Megasquirt help around Aberdeen

[deetes]

Anybody around Aberdeen with experience of Megasquirt FI plus ignition mapping on Rover based V8. Had big probs since going to wasted sparks.

Been to Wallace Performance but they're not realy into V8's. Wondered about Ricky Gauld.

Any suggestions would be gratefully received.

[istoo]

i would suggest Ricky Gauld or JD Motors, i know a few folk who have used mega squirt but on 4/5 pot Audis, and a lot of patience.

Edited by istoo on Monday 30th June 19:40

[GreenV8S]

deetes said:

Anybody around Aberdeen with experience of Megasquirt FI plus ignition mapping on Rover based V8. Had big probs since going to wasted sparks.

There's been a lot about this on the MegaSquirt forums. Is it a problem with the kickback from the coil? Have you tried adding caps to the driver circuit? (The standard advice says add them to the +12v side, although conventional wisdom would have them between the -ve side and earth.)

[deetes]

GreenV8S said:

There's been a lot about this on the MegaSquirt forums. Is it a problem with the kickback from the coil? Have you tried adding caps to the driver circuit? (The standard advice says add them to the +12v side, although conventional wisdom would have them between the -ve side and earth.)

Kick back from coils? How would I check for that? Caps? Sorry electronics is not my forte. Hence the problems I've been having.

The engine ticks over OK but when you rev it it sounds lick there's a misfire. On the dyno last year, fuel only on MS, it made 215bhp and I reckoned that was about right for a TVR390. This year with fuel and wasted spark, using ford coil packs, it was down to about 170bhp. We'd had to retard the ignition by quite a lot to stop it pinking and because of that it feels very gutless. Re the pinking, it was all over the rev range, even blipping the throttle for down change would do it.

Bit hacked off about the whole MS experience really, wish I'd gone for Emerald etc as it would be far easier to pick up the phone and ask for advice. The guy I bought the MS from is very difficult to speak to. He does reply to emails usually.

[Big Daz]

I am running Megasquirt also, albeit on a zetec, Also had issues but the man who helped us out was Phil from http://www.extraefi.co.uk/
He helped develope it and wrote some of the code. Very helpful and prompt replies also.

[GreenV8S]

deetes said:

GreenV8S said:

There's been a lot about this on the MegaSquirt forums. Is it a problem with the kickback from the coil? Have you tried adding caps to the driver circuit? (The standard advice says add them to the +12v side, although conventional wisdom would have them between the -ve side and earth.)

Kick back from coils? How would I check for that? Caps? Sorry electronics is not my forte. Hence the problems I've been having.

The engine ticks over OK but when you rev it it sounds lick there's a misfire. On the dyno last year, fuel only on MS, it made 215bhp and I reckoned that was about right for a TVR390. This year with fuel and wasted spark, using ford coil packs, it was down to about 170bhp. We'd had to retard the ignition by quite a lot to stop it pinking and because of that it feels very gutless. Re the pinking, it was all over the rev range, even blipping the throttle for down change would do it.

Bit hacked off about the whole MS experience really, wish I'd gone for Emerald etc as it would be far easier to pick up the phone and ask for advice. The guy I bought the MS from is very difficult to speak to. He does reply to emails usually.

You have to bear in mind that MegaSquirt is (a) experimental and (b) DIY. There are plenty of people willing to give you advice on the MegaSquirt forums, but ultimately you will have to be willing and able to roll your sleeves up and understand what's going on if you're going to fix it yourself.

The combination of pinking and poor power makes me suspect that it's running lean, what does your wideband lambda tell you about the mixture?

Are you driving the coil packs directly from the ECU? Have you got non-resistive plugs, extenders and HT leads? If the answers are all 'yes' then you could be suffering from the inductive spike that occurs on the low tension side of the coil each time it fires. Adding resistance on the HT side helps, but you can also add capacitors to the coil to reduce the spikes.

Can you reproduce the symptoms with a laptop connected? Data logging on? Does the ECU show the correct rpm and map, is the injector pulse width looking sensible as the load/revs change?

[deetes]

Big Daz

It was actually Phil I bought the MS from. Very helpful when you can get a hold of him(on the phone I mean). He usually replies to my emails very promptly. Sometimes you just need a little reassurance .

Green V8S

I know that it's DIY etc, but I don't seem to be able to pin point the problem and it's bugging me

Narrow Band Lambda. Dyno guy said it was Ok with his wideband up the exhaust. Got a wideband to fit at some point, but just wanted to get it running.

Direct driven coils, resited plugs as per Phils recomendation( plug gap around 1mm), new leads from Performance Ignition Leads. Extenders but I don't think they're resisted.

There were capacitors with both coils. Do I need more?

Still haven't got the rev counter working. tried the two differnet methods / circuits that were in the manual but no result, so i don't know if the rpm's are correct or not.

I have datalogged a couple of times since going to wasted spark. I could send you one of them if it would help.

[GreenV8S]

Rolling road guy monitored AFR under load and said it was OK while you did the 170 BHP pull? I'd still want to have a wideband in there but this makes it seem less likely to be an AFR problem. That's a shame because running lean would exactly fit those symptoms otherwise. If it's lean enough to cause a misfire you would have needed to be out past 16:1 so as a quick and dirty test you could add say 20% to the fuel map in the region that is giving the problem and see if it makes any difference.

