1994 850 - Unable to start - Page 3

madmalky · Jul 2nd, 2014, 21:04

had 1996 850t5 with similar problem.rpm sensor test fine then old Volvo mechanic told me to go to scrappies and get another one,which I did even though had been tested working started first time never looked back...cost couple o quid from scrappies...just a thought..

KBB · Jul 3rd, 2014, 06:23

Looking at the diagram You are right the injectors are in parallel so will bank fire simultaneously. And the text you posted also supports that during cranking the injectors will be fired 2 times per crank revolution which they are and then drop down to injector event per revolution.

You have spark at the correct time but how strong is the spark, a good coil should be able to jump a 3cm gap to ground with a strong blue spark. If it only jumps a lesser gap with an orange spark the coil is weak.

When cranking introduce some starting fluid or even better LPG into the intake, if it attempts to start better than it was or starts and runs then it would confirm a fuel delivery issue.

scutyde · Jul 4th, 2014, 10:27

If the engine comes from a V70 afaik the wires in the RPM Sensor need to be swapped as the rpm sensor counts the holes in the V70 and not the notches as in 850.

Cristian

vitos · Jul 16th, 2014, 17:42

Hi guys,

sorry for my recent absence, I was out of reach for a while. But now I have some time for this swedish puzzle again. This weekend, I'm going to spend some time with it, so I'll post here if there will be any progress.

To KBB: It really looks like ECU acts normally with controlling injectors. I thought it's weird because of I was counting inject pulses when looking at cam revolution not crankshaft revolution... my fault.

Hard to say how strong the coil is but spark is blue and nice (with spark plug attached). However, I also tried another (but used) coil and symptoms remained the same. Some gas or starter fluid should lay somewhere in my garage, I'll try it too, thanks.

to scutyde: Halo Cristian, vielen dank für deine hilfe! It's real surprise for me, if there were two types of flywheels there realy should be a V70 one. I'll check wiring diagrams and swap those two wires it worths trying.

I'll be back with news on weekend.

Alphashooter · Jan 20th, 2015, 20:18

Vitos, Did You solve the problem with your car?
I have a similar problem but it only shows up during winter and very intermittent. During coldstart the injectors opens one time, the engine fires up on this first spray but then immediately dies again because there is no more injectorpulses. However I have spark all the time, even during stall. After 3 to 4 attempts the engine always starts and then runs perfect.
I have a 2,5L 10V B5252s 1996

No errorcodes. I suspect a bad cam position sensor.

Jul 4th, 2014, 10:27	#23
scutyde Retrofit master Last Online: Mar 28th, 2022 10:14 Join Date: Mar 2010 Location: Berlin	If the engine comes from a V70 afaik the wires in the RPM Sensor need to be swapped as the rpm sensor counts the holes in the V70 and not the notches as in 850. Cristian __________________ Volvo 850 2.5 20V MY95 Pictures Here what I retroffited so far List

Jul 2nd, 2014, 21:04	#21
madmalky New Member Last Online: Apr 13th, 2022 11:02 Join Date: Jul 2014 Location: galashiels	had 1996 850t5 with similar problem.rpm sensor test fine then old Volvo mechanic told me to go to scrappies and get another one,which I did even though had been tested working started first time never looked back...cost couple o quid from scrappies...just a thought..

Jul 3rd, 2014, 06:23	#22
KBB Master Tech Last Online: May 18th, 2020 10:57 Join Date: Dec 2006 Location: On Contract Dubai Automotve Technical Academy	Looking at the diagram You are right the injectors are in parallel so will bank fire simultaneously. And the text you posted also supports that during cranking the injectors will be fired 2 times per crank revolution which they are and then drop down to injector event per revolution. You have spark at the correct time but how strong is the spark, a good coil should be able to jump a 3cm gap to ground with a strong blue spark. If it only jumps a lesser gap with an orange spark the coil is weak. When cranking introduce some starting fluid or even better LPG into the intake, if it attempts to start better than it was or starts and runs then it would confirm a fuel delivery issue.

Jul 16th, 2014, 17:42	#24
vitos New Member Last Online: Aug 2nd, 2014 09:20 Join Date: Jun 2014 Location: Hradec Kralove	Hi guys, sorry for my recent absence, I was out of reach for a while. But now I have some time for this swedish puzzle again. This weekend, I'm going to spend some time with it, so I'll post here if there will be any progress. To KBB: It really looks like ECU acts normally with controlling injectors. I thought it's weird because of I was counting inject pulses when looking at cam revolution not crankshaft revolution... my fault. Hard to say how strong the coil is but spark is blue and nice (with spark plug attached). However, I also tried another (but used) coil and symptoms remained the same. Some gas or starter fluid should lay somewhere in my garage, I'll try it too, thanks. to scutyde: Halo Cristian, vielen dank für deine hilfe! It's real surprise for me, if there were two types of flywheels there realy should be a V70 one. I'll check wiring diagrams and swap those two wires it worths trying. I'll be back with news on weekend.

Jan 20th, 2015, 20:18	#25
Alphashooter New Member Last Online: Jan 20th, 2015 20:18 Join Date: Jan 2015 Location: Malmö	Vitos, Did You solve the problem with your car? I have a similar problem but it only shows up during winter and very intermittent. During coldstart the injectors opens one time, the engine fires up on this first spray but then immediately dies again because there is no more injectorpulses. However I have spark all the time, even during stall. After 3 to 4 attempts the engine always starts and then runs perfect. I have a 2,5L 10V B5252s 1996 No errorcodes. I suspect a bad cam position sensor.

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