Hard to start when hot

Thanks, TornadoRed. These may be in the wrong order!
[image]http://pics.tdiclub.com/showphoto.php?photo=20914&password=&sort=1&cat=500&page=1[/image]
[image]http://pics.tdiclub.com/showphoto.php?photo=20916&password=&sort=1&cat=500&page=1[/image]
[image]http://pics.tdiclub.com/showphoto.php?photo=20915&password=&sort=1&cat=500&page=1[/image] [image]http://pics.tdiclub.com/showphoto.php?photo=20914&password=&sort=1&cat=500&page=1[/image]

What Now?

Jerry,

Thanks for your help!

Dave

Thanks (Dave and Jerry) for posting such nice photos and very complete instructions. My husband has already started on the project and I will post with results.

Thanks for the help & pictures. I picked up 10,000 ohms resistors at Radio Shack they came in a packet of five for 99 cents. I installed one as shown and no more CEL I have been looking at that light for a couple of years and really got use to it. Now I feel like something is missing. Engine fires up immediatly and always has since the switch was installed. Saves a lot of wear and tear on the starter.

Mod is done and so far everything is great. Thanks again.

Hi all...thanks a lot for this work-around. I totally agree with the fix, its just not worth it to keep fiddling with this darn hot start problem.

Just one question....is anyone positive it is the #3 connector? The only reason I question this is because of the photos above look like the sitch/resistor is going to the #2 connector. And, Hamman's description (upper right side of connector from drives perspective) would correspond to connector #2.

I could be totally missing something here so some re-assurance would be nice.

Thanks.

bumping

I am seriously going to have to consider this mod. My starting issues are driving me crazy.

I'm also having this problem, but the cause seems to be diffrent.

The tests revealed only .5 volts going to my glow plugs, instead of the required 12v. They traced it back, for whatever reason, there is 12 v going into the computer, but coming out to the relay, which in turn sends voltage to the glow plug, only .5 v comes out of the computer.

So, going to see a diesel guru tonight, in hopes he can figure out the problem.

I doubt the glowplugs have anything to do with it, the car would be well above 40degree', the glowplugs wouldn't even cycle.

I replaced my glow harness, my plugs and even adapted so they run longer. Starts *somewhat* easier, but not always.

It's also kinda random. Sometimes it's fine sometimes it not.
I'm starting to think some form of IP seal or siphon activity happening.

Ducati: I hope you know this, but the 99.5 cars are plagued with hotstart problems because of the code within the ECU. There is nothing that is going to fix it. A fresh battery and good starter will help, but you'll never get rid of the problem....

The only way I have found to get rid of this, was with a Rocketchip upgrade. Jeff starts out with the Euro code, which doesn't contain this problem. Something to do with 8bit start code, compared to 16bit in the Euro (I dunno, Jeff could explain better )

Ok..got home today, diconnected my ETS...car started right up, plugged it back in, cranked for 5-6 seconds......so, Hamman modification to be done...just one question Hamman, (might be a dumb one) when it's cold, do you still push the button in?

Thanks...Serge

Not usually, the original circuit is still in place when the button is
"up". I have used it though is chilly weather and the car starts
up a bit quicker.

Dave

Hamman said:

Not usually, the original circuit is still in place when the button is
"up". I have used it though is chilly weather and the car starts
up a bit quicker.

Dave

Click to expand...

Thanks...

Souzafone said:

Do a search, theres a huge thread on this already. Bottom line is all 99.5's in North America do it. The only way to resolve it is through re-programming. Mine is now cured.

Click to expand...

One guy already posted that he had his ECU reprogrmmed and now, he has no more hot start up problem. Hmmm, would like to know how one gets it reprogrammed?

Anyone know?

Serge

Hard to start when hot - Hamman Mod "Automated"

I am pleased to be a new member of TDIclub.com. I have owned my NB for a year now and this is my first experience with a diesel. I must say that out of all the forums that I have used, this one seems to have the most loyal VW owners that I have witnessed.

When I bought the car, the only complaint the former owner had was that the car was sometimes hard to start especially when it was hot.

I put up with this but figured that it was time to do something after throwing another P0380 code, believing that the hard starting and the P0380 were somehow related.

My 99.5 NB was about to get a bunch of new parts; battery, starter, glow plugs, glow plug relay, glow plug harness, $$$ etc...,

Then I signed up with tdiclub.com and came accross the Hammam Mod. I am no stranger to VW ECU's and wiring having performed several gas engine swaps.

I discussed the use of a push button with my wife and she didn't really get it. She drives the car more than I do, so I knew that for this modification to work, I had to automate the process so that she didn't have to worry about pushing a red button at the right time.

Today, I performed the modification but I substitued a simple relay for the prescribed red switch. I tied into the starter solenoid circuit as my trigger and it works. The engine isn't straining to start and there is no button to push.

I used this circuit as my trigger because I wanted to make sure that the 10k resistor was only active when the key was turned to "start".

Here is the wiring plan that I used:
1) Cut and connect the #3 wire (blue and brown or red) from the CTS plug to relay terminal 87a (Normally Closed).
2) Connect the other end of #3 wire to relay terminal 30.
3) Tap into the starter soleniod wire and connect to relay terminal 86.
4) Run a wire to a good ground from relay terminal 85.
5) Connect a 10K 1/4w resistor to relay terminal 87 (Normally Open) and then splice the loose end into the wire connected to relay terminal 30.

I hope this helps those who wish to tackle it.

