Misfire/rough running

[iani]

My EFI TR6 has started playing up, the car has been off the road for a few months as I rewired it, since putting it back together it hasn't ran correctly. I have fitted a new lambda sensor, readings look normal, I have changed the plugs twice, the ones in the pic have done less than 50 miles and I'd say they mostly look like the car is running rich. The car sounds like it's running on 5, there is a strong spark at each plug and I've swapped out the coil pack just in case it was breaking down but no difference. Any ideas where to look next?

 

[Nick Jones]

How old is the fuel?  Have you put any fresh in since its been stood up?

When you say it's got a strong spark, is that view with the actual plugs you are using - some NGKs hate to get wet and die.......

When you say normal O2 sensor readings......? what sort of range?  Outright misfires show up lean or tend to raise the AFR reading due to the air going through with the unburned charge.

[iani]

29 minutes ago, Nick Jones said:

How old is the fuel?  Have you put any fresh in since its been stood up?

When you say it's got a strong spark, is that view with the actual plugs you are using - some NGKs hate to get wet and die.......

When you say normal O2 sensor readings......? what sort of range?  Outright misfires show up lean or tend to raise the AFR reading due to the air going through with the unburned charge.

I haven't recorded the details Nick but I haven't noticed anything abnormal, if I accelerate it enriches, down to 12.5 or so, leaning off on overrun and when maintaining constant speed but nothing abnormal. The fuel is fresh, the lambda sensor & wideband controller are new. 

[Nick Jones]

Ok... that sounds fair on the AFR front.

If the plugs are laid out in order, #4 doesn’t look like it’s firing and #1 is a bit on the black side.

If you’re confident you have spark then check the injectors and the wiring. Are the injectors batch fired or sequential?

[iani]

3 minutes ago, Nick Jones said:

Ok... that sounds fair on the AFR front.

If the plugs are laid out in order, #4 doesn’t look like it’s firing and #1 is a bit on the black side.

If you’re confident you have spark then check the injectors and the wiring. Are the injectors batch fired or sequential?

Batch fired Nick, still running wasted spark, will check wiring at ECU end, I checked the coil end today and all looks fine.

[Nick Jones]

Have you disturbed the throttle linkage at all? Unbalanced throttle bodies can play merry hell with mixtures across different cylinders at idle and light throttle especially. Though I suspect the Jenvey (?) linkage is rather superior to the OE Triumph efforts.

[mpbarrett]

As you have changed the LAmbda sensor have you checked the voltage output range of the Lambda sensor? On mine (I have a readout as well, it flashes up the current range when the sensor is switched on) you can change the range and have to setup the MS calibration to suit. Might be worth checking that the MS AFR reading agrees with the sensor AFR, time to plug the laptop in. If it wrong then the mixture will be wrong.

Mike

[iani]

Thanks guys, you kickstarted my mind on this.

The car was running fine before I rewired it, I fitted a new Autosparks loom and I made up a fresh EFI loom, all fitted according to the instructions from Emerald.

On firing the car up, it was running but whilst my AFR gauge was giving fluctuating readings, the reading in the Emerald software was constant, this was down to my having wired up as per the instructions which differ from how the software is actually configured, the paperwork shows conflicting information depending upon where you are reading. I changed the pin to reflect the settings and all was well apart from the aforementioned misfire.

I just had a thought, whilst I was driving the car with it in adaptive mode but not receiving any AFR readings, the map could have become corrupted. I have just loaded a map from before the rewire and have brought the car up to temperature in the garage, it sounds great, I'll take it out later and see if the misfire has gone, I'll update later.

Ian

[iani]

I was wrong, test drive showed no improvement, back to basics, I had already checked the ignition wiring, I checked the injector wiring at the ECU, all good, so I then tugged at the wiring on the 7 way connector to the VX Injector loom and the first wire I touched came out, all sorted and the car is running great. Thanks all.

Ian

[Nick Jones]

Nice to have cheap solution and a happy ending 

[iani]

9 minutes ago, Nick Jones said:

Nice to have cheap solution and a happy ending 

I'm really rather annoyed with myself Nick, I have had a lot of termination challenges with the EFI loom, I thought I'd been extra careful making these connections up but obviously not careful enough. 

[Nick Jones]

We had lots of issues with the Speeduino on the Spitfire. But the crappy Molex connectors used aren’t really fit for purpose.

A lot suffer from the same basic problems though - rather flimsy retaining prongs that don’t lock in properly either because the wire is slightly too fat or the prong has got a bit flattened.

I had some issues with the Vitesse FI loom during the build due to rather unsuitable ECU connectors (computer not automotive) and having to re-use automotive connectors because they were much harder to find new in 2005.