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Discussion Starter #1
Hey,
First a little about my car..

GTV V6 Phase 2 2001 70,000 miles
BMC CDA intake
Longlife exhaust system (want to change)
Lightened fly wheel, gta clutch.


Took my care to its first ever dyno day today, just to see what it was producing. i understand there not always very accurate and also the car could have lost some ponies in the years, however i was expecting from a 218 bhp engine something close to that figure.

To be honest i would have been happy with 200+ bhp!

My friend put his Honda prelude on first (150bhp standard non vtec) with a decat and air filter and managed to get 190bhp

My turn comes and i got 183.9 bhp...

So i have got home this afternoon and hooked it up to the fiatmultiscan. two error codes are sitting there P1173 and P1176, both relating to lean mixture. I am hoping this is a simple sensor issue that has lowered the power. If not could it be something else that's not being picked up??

After a bit of research I've found these to be linked to quite a few different problems. I am guessing the most obvious issue could be the MAF but I'm slightly hesitant to drop £200 on a new MAF if it isn't the issue.

Does anyone have any suggestions as to how i can found out what the problem is?

Thanks
 

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Take it to somewhere like Autolusso & have them run a live diagnostics check.

Many standard 3.0 24v engines actually produce more than the factory figures, so yours definitely has a problem....or two!?

Clive
 

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Discussion Starter #3
Cheers for the reply Clive,

I've got a friend who has a MAF for cheap so I think i'll pop that in and see if it makes a difference. If not I'll do as you suggested and take it to Autolusso
 

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Check the dyno printout again.

184 measured at the wheels (whp) would be about 215 bhp measured at the crank (flywheel).

You might be worrying over nothing.
 

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saw a Fith Gear progam from ages back

they did a Dyno experiment

tested as was and it god xyz power
changed plugs .............. +5bhp
changed air filter ............ +2 bhp
put some redex kind product fuel injection cleaner +4bhp
few other things they changed but it ended up being a healthy increase from just simple easy changes
 

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Timing out?
Although I'm more concerned with how your Honda friend gained 40bhp from a decat and air filter?!? Is that really possible?
 

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Check the dyno printout again.

184 measured at the wheels (whp) would be about 215 bhp measured at the crank (flywheel).

You might be worrying over nothing.
If that was the case then his pal's Honda would also be producing around 220+bhp!

I've just checked a couple of dyno printouts & the graphs both show/calculate the power at the flywheel.

Clive
 

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Discussion Starter #8
Sorry just checked the Honda had 160 bhp to start with, so an increase of 30bhp. Still sounds a lot to me. Also checked with the dyno guys and they say it's calculated for flywheel bhp. Which is apparently standard thing to do in the uk. So it is bout 40 bhp down. I'll change the maf this week and see if it runs better if not, it's going to be booked in for diagnostics at autolusso.
 

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Also, compared to the 2 non remapped printouts I've got, yours seems to be trailing off a bit early, should still be rising for another 250-750rpm.

Clive
 

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At the risk of reigniting a debate that has been discussed ad nuseam the stock induction system with resonators (as opposed to the CDA) smooths out the torque curve slightly. If you do swap the MAF remember to reset the ECU before putting it on the rolling road. By the way you can buy the MAF sensor without the housing for less than £100 and swap it over. just drill out the torx screws on the old housing and use nuts & bolts instead).
Sam
 

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Numbers

Whilst I understand that now you know there is a problem you want to get it rectified. Though to me this is exactly where the problem is.
Out of curiosity Simon, did you just go for the dyno because it was available/free or maybe your mate was doing it?
I ask because quite often these dyno days are freebies to get people in and see what their cars have rather than you thinking that it maybe under performing.
Good potential money earner.

What I'm saying is unless the car felt bad then it is not something I would bother with myself. They end up being numbers to talk about in the pub.

Lastly I'm sure once the motor puts a few miles on it is going to lose horses.
 

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Discussion Starter #13
I went to the dyno day mostly just because my mate was going so thought it would be a nice day out and having a few mods done to it i was curious as to if they would affect anything.

I can't help thinking that if it is 40 BHP down then there must be something "bad" with the car especially as it has only done 70,000 so shouldn't have lost that many horses.

I totally understand the idea of not caring how much horsepower it is churning out if it feels good but if it is this low and i can fix i surely it will feel lot better?

I suppose to me this dyno day was quite helpful as almost a check up to see how the car is doing.
 

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What grade of fuel were you using? 95 Octane will be lower probably due to the knock sensor retarding ignition.
Other variable would be air temperature, higher temperature lower performance. You could be chasing your tail due to many variables rather than an obvious fault
 

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What grade of fuel were you using? 95 Octane will be lower probably due to the knock sensor retarding ignition.
Other variable would be air temperature, higher temperature lower performance. You could be chasing your tail due to many variables rather than an obvious fault
Sorry Krisp but none, or even all, of the above would lose 40bhp!

These cars are designed to run on 95 ron fuel, higher is a waste of money.

Clive
 

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Tyre pressures, ie rolling resistance is another factor. Calibration of dyno, repeatability of the equipment all effect readings. Were the original tests for output accurate, or were they done on higher octane fuel. It is not as simple as you believe Clive.
It may not be all the loss but accuracy cannot be guaranteed. The dyno may not be calibrated back to national standards so it is not so simple. The loss may be a lot less. I see variability on test of performance every day in my work and the snapshot of this test could have many causes or error.
Ultimately was Simon happy before the dyno run? If so do not wor
 

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Tyre pressures, ie rolling resistance is another factor. Calibration of dyno, repeatability of the equipment all effect readings. Were the original tests for output accurate, or were they done on higher octane fuel. It is not as simple as you believe Clive.
It may not be all the loss but accuracy cannot be guaranteed. The dyno may not be calibrated back to national standards so it is not so simple. The loss may be a lot less. I see variability on test of performance every day in my work and the snapshot of this test could have many causes or error.
Ultimately was Simon happy before the dyno run? If so do not wor
All of your theoretical points don't explain the Honda's test just before the Alfa's.

I'd be looking for a reason on the car, not the test equipment/fuel/tyre pressures/air temperature etc.

Clive
 

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I went to the dyno day mostly just because my mate was going so thought it would be a nice day out and having a few mods done to it i was curious as to if they would affect anything.

I can't help thinking that if it is 40 BHP down then there must be something "bad" with the car especially as it has only done 70,000 so shouldn't have lost that many horses.

I totally understand the idea of not caring how much horsepower it is churning out if it feels good but if it is this low and i can fix i surely it will feel lot better?

I suppose to me this dyno day was quite helpful as almost a check up to see how the car is doing.
I quite agree, you need to work it out as there is obviously something wrong. I'd still wager at 70k there will be some losses but not 40bhp. I have had some 'sporting' cars myself but for that reason have avoided dyno days. I know Ferrari certainly used to give you 'ish' BHP figures and people who had them dyno'd saw above and below figures.

Did you see the Top Gear episode (think it was cheap supercars) where they had them all dyno'd? I think it was a Merak Clarkson had and he thought it was an SS. It turned out to be pretty **** in the BHP dept. and not an SS :lol:
 

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I´d have a look if the spark plugs and ignition coils are in good condition. How old are they?
Check as well the oxygen sensors, the MAF and check for leaks in air intake (between MAF and plenum) and manifold side.
There´s also a small chance that one of the Cats had its best days already....

P1173 sounds like you need someone with the Alfa examiner or appropriate software/cable

BMC Box isn´t helping... but thats just my opinion.

Code:
Sorry for my english, german guy is searching a new home here in this forum ;-)
 
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