We mainly saw its introduction on 1997 to 98 VWs, mostly commercial
So long as your measuring blocks are good for your brake switch (all 111) then this is probably your problem

ok , that makes sense , and with my "faulty" temp sensor , that will not be helping ...

ok time to trace some wires. see whats wrong with temp sensor , as thats new from VW. lets get rid of fault code first and move on

[passatafn]

Hi there, i am sorry to hear about your problem with your engine. I have a 1999 passat with the same engine and I am experiencing the SAME problem. very frustrating! started randomly last week one morning.i have cleaned the turbo with mr muscle and replaced a couple of vacuum pipes. aftet revving to get power i now get loads! much faster than it used to be but occasionally loses power while driving. please can you tell me how you got on. have you fixed the problem yet??

many thanks.

[passatafn]

recently had new thermostat and has been running great. reads exactly 90 and warms up properly now don't have temp sensor prob i think. replaced last year or before.. lovely heating from climatronic aircon too!

[16vmini]

still not got around to fixing it .. i just rev it untill whatever resets and i drive ...

sorry...

Matt

[passatafn]

Just to let you know that I have had quite a pleasant drive after disconnecting the MAF (mass air flow) sensor. which is very easy to do. think i have found the problem and will be buying a new one soon! i will update you if power problem persists. seemingly smoother and better mpg urban driving. this has been suggested to cure other problems. aparrently the MAF can give faulty readings but not always present an error code. please try it and let me know! try to drive without revving first. good luck.

[passatafn]

still working. new maf is 120 from vw. drives niicely enough with loads of power so gonna wait til we can afford new sensor.

[16vmini]

dug my camper out of hibernation after 3 years , surprise surprise i still have same issue ..

now i am trying to track down a pinout for the ECU , anyone point me in right direction ... lost all my info from back then.

[syncroandy]

Mon Sep 23, 2013 5:49 pm:

If you have no functioning brake signal to the ECU, you'll get no engine braking (fuel shutoff) assistance when you want to slow down. I don't know how bad the effect on drivability would be, I don't particularly want to try it. As regards your problem, you need to get VAGCOM on there and check each ECU input/output is within normal parameters, and deal with it accordingly. I don't see what cruise control might have to do with it, you'd have to (a) have it fitted (b) switched on, and (c) be moving at 30mph+ for it to be doing anything.

PS. For a start download the free version (VCDS Lite) and use a cheap Ebay cable. Lots of good TDI resources out there to help, if you look. eg. Rosstech wiki, Tdiclub, Myturbodiesel.

[16vmini]

ok , its coming home this weekend , so will try again lol