Poor Performance!?

[mrknighty]

I've had my Megajolt system up and running for about six months and no matter what I change I can’t get the engine to perform correctly, the car I have installed the Megajolt on is a Peugeot 205 Gti 1.6, which has twin Carbs and 300 degree duration cam.

The problem I have is at high RPM between 5500 and 6000 rpm the engine will misfire which you can drive through if your in a low gear i.e. 1st, 2nd or 3rd. I have tried lots of ignition map with various style curves and total advance figures, I have also tried lot of different jets and jet combinations to try and solve the misfire but it only makes a very small different to the misfire.

I have checked and double-check the wiring of the system. I have a new Coil pack, plugs, leads and the Megajolt was built by Brent. The system is working correctly, which I have proven with the timing light and the car drive very smooth, but has a high rpm misfire.

The strange thing that I have noticed is the spark is not very big and spark plug are not the correct colour, more of a white rather than a healthy grey. I know the fuelling is correct because I have any Air/Fuel ratio gauge mounted in the car.

Today I swapped the car back to the standard Distributor and the engine pulled much better thought the rev range with no misfires at high RPM.

Is the Megajolt up to running a Performance engine?

If anyone could help would be great as I'm running out of ideas.

Regards

John

[brentp]

Might be a shot in the dark, but a friend of mine with an EDIS setup was experiencing a mis-fire between 4 and 5000 RPM. The cause? the bracket holding the EDIS sensor had a harmonic around that RPM which caused vibration on the bracket, and a mis-read by the EDIS module.

Bottom line, the EDIS system has been proven to be capable running up to 20 lbs of boost on turbocharged V8 ford mustangs- I have mine running on a 1.6L 4AG motor, turbocharged, pushing 230 HP at the wheels, no issues with ignition performance whatsoever.

Perhaps others will contribute some ideas. Have you switched your EDIS module with another?

Brent

[mrknighty]

yes I have swapped the EDIS module.

Would the problem of the sensor vibrating show up on the run time display because that looks fine?

Are you using a Performance coil pack? The coil pack I am using is from a Ford Escort 1.8 Zetec.

John

[brentp]

It depends how fast you're going past that point in the RPM range. Try sweeping through the rev range very slowly, or simply hold the engine right at that RPM to see what would happen.

The sensor vibrating would manifest itself as missed sparks, as the EDIS module would lose sync with the timing wheel, then re-acquire it as the RPM passes through the region where the harmonic exists.

[mrknighty]

The misfire is still present if you drive up though the rev range slow or fast. I don't think it is the sensor vibrating. The sensor is mounted on a 25mm thick bracket with good support and one dowel for location plus an M8 bolt holding it in place. The sensor bracket and position was original use by Peugeot for a diagnostic sensor.

The misfire is cause by the carbs because the ignition is not performing correct.

John

[MartinM]

John

Hmmmm...there's nothing fundamentally wrong with the Megajolt at high rpm or with competition engines - my 205GTi revs extremely smoothly through this range and onwards to 6800rpm or so, and I have a Megajolt in a highly tuned Vauxhall Red Top 2L on 45's that revs to 8200rpm quite happily.

And you also seem to be saying that once you get above 6000rpm yours is OK as well?

Have you got a MAP sensor, a TPS or neither?

"The strange thing that I have noticed is the spark is not very big"
When is it not big? It should be massive - at cranking speed I get a spark that can jump about an inch. Wasted spark coils seem much more efficient than the old oil-filled types.

"spark plug are not the correct colour, more of a white rather than a healthy grey. I know the fuelling is correct because I have any Air/Fuel ratio gauge mounted in the car."
That does sounds like a fuelling problem to me. How do you know the air/fuel ratio gauge is correct? Is that a good measure of fuelling? (I don't know much about A/F gauges)

"Today I swapped the car back to the standard Distributor and the engine pulled much better thought the rev range with no misfires at high RPM."
Well there's certianly something wrong if the standard distributor is better.

"Is the Megajolt up to running a Performance engine?"
Yes

Have you tried to look at the advance with a timing light in this 5500-6000rpm range (I don't even know if timing lights work at that speed, but I presume they do)?

Is the trigger wheel on the crank pulley? Is it solid steel or pressed? What's the wheel to sensor gap?

Are all your investigations done in the garage/out on the road, or are these faults observed on a rolling road with an operator who knows what he's/she's doing?

