Long story short - previous owner mapped my car but the map he put on it was a generic one and is causing issues. I have booked the car in to get a custom map done.

The thing is, the mechanic wants to remove the injectors and send them off for testing before he does the map. I'm not sure it's gonna be feasible (the SC has to be removed etc).

I'm wondering if this is really necessary, I'm getting no injector related fault codes etc. Is there a way to test the injectors without removing them?

Any help much appreciated!!

 

What 'issues' are you seeing? The supercharger removal takes about 5 hours the first time someone does it. You can look at fuel trims and O2 sensor results with a OBDII logger as well as test the impedance of the injectors without removing the SC but, getting physical access to the injectors requires removing the supercharger. In general it's not a bad idea to have a car in confirmed good working order before making enhancements.

 

Fuel trims are up nearly 20% on both banks, bank 2 isn't quite as bad. It looked like a vacuum leak but after spending a full day at a Jag specialist, we ruled that out. O2 sensors and MAF sensor also fine.

Previous owner fitted a 200 cell cat, huge exhaust, changed the SC pulley, and loads of other things.

After going to another specialist, we've come to the conclusion that the remap the previous owner got must've been done very poorly, as everything else tests OK.

 

While the injectors might be an issue, if both banks are showing +20% I would look first at other causes (vacuum leak, exhaust leak). Did you do a smoke test? The plastic manifolds and hoses (PCV, etc.) tend to crack as they age. Is it possible to go back to the stock mapping? Also, what remapping approach did they use? Tuning a pre-06 is very difficult and usually requires a bench tune vs OBDII tune.

 

Do the fuel trims come down when you drive it?

 

As you increase RPM the LTFT goes down, but the STFT go up to compensate, so the total fuel trim never changes too much.

 

ok is that revving it or driving it?

 

Sorry about the delay, just double checked and it's both.

 

Okay maybe not a vacuum leak then but I do not want to speculate what it may be

 

Tricky one isn't it. It's gotta be the remap, or lack thereof.