Weird mapping issues with blow through MAF

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skiddusmarkus

Active Member
I switched my MAF for a hardpipe blow through one and it seemed to run ok, but as it can effect the mixture I decided to have it remapped to suit.Also had a Bosch 044 and new fuel relay fitted and cam timing set up.
Anyway, just spoke to the mapper and he says it's doing some strange things where it keeps going incedibly rich, off his lambda scale once on boost, but that it doesn't do it at the same revs every time so he can't just take the fuel out at that part of the map.
My 1st thoughts are that it's the drawthrough MAF, so am going up tomorrow and going to put my old Z32 maf back on as draw through and just switch the plug from the draw through to that as that way I don't have to mess about too much with pipework.
I'm aware though that the pump and relay could also bring their own issues and as they are new to the setup they could be equally to blame.I don't think it's the cam timing I don't see how that could affect the fuelling like this.

Any thoughts on this?
 
red reading

red reading

Active Member
I gather you have not got ed mapping the car then, what are the voltages the maf is putting out? as the fueling should change with flow and that is dictated with the maf voltage. also have you got a air leak? and is the fuel pressure staying constant and rising with boost? is the fuel pump located in the bottom of the tank with a good pick-up?
 
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skiddusmarkus

Active Member
No Danny, got an experienced local mapper doing it.

Not sure on voltages but can find that out tomorrow when I go up.Will have a look over for air leaks too.I have the standard fpr on with a walbro I had fitted last time it was mapped, but now with a swirl pot and the 044 pulling the fuel out of that.
I only supplied 1 relay though for the new power supply for the pump(wasn't originally going to fit a 2nd pump and swirl pot) but I can't see it being this as in my mind that would be more likely to make it run lean than rich if there was a problem with power to the pump/s.
 
gtirx2

gtirx2

Member
Not something stupid like your dumpvalve leaking now and then,have you upped the boost since it was last mapped?
 
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skiddusmarkus

Active Member
Yeah, seemed fine and car seemed ok on blowthrough but didn't push it as had read about how it can lean out your fuel a bit.It might be something as simple as an air leak like you said.Would rather me checking it really as I don't charge myself labour for problem solving.
I want to look for easy things 1st hence why switching a plug from 1 maf to another is 1st on my list then checking all the joins for leaks.
 
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skiddusmarkus

Active Member
Don't think he got as far as increasing the boost.It was set at 1.45 bar and no leaks from the BOV(an hks sqv, bought from Hiteq about 10 years ago pre ebay fake shite).It's done tiny mileage too on relatively low boost.Probably 10k miles on just over a bar and about 5-600miles on 1.45 with most of that offboost.
 
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skiddusmarkus

Active Member
Well I went up and made sure all the silicones were tight, found one which could have ben an issue as it had a mikalor clamp very close to a bend and so I swapped it for 2 jubilees with the tighteners at opposites to each other.

I also swapped the inlet piping about and managed to fit my old setup with the z32 hardpipe still in place so it can now be draw through or blowthrough just by moving the plug a few inches.The reason being it's then very easy to see which it runs better on.

I have 2 nistune ECU's and I'd asked that he map the one I bought a month or so ago and leave my Fusion mapped one as it was.The reason being something always goes wrong with these cars and I wanted to be able to put things back to how they were easily(that's why I have hung onto my old inlet and drawthrough z32 maf and filter).

The mapper had originally started the car with the newer ecu on and it ran incredibly badly as was for a totally different setup, so copied the file across from my Fusion mapped one to get a base map to start on and remap from there.
Anyways, I drove it and it and it didn't pull very well compared to pre-work being done on the blowthrough, so switched to draw and it drove a bit better.Went back and discussed what else it could be.He suggested swapping the ecus over and I drove it on the original ecu and it immediately pulled better on both setups (the draw through being the better one as the car is mapped for that)and didn't feel as flat as before.

