Long crank and tack. jumping

beetlebob · Post by **beetlebob** » 18 Nov 2011, 06:50

OK I have a 01 V70 T-5 With a long crank time and a tack jumping all over the place. Car will start and run good once it starts. It belongs to a used car lot who has taken to 4 other shops and does not know what any of them have done. Go figure.Will it has a new cam and crank sensor in it and still no help. BUT it has a reman trans in it(Painted black). So what I was wondering is I have seen somewhere that if the mateing surfaces of the trans to engine are not good will give you this problem but have been unable to find the post again. The owner of the shop I work for said that that is a load of bull. Can anyone help with that problem and has anyone tried to use jumper wires from trans to block to fix this problem. Hope I gave enough info and for any help anyone can give. Bob

beetlebob · Post by **beetlebob** » 19 Nov 2011, 07:13

Also to add fuel pressure good,no codes in any processor,and sometimes car just starts up fine.Can not see any problems in wiring system from being pinched and have checked all connections that might of been disconnected when trans way worked on. Thanks all

RaymanSean · Post by **RaymanSean** » 22 Nov 2011, 14:52

My first guess would be leaking fuel check valve. A leaking check valve would allow the fuel pressure to bleed down when the car is not running making it hard to restart. Also, I am not sure of the fuel system in these cars but I wonder if the fuel return line is clogged, this could lead to vapor lock and/or flooded engine.

beetlebob · Post by **beetlebob** » 22 Nov 2011, 15:11

Thanks but no fuel return line and fuel pressures great. The think that has me puzzled is the tack jumping all over the palce when cranking. Something is sending a crazy signal to the tack.It is not in the wiring or the crank sensor. Tried 2 different ones and checked all of the wiring.

RaymanSean · Post by **RaymanSean** » 22 Nov 2011, 19:47

If you take it to a good independent shop or if you are lucky to have a great dealer service tech then they will be able to hook up the Volvo diagnostic tools and pinpoint the problem (you are looking for the ragged guy that is soft spoken seems to walk the walk, this could be some highschool drop out or it could be the 60 year old man who should be running the shop but prefers to fix cars instead of replacing parts and selling you things that you don't need). If you truly have an electrical problem like this it could be one of several things and until you are interrogating components or it fails hard you will not be able locate the problem. If it fails hard, ie car will not start, you can look at ignition timing/ fuel/ air. Once you know which the engine is not getting at the proper time then you can cross the others off the list (good fuel pressure does not mean you are getting enough fuel, spark does not mean that the spark is happening at the top of the compression stroke, air is tricky as there is a MAFS, throttle valve and an Idle control valve, if any of those are not right then the engine can not control the amount of air flowing into the combustion chamber). Remember that at the end of the day all an engine needs to run is air fuel and spark at the right time in the right amounts . You need to figure out which one(s) the engine is not receiving and start working from there. Otherwise you are best off with an Oscope and perhaps a signal generator to try to track the problem down, that is if you know what the signals are supposed to look like and also know how the circuits should respond to them. If you don't know what the signal is supposed to look like then you might as well learn to live with it until it fails hard or reliably.

By the way where are you located? Someone on here may know of a great mechanic that could find your problem. I unfortunately do not know of a great Volvo mechanic in my neck of the woods, but then again I have only had a volvo for 1 year and do all the work on my other cars myself.

Post by **jimmy57** » 23 Nov 2011, 00:02

The paint has to be cleaned off the surface of the transmission where it bolts up to the engine. That surface can't be painted or grimy. Rifle barrel cleaner kit with the long brushes and some brake cleaner will do the trick if all the bolts are loosened off so the trans and engine can be separated 3/8-1/2 inch for scrubbing access with the rifle cleaning brush.
The magnetic field lines created by starter when it is engaged messes up the crank position sensor signal unless the just barely adequate shielding of the trans bell housing is completed by it being in good contact with engine.
I have seen this several times with pained reman'd gearboxes.

RaymanSean · Post by **RaymanSean** » 23 Nov 2011, 04:08

jimmy57 wrote:The magnetic field lines created by starter when it is engaged messes up the crank position sensor signal unless the just barely adequate shielding of the trans bell housing is completed by it being in good contact with engine.
I have seen this several times with pained reman'd gearboxes.

WOW! At least someone figured this out. I could only imagine how long it took them to do so.

beetlebob · Post by **beetlebob** » 24 Nov 2011, 07:12

Thank you jimmy57.I was trying to find out why this surface was causing a problem and adding ground wires did not help. As for Rayman I am an ASE master tech with over 18 years of working on Volvos in a independant shop. I do not just throw parts on a car to get it fixed. I wanted to know why the surface needed to be so clean to make the car start and run good and now I and everyone else will know why.I do have people who live in your home town drive to see me to fix there car so you know I live within 1.5 hours from you.There are good techs in every town all youhave to do is look and do not go in with an additute. We are here to help you. Thanks you for all of your answers I will see if the customer wants me to go into further(used car lot) and see if this fixes the problem. God bless

Post by **JRL** » 24 Nov 2011, 08:46

Very interesting and very helpful
I would not have thought of this, please let us know if that does the trick!

beetlebob · Post by **beetlebob** » 16 Dec 2011, 14:06

OK I had to remove the trans out of the car to clean out all of the paint. The torque convertor had enough paint on it to paint the whole car. I had to use 2 cans of Aircraft Paint remover to get it all off of the trans. bellhousing(inside)and the convertor. CAr starts GREAT. Have tried several times and all good. So with that it is FIXED. Yea!!!! Thanks for the help and my hat is off to Rayman