CedarAudi

Could a faulty purge valve also be the cause of a code for a large leak by the leak detection pump? Any help would be appreciated. I have been fighting this problem for about a year. Hard starting, not starting, flooding, etc.

77'911

You might post more info, like the year, mileage, and some of the maintenance history. First, if you've not changed the fuel filter in the last 30k, then its time. I would also recommend the following:
-replace pcv and suction valve in crankcase ventilation system
-clean out thottle body
-hook up VAG-Com to check out running values and factory codes
-if its been flooding, change out the plugs(copper NGK, std oem)and oil.
-install new fuel injector o-ring seals(upper and lower, ie qty. 12)
-check battery integrity/quality as well as load and no-load conditions for the alt.
The above mentioned items are where I would start.

CedarAudi

The question was can a faulty purge valve cause the OBD to throw the CODE for a large leak from the LDP.
I appreciate your response however I cannot ascertain how it pertains to my problem.

98 A4, 2.8 30 valve, 140K, maintenance perfect. Car runs great once it starts.

77'911

"Hard starting,not starting, flooding, etc." were your words, not mine. Sometimes an evap code is nothing, the parameter gets tripped and a DTC is posted into the ecu. A faulty purge valve can throw a number of different codes.You can erase it with a VAG-Com and go your merry way. Its seems you've probably got a gross vaccuum leak for starters. The car is not getting proper air or fuel mixture on start-up, which can be related to the evap system having a leak or a number of other issues, especially with a car at 140k. I think you've got more then one issue working here. My suggestions were to help narrow down causality. You might consider picking up a factory manual to go over the evap diagram. You have not mentioned the specific code which would help. I would not trust one out of a standard OBD reader as they won't, and can not read or interpret the factory specific codes which a VAG-Com will.

CedarAudi

I appreciate what you are saying and it is very valid, however I have been dealing with this for a year and have done virtually everything you mentioned. I was asking if a faulty purge valve can cause an LDP code, because they are both part of the same system and both can impact starting. The main reason I started looking into the evap system is that EVERY time you get gas it is very difficult to start. Starting on a daily basis, this only occurs, maybe twice a week. This is accompanied with huge clouds of white smoke and the accompanying smell of gas.

I have a factory manual and as far as diagnosis is concerned I find it virtually worthless.

The codes the car threw were PO455 and PO441. I trust these are not transient codes since the cars behavior is indicative of a problem in this system.

I have checked the system for actual leaks with no success.

I would prefer not to replace components that are functioning. Therein lies the reason for my question. Can a malfunctioning purge valve cause an LDP code.

Again thank you for your input

FlashA4B5

Hello,
Had the same hot start problem and when filling the gas tank full. No check light for about a year until about Feb. Got codes:
P0455 evap large leak
P0441 evap flow faulty
P1138 bank 2 too lean
P1136 bank 1 too lean
Changed purge valve and both pre-cat O2 sensors. It's been a couple of weeks and no check light and no codes showing; and best of all so far on fill or hot start no issues.
CedarAudi - the purge valve is a real inexpensive change (about $80) so worth it to try this swap to see if it fixes the problem (codes 455 and 441 on searches people have indicated this is the problem).
But, the Evap test for the scanner is still not complete. I'm trying to figure out what scanario I need to go through to have the Evap test complete so I can run through air care emissions tests. Anyone know what conditions the car needs to go through to complete this test?

98.5 A4 2.8QT

Geoffrey Bove

I got the exact same code combination on my 1998 A4 30V...... I took out the charcoal canister and the aluminum adapter to the tank hose was corroded. I cleaned the inside of the hose, put some sealer on it, and used a wide stainless hose clamp. Bingo, no codes. Did I get lucky or should we look for these little things?