Odd 850 no start issue

BatStig · Post by **BatStig** » 02 Oct 2020, 15:03

This is a bit long winded, so my apologies up front.

I recently purchased a 1997 Volvo 850 GLT. It has a 15G turbo and an ECU from Vast Tuning. I burnt a valve on my 4500km drive home and have since had the cylinder head rebuilt. I put the car back together and she ran well. I flashed a new tune from Vast onto the car and did some logging. I then flashed another tune and then she cranked but wouldn't start. I have no spark. Fuel squirts out when I push the Schraeder valve on the fuel rail. I flashed back to the previous tune. Still no spark. I replaced the spark plug wires, distributor cap and rotor, as well as the cam position sensor. Still no spark. I got my hands on an ECU from a scrapyard. Not the correct one, 0 261 203 072 ('95 T5?), but it's an ECU. With the scrapyard ECU the car has spark and will start but won't idle unless I keep my foot on the gas. Vast sent me another ECU. I just installed it and still have the same problem; crank but no start. I was about to check for spark again, but it has started to rain. I will be heading back out as soon as it stops.

Does anyone have any suggestions on what I should do next? I am at a loss here. Any help you can provide would be greatly appreciated.

Thank you.

New info: flashed a stock tune onto the Vast ECU and it behaves like the scrapyard ECU: the plugs are now sparking and it starts but won't idle/stay running if I take my foot off the gas.

Post by **Chuck W** » 02 Oct 2020, 17:55

Are the tunes you're flashing all VAST tunes?

BatStig · Post by **BatStig** » 02 Oct 2020, 18:29

Chuck W wrote: ↑02 Oct 2020, 17:55 Are the tunes you're flashing all VAST tunes?

Yup. Straight from Aaron. He said that he double checked the files and everything is okay.

Post by **erikv11** » 02 Oct 2020, 18:46

The last ECU from VAST, did you flash onto it or just popped it in as you received it? Wondering if it could be a problem with your flashing rig somehow corrupting the file/ECU.

BatStig · Post by **BatStig** » 02 Oct 2020, 19:38

erikv11 wrote: ↑02 Oct 2020, 18:46 The last ECU from VAST, did you flash onto it or just popped it in as you received it? Wondering if it could be a problem with your flashing rig somehow corrupting the file/ECU.

The previous owner had installed a VAST ECU. I flashed it once and it ran fine. I flashed it a second time and then there was no spark. I flashed the previous tune and still no spark. VAST sent a new ECU and again no spark. I had him also send one of his VAG COM cables just in case my cable did something stupid. He resent the tune and I flashed it with his cable. Nothing.

Post by **scot850** » 03 Oct 2020, 12:27

Is the engine turning over but just not firing? It could be the immobiliser not sending a spark.

Couple of simple things to try:

1) Disconnect the battery and touch the leads. This resets the electrical system.
2) Re-connect the battery, +ve lead first.
3) Manually lock/un-lock the drivers' door lock with the key in the door lock.

Neil.

BatStig · Post by **BatStig** » 03 Oct 2020, 13:51

scot850 wrote: ↑03 Oct 2020, 12:27 Is the engine turning over but just not firing? It could be the immobiliser not sending a spark.

Couple of simple things to try:

1) Disconnect the battery and touch the leads. This resets the electrical system.
2) Re-connect the battery, +ve lead first.
3) Manually lock/un-lock the drivers' door lock with the key in the door lock.

Neil.

Thanks. I will give this a try.

I will also add new information. Vast sent me a stock tune and it now has spark. With the stock tune it behaves the same as the scrapyard ECU; it starts but will not idle/stay running if I take my foot off the gas.

Post by **Chuck W** » 03 Oct 2020, 14:14

Sounds like something corrupt in the tunes.

What injectors are on the car? Any other mods besides the turbo and ECU?

BatStig · Post by **BatStig** » 03 Oct 2020, 15:28

Chuck W wrote: ↑03 Oct 2020, 14:14 Sounds like something corrupt in the tunes.

What injectors are on the car? Any other mods besides the turbo and ECU?

Orange injectors, which Vast is aware of. Other mods? Nothing to do with the engine. Exhaust. Suspension. That's it.

Post by **Chuck W** » 04 Oct 2020, 17:59

What are the last 3 digits on the ECU you're flashing?