Crash course for a base map - '98 Grand Cherokee 4.0 Turbo

Update...

Got it all together with the bigger injectors and decided to force open loop and dial it in first.

Right now, its running good. I pulled a lot of timing out of it and have fuel coming in around 11-11.5:1 when in boost.

Now my questions...

How much timing is safe on a non intercooled 4.0 with 7lbs on 93 octane? Ive got very little advance in it under any positive pressure.

Also, im seeing boost in part throttle conditions when going up hills or taking off from a stop. Fairly low load but right now, I've got the afr setup to be in the 11s under any positive pressure. Could I safely dial this back a bit since load is low and boost is low? Could I bring this area up to say 12.5 and still be safe?

Thanks

Quote:

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Originally Posted by Mr4btTahoe

Update...

Got it all together with the bigger injectors and decided to force open loop and dial it in first.

Right now, its running good. I pulled a lot of timing out of it and have fuel coming in around 11-11.5:1 when in boost.

Now my questions...

How much timing is safe on a non intercooled 4.0 with 7lbs on 93 octane? Ive got very little advance in it under any positive pressure.

Also, im seeing boost in part throttle conditions when going up hills or taking off from a stop. Fairly low load but right now, I've got the afr setup to be in the 11s under any positive pressure. Could I safely dial this back a bit since load is low and boost is low? Could I bring this area up to say 12.5 and still be safe?

Thanks

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You might be able to compare my '06 tune file to figure out where the timing should be. The tables are probably not exactly the same in HPT though as we are on different PCMs. Mine's a stock 4.0 auto (42RLE/4.88 gears/32" tires) running 7 lbs. on 93 octane with no intercooler but I am spraying it with washer fluid starting at 5 lbs. That shouldn't matter for low load/boost conditions. While it's far from perfect, I've got 22,000 miles on this tune and have never altered the spark settings.

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Originally Posted by TJTurbo

You might be able to compare my '06 tune file to figure out where the timing should be. The tables are probably not exactly the same in HPT though as we are on different PCMs. Mine's a stock 4.0 auto (42RLE/4.88 gears/32" tires) running 7 lbs. on 93 octane with no intercooler but I am spraying it with washer fluid starting at 5 lbs. That shouldn't matter for low load/boost conditions. While it's far from perfect, I've got 22,000 miles on this tune and have never altered the spark settings.

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Thanks bud.

Now looking at yours... I've been overlooking the majority of my spark control... and have no idea how I haven't killed this thing. Lol

I was only messing with base spark tables. Well once coolant temp hits 194F... it no longer looks at the base table but looks at the warm spark table... which has me seeing 25+advance while in boost. Hmm...

Grabbing the laptop and pulling ALL of that out. Going to force it to follow the base map for now. Based on your base map, it looks like I can put a little back in it under light boost.. so I'll tweak that a bit too.

Glad I could be of help. You probably are way further along in understanding how all this works than I am. I'm currently learning to smooth out the VE tables. The file I attached I had just reduced the VE adder for ECT. I have modified my cooling system by adding capacity and was rarely hitting the 203* temp where the adder stops. My normal operating temperature stays around 193*-203* year round now. The changes I made to disengage the A/C compressor at around 2850 RPMs works well for passing gear if you have an automatic as well.

Well now I've got timing pulled back to what I think is conservative.

Just coming into boost and up to ~4psi, I'm seeing a peak of 8 deg. advance. Above 4psi and it drops to 6 deg.. down to 3 deg. at the bottom of the map.

Since Chrysler thought it was a good idea to remove the knock sensor from the JTEC based 4.0, I ordered a Knocklink G4 kit that will put a nice little indicator on the dash between the wideband and boost gauges. From the reviews I've read, it works fairly well. This will at least give me some form of heads up when things aren't going right.