The only question that I have is the effect on the starter solenoid performance with an extra little current draw to switch the relay.

PB_NB said:

Today, I performed the modification but I substitued a simple relay for the prescribed red switch. I tied into the starter solenoid circuit as my trigger and it works.

Click to expand...

Sounds great! Two questions. What kind of relay did you get to use? How did you find the starter solenoid circuit?

I'd love to have fast hot starts automatically -- just like it's supposed to be!

The type of relay is:

SPDT Relay : (Single Pole Double Throw Relay) an electromagnetic switch, consist of a coil (terminals 85 & 86), 1 common terminal (30), 1 normally closed terminal (87a), and one normally open terminal (87).

This is a very typical relay used to control fog lights and many other high power auto applications and can be found at The Source or Canadian Tire or any auto parts store. The numbers listed above will be stamped next to each of the 5 terminals.

As for the starter solenoid circuit, I went straight to the starter and taped into the small wire there. I didn't want to attempt to trace it through the harness as I haven't recieved my Bentley Book yet so I wanted to keep it simple.

Before I attempted this, I tested the results as per Hamman's original posts, so I disconnected the CTS plug and started the car. It cranked twice and started. I couldn't believe it was that simple to tell. However, I did get an error code P1256 which I have subsequently cleared.

This is a reasonable workaround to something that appears to be a software problem or mapping problem in the ECU.

I think I will persue a RocketChip as well.

Thanks for the extra info. I recognize the terminal numbers from when I added DRLs to my Audi (which uses the lower lights that they call fogs as DRLs). I knew it seemed familiar. Did you put it in something under the hood or is it just loose in there?

Had mine done about 3 weeks ago and it's great. I was going through a battery every 12-18 months and replaced my starter. I had mine installed behind the signal indicator so that its not visible when driving.

dataiv said:

Thanks for the extra info. I recognize the terminal numbers from when I added DRLs to my Audi (which uses the lower lights that they call fogs as DRLs). I knew it seemed familiar. Did you put it in something under the hood or is it just loose in there?

Click to expand...

I wrapped the wires and then zap strapped them to another bunch of wires to avoid the clutch and shifter congestion. I also supported the relay off the big black power lead to the left of the battery.

Also took the opportunity to clean up the ground connection under the battery tray while I was there.

Here is a diagram of the wiring that I used:
http://pics.tdiclub.com/data/uploads/69936/Graphic1.jpg

PB_NB said:

I wrapped the wires and then zap strapped them to another bunch of wires to avoid the clutch and shifter congestion. I also supported the relay off the big black power lead to the left of the battery.

Also took the opportunity to clean up the ground connection under the battery tray while I was there.

Here is a diagram of the wiring that I used:
http://pics.tdiclub.com/data/uploads/69936/Graphic1.jpg

Click to expand...

I suggested the same (a relay) a year ago in an earlier thread. (Your drawing looks much nicer than mine.) I personally think the Hamman Mod is the best way to solve the hot cranking issue using the starter relay wire eliminates the manual switch and everything can stay under the hood. Most any 12 volt DC relay will work.

Being a master mechanic (primary) with electrical/electronics secondary I don't have a problem with the fix. I'll be standing by for the Real Fix as I've also spend hours trying to solve the hot start problem and totally disagree with the old "It's the Battery", "It's the Starter", "It's the Cables", "It's the... Left Brake Pad".

Mike

MCathcart said:

"It's the Battery", "It's the Starter", "It's the Cables", "It's the... Left Brake Pad".

Mike

Click to expand...

I like your last resolution. You may be onto something with the brake pads!

Anyhow, I am hoping that I can get a Rocketchip type modification. I have contacted Rocketchip and explained what I would like to see in changes to the programming, i.e. remapped pump timing to aid in starting. I have not had a response yet, but once I do, I hope to have a better direction for this starting problem.

For now, I am glad that Hamman figured out and shared his CTS terminal #3 work around.

PB

Very interesting post. I like the mod. Esp making it "automatic" via the starting curcuit.

For purists, I like OEM anything/everything. If the issue is not sensor/timing/part related and is a software bug, then a $10 fix is in order. Especially when it comes down to buying those other expensive items (battery, starter, relays, relay harness, GP), that aren't fixing the (real?) issue.

I've got a similar start issue, though only when cold (50-60 degrees). This is a better band-aide to unplugging the temp sensor.

Thanks.

there's an easy fix to cold start issues, adapt your glow plugs to run a bit longer. I did this and resolved my problems right off.

I'm looking at this much like those with warm-start issues. My glow plugs aren't coming on yet and I've got an issue that isn't solved via the usual fixes. This would work well. Remember, I'm at 50+ degrees, so I'm above the threshold of them coming on (@40).

One question:
I am concerned with battery drain. It's one thing to crank the motor or have the glow plugs on. It's different to have them both going at the same time. Do the glow plugs stay on normally during cold (<40 degrees) cranking? Or only while the ignition is in the on position before cranking?

Maybe a manual momentary switch is better (turn ignition on, momentary switch for a few seconds, release switch, crank) rather than have the glow plugs on while cranking.

Possible side effects of constant cold starts ?

1.Higher fuel consumption, due to constant cold starts even when hot
2.Higher demand on Battery, due to glow plugs working on every start.
3.Decrease in glow plug life,
4.Potential clogging of manifolds due to richer mixture ( less air )
5.Potential electrical gremlins being introduced due to spliced cables
6.Any warrenties null & void


Just trying to look at the angles here !!!