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Missing 25 Horses

4K views 51 replies 21 participants last post by  GeoffCapes 
#1 ·
I went to Red Dot today to get the GT remapped.

However, it was missing 25 BHP. Literally.
On the rollers it only managed 126bhp with no visible signs of anything wrong.
Then they remapped it and it made just 160. 25 less than normal.
The EGR was mapped out, but I'm going to fit blanking plate anyway.

But that wouldn't gain me 25 gee gees.

Any ideas? They thought it could possibly be the exhaust restricting things, possibly the cats.
 
#4 ·
The way I look at it, it's got to be something that restricts power as the loss is constant.

Would that be turbo related?
 
#5 ·
When I had the inlet manifold changed and swirls deleted on my 2.4 spider, I immediately felt more responsiveness, lot more eager and no smoke.
Get that manifold cleaned.....
May not return 25bhp though
 
#6 ·
That's the thing. Mine doesn't smoke much at all.
 
#10 ·
Might get it up to Sunnyside and get Felice to run the diagnostics to see if that shows up anything?

The thing is, with the map on it it drives better than ever. Huge amount of torque, but obviously down on power. (Has 160bhp now).

Very confusing.
 
#17 ·
She's just had a new clutch.
 
#14 ·
As others say it'll be a restriction in air flow rather than anything else.
You've had quite a bit of work done to the car in terms of maintenance.

Maybe some new gear oil wouldn't go a miss. But yes 25 horses is quite a bit to loose. Making the poor GT a bit better than the average. I mean 160hp in a diesel really isn't that much.
 
#21 ·
If you say it's not smoking very much at all which would suggest it's leaned out - don't MAFs fail toward lean? that'd cost you some BHP.
 
#22 ·
It had a new MAF about 8 months ago.

I changed the air filter today.
This is what the old one looked like.
Automotive exterior Auto part
:yikes::yikes::yikes:

Took it for a quick spin, and it feels a lot quicker.
Could this be the cause.

The black bit was white on the new one. Was soaked in oil.
Which I think was from when I had a split pipe, which in turn caused the MAF to fail.
 
#23 ·
It had a new MAF about 8 months ago.

I changed the air filter today.
This is what the old one looked like.
View attachment 510090 :yikes::yikes::yikes:

Took it for a quick spin, and it feels a lot quicker.
Could this be the cause.

The black bit was white on the new one. Was soaked in oil.
Which I think was from when I had a split pipe, which in turn caused the MAF to fail.
Wow!! Thats filthy my pollen filters looked a bit like that haha, all clean now.

How did you get the filter out? I tried undoing the clips at the bottom but can only open the box about 3 inches or so, could of ripped the old one out but would not be able to get the new one in very well then.

PS. That would certainly be sappiung a bit of power for sure, not sure about 25bhp though?
 
#27 · (Edited)
I didn't change the air filter when I changed the MAF. In hindsight maybe I should have.

Looking at the filter it could be the original! :yikes:
 
#26 ·
I'd say that's it right there!

It's good practice to change the air filter when changing the maf from what I'd read when I had trouble with mine caused by a leaky airbox.

With your filter being that bad there may have been a chance your new MAF may have become dirty/damaged. Just a though in case you put it back on rollers and find your still a few pony's short.
 
#28 ·
I think if your bothering remapping and rolling roading, putting afresh air filter in every year or 5,000 mile is worth while.
I use a k+n washable so probably just about braking even/into profit in cost after 7 years.
if I was to do over id just keep sticking in oe filters.
while im under there doing the oil, its only a bit longer to do the air filter(on the stilo)(but longer with a wash ,oil and dry).and I usually give the maf a blast (maf cleaner)also, as taking it off makes the air filter job easier
same with map sensor ,no reason not to clean annually.
I bet your mpg goes up a bit with fresh filter in.
Im sure manufacturers are stating 30,000 mile plus changes but is it worth it to leave them that long ?
same with fuel filters, im think mine is supposed to be 60,000km ?
no thanks I change every 2 years min prob 10,000miles.
I think this sort of service plus oil and filter is what id recommend before any sort of remap or rolling road work.
 
#33 ·
There has been a bit of an improvement but not had a good enough run out yet to tell for sure.
De-Cat gets delivered this afternoon, so that'll liberate a few more gee gees! :smoker:
 
#37 ·
Ain't that the truth!!!

Been there, seen that, got the t-shirt.
 
#35 ·
Three weeks ago I noted that my car was 'holding back', significantly so in the morning.

I decided to check the egr. I took it off and it wasn't bad actually as its only a year old, however I had a look at the inlet manifold port which the egr valve connects to and it was chocked full of solid soot! As in there was barely and airflow space. I hacked a way with it at a screw driver for about 15 minutes. I then put the egr back on, took it for a drive and the difference was huge.

If I had to put a figure on it I'd say 5-10bhp. Its like filling up with ASDA fuel for a week, then filling with Vpower times by 3.
 
#36 ·
My EGR was 'mapped' out, even so, I've bought some blanking plates, they get delivered with my de-cat.
Hopefully when I get the GT back on the rolling road it'll be like a new car!
 
#38 ·
I've now removed the front cat.

And it absolutely flies! I think the missing 25 horse are no longer missing.

I think a combination of the the re-map, new air filter and the de-cat, I'd be surprised if it wasn't pushing out 200+bhp. :smoker::smoker::smoker:

Tire Automotive tire Wheel Mode of transport Vehicle
 
#41 ·
I've now removed the front cat.

And it absolutely flies! I think the missing 25 horse are no longer missing.

I think a combination of the the re-map, new air filter and the de-cat, I'd be surprised if it wasn't pushing out 200+bhp. :smoker::smoker::smoker:

View attachment 514978
Thats the middle cat. Is the front one still fitted? (it bolts directly to the turbocharger)
 
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