[tuxfour]

Been having an increasingly serious hard starting issue. I've been working on narrowing it down. It doesn't seem to be an air leak as I don't see any significant air in the lines and it doesn't seem to be related to how long I leave the car. I can shut it off and try to start it immediately and its just as hard to start. 5-15 cranks instead of 2 like it used to be. Timing is in spec but very close to the advanced line.

Tank is clean(looks brand new inside)
brand new sending unit
Blew out fuel lines
brand new filter and thermo T
pulled the pressure relief valve out of the IP and the guts had come out. reassembled and re-installed
just did the timing belt. problem started before that so that didn't cause the problem though it didn't fix it either

I just recently discovered my IQ is reading around 7. Not sure if thats my problem but I'll be mechanically adjusting it this weekend. I was able to get it to 6.5ish through VAG. I did notice my IP is pretty dirty on the outside and i'm thinking maybe I have a minute leak of some kind thats only recently gotten bad enough to cause starting issues. Car's a bit of a dog but otherwise runs ok. Would a tiny leak cause starting issues that quickly after shutting down? Regardless I'll be replacing whatever seals I can get to as well as the fuel temp sensor when I adjust the IQ.

Full disclosure: I run a two tank WVO system. what really has me baffled is that the car starts fine if I leave it on veg and stop and start it but with diesel in the pump it has a problem. I'm leaning toward the higher viscosity of the veg keeps the tiny leak at bay but when I have diesel in the pump the viscosity is low enough to allow the leak to effect starting. I only run veg well heated so we're not talking thick but even hot i'm sure its not as thin as diesel. I originally thought it was the difference of the veg vs the diesel side of the system but after putting diesel into the veg side I'm having the same issue on that side pointing me to the fuel type itself.

any thoughts?

 

[chittychittybangbang]

How did you notice the IQ so high? So you could only adjust it down to 6.5 through vag com?

A tiny air leak can cause air to get in and although the pump is self priming, it take a while for trapped air to get out. did you check the fuel return lines?

Why replace the fuel temp sensor? I don't think it will cause this problem.

It's possible the WVO has coated the pump and is causing internal problems. Maybe the quantity adjuster arm is sticking?

Any other posters take note that we're here to help and not to scold

 

[Keithuk]

offtopic2

Wook60 - Car: 2001 doesn't tell us much with all those mods?

 

[tuxfour]

chitty,

I've been trolling around and had come upon a thread mentioning an IQ higher than 6 on a stock car could be a cause of starting or low power problems so I hooked up the old vag com to check it out. last night when I check it it actually read 11 but the car wasn't totally warmed up. I stopped halfway to work this morning and checked it. That's when it read 7ish so I dialed the number up (to bring the IQ down) but it would only get me as low as 6.5ish. The value was stock (32768) btw. How much are you normally able to adjust via software?

both fuel return and feed are virtually air free and if I leave it overnight the amount of air in the lines doesn't increase or anything. I have a clear inline filter on both the feed and return mainly to look for/collect air.

I've read that a faulty fuel temp sender might cause fuel delivery problems but mainly I'm replacing it since I'll be in there reaplcing seals and such and its only $20.

While i'm in there changing seals I'll take a good look at the IP internals for signs of gumming up.

A little background: I've had the car since 45K (180K now)and have been running WVO for pretty much the whole time. I focus on getting the veg very clean and water free before it goes in the car. I monitor multiple temps in the car so I don't switch over too early and so I know my temps are nice and high at the IP. I also have a vac guage teed off the fuel line so I can tell if the veg or diesel fuel filter is starting to get restricted. I pull more vac on the diesel side than the veg by the way. I haven't had any problems thus far other than the usual TDI stuff. I just recently did my second timing belt job. The original owner had the system installed. i've changed it quite a bit but I can't speak for her WVO practices so for all I know some pretty nasty stuff was used before I took ownership. Still I've gotten almost 140K out of it without major issues.

I had an air leak about a year ago (thermostatic Tee) and it would take an hour or more of sitting for a hard start to occur. This is causing a hard start almost immediately after shutting down. the fuel isn't draining back to the tank but I suppose if there's a small leak in the IP that right after shutdown the fuel in the IP itself might leak air causing a small loss in prime. We're not talking about one of those "I'm not sure its going to start" cranks. just about 3-5 times longer cranking than normal so the pump doesn't loose that much prime if that's the problem. I also haven't seen any liquid fuel anywhere around the IP so i'm thinking its an ingestion of air rather than a leaking of fuel.

Thanks for the help ahead of time by the way. I fully expect some abuse for using WVO and I'm not looking to argue for or against. From a purely technical standpoint what else could this be?

 

[chittychittybangbang]

Other than some engine management problem like a bad ECU or wiring problem to the pump, I don't know. If you said it was related to power problems I'd say check the MAF. It's possible there's some nozzle or injector problem but that will not cause the IQ problem. At this time my suggestion would to do the hammer mod and see what happens. It won't hurt anything.

 

[tuxfour]

Ok I'll try that tonight. I'll just be loosening up the bolts and doing the mod without putting in the new seals. I don't want to get into all that on a week night. I'll do the whole thing over again this weekend but I can't wait till then to see if the hammer helps.

thanks again

 

[tuxfour]

well the hammer definitley helped with the performance of the car. much less of a dog now. once I get the starting issue sorted out I'll be looking into unsticking my turbo vanes. Too soon to tell if it fixed the starting issue though.

I currently have about 2/3 diesel 1/3 wvo in the veg side and the car will start fine on that. Still seems to have issues starting on the diesel side. I'm still not 100% convinced that its the fuel type and not just a leak somewhere yet to be found on the diesel side. once I use up the veg tank and fill it 100% with diesel I'll find out if the car has problems starting on diesel fuel or just on the diesel side of my system.

another thought. could one of the QA seals degrading have caused the IQ to change dues to settling or something? The car's never been super responzive so I'm not sure the IQ hasn't always been high but I'll never know.