1995 850 2.0 10v engine temperature related problems

[Kokonradus]

Hello,

I have some issues with my 850 2.0 10v 1995 that are bit hard to diagnose. I bought it from a guy who kept it over 2 years on backyard because he was not able to troubleshoot that, he took it in two of most renomed Volvo shops in country and they could not troubleshoot it either.

Symptoms:
Since I bought it has a cold start problem (reason why the previous owner sold it) really hard starting when cold, almost minute of cranking and playing with gas till it fires up (when the engine is warm it starts immediately). Last week I was on a trip, it was running well and than it started to losing power and it just died. When I try to start it, It fires right up and after second, when idle comes down it just start dying fires few times and dies. When I add more throttle it dies faster. The lambda light is on. Car is with LPG and dies on LPG as well. Behaving same when I disconect LPG ECU and emulato so it is not that.

I have done:
Diagnostic module (Felix 5,2) port A2 (fuel & ignition system)- 1-1-3 - short term fuel mixture too weak. No more codes. Measured fuel pressure, intake vacuum, exhaust pressure (bouncing, but propably in acceptable range) - all values are good. Compression test 155-165psi. Reference voltage on o2 sensor signal from ECU 4,7-5V, On TPS same. Cleaned the idle control valve. Tried to disconnect every sensor particulary, problem presist.
Parts I have replaced (all parts OEM in best quality avaliable) :
-O2 sensor (whole signal wire from connector to ECU replaced also to prevent the case of damaged wire from spoiling o2 signal)
-ECT sensor (resistance values are good)
-TP sensor
-Crank sensor
-Camshaft sensor
-Air intake temp sensor
-air filter changed
-Timing with w. pump
-fuel pump
-fuel pump relay
-fuel filter
-fuel pressure regulator
-injectors (from another 850, cleaned and tested)
-Ignition coil
-Ignition plugs
-cables
-ignition rotor

Another issues may or may not be linked to it :

PCV system clogged, rough idle - 900rpm (200rpm +-), Failed emissions test (before changing O2 sensor). Dashboard circuit panel issue- rpm meter works, interermittent, coolant low level control light even if coolant level is right,

It is my second 850 car, so I don´t have that much experience with these like some of you volvo guys have. Thank you for help, or any tips with troubleshooting that I have not done yet. Sooner or later I will find what is the culprit and I will post the conclusion for someone with same problem.

P.S. What is the proper method for testing the engine temp sensor wiring? Do I have to remove ECU and find the pins for the sensor wiring?

Thank you very much for your knowlage and help

Sebastian

[scot850]

Cold starting is typically ECT sensor or fuel pressure. Does the car start ok when warm?

The ECT sensor is critical on these cars. Misha might remind us what is the non-Volvo brand (OEM I think is Vernet? which is not available over here).

If the PCV is bad, this will affect the car running. I can't remember what is fitted to Euro spec cars and 95 is a change over year.

I know in many parts of the world you have to use what is available in terms of parts, especially for older cars. There are a few brands that just don't work with these cars.

IAC could be blocked. Has your car got this and have you cleaned it out? It is mounted just below the throttle cable mounting under the black plastic cover. A blocked PCV could cause this to block, and they block even when the PCV is bad.

Has the flame trap ever been cleaned or has it been removed?

Can you let me know what brands you have used for:

1) ECT
2) Distributor cap and rotor
3) Fuel pump relay
4) If you have replaced the spark plug cables what brand did you use?
5) Did you clean the throttle body?
6) Have you checked the MAF or clean it?

Long cranking can be the sign of a bad fuel pressure regulator, but I see you changed that and the fuel filter. What fuel pressure do you get at the fuel rail? For your car I would expect around 42 psi and maybe dropping to around high 30's running.

Neil.

[misha]

U.S market don't have 10v cars.

Dtc you have is telling you that fuel mixture is too weak....could be lack of fuel or lack of air.

However...when there is LPG system fitted...it's harder to diagnose the problem because there is too much splicing into original wiring loom which will corrupt proper signals for sensors(higher resistance or lower voltage because of splicing into the original wiring loom).

[scot850]

Canada did get 10V cars. US I believe did not. I nearly bought a 95 850 10V wagon last year but it didn't work out.

Misha is correct in LPG systems can cause a lot of complications in the diagnostics. I still believe checking what you can of the normal system as you say both systems have the same issue.

We don't get LPG here in cars but pick up trucks and buses can be set up to run on Propane. Not sure if this is still being done.

Neil.

[Kokonradus]

Thank you

Yes, the car was starting perfectly when warm and when was cold the cranking took always about half minute or more. Now the cold starts are the same, but whet it is hot it starts and immediately dies so its undrivable. Only way to move the car is start it when its cold by long long cranking, then drive about 2 miles till it get hot and than it dies. (when its hot there is no long cranking it just fires right up starts running for about second, than dies).

ECT sensor is from my second 850 where it works well,

Fuel pressure is 3 bar (43psi) when key is in on position, 2,3-2,5 bar (33-36psi) when its running.

I have only cleaned external bosch idle control valve, that hoses from air intake goes through. Didn´t know there is something in throttle body that controls idle. I will try to find it and clean it)

Yes I´ve cleaned throttle body and throttle plate, there is no mess.

I did not clean the flame trap, but i think it is not plugged because when i was doing vacuum smoke test, smoke was coming from the flame trap.

The brands of parts: cables and spark plugs are Bosch. All other parts I´ve mentioned were from another 850 where was working properly.

This car does not have MAF, it has air intake temp sensor which I changed from another car as well.

The fuel pressure regulator is as well from another car but I did not test it. Would you recommand to get a new fuel pressure regulator? Which brand is fine?

About LPG: It is an old simple system Landi renzo - Lambda control system a1 v05. LPG ECU has only 2 sensor wires - O2 sensor signal, And throttle position signal. Wiring is OK. I measured it, also disconnected whole LPG electronics and issues presisted.

[Kokonradus]

Finally PROBLEM SOLVED

Fuel mixture problems was caused by bad contact in ECT sensor connector.
Starting problems was caused by bad fuel pressure regulator (fuel pressure drop right afrer starting when the vacuum sucks the mebrane)