Hard to start when hot issue.....

DieselFumes

Veteran Member
Joined
Oct 18, 2002
Location
Greenwood, IN
TDI
2002 Jetta TDI
LNXGUY said:
I doubt your thermostat is bad.. If you aren't overheating, I wouldn't worry about it....
Depends on whether it's stuck open or closed. If open your coolant is constantly being cooled, hence the effect of using the heater causes the temp to drop and when not in use for it to rise. If it's stuck closed then your engine could overheat.
 

mailman

Veteran Member
Joined
Oct 30, 2002
Location
USA - CT
TDI
99.5 Black Jetta TDI
Reading through the old posts on this issue, it seems that the only sensible cause is that the 99.5 TDIs got stuck with some bum software. There seems to be two fixes ...

1. Chip the CPU - one option here is to load the European performance curves that give more power and better economy. An attractive option for $140 ... except that you will be without a car for about a week because the CPU has to be shipped out. Not liking that too much.

2. Hammond mod - $5 well spent. I realize that nobody likes to hack into their factory wiring, but I am slowly coming around and this does seem like the best option to me. Car remains operable, and it only costs $5.

I think I have another project to tackle over the holiday weekend .....

Keep up the great posts!! :)
 

richieracket

Veteran Member
Joined
Jul 27, 2005
Location
New Jersey Shore
TDI
2012 Jetta TDI , DSG
go for it--it has worked flawlessly for me ever since i did it 3 weeks ago. once in a while i forget to push the button when the car is warm and she starts the same old cranking stuff. push the button and it is instant start.
 

amgad

Veteran Member
Joined
Nov 27, 2000
Location
Marbella, Malaga, Spain
TDI
1998
The Hammond mod is always an option, that much is true...but is no one really interested in finding the real cause?

I would go for the starter motor. bypassing the engine coolant temperature sensor only gets the GP to work as if the car was cold and help a defective starter work easier.

Will get my starter stripped and reconditioned this week and will let you guys know.
 

richieracket

Veteran Member
Joined
Jul 27, 2005
Location
New Jersey Shore
TDI
2012 Jetta TDI , DSG
well, that's not exactly what the hammon mod does. gp's do not function when temp is below 42 (or something like that). when you push the button, you may instantly start the car---no waiting for the gp or anything like that. what the mod does do, by most of the accounts here,(and you are correct, no one seems to have figured out exactly what else it does) it changes the pump timing for that instant, creating an instant start situation.
anyways, for my taste, too many accounts here of guys throwing tons of money at the situation with no benefit. I took the high road.
good luck, and keep us posted.
 

amgad

Veteran Member
Joined
Nov 27, 2000
Location
Marbella, Malaga, Spain
TDI
1998
Took my old starter to a professional guy with starters. Not the one in the car now, but the replacement I had reconditioned from VW, and took out from the car because it started failing.


Anyway he said that it was perfect, cleaned and lubed it.

Will go in a couple of days so he can fit it in the car and remove the one i have know that doesnt start when hot, for analysis.

Will let you know.
 

mailman

Veteran Member
Joined
Oct 30, 2002
Location
USA - CT
TDI
99.5 Black Jetta TDI
This morning, the Hamman mod was successfully performed on my 99.5 Jetta TDI.

Field tested better than I expected. Today, during a warm start I held the button down while cranking and the engine barely turned over before springing to life. Before the mod, I would have been cranking 5-7 seconds. Quick warm starts ... this is exactly what I was shooting for. Thanks Hamman! :D

I chose to mount the button in close proximity to the ignition switch on the steering column plastic cover. That way, I can perform single handed starts by pressing the button with one finger while turning the key with the same hand. Works like a champ!

Really put my soldering skills to the test, though. Very tight quarters to solder in under the hood. You really gotta want it!

Thanks again, Hamman. :)
 

mailman

Veteran Member
Joined
Oct 30, 2002
Location
USA - CT
TDI
99.5 Black Jetta TDI
amgad said:
To everyone, changed the starter, works perfectly... for how long, dont know.

Someone else try...
Excellent ... I'm glad you solved your problem, too!

I couldn't help but notice that your profile indicates that you have a 1998 Golf IV TDI. Is that correct? Did VW market fourth generation Golfs in 1998?

I'm thinking your problem was different than that experienced by the remaining 99.5 TDI owners. Just a hunch.

Anyway, congratulations on your fix!

Hamman mod has been working flawlessly for my 99.5 TDI! :D
My problem definitely was not related to the starting system. My engine cranks over fine ... it just wasn't starting! My starter and battery are in good condition. It is definitely injection timing related ... glow plugs can't be helping because they don't have time to warm up. I mean, I hit the button while cranking and the engine now instantly springs to life. Very dramatic difference compared to before the Hammam mod.

Keep up all the great posts!
 

amgad

Veteran Member
Joined
Nov 27, 2000
Location
Marbella, Malaga, Spain
TDI
1998
mailman said:
Excellent ... I'm glad you solved your problem, too!

I couldn't help but notice that your profile indicates that you have a 1998 Golf IV TDI. Is that correct? Did VW market fourth generation Golfs in 1998?

