Engine Missing Under Power

[Cammo1971]

Hi all,

I have a BAMKII which has 83,000km on the clock. I've owned the car since new and it has never missed a beat. Recently I decided to give it a tune, being a little cautious the car was tuned up to around 8 psi and it started backfiring. The plugs were regapped and this problem went away, however the car started missing when under load at about 3000RPM.

I thought maybe the plugs may have been a culprit as they were 83,000km old so replaced them, I put some new plugs in regapped to 0.7mm and the problem seems to be worse and sporadically occurs at higher revs as well, so I thought I'd ask a few questions to help me diagnose the problem.

- After reading a number of threads I'm suspecting an issue with coils but would like to know why this would not be noticable when the car is running 6psi, does a weak coil become pronounced when running more boost?

- When I changed the plugs my spark plug spanner kept losing its rubber so I placed a little bit of silicon lubricant on the rubber to allow the plugs to slip out, could this be a contributor?

- When I removed the ducting for the turbo from the trottle body I noticed that the rubber mount has a small tear in it, it is under the hose clamp and if it was letting pressure out it would only be a small amount but would this cause the car to miss? I may be missing some power if I have a leak but I would be suprised if it would be the culprit for the miss. (this will be getting replaced)

- Finally, I've heard that coil packs can be tested with a multimeter to test if they are strong/weak. Is this true and does anybody know the process as to make diagnosis a little easier

Any assistance would be appreciated.

Cammo

[Cammo1971]

OK, I have flashed the car back to standard tune and it runs fine, no matter how hard I push it the car doesn't miss a beat.

I'm thinking it's not a coil but maybe there is some other hardware that I need to modify for the car to run at 8-10psi

Cheers,

[ravenhard]

could be a number of things, plugs and coils are the first thing people check from there it could be fuel related. Partially blocked fuel fitler, rooted fuel pump, dirty injector/s. Does it do it more when you have a full tank or doesnt it matter?

From there could be the tune itself. Is it a generic tune or custom? Have you run it on the dyno and check the boost and AFR's?

Also could be a boost leak somewhere. When I first installed my intercooler kit I use to surge and miss until I checked and went over every silicone joiner, vacumm hose and retightened everything.

Failing that some people have reported on here a dislodged/blocked CAT causing loss of power

If you still can find it, suggest going to a tuner with lots of experience with fords

Good luck finding it and let us know what was the cause when it gets fixed.

[Cammo1971]

OK,

I have replaced the fuel filter and plugs with no improvement.

Finally I replaced the coils at a cost of $340 for original ford coils. Found a crack in one of the old coils and the car was running right through the rev range.

I have put an 8psi program in and now the car starts to surge at around 4000rpm, plenty of go and then it starts to bog down. Like its struggling for air or fuel. Would any of these be an issue with only 8psi boost, also the car is stalling when at idle, it is idleing up and down. The car runs fine on a standard tune.

Again any help would be appreciated.

Thanks

Cam

[qik1]

you may need to regap ya plugs they generally recommend to .7 -.8 but if that's not the fix id have a look at the cat but if that doesnt fix it id leave the std tune in til you can get a tuner to look at to see if its mechanical or tune related.

[neil101]

Is your throttle body clean? if it isn't clean it that should fix your idle.

Is it a custom tune or generic? when you say surgeing do you mean compressor surge or fuel surge?

Do you still have std exhaust? if you do your cat may have failed or even if you do have an exhaust and it's been on there a while it could of failed.

These cars are funny with cats we change so many at work only a couple seem to work and last I've gone through a few on my car.

Hope this helps anymore questions you have pm me I'll try my best to help hard without seeing or feeling what the car is doing.

Neil

[Cammo1971]

Thanks for your help.

I will get the car to an exhaust centre to deal with my cat.

I am working towards a custom tune but every time I play with the boost the car runs like a dog. First it was backfiring so re-gapped the plugs, then it was breaking down under acceleration at 3,500 RPM so I replaced the coils (found a big split in one of the rubber boot so probably could have fixed it with some insulation tape but the car has new coils, such is life).

Now I have spoken to the guy who is going to do the custom tune, he supplied me with my current programming so I could test the car and he informs me that he won't be able to do a full custom tune until the car is running properly. He has also suggested that the Cat may be my problem.

He will get the car late next week by which time I hope to have the cat sorted. What is the best fix for a cat. I'm sure the local exhaust centre won't gut it for me so I'm thinking of getting flanges put on it so I can deal with that myself. Are there any risks of doing this?

The alternative is to have a high flow cat installed but I have been told that no cat is better than Highflow.

Cheers

Cam