94 850T check engine light while accelerating

henrysin44 · Post by **henrysin44** » 12 May 2020, 19:13

RickHaleParker wrote: ↑12 May 2020, 18:57
henrysin44 wrote: ↑12 May 2020, 18:49 Don't exactly know how that could cause a CEL after a week but the cluster has always acted up for years now.
Cracked solder joint, path or connector got aggravated when you pulled the cluster.

Hopefully so, the solder did look like cold joints, I'll try out another cluster tomorrow

Post by **misha** » 13 May 2020, 03:16

henrysin44 wrote: ↑12 May 2020, 18:49 ...Don't exactly know how that could cause a CEL after a week but the cluster has always acted up for years now.

As a side note not all the lights come up when key is in position 2, or while starting, but all are functional.

That cluster is bad and you will need to replace it.
Could be a bad connector to the cluster or cold solders on the cluster.

Post by **BEJinFbk** » 13 May 2020, 16:05

Dumb question - Are you sure it’s the CEL?

This sounds like exactly what happens when
you get low on windshield washer fluid.
If I catch it out of the corner of my eye,
sometimes it tricks me...

Post by **misha** » 13 May 2020, 16:29

That light is on the opposite side of the cluster.
However...his cluster is not working properly....just 2 or 3 lights on bulb check and all of them are replaced and checked.

It's either a connector or cluster is bad.

henrysin44 · Post by **henrysin44** » 14 May 2020, 03:15

Yesterday I replaced the knock off RPM sensor with an OEM sensor. There is no change from doing it, CEL still comes on during hard acceleration, but im glad i swapped it out, doubt the knock off would last much longer. Maybe I just need new spark plugs? Theyre coppers and im pretty sure ive been running them for at-least 10K.

As for the cluster, its not defective

. I did however figure out why the key-on lights don't come on! When the battery/charging light comes on it will also turn on most of the dash warning lights, which would also explain why the key-on lights come on if the alternator belt snaps. (pic below). So my battery light isn't getting a signal from the charging system, which doesn't bother me yet.

EDIT: The alternator signal wire was disconnected, now my dash shows all the warning lights when in position 2. Still have a CEL on acceleration though.

Post by **misha** » 14 May 2020, 09:07

It should...because if the warning light doesn't work...your alternator will not have output.
The light works as "awakening" for alternator.

EDIT...i just saw that you re-connected the wire.

Post by **Chuck W** » 14 May 2020, 13:24

How long have you been driving it since the battery disconnect?
It could clear up after the ECU readjusts a bit.

You could have a sensor that is out of spec, enough to cause an issue when the ECU is reset, but will then clear up after a while. My M4.4/green injector-swapped '97 does the same thing. It would "reset" after having the battery disconnected for a time and then would flash the CEL at me on acceleration for a few drives until clearing up.

How old is the Engine Coolant Sensor? When was the last time you checked the connector?

I think with the M4.4 ECUs that flashing on acceleration is a knock sense reaction.

Misha is much more an expert on this stuff than I am, though.

henrysin44 · Post by **henrysin44** » 14 May 2020, 15:55

misha wrote: ↑14 May 2020, 09:07 It should...because if the warning light doesn't work...your alternator will not have output.
The light works as "awakening" for alternator.

EDIT...i just saw that you re-connected the wire.

That would definitely explain why my headlights would be dim until i started driving.

Chuck W wrote: ↑14 May 2020, 13:24 How long have you been driving it since the battery disconnect?
It could clear up after the ECU readjusts a bit.

You could have a sensor that is out of spec, enough to cause an issue when the ECU is reset, but will then clear up after a while. My M4.4/green injector-swapped '97 does the same thing. It would "reset" after having the battery disconnected for a time and then would flash the CEL at me on acceleration for a few drives until clearing up.

How old is the Engine Coolant Sensor? When was the last time you checked the connector?

I think with the M4.4 ECUs that flashing on acceleration is a knock sense reaction.

Misha is much more an expert on this stuff than I am, though.

I've drove about 150 miles total sense the reset, the coolant sensor is only about a year old and I re-did the connector wiring when I replaced the sensor.
I really hope the CEL is not a reaction to a engine knock, engine sounds healthy though.

Post by **Chuck W** » 14 May 2020, 16:43

I guess it's also possible that you had low voltage going to your ignition system, which could cause an issue when the engine was under load.

Post by **misha** » 14 May 2020, 17:17

henrysin44 wrote: ↑14 May 2020, 15:55 ...That would definitely explain why my headlights would be dim until i started driving.

You had a good luck that your battery was in good shape.
Since you ran a car with low voltage charging system...i would suggest to remove negative battery terminal for a few hours in order to reset car's management system and all bad things it could catch because of low voltage.

After that,perform a re-learning procedure for ecu and check voltage output on battery terminals.
Re-learning procedure:
http://www.volvotips.com/index.php/850- ... rocedures/

94 850T check engine light while accelerating

Re: 94 850T check engine light while accelerating