I'm thinking your problem was different than that experienced by the remaining 99.5 TDI owners. Just a hunch.

Anyway, congratulations on your fix!

Hamman mod has been working flawlessly for my 99.5 TDI! :D
My problem definitely was not related to the starting system. My engine cranks over fine ... it just wasn't starting! My starter and battery are in good condition. It is definitely injection timing related ... glow plugs can't be helping because they don't have time to warm up. I mean, I hit the button while cranking and the engine now instantly springs to life. Very dramatic difference compared to before the Hammam mod.

Keep up all the great posts!
4th generation golfs have been marketed since Nov 1997, mine is october 1998. With respecto to the starter, my old starter seemed to start fine too, but its not until you change it that you notice the difference.


Anyway see what the rest of you guys can come up with.
 

VWZapper

Active member
Joined
May 11, 2001
Location
Blairstown, NJ
TDI
1999.5
mailman said:
Am I the only one who is noticing that every post about the hard starting when warm has a 99.5 model?

I'm almost certain it is a timing advance issue, and maybe the 99.5 models got stuck with an old software rev that was updated for the 00 and up models.

Just a theory.
Yes, I also have a 99.5 Jetta TDI with the same annoying long crank to start when hot. It did seem to get gradually worse over time. The car is running with the fuel injection advanced (above the graph) and I was considering changing the timing (I have Vag-Com). I will probably change it anyway, but I like the Hamman mod. I have been dealing with it for deals. I have a 1000CCA battery and I believe crank speed is fine.
 

MCathcart

Veteran Member
Joined
Apr 18, 2001
Location
North Myrtle Beach, SC
TDI
2003 Jetta
I hate to bust a bunch of bubbles on this but my 1998 has the Exact Same Problem (so it's not just 99.5's but I'd guess 99.5's and Earlier). I tried disconnecting the coolant temp sensor and it made no difference on my '98 Tdi. We have a '00 Jetta and if you just Bump the Starter it's RUNNING! Some pretty funny ideas... I'll say that and I'm totally tired of the "It's the Starter... It's the Battery" answers. A higher Amp battery will Spin it Faster and yes it will Crank Better but It Ain't Fixed!

Since disconnecting my Coolant Temp Sensor did help I hate to do Herm's mod.

Mike
 

tdi_greendale

Well-known member
Joined
Jan 18, 2004
Location
West Boylston, MA
TDI
1999 Jetta Silver
I have a new battery and starter. Try the temp sensor disconnect. Starts ok in the morning now. Let it sit while I am at work, its fine. If I drive around, stop and then try to start that's when its hard. My father's symptoms are a little different
 

No Exit

Veteran Member
Joined
Mar 29, 2006
Location
Herndon, VA
Add me to the list... 99.5 with a ~4 second start time when warm. The car has 185k miles on it and has probably had this problem for a while. The previous owner mentioned something and threw in the new glow plugs he bought for the car.

I'll be going the chip route... and then injectors... which will lead to a new clutch. If that doesnt do it, I guess I'll have to spend the extra $5 for a button. Wondering if you could wire it to your clutch... you gotta step on that anyways to start up the engine on a 5sp . The button idea is kinda cool though... sort of like a theft deterent.

Edit:
mailman said:
Am I the only one who is noticing that every post about the hard starting when warm has a 99.5 model?

I'm almost certain it is a timing advance issue, and maybe the 99.5 models got stuck with an old software rev that was updated for the 00 and up models.

Just a theory.
So much info, so little time...

compu_85 said:
Yep... the ECU from the 99.5 is actually a US spcific piece of hardware... it's missing the pins for the immoblizer. It's incompatable with everything but 99.5 US spec cars (unless you do some rewireing)

-Jason
from this thread http://forums.tdiclub.com/showthread.php?t=136262

Might be something to that software theory...

So... if the chip only works in the 99.5 car does that mean that the car will only work with that chip? OR can we put a newer chip in the 99.5 car?
 
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chromeBuddha

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Joined
Jun 30, 2006
Location
Arlington, TX - DFW metroplex
TDI
2002 Golf TDI manual
'02 Golf with Hard Start

I recently bought a 2002 Golf TDI. The car has 80K miles (due for TB) and gets 47mpg hwy @ 75mph, about 36 mpg in 80/20 city/hwy. The car starts great when cool, hard when warm after a rest of 5-55 minutes. Having bought the car used, I am not sure of the maintenance history. I have done an oil change, will do a fuel filter change shortly...

I will check out the ETS disconnect next time I have it warm...

Other stuff I need to do:
Intercooler flush
Intake clean

Also, as a person new to TDI, I have read about people enjoying the sound of their turbo when they let off the gas...but I hear nothing. Is no noise a problem???
cB

P.S. I am located in Arlington, TX (DFW). Average air temp 95 F these days.
 