The other possible problem is an ignition fault. There are all sorts of ways to get it wrong, for example if you have the output inverted the timing and dwell will go all over the place with revs, so you really need to get a passive strobe or HT test lamp on and confirm that you've got a strong spark across the rev range, and then put an active strobe on and confirm that the timing is about right across the rev range. Personally wouldn't recommend putting it on a rolling road until it's running right, unless you have somebody there willing and able to diagnose problems like this. Rolling roads are very expensive places to do fault finding.

Can you confirm that when you connect your PC and run Megatune it shows the revs correctly and no resets, while the problem occurs?

[deetes]

GreenV8S said:

Rolling road guy monitored AFR under load and said it was OK while you did the 170 BHP pull? I'd still want to have a wideband in there but this makes it seem less likely to be an AFR problem. That's a shame because running lean would exactly fit those symptoms otherwise. If it's lean enough to cause a misfire you would have needed to be out past 16:1 so as a quick and dirty test you could add say 20% to the fuel map in the region that is giving the problem and see if it makes any difference.

The other possible problem is an ignition fault. There are all sorts of ways to get it wrong, for example if you have the output inverted the timing and dwell will go all over the place with revs, so you really need to get a passive strobe or HT test lamp on and confirm that you've got a strong spark across the rev range, and then put an active strobe on and confirm that the timing is about right across the rev range. Personally wouldn't recommend putting it on a rolling road until it's running right, unless you have somebody there willing and able to diagnose problems like this. Rolling roads are very expensive places to do fault finding.

Can you confirm that when you connect your PC and run Megatune it shows the revs correctly and no resets, while the problem occurs?

I did check the timing using an active, I'm assuming that active means adjustable, timing light and the results showed that the actual timing was reading more than MS indicated and as the revs increased this difference got larger, ie at 900rpm MS was 9 degrees the actual reading was 10 degrees. By 2500rpm MS was reading 33 degrees and the actual reading was 45 degrees. I sent my MS supplier these figures and he said that this type of timing light didn't work with wasted spark.

I enquired about getting the car on an engine analyser to check the sparks at high rpm, but was told that they don't work on wasted spark

I know what you mean about the cost of the dyno, as it cost me £150 to find out that I'd lost power.

I rechecked the trigger angle with the adjustment turned off and reset to 55 degrees from 60.

The rpms on MS seem ok and I haven't noticed if there have been any resets

[GreenV8S]

deetes said:

I did check the timing using an active, I'm assuming that active means adjustable, timing light and the results showed that the actual timing was reading more than MS indicated and as the revs increased this difference got larger, ie at 900rpm MS was 9 degrees the actual reading was 10 degrees. By 2500rpm MS was reading 33 degrees and the actual reading was 45 degrees. I sent my MS supplier these figures and he said that this type of timing light didn't work with wasted spark.

I enquired about getting the car on an engine analyser to check the sparks at high rpm, but was told that they don't work on wasted spark

I know what you mean about the cost of the dyno, as it cost me £150 to find out that I'd lost power.

I rechecked the trigger angle with the adjustment turned off and reset to 55 degrees from 60.

The rpms on MS seem ok and I haven't noticed if there have been any resets

I think your supplier is the same person who supplied mine, and I've been very pleased with the support he's given me so I am hesitant to contradict him, but there's no fundamental problem using an active timing light or dwell meter on a wasted spark setup.

Many active strobe lights provide an adjustment feature which lets you offset the flash time by a specified number of degrees, and also provide an RPM readout. Both of these features require the unit to know how many sparks they are seeing per engine cycle. If you use these features and want them to work correctly you will need to tell them that you have a two cylinder engine. If it won't accept that, tell it it's seeing a 4 cylinder engine and just be aware that the RPM display will be half the true RPM and the true timing offset will be half the timing offset displayed. Or ignore the RPM display, leave the timing offset at zero and just judge what the advance is by where the timing marks are on the flash. You can easily draw marks on the balance weight to show timing up to say 40 degrees.

The main purpose of doing this is to show that the spark advance you're actually getting roughly matches what's configured in MS. You should easily be able to see the timing change according to your ignition map so e.g. MS shows timing advance from 10 deg to 40 deg you should see the timing marks on the flash move round by 30 deg.

Be aware that the timing marks are often inaccurate so although the flash ssems to show 10 deg of advance, don't assume that's a true figure unless/until you have verified the timing marks against mechanical top dead center. But all you're looking for at the moment is that the timing changes as specified in the map, and for this the accuracy of the timing marks isn't critical.

Similarly for a dwell meter, you would expect MS to provide a constant coil charge time so the dwell time should be constant with revs, and if you display dwell angle you will see this increase in proportion to revs. To display the dwell angle accurately you need to tell it the number of cylinders (2), so if you tell it (1) or (4) you will get double or half the true reading. It really doesn't matter since you can mentally half/double what it's showing you, in any case the main thing is to show the dwell time is roughly constant with revs (corresponding to dwell angle increasing in proprtion to revs).

[deetes]

My timing lights not that sophisticated. I can adjust the angle and that's it. This is what I did to obtain the figiures I gave you. I adjusted the timing light to get the TDC mark lined up and read the reading off the adjustment.

So I could mark the pulley and check the timing with the adjustment turned off??

Anyway, I never even looked at it today, as I was fabricating a new air filter for my KTM. Not finished that either. I'll have to get another dose of enthusiasm before I go near the TVR

Did have a thought of comparing the fuel map for last year and this year to see if there was any huge differences.

Thanks for your help. They've given me some things to look at.