dead throttle pedal???

richy · 04-06-15, 08:55 AM

Any one know how to cure the dead throttle pedal problem on my 1993 Audi 80 TDI 1.9 with a 1z engine ? Dip clutch pedal & allow to return to idle & it's all ok again. Doesn't happen all the time & obviously only when driving , can go for weeks with no problem then just do it for weeks. Replaced pedal actuator unit when it first started but this did not cure the problem.Been doing it for 4+ years now just would like to know why......

msh · 05-06-15, 07:36 AM

What does mean "dead"? No response at all or limited response?

I haven't experienced it by myself, but due to local diesel craze around credit crunch, there were a lot of TDI swaps into other cars, and some less careful owners/builders ran into problem with something like that, where engine barely responded to throttle. Reason was simple - they figured that TDI engine management requires brake and clutch pedal switches just for cruise control functionality, and they thought "hey, I don't need that, I just want to drive pedal to the metal!" and they left them out. But in reality TDI ECU uses them also for throttle pedal self diagnosis, so, if you're not using brakes and clutch, you're not driving, so if the throttle pedal still changes it's position, it has malfunctioned, and so limp home mode is to limit response to throttle in order not to endanger others on road and engine as well...

If you can connect it to PC, check if the ECU sees clutch switch, brake pedal switch and brake light switch. If you can't, remove them, take them apart, clean the contacts and afterwards, after putting them back, make sure that they are actuated.

richy · 16-06-15, 09:06 AM

sorry for the late reply, what I mean by dead throttle is no response/action, it seems that when coasting/foot off throttle injection is stopped until you reapply the throttle or engine rpm drops below approx 1100 rpm.So driving at 40 mph remove foot from throttle no injection then when throttle re applied injection starts again as normal but on mine this does not always happen so dip the clutch,rpm drops to 1100 rpm & injection restarts & driving returns to normal,there is a slight alteration to engine noise when injection restarts (running lean for a second is my best description) but this problem does not always happen.
To connect to pc do you mean via vagcom?
puzzled Rich ............

Tubsport · 11-11-15, 04:41 PM

Could it be a brake switch problem - if you drive with power on, and press the brake with left foot holding power on, the throttle will cut out as a safety device, could it be that your brake light switch sometimes holds on when you are not pressing the brake pedal, causing the lack of throttle??

11-11-15, 04:41 PM	#4
Tubsport Grown up member Classic Audi Club Member Join Date: May 2010 Location: Haywards Heath, West Sussex Posts: 69	Could it be a brake switch problem - if you drive with power on, and press the brake with left foot holding power on, the throttle will cut out as a safety device, could it be that your brake light switch sometimes holds on when you are not pressing the brake pedal, causing the lack of throttle?? __________________ Type 85 80 quattro hillclimb car 10vt power VW T5GP 2700 Bluemotion work mobile BMW E46 330d sport touring manual - FOR SALE!!!! (well, its not got 4 rings!!) A4 2.8 avant quattro daily - Written Off 100 avant quattro auto 2.8 - Sold 100 avant 2.6 - Scrapyard/Written by lady with no eyesight VW Golf mk2 - 1st Car - Sold far too cheap!

05-06-15, 07:36 AM	#2
msh 4 ring whore! Join Date: Jun 2008 Location: Rucava, Latvija Posts: 3,816	What does mean "dead"? No response at all or limited response? I haven't experienced it by myself, but due to local diesel craze around credit crunch, there were a lot of TDI swaps into other cars, and some less careful owners/builders ran into problem with something like that, where engine barely responded to throttle. Reason was simple - they figured that TDI engine management requires brake and clutch pedal switches just for cruise control functionality, and they thought "hey, I don't need that, I just want to drive pedal to the metal!" and they left them out. But in reality TDI ECU uses them also for throttle pedal self diagnosis, so, if you're not using brakes and clutch, you're not driving, so if the throttle pedal still changes it's position, it has malfunctioned, and so limp home mode is to limit response to throttle in order not to endanger others on road and engine as well... If you can connect it to PC, check if the ECU sees clutch switch, brake pedal switch and brake light switch. If you can't, remove them, take them apart, clean the contacts and afterwards, after putting them back, make sure that they are actuated.

16-06-15, 09:06 AM	#3
richy Grown up member Join Date: May 2013 Location: Isle of Man Posts: 53	sorry for the late reply, what I mean by dead throttle is no response/action, it seems that when coasting/foot off throttle injection is stopped until you reapply the throttle or engine rpm drops below approx 1100 rpm.So driving at 40 mph remove foot from throttle no injection then when throttle re applied injection starts again as normal but on mine this does not always happen so dip the clutch,rpm drops to 1100 rpm & injection restarts & driving returns to normal,there is a slight alteration to engine noise when injection restarts (running lean for a second is my best description) but this problem does not always happen. To connect to pc do you mean via vagcom? puzzled Rich ............