Last edited:

MCathcart

Veteran Member
Joined
Apr 18, 2001
Location
North Myrtle Beach, SC
TDI
2003 Jetta
chromeBuddha said:
Also, as a person new to TDI, I have read about people enjoying the sound of their turbo when they let off the gas...but I hear nothing. Is no noise a problem???
cB
I have to open the door open to hear the turbo. I'm a ex-biker and muscian and after toooo many live rounds I can't hear some things but I can tell you this when the Turdbo stops doing it's thing... I can Feel it!:D

Captain Mike
 

Ker

Active member
Joined
May 15, 2006
Most irritating...

Same same here.. car starts like its taking eternity and beyond to start when HOT.

Got a NB from 99 engine ALH (european).

I mean c'mon its a diesel engine fcs.. it should start faster when its hot! No!?
Anyway ive been reading trough this topic, and the hammon mod is a excelent bypass! Thanks for that!

But isnt there a software tweak... in like tricking or programming the ecu to always lit up the glowplugs when the egnition key is turned..?
What disadvantage would that have..?

And i read chiping the car resolves the situation also..? Any experiences on that..?

ps: i am a freshman
 

CraigM

Active member
Joined
Jun 15, 2006
Location
Scotland UK
TDI
Alfa Romeo 156 JTD
I have a 1999 Bora which had the same hot start problem - it would start fine when cold, but would turn over for 5+ seconds before starting when hot. The problem was caused by a faulty crank angle sensor which was replaced and it has started perfectly when hot since.
 

Ker

Active member
Joined
May 15, 2006
Crank Angle Sensor??

Hi CraigM thanks for posting youre reply. What is this Crank Angle Sensor..?
Do you have any info, price etc on this part..? It would help me (us) allot! Cheers!

Greets,
Ker
 

CraigM

Active member
Joined
Jun 15, 2006
Location
Scotland UK
TDI
Alfa Romeo 156 JTD
Sorry, I don't have any info on the sensor as it was replaced on mine by the garage who sold me the car - the guy told me that it was the crank angle sensor that needed replaced to cure the hot start problem.

The only thing I can find listed anywhere is the crank position sensor which may be the same thing??? Go to http://www.rockauto.com and have a look at the parts catalogue - VW> 1999> Golf TDI> 1.9 TDI> Ignition you will find the "crankshaft position sensor" listed there.

Not sure if this is the same as the crank angle sensor - but seeing as it is listed under "ignition" it may well have something to do with the starting of the engine?
 

chromeBuddha

Veteran Member
Joined
Jun 30, 2006
Location
Arlington, TX - DFW metroplex
TDI
2002 Golf TDI manual
I think I originally mis-diagnosed my problem. It isn't that it starts hard...it's that it cranks quickly, seems to come to life, then dies after a couple engine rotations... The last time it happened I noticed that the symbol on the dash with the silouette of the car with a key in it was on...Imobilizer??? Since I noticed that I have started waiting until that goes out before cranking the car over... Haven't had it die yet.

Does anyone know what would be causing the Imob to have a delay???

Thanks for any info.

chrome
 

Ker

Active member
Joined
May 15, 2006
Thanks allot CraigM!
The part youre talking about should be looking like this here right? I think the "gas" version is called crank angle sensor, and the "diesel" version is called crankshaft position sensor or sumthing..??

Thats the only comparison i can come up with. :D Thanks allot anyways.

@ chrome i am sorry cant help you on that one m8. Good luck!
 

rskovira

Active member
Joined
Feb 13, 2003
Location
Carlisle, Pa.
TDI
Jetta 2000 green
Hard starting issue

Typical problem with hard starting when hot. Unplug coolant sensor and it starts as soon as you touch the key. Relaced the coolant sensor and same problem. My question is what would happen if you just leave the coolant sensor unpluged. Does the GPs stay on or not?
 

Ker

Active member
Joined
May 15, 2006
I think thats a bad idea. If the ecu thinks that the engine is cold all the time, it will drasticly effect you MPG's.
When the engine is cold it injects more fuell to the engine untill it reaches running temp.

Besides that i think it will throw an error code, and maybe even a CEL. So in short not advisable.

Lets see what others have to say...

Greets,
Ker
 

bam_bam_dip

Veteran Member
Joined
Nov 17, 2004
Location
Belton, TX
TDI
99.5 Jetta TDI GL
Camshaft Position Sensor

Camshaft Position Sensor
This is interesting. Could this be the holy grail for the 99.5 hard start???

Though searching does reveal some hits on this sensor. I haven't seen many that list hard starting when warm as a symptom.
I, too, am growing tired of the 5+ sec crank. I've been lurking for a while on just about every hard start thread. The hamman mod, while interesting does not solve the problem, but it is a good work around.
 

Herm TDI

Vendor
Joined
Nov 21, 2001
Location
Richmond, Maine...The far side of Witsend
TDI
2002 Golf GLS Malone Stage 3, P+520 nozzles, 11MM Inj pump, Sachs VR6 clutch, Stelth Race Pipe, Immo Deleat, EGR Deleat
ta79pr said:
where is that sensor, behind the balancer?
Has anyone changed one?
This sensor (038-907-319) is located on the front of the engine block down in the area of the oil cooler.
 
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