Looks like my maf is shot. Engine light, random restricted performance, sputtering...

Question about the 3.5 inch maf by ProM, is it just a plug and play? Or is there more wiring needed?

I have the 92mm/3.6" MAF from Pro-M

For me, I had to wire an independent IAT sensor, then all was fine.

The IAT sensor they supply is incorrect.

I just bought a spare complete 75mm MAF off ebay for $45 with shipping. I'd be happy to let you have it for the $45 I paid.

If you want to upgrade and get the Pro-M, you will need to wire the separate IAT sensor, I paid $74 for the sensor from Gaudin in Nevada for the one I am using.

I would recommend the 117mm over the 92mm though if you are going for max performance

Just a warning, they will not take any part back, even unused, even if they tell you they will take an un-used part back, even if they give you wrong information. They told me the drop in sensor could be calibrated for Jags, so I bought one, then sent it to them to be calibrated, then they said they were unable to and I would need a different MAF, no refund, no credit, just completely stuck me with the cost of an extra part.

The 92mm supports 1500 hp already, so why do you recommend one that supports 2000 hp?

lol

so I need that IAT sensor?

8*200hp NOS shots

For the same reason YOU went to a larger intake track, less vacuum = more power. DuhhH !

The stock 75mm would then support your 524 rwhp so why did YOU go bigger??

Are you going to follow your own advice and switch back to a stock MAF?

No?..... then what exactly is it that your are trying to say here??

I use for the 524 RWHP+ the 3.5"MAF tube (that supports 800 HP according to ProM).

So why are you advising someone to choose something you don't even have experience yourself?

Let me give you the example of first answering the question asked before taking the post in a new direction:

My advice was based on the mathematical facts that:

Larger diameter= less vacuum at the same flow.

Less vacuum= more power

So then is your point that a larger MAF will not have less vacuum at the same flow and therefore will not make more power?

Would you prefer numbers?

This is why I am saying you are not following the advice you are giving in your above post:

If, using the figures you gave above, the 117mm MAF supports 2000 hp and is 2.43x the surface area of the 75mm stock unit, then the 75mm would support 2000/2.43= 824 HP, based on the same ratio of HP per surface area, as claimed by the "117 supports 2000 HP", but yet you still bought a larger MAF, and, not following your own advice of not possibly understanding the results of doing something you had not done before, as, up to that time, you had no experience with a larger MAF on your car.


I strongly suspect that you knew that a larger MAF would do as I said above, reduce vacuum and improve power.

See, I can answer questions with questions too, except in this post I gave the example of how to first respond to the question asked, can you?

So your point again was?

If you have reached 0 vacuum, increasing the size of the tube/maf will not make any difference anymore, it really doesn’t get more complicated than this.

I’m pretty close to 0 with 600 hp and the 3.5”tube for the 800 HP versions. So on the TS kit, it will not make a difference to go larger.

If ProM is supporting you that the bigger 2000 HP range maf will work just as well on a 400 (or 450, or whatever) hp engine, then go for it, its your money, and obviously you're the expert.

PS I have always advised to reduce your vacuum for more power, never made that a secret!

If you stick in a sufficiently large MAF ... at some point the MAF would have difficulty in producing reliable readings. It would be like a traffic cop standing on the shoulder of a 12 lane highway trying to direct traffic.

Now is that any way to talk to someone who was a great deal of help to you during your install?

I see, then I stand corrected.

See, now was that so hard, actually answering the question?

Now that you tell me your reasoning that you are drawing close to zero vacuum, I can understand your position.

No, I am not an expert on these things, Duhh, obviously <----humbly eating crow

I am skeptical, however that you are pulling near zero vacuum with 620 HP at 20 lbs of boost.

You have by far asked the most questions I know off, and are by far the person I have answered the most qestions for.

Have I disappointed you there? Am perplexed that you can even post something like this, but it probably suggests you’re not reading them. I don’t mind that particular part, I post my experience/thoughts for the forum so anyone can do with it what they like.

Even on a more specific note, haven’t you not counted how many times I’ve advised you over the time, starting with newby, that you need to work on your vacuum to gain more rwhp! I doubt even that you have ever tested it yourself.

Back to topic: As plums says, if you widen the range to measure, the error margin might be higher/resolution lower, so 1st ask the ProM as suggested if you (or anyone still want to go bigger.

Can we keep things civil and on topic. I shouldn't really need to be deleting posts from you guys.

I'm still trying to get my head around the anomaly of trying to achieve 0 vacuum i.e. positive pressure. If I reduce the vacuum I increase the pressure.

Surely you will want to increase the vacuum to lower the pressure?

Or am I just having a bad day?

Look at it as a forced induction engine, the supercharger creates a vacuum, pulling air into the engine thru restrictions, maf, filter and a couple of sharp bends the induction tract is the bottleneck. Your aerodynamics hat is causing the syntax error work on induction filter and monitored air in = HP. Zero is easily achieved on NA engines with a bonnet scoop and 100mph

@ Marko, if you're going the TS route, then adding a hot MAF might be a good prep move. If you're doing the work...if not I suspect it could lead to a non runner for a while. You'll need to ask the two chaps who've experience of, and posted in, (ehem, Andre and the fish guy ) this thread for fitting details, calibration/installation issues etc. Once in and running you're one step closer.

Thanks Sean, I've thought some more about the syntax.

The supercharger:

Pushes air into the engine, but the converse is that is has to 'Pull' that air from an outside environment.

Push = Right
Pull = Left

So more push to the right will = more pull from the left and if there are restrictions in the left, then the Push/Pull position shifts over to the left. i.e. inefficient, and talked about as the 'Vacuum'.

In this case the noted vacuum generated by the SC.

For this engine set up, I can see that there are obvious parameters.

There would be no point in installing a massive MAF because it can't use it advantageously. e.g. I'll keep a couple of bottles of my friend's fav scotch in stock, but no point keeping a case. (hic)

If I am wrong, feel free to call me all the names on the planet.

I'll not take any offence, (simply I will delete them and this post).

Well, i'm going to upgrade the intake tubing to 3.5 in. throughout and keep the oem MAF for now, but looking at the pro slot 3.5 in ProM MAF... i cleaned it and sealed up all the leaks for now and its running a little rough on idle but i suspect its cause there is a big K&N filter sucking in hot air. ... no check engine lights, no restricted performance. Man, is the jaguar seals shitty. Lets in air all over the place.

Avos: I see that the Jag 4.0 is capable for 1100 cfm for the intake... does the twin screw increase that? I just bought a HPR filter from Spectre at 1100 cfm, but will upgrade it if need be.

Have no experience with the filter you name, but a K&N RE-0920 would already be a good start.

Avos, that filter runs 900 ccm, whereas the Spectre filter i mentioned runs 1100 cfm. I believe that Count Iblis mentioned that the AJ27 is capable of 1100 cfm

You're mixing up 2 things, the 4.0 XJR engine can consume 1100 kg of air per hour, that is about 540 cfm or so if I calculated right. The flow measurements of filters etc are a check of how much air flow they have under a certain pressure, so completely different things.