Backfire and Fault Codes

[lotuska]

Got a problem today, the car starts and runs fine until you accelerate hard. The car backfires and I get 3 fault codes 41, 42 & 54.

Car has new CAS, base timing is correct, ignition coil connections also ok??

I've attached an elanscan trace, can anyone suggest a possible cause?

[GeoffSmith]

Mark,

I've had a quick look and there is obviously something strange going on. There is obviously a major disturbance between ~143 and ~147s:

• The coolant raw drops very low.
• The coolant>50°C flag (Flag50bit0) is reset.
• The CAS fault (bit9), EST (Electronic Spark Timing) monitor error (bit7) and CO pot circuit (bit17) flags are all set during this first glitch.
• The throttle position and boost drop down to zero.
• You had been collecting data at ~200ms intervals but there is a loss of data for about 3s during this period.

There is also a minor glitch in the coolant raw data between 224-228s.

Could it be a dodgy connection - maybe ECU?

Geoff

[lotuska]

Geoff,

Thanks for having a look, I also noticed the gaps...so I removed the ecu and checked the connectors, couldn't see anything.

The odd thing is it only happens under hard acceleration??

Mark

[Monty]

wild guess, but since you`ve got the new HALL fitted just check the wiring hasn`t come lose

might also be worth ordering another HALL.

also sounds like a bad coil but don`t think that would through up a code

[lotuska]

Still trying to fix this, so far I've changed the plug leads (this has cured the massive loss of data when using ElanScan) but I still get the error codes.

I've now just tried to change the Hall sensor....still no affect.

However one thing I had a problem with was that the wiring on the new Hall sensor its different to the first one I had!! (I've previously fitted a new one)

Thought this might help others...

[Specky]

Here's a pic of mine

Must admit I think the build standard is very poor on the replacement HES.

Check for movement on the HES head, the two rivets are shocking...

With the code 42, I would go downt the Coil and HT route..

TTFN

[SGSR]

ive been having exactly the same problems, checked all connections an still no improvement. Its a bit intermittent thou as it doesnt always happen and if i ease off for a bit it goes away.

[Sy V]

Have you checked the integrity and insulation of the earth lead attached to one of the three coil mounting bolts that go through the inner wing?

[paza1]

If you've tried the above mentioned solutions with no joy, try removing the coil, splitting the 2 coils from their base, cleaning it up and refitting. Give it ago, no expense, could help.
Mark

[lotuska]

Right I think I've sorted this problem now...good news is that the fix cost me nothing!!

The problem was down to the cam angle sensor, not the coil pack, hall sensor or any bad wiring!!

It appears that the gap I had between the tip of the cam angle sensor and the cam reluctor ring was too small...Now I didn't think that a gap too small could cause problems (unless you get physical contact and it breaks) but an artical I found here suggests otherwise.

It states:
Air gaps smaller than .030 inches will create higher than normal voltages and some high speed abnormalities with the threshold voltages, internally in the DIS module, and potential circuit damage. Air gaps larger than .070 inches will result in weaker voltage signals and some engine starting problems due to weak and erratic signals. The signals can be too weak for the module to count.

So I tried several different gaps:
1) .050 inches...car won't even start
2) .010 inches...car ran, but misfiring and errors under high load
3) .020 inches...car ran fine no issues
4) .030 inches...car ran, but misfiring and errors under high load

So I've set it at .020 inches...the odd thing is that I don't ever recall anyone suggesting that the cam angle sensor could have an impact on the running of a car.

I'd also like to know what gap others have.

[lotuska]

Oh and just so people know which bit I'm talking about here's a picture:

[Monty]

I`ve not heard that one before and only heard of the HES or bearing giving a problem. Didn`t even know that parts was adjustable good to know for future reference

0.02 Inch(s) = 0.508 Millimetre(s)

[GeoffSmith]

I imagine it would be quite critical - luckily, I noticed mine was dull of steel strands after I'd cleaned up the casting with wire wool.

[tigerdog]

And very interesting, as Smaug occasionally exhibits high speed, high load misfire. It certainly won't hurt to check - costs nothing and easily accomplished.

[texaselite]

Oh and just so people know which bit I'm talking about here's a picture:

What did you use to increase the gap (since I imagine it's impossible to decrease it)?

[lotuska]

If you look at the picture there is a bolt (I can't remember if there is 1 or 2) - its directly above the red circle, just loosen that and you can move the whole assembly in and out and increase or decrease the gap.