The basic questions also have to be asked:
- if you check the timing with a timing light does the observed timing match the advance curves set in the Megajolt? - they should be spot on, of course
- what is the Rev Limit programmable output set to? - should be well over 6500rpm
- with the Megajolt completely disconnected what's the observed timing value at idle and say 2000rpm? - should be 10 BTDC exactly

[mrknighty]

I am using the flywheel as the trigger wheel, with the slots machined by my self-using a CNC Lathe with live tooling. The gap is set to 1mm between flywheel and sensor.

I have tried it with and without the MAP sensor, makes no difference.

I know the Air/fuel ratio gauge is work correctly because it read the same values for both ignition systems, yet the standard distributor still performs a lot better.

The Megajolt is functioning correctly, which I have observed with timing light, 10 BTDC on idle and jumps to 15 BTDC when engines revs are increased. My timing light does not work above 3000rpm the strobe light just stops on rather than flash but I've had the timing gun set-up in the car and the light does not flicker or flash when the engine misfires. Which would suggest the ignition is still firing.

With the plugs remove and the engine cranking over the spark is not as big as the standard distributor in fact seems to be on the small side. I think this is the problem. I am using a Coil pack from an Escort, which is on of the early style ones (brand new). Is this the correct coil for my application?

How can I test the EDIS module to see if its output the right amounts of power to produce a health spark??

There are no rev limiters set in the software plus I can drive though the misfire.

All investigations are carried out by myself on the road. I'm sure I've got a fair idea of how stuff works.

John

[DannyP]

Maybe something bizarre like an RF noise bothering the EDIS because of bad or even just different than stock groundshielding? Maybe your ground shield around the sensor wire is acting like an antenna?

[morts]

Old topic this but i have the same problem on an XR2. The car just goes to crap between 6000-6500rpm but will if you keep at it pull itself through.

It also will not pull smoothly or at least as smoothly as it did before below 2500rpm but for the moment we're assuming its a different problem. At least it feels like a different problem.

We will be putting the old system back on to get the timing from soon as it was only a 2d setup before to rule out our mapping. If the megajolt is running exactly the same timing as the distributer was the engine should run the same!?

We're also going to try disconnecting the megajolt and seeing if the problem still occurs with limphome advance to try and see if the problem is within our wiring.

Also the above mentioned mounting of the edis, checking our ground and the buffering or interferance value or whatever it is in the megajolt is on my list.

I'll post back when we've done the above.

Any ideas would be appreciated.


Thanks

[NITROPIXIE]

Possibly a coil pack on its way out??? Do you have a spare at hand to compare. Test the resistance between each of the coils on the low tension side, where the three pin connector is, pins 1 & 2 and then 2 & 3.

[Broke4speed]

Sorry man, but if the plugs are white, then it's lean. Trust the plugs and ignore the air fuel gauge (is it a wideband or a narrowband gauge?).

Plugs don't lie, gauges do. Perhaps the EDIS is simply magnifying an existing fueling problem by providing a stronger spark at high RPMs than the stock distributor can. What are your plugs gapped at?

[morts]

Coil pack was brand new on my setup.

moved the edis module and nothing changed. Tried running the car in just limp home mode (megajolt disconnected) and the problem has dropped to between 5000-5500rpm.

This makes me think there's something missing in our map that the dizzy is doing. our low speed problem got worse as you would expect with only 10 degrees advance running twin 40's with large chokes and a 285 cam.

Going to refit the dizzy and find out exactly what is was doing but for now i'm going to use the datalogger to figure out exactly what rpm it starts and adjust the timing 1 degree at a time to see if that works.

Keep you all posted in the hope it might help out someone else with this problem

[Quagmire]

I have to agree with Broke4speed that if your plugs are white then you are running too lean. They should be a nice chocolatey brown colour. Are they any darker after running on the dizzy for a while? If so then that virtually proves that the weaker spark of the dizzy is in effect giving you a richer (and more correct) mixture.

I have seen a few people on the Land-Rover forums who have had to make changes to fuelling as the EDIS gives such a good spark.

[NITROPIXIE]

Morts have you noticed the colour of your plugs?? Are they defo white as you have not actually said if they are or not. The reply with white plugs was given over 3 years ago so may not be relevant.

[cng1]

As has already been mentioned already problems like this are often down to the crank sensor or trigger-wheel alignment or flexing of the sensor bracket. Check that your crank sensor is an even distance away from the teeth all the way round, aim for 0.25mm or better or runout and then check that your sensor mount is rock solid. The bracket should be 3mm thick steel or thicker if it is ali, any thinner and the harmonics may be brutal enough to knock things out of sync.