Lack of power and misfiring issue - Romano RISN

[frembrit]

Hi all,

Hope you can help.

Been having issues, for a while now, with the car losing power and misfiring when it's wet/raining, and thought along the lines of the usual, so the coil pack, plugs and HT leads have been replaced, but it's still the same. So, I'm thinking it may be a LPG ECU issue.

Some more info can be found here http://www.talkford.com/topic/206552-no ... -ignition/ Sorry, it goes on a bit.

To add to the above, I've noticed that the car is using a lot more petrol than normal (expect it to use a bit more because of the cold weather); used £80 worth in January compared to the usual £25 in a month.

What I would like to know is, is it possible for the Romano ECU to become faulty and cause problems like this? is it somehow indicating that it is using LPG, but mixing in petrol too? The power issues happen when running on petrol too. Is there any way I could completely isolate the Romano ECU from the car to test?

Thanks,
Dave.

[Tubbs]

What car is it ? More likely you are having a petrol ecu issue that is causing problems, the romano ecu is basically an AEB ecu, which are very reliable generally, and when they fail, they fail. Nobody home. Lights out on the switch. You can bypass the petrol injector wiring by connecting blue to the blue with a black trace. Red and trace, green and trace and yellow and trace. Either solder or with jumpers at the multiplug down from the loom. If its a 6 or 8 cylinder you have 2 plugs.

[frembrit]

Thanks. Would that basically stop the LPG injectors being turned on.

It's a Mondeo ST24 (2.5 V6)

[Tubbs]

So its got two plugs, generally blue, red, green on each of the looms. Just basically bypassing the lpg system totally if you connect the wires going to the two separate plugs. But mark which is which or your banks will be mixed up when you plug them back in. Red band is bank 2.

[classicswede]

To me it sounds more like a crank or cam sensors being effected by the damp?

Where is the Romano ECU mounted, is it in a position that does get wet?

[frembrit]

Thanks, I'll check those out too.

It's located behind the nearside suspension turret above the wheel arch.

You can't quite see it in the photo, but it's next to the brake servo. (top right) Basically the opposite side to where the power steering fluid bottle is. (top left)

[Gilbertd]

With LPG nozzles fitted there I'm surprised you only get a problem when it's wet!

[frembrit]

Really?! Where should they go?

The system was fitted over 6 years ago and it's been absolutely fine. Not too sure they guy who fitted it was that good though as the LPG inspector chap that had a look over my car a few months after the install, said he was being investigated due to a few complaints. About a year later, the fitter was no longer trading.

[rossko]

The closer the injection points are to the engine, the better - in general. I dont think those that are that horrendous to be honest. Ideally it'll be less than 300mm from cylinder head, via manifold, via small hose, to the gas injectors, and I reckon you've got that. Overlong wouldn't affect general running much, it's all about transient response.

I understand the suspicion over gas but it's non-trivial to isolate the gas wiring for a trial; it's as likely to introduce new quirks as anything.

...The power issues happen when running on petrol too.

That's the clue. I like the crank/cam sensor suggestion. Is the engine management bright enough to throw you some fault codes?

I'd review petrol usage after the other is fixed; it might be causing the RIS-N to revert to petrol mode every so often or something, say if it sees loss of RPM.

[frembrit]

Thanks.

Having a look at the sensors now. I don't think they cost too much so will most likely buy them during the week.

[classicswede]

With LPG nozzles fitted there I'm surprised you only get a problem when it's wet!

I don't think I have ever seen a tidy Romano installation ever and nozzles mounted half way up the manifold is typical. Usualy moving then to nearer where they should be does improve LPG running but has nothing to do with this running issue on both fuels.

[classicswede]

I do have patch looms to bi pass the LPG ECU but I very much doubt the LPG wiring has anything to do with your running problem. As you have done most of the ignition system already the crank or cam sensors would be the most likely thing left.

Also just thought about it now there will be a brown wire going to the coil pack somewhere to give RPM signal to the gas ecu. If that has rubbed through somehwere along its length that could well cause the kind of problem you are seeing. Have a check of that wire

[frembrit]

Really appreciate the help.

I checked that wire the other week and had to tape it up better as the plastic cable trunking stuff was cutting in to it, but otherwise it was ok.

The car is running slightly better now that I've unplugged, cleaned the connectors and reconnected a few times. I'll get a crank sensor next week.

Thanks again.

[frembrit]

Update:

Fitted the Crank sensor on the 16th Feb and it seemed to run a better on petrol but still missing on lpg.

18th Feb: checked the plugs and one had some tracking down the ceramic, so replaced that and ordered some silicone grease.
23rd Feb: applied silicone grease. But also found that one of the HT leads had snapped (not sure if I broke it pulling it off or judging by the carbon build up it had failed sometime). Car running a lot better after this.

Of course, it has been dry since then and the car has been running almost perfectly. It rained overnight on the 6th March and on the morning of the 7th the car was back with its problems again. As the car was parked up overnight and the problems came back almost instantly from setting off for work, I'm now thinking a long the lines that may be the main ECU is getting wet as it is mounted above the pedals but inserted from the engine bay. Looking at it, I can see that water would run down the windscreen/A pillar area and then run under the power steering bottle (top left of the photo). The ECU is behind and under that bottle.

I've noticed too that with the reduced/rough power delivery, it also does not open the secondary valves on the air intake which is operated by the inlet manifold runner control (IMRC box). This was also the case previously, but works fine when everything is ok/dry. This box is controlled electrically and activates when accelerating hard or when the revs climb above 3250rpm (roughly).

Hope to get the ECU out this weekend, weather permitting. ( and fit new front springs as one snapped the other day )

Starting to think that it may be off to car heaven soon.

[rossko]

You said you'd replaced all the ignition parts. Not all at once, perhaps? If you found tracking on a plug you should also throw away the lead - both will be damaged, so if you only replace one at a time you'll never get rid of it.

[frembrit]

Yes, all the plugs and leads were all replaced for new in November. I just thought I'd check them again and that's when I found the plug with tracking marks on ( not a lot), and then the broken lead...I don't think the quality of the leads are very good (Unipart) compared to the last set of Bosch leads.

I understand what you're saying about replacing leads and plugs, I'm going to try and get this set of leads replaced under warranty.

[alexf2828-2]

Try putting NGK plugs in and gap them, I found they were best, issues can also be down to valve wear-my rover used to run badly when cold on petrol & LPG but was ok when warm