# Hard starting when cold on '91 Jetta Digifant II



## Caleb (May 19, 1999)

I have a '91 Jetta with the 1.8 8v Digifant II engine. It starts hard when cold. It seems to crank a little slow and initially doesn't act like it is hitting on any cylinders then after several seconds of cranking it will start to hit on about one cylinder. After several more seconds it will hit on a second and then fire up not long after that. The cranking speed seems to increase once the engine starts to fire on at least one cylinder. It is not the starter causing the slow crank I think it is some sensor or something not giving it enough fuel. It acts like the mixture is lean when it is cranking.
So far I have checked the fuel pressure. Both operating pressure and residual pressure. All pressures are very good. No problems there. Even holds 12 psi when left to sit overnight.
I have found and fixed a vacuum leak at the ISV. Also fixed an exhaust leak at the cat.
I also swapped coolant temp sensors with a known good one and it make no difference.
The car will not do this when warm. When warm it fires right up no problems. Only when cold is it a problem. Mainly when sitting overnight and first start up in the morning. It always starts but it just starts very hard. I have many used parts around the house so I don't mind swapping a few parts as a quick check but I am not sure where to even start.


----------



## mk2gtilover (Dec 5, 2007)

sounds like a weak starter and or a weak battery, cold sucks the cranking amps out


----------



## Caleb (May 19, 1999)

*Re: (mk2gtilover)*

Starter is new and battery checks out fine.


----------



## mk2gtilover (Dec 5, 2007)

might seem obvious, but possibly a loose or coroded ground.


----------



## Caleb (May 19, 1999)

*Re: (mk2gtilover)*


_Quote, originally posted by *mk2gtilover* »_might seem obvious, but possibly a loose or coroded ground.

But if that was the case why would it be fine when warm. This is just when cold. Like if the car sits overnight. A ground would be all the time.


----------



## Peter_M5 (Jan 16, 2005)

bump because i have the same problem
except mine is probably the starter...still working on ruling it out. May I ask how do you know your starter is good did you take it out and test it with some jumper cables?


----------



## Caleb (May 19, 1999)

*Re: (Peter_M5)*

I took the car in on trade from a customer of mine a few days ago. I know that before that several months ago he replaced the starter. I am assuming it is good based on that. And the fact that the car acts 100% normal when is it not stone cold. I don't figure it would act up when cold but not warm.
Also the engine is clearly not hitting on any cylinders when first cranking then it begins to hit on one then two cylinders. The starter would obviously not be the cause of that. I am thinking the the slow cranking is a result of what this causing that problem.


----------



## pewpewlasers (Jun 12, 2009)

*Re: (Caleb)*

Things to check 

-check and make sure the connections on your starter and clean and secure

- Negative Terminal ground from the battery to the battery tray and to the tranny. Ive seen them get really bad and the car still starts "ok" when warm, if they are green you should replace them.
-Check the 30A fuse on top of your started lockout relay under your dash, and the relay itself.
-Do you notice that your door indicators dont work so well sometimes with the key in the ignition, or do they work pretty fluidly. If they seem to work intermitently you may need an ignition switch


----------



## Caleb (May 19, 1999)

*Re: (pewpewlasers)*


_Quote, originally posted by *pewpewlasers* »_-Do you notice that your door indicators dont work so well sometimes with the key in the ignition, or do they work pretty fluidly. If they seem to work intermitently you may need an ignition switch


What do you mean by door indicators?


----------



## 1988Audi80NA (Nov 27, 2009)

*Re: (Caleb)*

The next logical step would be to check the air temp sensor that is integrated into the air flow sensor.
Not a serviceable part but you can test it by checking the resistance across the no1 and no4 terminals of the air flow sensor. The terminals are Right to Left 1-2-3-4. 3-4,000 Ohms at 50*F and 5-6500 Ohms at 32*F.
This seems like the next step to take.


----------



## ziddey (Apr 16, 2006)

*Re: (1988Audi80NA)*

digifant is supposed to cold start like a dream.
maybe try replacing the blue coolant temp sensor
I've got two foxes. One has the original starter and updated ground wires and it cranks strong as hell. The other has a new starter, but is absolutely lousy when cold (new battery). Once warm, it cranks perfectly. Poor electrical wires / contact is my guess. Once it warms up, the resistances drop


----------



## Caleb (May 19, 1999)

*Re: (ziddey)*


_Quote, originally posted by *ziddey* »_maybe try replacing the blue coolant temp sensor the 

My original post states that I have replaced it already


----------



## pewpewlasers (Jun 12, 2009)

*Re: (Caleb)*

the dumb musical relay when u open your door, if that works intermitantly you most likley have a bad ground somewhere.
ive worked on tons of digi cars and 98% of the time when **** doesnt work right its because of a bad ground somewhere


----------



## Peter_M5 (Jan 16, 2005)

that's funny because when I first got the car I noticed it didn't have the musical sound - I got to check and recheck all the grounds


----------



## randi dub (Jan 5, 2008)

*Re: Hard starting when cold on '91 Jetta Digifant II (Caleb)*

hey your car could be flooding out after you have used it and its cooled off, bad injector/s , going bad computer , hopefully just a loose or bad ground , or in some cases the battery cable from the + to the starter itself corodes and does not let current through at first kinda of has to build it up, all easy fixes just need to find out which one is the problem good luck http://****************.com/smile/emthup.gif


----------



## pewpewlasers (Jun 12, 2009)

*Re: Hard starting when cold on '91 Jetta Digifant II (randi dub)*

Someone may have removed the Musical relay from the relay box, its the only relay with a speaker on it in the car.
anyhow check your negative terminal ground wire from your battery, stock they are just exposed wires, its the big one that goes from
Terminal--> battery tray--> transmission bell housing.
Usually that wire is green and corroded and needs replaced, pretty sure u can buy a negative terminal package at walmart for 7 bucks with the wires, its generic but will work.
Also there are 2 ground on a ground plate that is attached to your Vavle cover, the big fat ground wire is your ECU ground and the smaller one is for your whole isv/o2 etc. the smaller wire can get really nasty so get a razor blade and cut back and check it if its green see how far back it goes green till then either cut and attach a new wire or clean it with a wire brush and vinegar, either case i usually take both those wires off that plate and sand a section of the metal runners on the valve cover and ground those 2 directly there.
hope that helps wish i had pics for ya but its dark out


----------



## pewpewlasers (Jun 12, 2009)

*Re: Hard starting when cold on '91 Jetta Digifant II (pewpewlasers)*

also did you ever unplug the coolant temp sensor while the engine was running?


----------



## Caleb (May 19, 1999)

*Re: Hard starting when cold on '91 Jetta Digifant II (pewpewlasers)*

No. I just had a known good used CTS that I swapped while the engine was cold as to not loose any coolant. I swapped it then started the car. The starting issue was not resolved so I determined that the problem was not CTS related. The car that the used CTS came out of had no starting issues at all.


----------



## Peter_M5 (Jan 16, 2005)

I fixed my cold start issue today...
After reading countless posts in regards to how terrible the grounds are on these cars. I decided to install new grounds and clean all the electrical connections in the engine bay. I installed new 8 gauge grounds from the main to tranny and to the valve cover. I cleaned all the electrical connections with contact cleaner and smeared dielectric grease between all the contact points. I removed the starter and sprayed it down with electrical cleaner and lastly changed all the spark plugs making sure all the gaps were 0.7 mm
Started stone cold with the first crank
success!
Hope that helps you out


_Modified by Peter_M5 at 7:41 PM 12-5-2009_


----------

