2000 S320 intermittent power loss

[mrfwonderful200]

Ive a late 99 S320 that has 145k miles, with intermittent faults showing on the onboard computer, "brake assist faulty" & "ESP malfunction" also but not at the same time it can seriously loose alot of power with severe engine vibration as if at least 2 of the six cylinders arent firing. I took to an independant mechanic whose diagnostic kit was unable to communicate with the engine management system, he suggested that the communication could be down to blown fuse & the misfiring could be one or more of the transformer/coils that supply the individual spark plugs! Anyone have any ideas on this one?

 

[Dieselman]

I would say the BAS/ESP fault could be as simple as the brake light switch wearing out or out of adjustment.
The misfiring does sound like a coil pack could be on the way out. Do not leave this fault it could become very expensive if it takes out the ECU.
Thinking about it the ECU might be the cause of the misfiring anyway, there were some failures of 3.2 litre ECU.

 

[mrfwonderful200]

Thanks Dieselman
I went onto a website www.tunemycar.com and they suggest that the ECU is the cause of missfiring and to protect the replacement/new ECU all the 6xcoil packs should be replaced! sounds V expensive! Would the faulty ECU also throw up the other fault reports with brake assist, coolant, ESP etc? The car has had an LPG conversion and some suggest that that can cause problems with the ECU!

 

[Robbo]

Would the faulty ECU also throw up the other fault reports with brake assist, coolant, ESP etc?

That may well be a weak battery. I'd try a new one first.

 

[miro]

Ive a late 99 S320 that has 145k miles, with intermittent faults showing on the onboard computer, "brake assist faulty" & "ESP malfunction" also but not at the same time it can seriously loose alot of power with severe engine vibration as if at least 2 of the six cylinders arent firing. I took to an independant mechanic whose diagnostic kit was unable to communicate with the engine management system, he suggested that the communication could be down to blown fuse & the misfiring could be one or more of the transformer/coils that supply the individual spark plugs! Anyone have any ideas on this one?

The 320 series of engines + transmission were known to leak coolant into the transmission. So get the oil tested in both ends to see how that is performing.

Coil packs, spark plugs and various angle sensors + MAF would be a safe bet to overhaul the slack response.

Air filters can also get overlooked.

BAS / ESP could be overdue brake fluid, brake switch or failing front fuse box. Which can also be an alternator and battery problem.

All it really needs is someone who's diagnostic can read the engine !

 

[silverarrow]

have a look at www.bba-reman.com for ecu and maf and advice
coil pack and maf and bls

 

[miro]

have a look at www.bba-reman.com for ecu and maf and advice
coil pack and maf and bls

How is refurbishment going to help if you dont know which part is faulty ?

 

[mrfwonderful200]

Thanks to everyone for your helpful suggestions!
I think I will start with an ECU rebuild, replacing all coil packs and a close inspection/replacement of the LT wiring harness between the ECU and coil packs also the battery is a bit weak on it, so a new battery! The powerloss is intermittent but substantial. Its a bit of a chicken / egg situation. Has the ECU damaged the coil packs or vice versa? The fact that the diagnostic kit (snapon) couldnt read the ECU suggests an ECU fault in itself, I think! All this work will be followed by a full service and I will check the transmission oil for coolant contamination! Then hopefully all faults will be cured!!!

 

[mrfwonderful200]

Having read another posting about powerloss problems, when the intermittent powerloss happened today I did as suggested and turned the key whilst rolling and immediately restarted again to find the problem had gone! Must be ECU? The same thing happens my sprinter van where the turbo switches off intermittently and a quick restart sorts it!!!

 

[Dieselman]

Having read another posting about powerloss problems, when the intermittent powerloss happened today I did as suggested and turned the key whilst rolling and immediately restarted again to find the problem had gone! Must be ECU? The same thing happens my sprinter van where the turbo switches off intermittently and a quick restart sorts it!!!

This doesn't necessarily mean the ECU is faulty, merely responding to the inputs it recieves and going into limp home. the switch off and on resets it until next time.

 

[mrfwonderful200]

Two weeks ago I fitted a new battery and since then the ESP & brake assist warnings have gone and no severe missfiring but the "check coolant" warning intermittently shows and when the engine idles it has a mild vibration but nowhere near as bad as it was previously though still very annoying, the engin also very intermittently stalls when idleing once every 100miles or so any ideas!!!