Idle dropping

M

must go faster

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Big lou said:
Are you in the S or base?
Click to expand...
Car is a base with a Celtic remap. Haven’t had any rattle noises but I did have a strange moment where the car stopped boosting all together.
When I got the code reader on it there was a fault listing error with intake pressure. Cleared the code and boost came back. Not happened again yet but did have me thinking about replacing the turbos £££ouch!!
 
Big lou

Big lou

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must go faster said:
Car is a base with a Celtic remap. Haven’t had any rattle noises but I did have a strange moment where the car stopped boosting all together.
When I got the code reader on it there was a fault listing error with intake pressure. Cleared the code and boost came back. Not happened again yet but did have me thinking about replacing the turbos £££ouch!!
Click to expand...
Yeah, clearing codes seems to fix a lot of things on maseratis. Hopefully no need to replace turbos especially in the lower milage range. Maybe 100k plus
 
CatmanV2

CatmanV2

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Big lou said:
Yeah, clearing codes seems to fix a lot of things on maseratis. Hopefully no need to replace turbos especially in the lower milage range. Maybe 100k plus
Click to expand...

I get one (I need to go check again) if I'm fat footed and hit throttle and brake at the same time. Something like implausible manifold pressure.

<edit>
Implausible low manifold pressure, basically. Clear and move on

C
 
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Big lou

Big lou

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CatmanV2 said:
I get one (I need to go check again) if I'm fat footed and hit throttle and brake at the same time. Something like implausible manifold pressure.

C
Click to expand...
you mean brake boosting or accidentally? Ive never had such a code luckily
 
CatmanV2

CatmanV2

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Big lou said:
you mean brake boosting or accidentally? Ive never had such a code luckily
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Oh very much by accident :) Normally when I'm tired, in traffic and wearing my size 12 (1) shoes


C

(1) Any other size is uncomfortable. It's what comes of having size 12 feet, I suspect...
 
Big lou

Big lou

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CatmanV2 said:
Oh very much by accident :) Normally when I'm tired, in traffic and wearing my size 12 (1) shoes


C

(1) Any other size is uncomfortable. It's what comes of having size 12 feet, I suspect...
Click to expand...
Sounds logical :D, you know what they say about big feet any way....
 
CatmanV2

CatmanV2

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So I'm going to continue this here, because I very much think I've discovered the root cause. If anyone has been following along, this was the issue that started it all. Slightly annoying.

Then started getting a CEL:

and swapped that out at the weekend:


OK it's better. It's *definitely* better, but it's not *right*. Still drops, catches. Hmmm, where have I seen something similar? Alfas with bad MAF. Of course, they only have one...

Quick play with my trusty Autel AP200 in the hotel carpark this evening:

I think I shall be ordering a new MAF for number one cylinder bank. Bosch part £55+VAT from Sparkplug.co.uk as opposed to £150+VAT from Scuderia. Anyone see an issue here?

PS: If you can't read the PDF it's a live data capture, snagged while I was revving a bit. It was reading 4.5 with the engine off....

MAF 1: 5.10 kg/h
MAF2: 29 kg/h

C
 

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Oneball

Oneball

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I’m surprised that’s not triggered an CEL. I’d have thought it would recognise what would be a discrepancy in in vs out or left vs right but maybe not. Fingers crossed it sorts it.
 
CatmanV2

CatmanV2

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Oneball said:
I’m surprised that’s not triggered an CEL. I’d have thought it would recognise what would be a discrepancy in in vs out or left vs right but maybe not. Fingers crossed it sorts it.
Click to expand...

Yeah, I get your point. Maybe it's just not something they thought of. It's about 10 minutes work for someone competent. I'll allow half a day ;)

C
 
CatmanV2

CatmanV2

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Oddly numbers haven't changed. Which is annoying. Idle seems smoother, but we've said that before. Miles to do tomorrow, so we should know more.

C
 
Oneball

Oneball

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I wonder if you have a wiring issue. Do both the MAFs change as expected with engine rpm?

Can you check voltage and ground at the MAF plug?
 
CatmanV2

CatmanV2

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Oneball said:
I wonder if you have a wiring issue. Do both the MAFs change as expected with engine rpm?

Can you check voltage and ground at the MAF plug?
Click to expand...

No MAF one is pretty static. MAF 2 changes as expected. Wiring would be a logical next step. It'll have to wait until I get back though I fear.

We did pull the plug on #2 and it read something like 1100 kg/h. We should have tried the same on #1 to see what happens when that one is pulled.

C
 
CatmanV2

CatmanV2

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Hmm, so now this is frustrating. Numbers are no different, idle is no different.

Nothing going to happen until I get back from Mexico now, but I think the plan is as follows:

1) Pull the plug on #1 MAF to see if we get the 1100 kg/h reading.
2) Put the old MAF into #2 and see what it reads (just to confirm if it was actually failed or not)
3) Put #2 MAF into bank 1 and see if it reads properly there.

I'm struggling to think we were sent a dud MAF (it's not impossible) but not struggling to think there's some wiring issue.

The AP200 shows three data streams that one might loosely call MAF:
Air-mass flow Hot-film air-mass sensor (assuming this is bank 1)
Hot-film Mass 2 (HFM 2) Air-mass flow sensor (assuming this is bank 2)
Air mass flow (assuming this is the additive of both the above as the numbers track like that)

Anyone have any light to shed on those assumptions?

TIA

C
 
Oneball

Oneball

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Can’t answer your question but if you’re unsure you can put a voltmeter across the maf and measure its output to confirm they are both the same.
 
CatmanV2

CatmanV2

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Oneball said:
Can’t answer your question but if you’re unsure you can put a voltmeter across the maf and measure its output to confirm they are both the same.
Click to expand...

Can't get to the damned thing, but worth having in the back pocket for sure.

Oneball said:
Reading your other posts there is the option that the readings are correct.
Click to expand...

Indeed. We feel unlikely though since as you rev the engine the reading on Bank 1 is basically static, whereas bank 2 rises and falls (which is, to my mind) expected behaviour

Happy to be educated, though!

C
 
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