Right now, I've got a boost leak I'm trying to find. Sounds like a hair dryer when into positive pressure. The turbo can be heard spooling up and then a sound of rushing air that wasn't there before. I've not found any leaks yet... could be the cheap BOV I'm running but not sure. Boost is a little slower to come up but it still builds boost. No exhaust leaks.

I can't tell you exactly what timing your engine wants, but a good place to start is 1-2 degrees of retard per lb of boost vs what it wants naturally aspirated with the same fuel. YMMV - listen and look for signs of knock.

Quote:

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Originally Posted by spoolboy

I can't tell you exactly what timing your engine wants, but a good place to start is 1-2 degrees of retard per lb of boost vs what it wants naturally aspirated with the same fuel. YMMV - listen and look for signs of knock.

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I've got quite a bit less in it now than that. When the Knocklink comes in, I'll start adding timing back in and see what it likes. Based on the other files I've seen, it looks like I'm a good 8 deg or so under what most run. This should pick up power a good bit. We'll see.

I think I found my leaks too. Either the new header cracked or it loosened up a bit. I'm going to look at that this weekend.

I'd think you'll end up around 20 at full load, but definitely don't set it there and assume it won't explode.

Quote:

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Originally Posted by spoolboy

I'd think you'll end up around 20 at full load, but definitely don't set it there and assume it won't explode.

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Lol.... for sure. I'll basically just pull it up a bit at a time and see how it likes it. If it starts to lose power or the knocklink starts showing signs, I'll back it off and call it.

This has been the most informative thing I have read on Jeep 4.0. Thank you all for this post and the responses..!!

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Originally Posted by NathanK

This has been the most informative thing I have read on Jeep 4.0. Thank you all for this post and the responses..!!

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Just keep in mind... we're pretty well winging it. Lol. I've already popped one head gasket which wouldn't have happened if I had known what I was doing... definitely a learning experience.

On that note..

Now I want to do some work on closed loop. I'm trying to figure out which setting actually commands open loop. What map or setting tells the pcm to go into open loop? It doesn't appear to be throttle position based unless I'm just overlooking something.

Well.. I tinkered around with closed loop a good bit but kept getting odd lean spikes and couldn't get the pcm to go open loop at part throttle no matter what I did. Then when it boost, it would go WAY rich.

Back to open loop for now and running great. I've leaned out the fuel a bit coming into boost and now with the knocklink setup, started putting timing back in it while in boost. The power gain is fairly substantial with no signs of knock so far. Just coming into boost (under 5psi), I'm seeing a peak of 18 degrees that tapers down to a peak of 8 at full boost.

So far... so good.

Well... so far, she's running like a top. Power is great... idle is smooth... transitions are great.. the 220k mile trans doesn't care for the new power.. so I'll be pulling it this winter and going through it.

Anyways.. I think I'm going to leave it be for now.

Thanks for all the input and help!

Quote:

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Originally Posted by Mr4btTahoe

Well... so far, she's running like a top. Power is great... idle is smooth... transitions are great.. the 220k mile trans doesn't care for the new power.. so I'll be pulling it this winter and going through it.

Anyways.. I think I'm going to leave it be for now.

Thanks for all the input and help!

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can you post the map for other nebws to start off?

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Originally Posted by FNF

can you post the map for other nebws to start off?

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FNF, great idea.


> just pull it up a bit at a time and see how it likes it. If it starts to lose power or the knocklink starts showing signs, I'll back it off and call it.

Good point, I think; definitely worth trying.

Chris
I stumbled across one of your post you and me have the same project going on I have a 97 ZJ I?ve just turbo charged.
I?m using a 2 bar map and 36lb injectors also. The only difference is I stroke mine to a 4.6L and I converted mine to a manual transmission I had somebody else work on it for me and the thing runs horrible Just picked up my HP tuner i?ve been watching some tuning courses and I?m probably gonna have the same questions you do I got to somehow get this thing back to a stock tune so I know where I?m starting from I hope you don?t mind that I follow your post sounds like you know more than me
thanks
Gus