Engine 850: B5234T/2.3/20v/T5: Starting issue

[stuartvolvo]

Hi guys. I replaced the thermostat today, as it had decieded to stick open, therfor the car would not get up to normal running temperature. At least that is another problem that is sorted. Anyway back to the starting issue. I also played around with the immobiliser and antenna ring today. The only codes i got up today was 'no response from key transponder' and no signal to ecu'. This was straight after the car wouldent start. I reset the codes and hey presto the car started straight away. i know that the ecu needs signals from the camshaft sensor, crankshaft sensor and imobiliser before it allows the car to spark. I have already checked all the sensors around the engine and know they are fine, but i have not paid much attention to the imobiliser and think that i am going to try and sort the imobiliser out.
A friend of mine has a car in his workshop, with exactly the smae type of symptoms, and has had one of his friends over, who is a professional automotive electrical engineer and has found out that the car has imobilised its self and therefor is preventing its self from starting. He also said that it is the imobiliser ecu that needs reprogrammed.
So i am going to keep an eye on his car, just to see the outcome, but Ian (the engineer) definatley said the problem with my car is either to do with the imobiliser or the engine ecu.

So ill look at the imobiliser and get back to you all.

Regards
Stuart

Quote
if i am not mistaken it went tits up when you were getting it tuned - read an interesting thread on another web site - who is having a look at it the tuner people who seemed to fall out with you big time or another garage and what have they checked and rulled out as causing the problem and their reasoning behind this position.

thanks
__________________


Yes it is the garage that did the tuning, They have now had the car a month and today told me there is nothing further they can do, they cannot fix it!!

I feel so ****ed off! They ****ing recked my car and have no interest in fixing it. Im gonna look into taking legal action. They cannot get away with this!!

Bison

[stuartvolvo]

Does anybody know the exact signals that should go down the violet / white and yellow/brown wires that go from the imobiliser to the ecu? i am just wanting to check that this is working correctly.

Regards
Stuart

I THINK I HAVE THE ANSWER TO OUR PROBS!!!!!!



Member




Join Date: Mar 2005
Location: Outside Sunny glasgow
Posts: 93 Quote:
Originally Posted by Paullyp
If you have an 850, bet you a pound to a penny that it is the relay which operates the fuel injection system that is faulty, this will cause intermittent starting and the loss of your spark, part number 3545803, COSTS £21,does not show up when doing a diagnostic check,P.

This relay is situated under the radiator cowling, takes 5 secs to remove, on opening the relay it has a set of contact points, the points can sometime fuse together, eventually they will free themselves, usually after you have changed the flywheel sensor, cambelt sensor and the coilpack. Ever 850 owner should carry a spare, if your car fails to start, change this relay before you head off to the garage, YOU HAVE BEEN WARNED.
A guy gave me a call the other day to tell me he had changed his turbo hoses for SAMCO ones and his car wouldn't start, yep you have guessed right, on fixing the top hose had knocked the relay and lost the connection.If anyone needs any clarification on this relay, pm me with a contact number,Paullyp


Trying it tomorrow!!

Bison

i found this prob after changing my rad, i must of disturbed it as it had starting probs since, gonna get a new one too

[Mark_in_Conwy]

Update on the J-relays: So far it seems that replacing the middle one (relay 106) had no effect. Today I have swapped the left-hand relay (viewed from the front) and again it started but I will need a couple of days to see if the intermittent fault is still happening. Boring trial and error, but I'm trying to be systematic about it.

I REALLY like this idea about the relay under the radiator cowling - this would explain why in my case the starting fault (at least until very recently) only occurred when the engine was hot. I also intend to blow £21 quid on trying a new one.

Cheers,
Mark

[Mark_in_Conwy]

Hi, me again...

Thanks again to Bison and Paullyp for directing me to the relay above the radiator. I just took it off to double check the part number and found one of the wires exposed/corroded. It must have been chafing on the fan cover.

See photo attached.

I am minded to replace the relay anyway, given what Paul said; the waterproof seal at its base was failing so it may be faulty. My fingers are crossed and I'll let you know if my starting fault is cured.

Cheers,
Mark

My car doesn't have that really ---- gutted!!! But could be.........


If your relay does not have the part no 3545803, I expect your is the later type engine and what you are looking at is the manifold absolute pressure sensor. Different kettle of fish, you have said that it is starting in the garage, therefore remember the golden rules
1. Check to see if you have a spark at plugs.. if so,coilpack and leads ok then.
If not...In order of probability Fuel rail relay/manifold absolute pressure sensor or connection, this will cause intermittent starting, sometimes months will pass. Symptoms are, car not starting, and then starts later on or next day, without any problems.Then flywheel sensor, lasts approx 125,000 to 150,000 miles usually, then camshaft position sensor.
2. If you have a spark and still does not start, check you are getting fuel. If not check fuses and relay and pump for activation noise.
3. Remove ecu and clean connections, you can attempt to reset the ecu by disconnecting the battery for 24 hours, remove ecu if doing this,(best calling me first for clarification...methinks).
4.We know that there are other factors, injectors, split or damaged hoses or pipework,timing etc etc.
What I have written above (longwinded I know) are the tried and tested methods and sequence, REMEMBER most starting issues will not show up during a diagnostic, and you will still have to pay the garage, check all of the above and fix or fit to the best of your skills if your car still doesn't start AT LEAST you will have eliminated some of the problem areas.PHEW...

I'll keep trying

Bison

[Jod T5]

Originally Posted by Bison

If your relay does not have the part no 3545803, I expect your is the later type engine and what you are looking at is the manifold absolute pressure sensor.

i am getting very confused here... a manifold absolute presure sensor is only to be found on the 10v systems running the fenix 5.2 system on the 850's the later 70's may have one but tbh i do not know....
the engines in particular being refered to are both 850 motronic 4.3 ecu controlled and therefore air is measured using the mass airflow sensor located on the air inlet pipe.....
cheers
jod

[stuartvolvo]

Well, after thinking about the car all day at work today and really depressing myself, as soon as i got home i decided to look at the imobiliser .I took the imobiliser out, checked all the wiring to the imobiliser and from the imobiliser to the ecu and checked the overlad realy for the imobiliser. I put everything back to gether, and i have not had this starting issue so far. Everytime you turn the key she will start straight away, no bother at all. I was wondering if it could have been a loose wire on the imobiliser? Car been running great all day today.

Im a bit happier now

Regards
Stuart