# ATQ hard to start only when hot!!! Reward!!!



## scottp (Aug 13, 2007)

2002 passat ATQ
It is hard to start only when hot. Any ideas???
I will send whoever figures this out a $50 Gift certificate (for whatever) for whoever figures it out!!!!


----------



## chudzikb (Sep 21, 2000)

*Re: ATQ hard to start only when hot!!! Reward!!! (scottp)*

Try a new fuel pump and regulator? Somehow you are not getting fuel up there? We need more information? Do you smell gas when cranking the motor? Can you pull a plug and check and see its condition when the non start condition is occurring? Any codes? Heat can affect many things...


----------



## scottp (Aug 13, 2007)

*Re: ATQ hard to start only when hot!!! Reward!!! (chudzikb)*

I have lots of codes, I get the usual secondary air codes (not enough flow) I also get catalytic converters below efficiency (both banks). 
I don't think they are related. I have not tried any new parts related to fuel system. Sometimes I notice the smell of gas after a hard start. 
I would love to install a fuel pressure gauge, but there isin't a test port (like on north american cars)
How does the in tank regulator work? Is there a vacuum line from front to back?


----------



## chudzikb (Sep 21, 2000)

*Re: ATQ hard to start only when hot!!! Reward!!! (scottp)*

There is a fuel pressure regulator present on the fuel rail, it can be tested to see if it is getting presure or releasing it. Probably not the problem, but, a good place to start with fundamentals.


----------



## Bboble (Mar 19, 2002)

*Re: ATQ hard to start only when hot!!! Reward!!! (scottp)*

Coolant temp sensor... The one thats impossible to get to bellow the intake boot!


----------



## scottp (Aug 13, 2007)

*Re: ATQ hard to start only when hot!!! Reward!!! (Bboble)*

I took that off. It was held in by a crummy plastic clip. Any ideas what could be causing this?


----------



## Bboble (Mar 19, 2002)

*Re: ATQ hard to start only when hot!!! Reward!!! (scottp)*

Bad coolant temp sensor will cause an improper mixture setting for a warm engine. Will run it too rich as if it were cool. If its black, replace with updated green sensor. A new o-ring, crummy plastic clip, and sensor should run less than 20 bucks...
Much luck!


----------



## scottp (Aug 13, 2007)

*Re: ATQ hard to start only when hot!!! Reward!!! (Bboble)*

I hace already replaced a green sensor with another green one.


----------



## spitpilot (Feb 14, 2000)

*Re: ATQ hard to start only when hot!!! Reward!!! (scottp)*

Issues with hard start when hot can be often caused by "vapor lock"..fuel boiling in the lines..VW has had various methods of maintaining pressure for a period of time after shut down to help prevent this from happening. In the ol CIS daze it was a spring loaded "fuel accumulator" that kept pressure on the system for 10min or so after engine shut down to allow FI system to cool a bit and avoid boiling the gas in the lines...I'd bet there is something similar in the Passat's FI system. As far as your CEL for secondary air injection "low flow"..look to the little cloth covered vac lines and the fittings on the Kombi valves (VW has a kit to replace all the stuff on the Kombi's..new beefed up vaccum elbows, hard lines etc. so I know they've had problems here and have upgraded the parts). I had this problem and after changin out all the little vac hoses (2 meters will do the V6) CEL went away...if you leak vaccum the Kombi valves don't open all the way...or if leak is bad enuff..at all and you get restricted air flow and the "low flow" CEL. Also check out the little one way vaccum valve (looks like a drip irrigator up near the "vaccum relay plate" on the engine top..mine was brittle and cracked as well as the hoses so when I tried to remove the little hoses from it..it broke in half!