I can only think the file copied across was corrupted somehow(was using a nistune consult cable, not a cheapo) or it was just pure coincidence, who knows.The problem is the mapper was working on someone else car today and didn't have time to set the car up to moniter lambdas, lock up his unit and come out with me for 10 mins to see how rich it now ran, so hoping for this to be done tomorrow.

Edit: I couldn't check fuel pressures as I don't have a guage and he hadn't logged the maf values.

As said, something always goes off plan, so I wanted somewhere local where I don't have to drive hours to get there.This way I could drive a few miles and try and find the problem myself so not costing me any labour and no worries about getting home etc.
 
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skiddusmarkus

Active Member
Car has now been out and fuelling tested on original ecu and it was better.Tuner said car ran better on drawthrough than blowthrough as it kept going rich at different parts of the map, which he puts down to the temperature varying as it's post turbo, whereas it is fairly consistant when it's drawthrough as the temp is more stable.

Anyway, that's the good news.The bad news is that it broke it's Forge alloy crank pulley and he had to wait 1.5 hours for a recovery truck and that my lambda sensor is giving some funny readings, going up to 2.5v when it should be 0-1v I think h said.Hiteq replaced this years ago, it hasn't done many miles but is probably 10 years old.
 
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skiddusmarkus

Active Member
Any ideas on why it would keep going rich at random rpm's under boost when running the blow through?It doesn't do it with the draw through so it can't be air leaks or it would go rich under draw through also?



This is how the blowthrough is, so you can see it has a nice straight feed into and out of it(it's the rectangle block on the long straight pipe) with the reducers as far away from the maf asthey can be.
 
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pulsarboby

Guest
think he may have already answered your question for you

if its going rich and leaning off and not stable then maybe charge temps are varying for some strange reason
could be that your ignition timing is out or running too much advance causing excess egt

im no tuner so clutching at straws here but think i would fit an egt sensor into manifold and another temp sensor on fmic return pipe to monitor the heat going through there.

or if it runs fine the other way on draw through then why change it
 
PobodY

PobodY

Moderators
Staff member
It's not related to that Aquamist system is it? - I know it's not especially close, and it should only be injecting when there's some flow towards the throttle bodies, but I noticed it and wondered if it was related.
 
campbellju

campbellju

Moderators
Staff member
Just a thought but from my old industrial control experience I would have said electrical noise is often a cause of funnies but on a car most things are either kept away or shielded. Looking at your photo the MSD unit looks quite close to your blow through setup.
 
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Fusion Ed

Fusion Ed

Active Member
Did another z32 blow through yesterday. No issues with it. Normal 32 behaviour (not the same as when they suck through but same as normal blow through)
 
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skiddusmarkus

Active Member
That's a picture of how it looked when I took it in, it now has a 2nd normal Z32 maf just under where that hard pipe is with my old blitz filter on(it just fits in) and the plastic maf is just as close to the coil and msd 6200 box as the hard one.How could I shield the MAF?Just some rubber around the coil and 6200?

I have been reading about it and some people say if you have metal on metal when using silicone couplers to join pipes it can vibrate and maybe cause issues, so that's a possibility but again I'd imagine it would rear its head at the same rpm's and not randomly.


Bob, I wanted to run blow through for the better driveability really, want to go that way if I can.Especially as I bought a hardpipe for it and re-did all the induction and intercooler piping to suit.

Ed, have you encountered this problem when mapping blow throughs?I can see why temps would rise with more boost but thought they'd do so consistantly enough that it could be sorted in the mapping.
 
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Fusion Ed

Fusion Ed

Active Member
Yours should be fine looking at the pics. I suggest you have something else going on which is being shown up by the z32.
 
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skiddusmarkus

Active Member
Such as what Ed?It works on draw through ok on your map with the extra 044 pump and new cam timing.

Maybe the stock z32 maf has shielding but the blow through not and it wasn't an issue for the person I bought it off as they have a different setup?
 
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