94 Volvo 850 TM, Car turns over but no start.

[rspi]

If you have fuel, the cam and crank sensors are fine.

[huzzsaba]

So I got around to testing the ignition coil by disconnecting the wire from the middle of the distributor. there was no spark. I then swapped in a ignition coil from my s70 and still no spark or very faint spark and only one throughout the numerous cranks. I even swapped the wire that goes from the coil to the distributor to rule it out and still nothing. I checked to make sure the connector for the ignition coil was on nice and snug as well

Now robert mentioned that if there is fuel, the cam and crank sensors are not the issue. then what could it be? If there is no spark coming from the ignition coil, then its probably not the distributor cap. the ignition wires look to be in good shape and look close to new with no cracks. Plugs look good too.

Just to refresh, this issue did not happen all of a sudden. It was a slow decline in the car's ability to start. since my brother bought the car, it always took 4-5 seconds to start and eventually after sitting for longer periods, would take a good 10-15 seconds to start. Then one very cold day, it decided to not start at all and since then hasn't started.

i appreciate the help. I hope to resolve this soon. Ive got too many non driven volvos on the driveway lol.

[huzzsaba]

So the cam sensor looked pretty clean and may have been replaced recently as i did not see any crumbling in the wiring. both crank sensor and cam sensor unplugged fairly easily and wiring looks like new. the crank sensor has some stuff on it that was easily wiped off.

What is the likelihood that it is the ecu that is causing this issue? this car was converted to manual by the previous owner, so im not sure if the original auto ecu is in there or a manual ecu.

I do have my stock s70 t5m sitting in my garage and can swap it, but i dont want to destroy my ecu in case something goes wrong.

Unfortunately we didnt get much info from the previous owner in regards to modifications, but would the ecu need to be replaced when doing a auto to manual conversion? I read that a manual ecu will not work in a auto car, but what about if it was swapped to a manual? would a manual ecu like the one from my s70 work to rule out the ecu being the cause of the no start?

[rspi]

I would NOT try to swap those ECM's, I'm pretty sure the fuel systems are pretty different and so are the years.

Sorry I don't have any good suggestions, I'll keep thinking.

[draser]

Before suspecting ecu need to make sure the crank sensor works, sends the pulses and they reach ecu - harness and ecu connector are good. Same for coil harness and connector at ecu end. Also ecu has correct batt voltage and grounds, wiring diagram needed. Do you have batt voltage on any of coil conn pins?

[huzzsaba]

Update: Replaced the cam sensor and ignition coil and nothing. I cranked the engine for a good 15 seconds multiple times and only managed to see one spark and a very faint one.
The crank sensor had some dust on it and didn't seem to be that old considering the wire and connector were in great shape. I could not test the resistance on it because I don;t have a multimeter, and asked a few mechanics who I know very well to test it, and they would not saying it wouldn't prove anything . Maybe they just wanted me to bring the car in and make some money.

I did notice however something on the plug part that plugs into the ignition coil. On one of the pins, it seems like the silver part was missing or burnt. It is hard to explain but I have attached a photo here as an example.

The plug in the photo is a 3 pin one but the ignition coil one is 4 pin i believe and one of the pins (second one seems to be burnt, or I cant see the silver part of the connector. I will try to get a photo of the actual connector in the morning.

[huzzsaba]

Well scratch that idea of the connector pin being burnt,since I just checked on my S70 and the connector on it look the same.

I also just found out from my bro that a few weeks before the car stopped working, the idle was fluctuation quite a bit during a road trip. Once he parked the car, and later started it, the fluctuation was gone. I know usually that leads one to the tps sensor. Can the tps sensor be the cause of this issue? We did try to start the car with the the tps sensor unplugged but still no start.

Also, Can someone please tell me how to check the check and see if there is a signal coming to the ignition coil? Keep in mind I'm more of a mechanical guy, and not good with checking electrical stuff, but step by step instructions and I can do it.


I guess those are the last things to check before swapping the ecu.

[huzzsaba]

After some more checking, I believe the injectors are not getting any signal. I will go ahead and replace the fuel injector relay and see what happens.

At the same time, I am going to check all the ground wires. Can someone direct me to where the main ground wires are. Please not this is a 1994 850 turbo in case the wiring is different from the 96-97 ones.

Thanks

[huzzsaba]

So I finally got the car started. I disconnected any grounds that I saw and cleaned them with a wire brush. Same with the terminals on the battery. I Went to start it and it cranked over 5-6 times and gave it some gas, and then started. I am not sure if it was the ground connections, but what is still a mystery is that even after driving it around for a bit, it still takes a good 5-6 cranks plus you have to push the gas pedal once for it to start. It otherwise runs like a top! I am not sure what it means.

[huzzsaba]

Guys I'm wondering why there is no response in over a week? Also, it went from no spark, to no injector pulse, to all of a sudden starting with some effort after cleaning the grounds. That probably helped I'm sure and although the car has started, it takes 5-6 cranks to get it started and you have to give it gas. I am sure this is not normal. it runs without any issues once started without missing a beat and with full power.