All the engine heat on these hoses takes its toll! Good luck on the hard starting issue! http://****************.com/smile/emthup.gif
Looked in the Bentley...gthe residual pressure is supposed to be 2.2bar (about 30psi) after 10 min..."if residual pressure falls below 2 bar they give you a test sequence with the VAG 1318 gauge set up to determine cause...listed components that may cause loss of residual pressure..
fuel pump check valve
fuel pressure regulator
leaks at injectors, orings in the fuel rail/injector connections
The order of causes is pump valve, regulator then leaks....if you can't run the detailed test sequence..I'd replace pressure reg first..its the cheaper than the pump..and see if that fixes the problem! let me know if I get the "reward"!










_Modified by spitpilot at 10:40 AM 8-19-2008_


----------



## scottp (Aug 13, 2007)

*Re: ATQ hard to start only when hot!!! Reward!!! (spitpilot)*

Any suggestions on how I can monitor fuel pressure after shut down? Should I try to heat wrap the fuel rail?


----------



## spitpilot (Feb 14, 2000)

*Re: ATQ hard to start only when hot!!! Reward!!! (scottp)*

The Bentley has a proceedure..of course it requires the VW gauge set up I mentioned above...I made one once outa 1/4" tubing fittings and a water pressure gauge for $10 or so...basically its a gauge and valve set up that allows you to montior pressure while car is running and then watch it after shut down.... http://****************.com/smile/emthup.gif


----------



## spitpilot (Feb 14, 2000)

*Re: ATQ hard to start only when hot!!! Reward!!! (scottp)*

I doubt heat wrappin the fuel rail will help much if the residual pressure isn't holding at all....I notice you're in ON...summer just pasted there right..wasn't it last Tuesday?...














You could just drive the car in the cool months...and walk the other few days of the year..just kiddin...I think...














Only two choices to really address the prob...test and determine whether its the pressure reg or fuel pump that';s the prob....or go the path of least loss...replace cheapest part first (fuel reg is around $50 or so I'd bet) and then do the pump if that doesn't fix pressure issue. http://****************.com/smile/emthup.gif


----------



## scottp (Aug 13, 2007)

*Re: ATQ hard to start only when hot!!! Reward!!! (spitpilot)*

I suggested heat wrap so the rail wouldn't get hot enough to boil the fuel. Do you recall what type and size of fittings vw uses for their fuel supply to the rail? I will do exactley what you suggested to tesit it out. Mayby the problem isin't fuel system related. What do you think? Thanks for your help!!!


----------



## spitpilot (Feb 14, 2000)

*Re: ATQ hard to start only when hot!!! Reward!!! (scottp)*

Insulating fuel rail would be "iffy" as solution to problem...if residual pressure is failing and still has a way to drop...you might fix problem with the wrap...only to have it reappear...not sure what size fittings are on the Passat..I used my rig on my ol MKIII which had simple tubes and clamps for the fuel line hook up....you might have to hit the junkyards to pick up fittings..or jury rig a compression fit with rubber tubing..its only 30 psi we're not talking 100's or even 1000's of psi like hyraulic systsems here so some carefull planning could produce a work around the fittins...but I'd hunt some up for safety reasons!...oh and do this outside where you have plenty of ventillation...hope you can get it done B4 first snowfall..that's the 1st of Sept up there..right?


----------



## scottp (Aug 13, 2007)

*Re: ATQ hard to start only when hot!!! Reward!!! (spitpilot)*

I just put on my snow tires just to be safe







. 
I was working on the car (looking for oil leaks actually) and started it up and removed the oil cal and it almost stalled. It didn't do that before. What could cause that? Scarry








I won't sleep tonight. Any ideas would be great!


----------



## spitpilot (Feb 14, 2000)

*Re: ATQ hard to start only when hot!!! Reward!!! (scottp)*

I'd check for vaccum leaks...these engines have a s$*tpot full of little vac hoses and the get hot alot..so they crack and leak...if you haven't replaced all the vacc hoses do it! Vac leaks will cause weak mixture and cause engine to stall out...when you open the oil cap you only add to the problem since PCV system is suckin away on the crankcase and takin the cap off is a major vacc leak!...Hey where's my gift card????????







