TDI 115hp - "Hot Start" vs "Cold Start"

TDI 115hp - \"Hot Start\" vs \"Cold Start\"

Hi !
I noticed that my car starts easily when cold then whet its hot. Whe it is hot, it needs 3-4 secs or crank to start. When its cold, it starts almost immediately.

Is there a good reason for this or is this normal ?
I thought it may be caused by the glow plugs, but now I dont think tha anymore because even when I start the car ts in very cold weather the glow plug light "desapears very fast", which (I think) shows that glow plugs are fine.

Comments please.
hugs.

The car is a VW Bora TDI 115hp 100% Stock with 86000kms.

TDI 115hp - \"Hot Start\" vs \"Cold Start\"

maybe a dodgy temp sender, do you have access to Vag com?

TDI 115hp - \"Hot Start\" vs \"Cold Start\"

I recently had the problem on my jetta and replaced the battery, but still had the problem. Then i replaced the stater and that took care of my warm start problem, starts right up now hot or cold /images/graemlins/grin.gif

RIch

TDI 115hp - \"Hot Start\" vs \"Cold Start\"

I have exactly that same problem with 1 of my TDI's. I'm going to find out for sure what is causing this, once I get my new HEX-USB (soon, I've just been busy) I'll let you know what I find out. It's DEFINITELY not normal, because my other TDI's all start INSTANTLY every single time, warm or cold, they fire immediately.

One is a 98 A3 90hp TDI and the others are all A4 90hp TDI's.

A few years ago, I could tell you just about anything there was to know on the Turbo Diesels, I owned 100's of them, fixed em up, & sold em whenever I could find any. Completely re-built lots of older non turbo diesel Rabbits, Pickups (Golfs), a few 1.6 Turbo diesels practically from scratch, & installed 1 new 1.9 Canadian TD a 1981 Golf too. (we still own it)

However these newer computerized TDI's are completely different, & you can't do anything without an interface & a laptop. It seems 90% of the MONKEYS they have working for VW have their heads up their ass, so that's no good.

(thank you ross-tech because I would NEVER let any of them "ID10T" Mechanics working for a VW dealership touch my car or I wouldn't even own it)

The one I have with the problem starts pretty much right away when it's cold, but once it's at normal operating temperature... sometimes I have to sit there & crank, & crank, & crank & crank a L O N G time before it starts. It's very annoying, and it's not the battery or starter, it's cranking away fast as ever.

Logic & experience with the older mechanical pump Turbo Diesels has me feeling like it's not injecting fuel until later after I've cranked it several times, just as if I lost 12v power to that fuel stop solenoid in the top of the old non TDI mechanical pump models. It's something to do with the fuel temp or a sensor problem. I'm sure it's a minor thing which is easily fixed once I find out what the heck it is.

Anyone had this problem?

I'll find out one way or another.

TDI 115hp - \"Hot Start\" vs \"Cold Start\"

There have been a number of threads dealing with this problem.

In short, the underlying problem is that the ECU allows the engine to fire up only after the cranking speed has reached in excess of 200 - something rpm. The reason is emissions. The threshold is cleared by a new starter-new battery combination but apparently not by a huge margin. If you have an old starter and a weak battery, the engine might just not crank at enough rpm's to be allowed to start.
Due to the higher compression when warm, the starter has to work harder on the warm engine.

Hence, for some people (including me) a new battery fixed the problem, others needed a rebuilt starter.

I would suggest to clean the battery/car body ground connection (use some di-electric grease after), clean the battery terminals likewise, make sure enough distilled water is in all cells, charge the battery fully, and see if that solves your problem. The original batteries are reported by some people to cause trouble after as little as two to three years.

I had my battery load tested and the guy said that the voltage drop was still ok...well, it wasn't ok for the TDI.
While, at first, the problem was intermittent, then more and more pronounced when the car was warm, it finally refused to start when cold.

TDI 115hp - \"Hot Start\" vs \"Cold Start\"

Some diesels (although I'm not sure specifically about ours) have a feature that advances the timing when the coolant temperature is low to help starting. So, if your timing was already retarded, the coolant advance would bring it into "acceptable" range, but once the car was at temperature, it would no longer advance the timing.

Can you check your timing with VAG-COM, and see if you are extra retarded? (well, if your timing is extra retarded? /images/graemlins/wink.gif)

If it is, advance your timing, which is good for you anyway.

TDI 115hp - \"Hot Start\" vs \"Cold Start\"

Timing out of adjustment or temperature solenoid problem sounds right to me.

The starter/battery being the problem? I duno, that sounded good... could be...I'll have to check that. My Golf starts instantly cold or warm. My Jetta starts quickly when cold, not when it's warm. I have a feeling if I swap both the batteries and starters in each car with the other, the Golf will still start instantly and the Jetta will still not start when warm.

This would at least be an easy way to eliminate battery/starter theory before I get my HEX-USB going to check it out yes??