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[Green Jeep]

Hi,

Been chatting with Willo and he's suggested moving the crank sensor to advance the timing slightly to increase performance.

Done the usual google search and not found any info, just wondreing if anyone else has more input?

Increase in driveability? Do I need to use 97 octane fuel to avoid pinking? Any downsides to the mod?

As ever thanks in advance Maf

[Delk]

You just have to slot the bolt holes and slide it over. The 4.0 will run on any fuel and 87 octane is standard in the states so you have no worries about pinging. It does make a bit of a difference and since it is free it is even better.

The only hard part is getting to the little bolts that hold it in.

http://jeep4.0performance.4mg.com/electronic.html

[willo]

straight from the horses mouth, I only got the info from Delk...

[isle of man]

I have been thinking about this, was going to say nowt but!! This is illogical, will cause overheating issues and have little/no performance effect to the engine.

Would get more benefit by fitting high grade spark plugs, or wearing your lucky clean under crackers on the day 

[Delk]

Those of little faith. Spark plugs start the fire, when you start the fire determines how big the fire becomes.

The computers are all set to a very basic and safe operating level to run on poor fuel and so forth. When you remap you computer you are just pushing all the levels closer to the limits. This is just a physical way of changing the timing on an injected engine without messing with the computer. The computer is still trying to light the spark at X degrees based on its programming but it is now X plus a few degrees because of the movement.

The 4.0 is bullet proof and the only people with pinging issues either have turbos installed or are running seriously high compression strokers. My stroker has a good amount of compression and still runs on cheap Tesco fuel without a complaint.

And with this mod if you are not happy you just loosen the bolts and slid the sensor back to the original location.

Overheating is normally caused by late ignition because the fuel is not being used for work and is wasted down the exhaust instead.

As for power it is not great but it is noticeable, but what can you expect for free. The best power is made just on the limits of pinging. As long as you don't cross that limit you are fine and in a 4.0 you would have to go a long way to do that.

Just ask anyone with an old school ignition if they would be happy to retard the distributor. I have a nice timing light and dwell meter in my garage that don't get much use any more but the principals are the same for old and new. Better the timing better the power.

[charlie jeep]

am i not right in thinking that the ecu would advance the ignition until it starts pinging and then back it off a little? in that case you could move the sensor wherever you want (ok, within reason - not onto another truck for instance!) but the ecu would compensate for that too?

Or is the TJ ECU too old for that sort of "on the fly" adjustment?

Charlie

[willo]

I'm gonna do it

[isle of man]

I'm gonna do it

SUCKER!!!

[Delk]

TJ ECU like most only sets timing on preset parameters from the factory. It has preset timing curves based on RPM and load and will adjust the timing accordingly. These curves are very far in the safe zone and can be inproved for performance.

Some systems have a knock sensor but this is only a safety item and will drag the timing a long way back then slowly let it move forward. If I remember the old Renix system in the YJ is like this and it is really noticalbe when the timing is retarded because the knock sensor is activated.

[Delk]

I never thought I would see the day there were disputes about old school engine tuning. Timing and air fuel mixture basics of making power. If these can be improved upon you get better power. These are the two simple items that chips adjust so they are closer to optimal to increase power. Chipping your computer does not change the compression ratio, air intake, throttle postion or anything else physical. Computers are all churned out in mass units designed to run in the the worst possable conditions for long periods of time. This means they are intrinsically safe and can be improved upon especially since the UK fuel is far better then the states.

Anyone who has ever spent enough time driving an old low powered vehicle like a series land rover will know how much of a difference adjusting the timing makes.

http://en.wikipedia.org/wiki/Ignition_timing

[isle of man]

Hook































Line









































Sinker!!!!

[Dave The Sparky]

Go IomanKY, he may look like a simpleton but underneath that glazed expression he talks complete sense.

[isle of man]

Go IomanKY, he may look like a simpleton but underneath that glazed expression he talks complete sense.

Your still a SHIRT!!!!

[Dave The Sparky]

Is that slang for a charming, decent, upstanding member of society?

[Delk]

Those who drive slow Toyota's should spend more time studying then fishing.

For a good understanding on how computer mapping works and how it can be altered look at the Split Second piggy back systems. These are fantastic bits of kit and well worth the money when they are needed.
http://www.lextreme.com/tune/splitsec/splitsec.pdf

Moving the CPS and adjustable MAP sensors makes basic linear adjustments by physically altering the measuring points. When you move the CPS 1 degree the timing will change 1 degree at idle all the way to full load. This is fine for making minor alterations to stockish engines and was all the was needed to make my Stroker run properly.

Back in the day when cash was spare and I didn't have kids to think about a supercharged YJ was a lot of fun to play with. This required major changes to the entire mapping structure to get it to run correctly. At low load the engine ran very close to normal parameters because there is no boost so timing and fueling didn't need to change. At high load under boost the timing needed to be retarded a lot to stop detonation. If you just retard the CPS 10 degrees the timing would have been fine under load but normal driving would have suffered. Same went for the fuel curves, it was a stock 4.0 so the fuel requirements were the same at low loads but the supercharger wanted much more fuel at high load. The computer can only compensate so much for larger injectors so the entire curve needs altering.

[isle of man]

It just so happens I have been down this route in 2005 with my TJ Wrangler that is supercharged!!! And sat here at home with me, I have more than a basic understanding of what works and what is smoke and mirrors.

My original comment was given after some considerable thought, perhaps I should have said nowt and let people find out for themselves.....

[willo]

Maybe the reason you diss this mod is because it is free and as we know you do like to splash the cash....

[XJ Fan]

Sorry for being pedantic, but isn't it called Pinking, no Pinging? 

Oh, and my tuppence worth is that it will make a difference, but only slight

[Cockney Boy]

Nobody has said what benefits in perfromance you would get by dicking about with the sensor location? In my eyes it wont be worth the hassle for a few extra BHP.

If you want more BHP then do it properly and then you will reap the benefits 

[wildwood]

Sorry for being pedantic, but isn't it called Pinking, no Pinging? 

Oh, and my tuppence worth is that it will make a difference, but only slight

Tis the difference between, 'Septic speak' and 'Limey speak'

Goes hand in hand with Tires and Color

[wildwood]

Nobody has said what benefits in perfromance you would get by dicking about with the sensor location? In my eyes it wont be worth the hassle for a few extra BHP.

If you want more BHP then do it properly and then you will reap the benefits 

seeing as most of us are running the 4 litre anvil that apart from not liking a drink of water or getting hot will last us our offroading lives......I would just do filter of air in and exhaust out and leave it at that..... Everything else is about getting the gearing right........

But as LS 5.3 s are getting cheap with revised electrickery then one of those churning out close to 400 bhp would be my next stop....... Cos it bolts up to a NV3500 and an AX15
Just my Friday stick stirring 2 cents as usual.........

[willo]

It is extra bhp for free.... What is this? The stick your head in the sand thread?

[Cockney Boy]

It is extra bhp for free.... What is this? The stick your head in the sand thread?

No such thing as a free lunch my good man. Somewhere along the line you will have to pay

[wildwood]

It is extra bhp for free.... What is this? The stick your head in the sand thread?

stick head in sand........noooooooo IOM might be approaching from behind...

[Dutch]

It is extra bhp for free.... What is this? The stick your head in the sand thread?

stick head in sand........noooooooo IOM might be approaching from behind...

Slow day WW ??