I still need $$ for swimsuits and suntan lotion down here! http://****************.com/smile/emthup.gif


----------



## scottp (Aug 13, 2007)

*Re: ATQ hard to start only when hot!!! Reward!!! (spitpilot)*

If the fuel pressure regulator is the problem you will get your gift card, or I'll shoot you some paypal If you use that. I don't hear any vacuum leaks. What is weird is that it is a new problem and it is severe. I would expect the IAC to kick up tyhe revs to help it stay alive. I'm going to buy a vacuum gauge so I can monitor vacuum and leak down of vacuum. 
Do you ues paypal? If so, include your address, so I have it.


----------



## spitpilot (Feb 14, 2000)

*Re: ATQ hard to start only when hot!!! Reward!!! (scottp)*

Just kiddin about the reward...I live by the "what goes around...comes around" motto...I've gotten a ton of advice, tips, tools etc over the years..(errr decades) and given...I hope...more back...hope my ramblins have shed some lite on your prob!!!


----------



## scottp (Aug 13, 2007)

*Re: ATQ hard to start only when hot!!! Reward!!! (spitpilot)*

Well I do respect that. I am the guy that keeps my word. I made a vacuum gauge so I can test things easily. 
My friend suggested that my hard start when hot could be a software that isin't up to date. Here is what I found on VAG COM. Do you know it it is all the latest versions?
Address 01
Protocol: KW1281
Controller: 3B0 907 551 CG 
Component: 2.8L V6/5V G 0001
Coding: 07551
Shop #: WSC 93913
Address 02
Protocol: KW1281
Controller: 3B0 927 156 AC 
Component: AG5 01V 2.8l5V USA 3939
Coding: 00104
Shop #: WSC 00028
Address 03
Protocol: KW1281
Controller: 3B0 614 111 
Component: ABS/ASR 5.3 FRONT D00
Coding: 00031
Shop #: WSC 00028


----------



## spitpilot (Feb 14, 2000)

*Re: ATQ hard to start only when hot!!! Reward!!! (scottp)*

I don't know anything about VAG codes etc...but I'd not think that a software issue would all of a sudden start causing a hot start problem...now a failing presssure reg and/or fuel pump check valve that gets some dirt in it causing it to fail to close all the way..those would cause a hot start problem to crop up all of a sudden. Get hold of a Bentley and look at the fuel system troubleshooting proceedures...bet if you can rig up a pressure gauge/valve set up like what is shown there you can pinpoint what the culprit is! http://****************.com/smile/emthup.gif


----------



## ronald1983 (Feb 15, 2009)

*Re: ATQ hard to start only when hot!!! Reward!!! (spitpilot)*

is the problem already solved?, i have the same problems on my passat v6 so maybe you can tell me what;s wrong?
hope to here , thank you\








[email protected]


----------



## Slimjimmn (Apr 8, 2006)

*Re: ATQ hard to start only when hot!!! Reward!!! (ronald1983)*

exactly what brand and model of spark plugs are you using?
pm me


----------



## ronald1983 (Feb 15, 2009)

*Re: ATQ hard to start only when hot!!! Reward!!! (Slimjimmn)*

i,ve the originel plugs from the factory. 
NGK 101000035hj r5 bkr6ekub


----------



## Slimjimmn (Apr 8, 2006)

*Re: ATQ hard to start only when hot!!! Reward!!! (ronald1983)*

when you rev the engine do the revs stay up or does it go up then down right away?
If the revs stay up slightly (like you are keeping the foot on the gas), Suspect the pcv valve is stuck. Its in the black plastic cross-over hose that goes from one valve cover to the other and the pcv valve is part of it and its the large 100mm circle thing next to the throttle body. Part is arround 80-100USD and it will most likely break when you remove it. 
Also when its warm does it crank and crank and crank, or does it crank and die and then crank then start?


_Modified by Slimjimmn at 7:26 PM 2-21-2009_


----------

